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Insects
Volume 12
Issue 10
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Insects, Volume 12, Issue 10 (October 2021) – 108 articles

Cover Story (view full-size image): High alpine meadows harbour rich butterfly diversity, but this diversity is threatened by climate change and changes in agricultural practices. To understand how species can be conserved, in- depth studies of their ecological requirements are necessary. This is why we analysed the ecology of the water ringlet Erebia pronoe in a study area in the eastern central Alps near Großglockner. We analysed the behaviour, resource use and population structure of this species. In general, Erebia pronoe adults use a wide array of resources combined with a slight specialisation to avoid niche overlap with closely related species. The resulting ecological flexibility seems to be an adaptation to unpredictable environmental conditions. The combination of opportunism and modest specialisation is a good basis for coping with future changes. View this paper
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10 pages, 2298 KiB  
Article
Expansion of CRISPR Targeting Sites Using an Integrated Gene-Editing System in Apis mellifera
by Liqiang Liang, Zhenghanqing Li, Qiufang Li, Xiuxiu Wang, Songkun Su and Hongyi Nie
Insects 2021, 12(10), 954; https://doi.org/10.3390/insects12100954 - 19 Oct 2021
Cited by 2 | Viewed by 2296
Abstract
CRISPR/Cas9, a predominant gene-editing tool, has been utilised to dissect the gene function in Apis mellifera. However, only the genomic region containing NGG PAM could be recognised and edited in A. mellifera, seriously hampering the application of CRISPR technology in honeybees. [...] Read more.
CRISPR/Cas9, a predominant gene-editing tool, has been utilised to dissect the gene function in Apis mellifera. However, only the genomic region containing NGG PAM could be recognised and edited in A. mellifera, seriously hampering the application of CRISPR technology in honeybees. In this study, we carried out the bioinformatics analysis for genome-wide targeting sites of NGG, TTN, and NNGRRT to determine the potential expansion of the SpCas9, SaCas9, Cpf1, and it was found that the targetable spectrum of the CRISPR editing system could be markedly extended via the integrated gene manipulation system. Meanwhile, the single guide RNA (sgRNA)/crRNA of different novel gene editing systems and the corresponding CRISPR proteins were co-injected into honeybee embryos, and their feasibility was tested in A. mellifera. The sequencing data revealed that both SaCas9 and Cpf1 are capable of mediating mutation in A. mellifera, albeit with relatively lower mutagenesis rates for Cpf1 and unstable editing for SaCas9. To our knowledge, our results provide the first demonstration that SaCas9 and Cpf1 can function to induce genome sequence alternation, which extended the editing scope to the targets with TTN and NNGRRT and enabled CRISPR-based genome research in a broader range in A. mellifera. Full article
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12 pages, 1442 KiB  
Article
The Effects of Nosema apis and Nosema ceranae Infection on Survival and Phenoloxidase Gene Expression in Galleria mellonella (Lepidoptera: Galleriidae) Compared to Apis mellifera
by Erkay Özgör
Insects 2021, 12(10), 953; https://doi.org/10.3390/insects12100953 - 19 Oct 2021
Cited by 2 | Viewed by 2958
Abstract
The study aims to prove the possibility of colonization of N. apis and N. ceranae to the intestine of the greater wax moth, detect the differences of greater wax moth based on the presence of Nosema species and examine the effect of Nosema [...] Read more.
The study aims to prove the possibility of colonization of N. apis and N. ceranae to the intestine of the greater wax moth, detect the differences of greater wax moth based on the presence of Nosema species and examine the effect of Nosema species on the phenoloxidase level of greater wax moth compared with honeybees. Each group was fed on the 1st day of the experiment with its appropriate diet containing 106 Nosema spores per insect. Each group was checked daily, and dead insects were counted. Furthermore, changes in the level of expression of the phenoloxidase-related gene after Nosema spp. treatment on the 6th, 9th and 12th days, which was detected by Q-PCR, and the mRNA level of phenoloxidase gene were measured in all experiment groups with the CFX Connect Real-Time PCR Detection System. This study shows that Apis mellifera L. has a 66.7% mortality rate in mixed Nosema infections, a 50% mortality rate in N. ceranae infection, a 40% mortality rate in N. apis infection, while there is no death in G. mellonella. A significant difference was found in the mixed Nosema infection group compared to the single Nosema infection groups by means of A. mellifera and G. mellonella (Duncan, p < 0.05). G. mellonella histopathology also shows that Nosema spores multiply in the epithelial cells of greater wax moth without causing any death. The increase in the mRNA level of Phenoloxidase gene in A. mellifera was detected (Kruskal–Wallis, p < 0.05), while the mRNA level of the Phenoloxidase gene did not change in G. mellonella (Kruskal–Wallis, p > 0.05). These findings prove that the Nosema species can colonize into the greater wax moth, which contributes to the dissemination of these Nosema species between beehives. Full article
(This article belongs to the Special Issue Infectious Diseases in Beneficial Insects: Current Status of Pébrine and Nosema Diseases and Their Progression)
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9 pages, 2079 KiB  
Article
Effect of Hypoxia on the Lethal Mortality Time of Adult Sitophilus oryzae L.
by Pragya Kandel, Michael E. Scharf, Linda J. Mason and Dieudonne Baributsa
Insects 2021, 12(10), 952; https://doi.org/10.3390/insects12100952 - 19 Oct 2021
Cited by 11 | Viewed by 2405
Abstract
Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain [...] Read more.
Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain actors to manage this pest. However, pesticides are increasingly becoming unattractive for pest control due to health hazards posed to applicators, consumers, the environment, and insect resistance. Modified atmospheres have the potential to manage stored insect pests as an alternative to pesticides. There is limited understanding of when insect pests die when grain is stored in airtight containers. This experiment was conducted to assess the time required to reach mortality of adult S. oryzae when exposed to 1, 3, and 5% oxygen levels. Results revealed that the LT50 for 1, 3, and 5% of oxygen were reached after 69.7 h, 187.8 h, and 386.6 h of exposure, respectively. No adult emergence was observed on infested grains following exposure to 1 and 3% oxygen levels. This result provides vital rationale for storing grain in hermetic storage conditions for at least 39 days to achieve adult S. oryzae mortality and minimize grain reinfestation. Full article
(This article belongs to the Section Insect Pest and Vector Management)
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25 pages, 20261 KiB  
Article
NO Synthesis in Immune-Challenged Locust Hemocytes and Potential Signaling to the CNS
by Stella Bergmann, Jan-Phillipp Gerhards, Anne Schmitz, Stefanie C. Becker and Michael Stern
Insects 2021, 12(10), 951; https://doi.org/10.3390/insects12100951 - 18 Oct 2021
Cited by 5 | Viewed by 2897
Abstract
Similar to vertebrates, insects are exposed to a broad variety of pathogens. The innate insect immune system provides several response mechanisms such as phagocytosis, melanization, and the synthesis of antimicrobial or cytotoxic compounds. The cytotoxic nitric oxide (NO), which is also a neurotransmitter, [...] Read more.
Similar to vertebrates, insects are exposed to a broad variety of pathogens. The innate insect immune system provides several response mechanisms such as phagocytosis, melanization, and the synthesis of antimicrobial or cytotoxic compounds. The cytotoxic nitric oxide (NO), which is also a neurotransmitter, is involved in the response to bacterial infections in various insects but has rarely been shown to be actually produced in hemocytes. We quantified the NO production in hemocytes of Locusta migratoria challenged with diverse immune stimuli by immunolabeling the by-product of NO synthesis, citrulline. Whereas in untreated adult locusts less than 5% of circulating hemocytes were citrulline-positive, the proportion rose to over 40% after 24 hours post injection of heat-inactivated bacteria. Hemocytes surrounded and melanized bacteria in locust nymphs by forming capsules. Such sessile hemocytes also produced NO. As in other insect species, activated hemocytes were found dorsally, close to the heart. In addition, we frequently observed citrulline-positive hemocytes and capsules near the ventral nerve cord. Neurites in the CNS of sterile locust embryos responded with elevation of the second messenger cGMP after contact with purified adult NO-producing hemocytes as revealed by immunofluorescence. We suggest that hemocytes can mediate a response in the CNS of an infected animal via the NO/cGMP signaling pathway. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
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14 pages, 1493 KiB  
Review
Lupin Root Weevils (Charagmus spp., Curculionidae: Sitonini), a Lupin Pest: A Review of Their Distribution, Biology, and Challenges in Integrated Pest Management
by Diego Piedra-García and Christine Struck
Insects 2021, 12(10), 950; https://doi.org/10.3390/insects12100950 - 18 Oct 2021
Cited by 2 | Viewed by 2552
Abstract
Lupins (Lupinus spp.) are an ancient yet important legume crop. In Europe, the protein-rich seeds serve as livestock feed and have the potential to be a healthy vegetarian component of human diets. In some regions in north-eastern Europe, lupins are heavily damaged [...] Read more.
Lupins (Lupinus spp.) are an ancient yet important legume crop. In Europe, the protein-rich seeds serve as livestock feed and have the potential to be a healthy vegetarian component of human diets. In some regions in north-eastern Europe, lupins are heavily damaged by two Curculionidae species, the lupin root weevils (LRWs) Charagmus gressorius (syn. Sitona gressorius) and Ch. griseus (syn. S. griseus). Narrow-leaved lupins (L. angustifolius) and white lupins (L. albus) are most affected. The weevils feed on lupin leaves, whereas their larvae feed on root nodules. Therefore, the larvae cause major root damage by creating lacerations that allow soil-borne plant pathogens to enter the plant tissue. These infestations lead to considerable yield losses and markedly reduced N-fixation of the root nodules. This review summarises the current knowledge on the origin, geographical distribution, and biology of these rarely described weevils. It focuses on management strategies, including preconceived insecticide use and potential ecological management methods, as key components of an integrated pest management programme against LRWs in Europe. Full article
(This article belongs to the Section Insect Pest and Vector Management)
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12 pages, 2653 KiB  
Article
Comparative Analysis of Eight Mitogenomes of Bark Beetles and Their Phylogenetic Implications
by Huicong Du, Jiaxing Fang, Xia Shi, Sufang Zhang, Fu Liu, Chunmei Yu, Zhen Zhang and Xiangbo Kong
Insects 2021, 12(10), 949; https://doi.org/10.3390/insects12100949 - 18 Oct 2021
Cited by 9 | Viewed by 2413
Abstract
Many bark beetles of the subfamily Scolytinae are the most economically important insect pests of coniferous forests worldwide. In this study, we sequenced the mitochondrial genomes of eight bark beetle species, including Dendroctonus micans, Orthotomicus erosus, Polygraphus poligraphus, Dryocoetes hectographus [...] Read more.
Many bark beetles of the subfamily Scolytinae are the most economically important insect pests of coniferous forests worldwide. In this study, we sequenced the mitochondrial genomes of eight bark beetle species, including Dendroctonus micans, Orthotomicus erosus, Polygraphus poligraphus, Dryocoetes hectographus, Ips nitidus, Ips typographus, Ips subelongatus, and Ips hauseri, to examine their structural characteristics and determine their phylogenetic relationships. We also used previously published mitochondrial genome sequence data from other Scolytinae species to identify and localize the eight species studied within the bark beetle phylogeny. Their gene arrangement matched the presumed ancestral pattern of these bark beetles. Start and stop codon usage, amino acid abundance, and the relative codon usage frequencies were conserved among bark beetles. Genetic distances between species ranged from 0.037 to 0.418, and evolutionary rates of protein-coding genes ranged from 0.07 for COI to 0.69 for ND2. Our results shed light on the phylogenetic relationships and taxonomic status of several bark beetles in the subfamily Scolytinae and highlight the need for further sequencing analyses and taxonomic revisions in additional bark beetle species. Full article
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13 pages, 4054 KiB  
Article
Dose-Dependent Blood-Feeding Activity and Ovarian Alterations to PM2.5 in Aedes aegypti
by Thipruethai Phanitchat, Sumate Ampawong, Artit Yawootti, Thammanitchpol Denpetkul, Napid Wadmanee, Mongkhon Sompornrattanaphan and Chaisith Sivakorn
Insects 2021, 12(10), 948; https://doi.org/10.3390/insects12100948 - 18 Oct 2021
Cited by 6 | Viewed by 2601
Abstract
High levels of fine particulate matter (PM2.5) air pollution are a concern for human health. Several studies have examined the effects of air pollution on human and animal health. However, there is a lack of knowledge about its effects on arbovirus [...] Read more.
High levels of fine particulate matter (PM2.5) air pollution are a concern for human health. Several studies have examined the effects of air pollution on human and animal health. However, there is a lack of knowledge about its effects on arbovirus vectors. Thus, we investigated whether PM2.5 concentration alters the blood-feeding activity of Ae. aegypti mosquitoes. We investigated the effect on the females’ propensity to blood feed at eight concentrations of PM2.5 ranging from 100 to 1000 μg/m3. Correlation analysis showed blood-feeding activity had a significant strong negative correlation with concentration of PM2.5 (rp = −0.85; p ≤ 0.00001). Exploratory linear and non-linear models showed an exponential decay relationship was the best fitting model (corrected Akaike’s information criterion, 193.0; Akaike’s weight, 0.766; adjusted R2, 0.780). Ultrastructural study demonstrated PM2.5 did not obstruct the respiratory system, but some fine particles were present on the antenna and abdominal body parts. Ovaries showed a dose–response relationship between PM2.5 level and vacuolated degeneration. In conclusion, the blood-feeding behavior of Ae. aegypti females may have an exponential decay relationship with PM2.5 level, and their ovaries may demonstrate dose-dependent degeneration. These findings may be important in understanding the vector’s biology and disease transmission in settings with high PM2.5 levels. These results are important to understand blood-feeding and feeding pattern of mosquitoes during PM2.5 pollution, which is important for disease transmission and vector control. Full article
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7 pages, 3969 KiB  
Communication
A Link between Atmospheric Pressure and Fertility of Drosophila Laboratory Strains
by Natalya V. Adonyeva, Petr N. Menshanov and Nataly Gruntenko
Insects 2021, 12(10), 947; https://doi.org/10.3390/insects12100947 - 18 Oct 2021
Cited by 6 | Viewed by 3052
Abstract
Standardization of conditions under which insects are kept is of great importance when studying their physiology and researchers do their best to maintain it. Nevertheless, sometimes an obvious side effect of some unaccounted factor affecting insects’ reproduction can be revealed even under thoroughly [...] Read more.
Standardization of conditions under which insects are kept is of great importance when studying their physiology and researchers do their best to maintain it. Nevertheless, sometimes an obvious side effect of some unaccounted factor affecting insects’ reproduction can be revealed even under thoroughly controlled laboratory conditions. We faced such a phenomenon when studying the fertility level in two wild type Drosophila melanogaster strains. For fertility analysis, 50 newly emerged females and 50 males of each strain under study were transferred to fresh medium daily within 10 days. We found out that fertility of both strains was stable on days 2–10 after the oviposition onset in one experiment, while in another one it was significantly decreased during days 5–10. When compared to publicly available meteorological data, these changes in the fertility level demonstrated a strong association with one weather factor: barometric pressure. Thus, we conclude that changes in atmospheric pressure can be considered a factor affecting insects reproduction and discuss a possible mechanism of their influence on fertility. Full article
(This article belongs to the Special Issue The Impact of Environmental Changes on Insects Behavior, Physiology and Biochemistry)
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16 pages, 2958 KiB  
Article
First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California
by David G. James, Maria C. Schaefer, Karen Krimmer Easton and Annie Carl
Insects 2021, 12(10), 946; https://doi.org/10.3390/insects12100946 - 18 Oct 2021
Cited by 10 | Viewed by 5302
Abstract
The western North American monarch butterfly population assessed by counts of non-reproductive overwintering butterflies at coastal sites in California declined to less than 2000 in 2020/21. Simultaneously, reports of reproductive monarchs increased in San Francisco urban areas, perhaps representing a shift in overwintering [...] Read more.
The western North American monarch butterfly population assessed by counts of non-reproductive overwintering butterflies at coastal sites in California declined to less than 2000 in 2020/21. Simultaneously, reports of reproductive monarchs increased in San Francisco urban areas, perhaps representing a shift in overwintering strategy. To better understand monarch winter breeding in the Bay area, we studied adult and immature populations in Santa Clara County during January–June 2021. Adult monarchs were common with numbers ranging from 0.23–1.54/min during ~30 min weekly surveys at one site, with lowest numbers late April to mid-May. Eggs and larvae, primarily on ornamental milkweeds, were found on nearly all survey dates with lowest numbers mid-late April to mid-May. Levels of infection of adults by the parasite Ophryocystis elektroscirrha were consistently high during the study (69.3–77.5%). From 499 monarchs tagged post-eclosion, recovery rates of 19.2–23.6% occurred from releases in January-February and May-June but only 11.9–13.0% from March-April releases. Although distances were small, butterflies tagged in April were recovered from greater distances than other months. Tagged monarchs flew primarily north or east. There were reduced numbers of adult monarchs during late April-mid-May with some evidence of northerly and easterly emigration at the same time from tagged butterflies, suggesting some movement out of the South Bay area, perhaps representing spring migration. We conclude that monarchs can successfully breed and maintain populations on ornamental milkweeds during winter at urban sites in the South Bay of San Francisco and may still migrate during spring to remain part of the wider western population. Full article
(This article belongs to the Collection Butterfly Diversity and Conservation)
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13 pages, 4918 KiB  
Article
Evaluation of Reference Genes for Quantitative Reverse Transcription Polymerase Chain Reaction in Bactrocera dorsalis (Diptera: Tephritidae) Subjected to Various Phytosanitary Treatments
by Yue Cao, Baishu Li, Naizhong Chen, Ding Yang, Li Li and Tao Liu
Insects 2021, 12(10), 945; https://doi.org/10.3390/insects12100945 - 18 Oct 2021
Cited by 4 | Viewed by 2065
Abstract
Bactrocera dorsalis is a major pest that causes serious damage to many fruits. Although phytosanitary treatment methods have been developed for Bactrocera control, there is a lack of information related to the gene expression pattern of B. dorsalis subjected to phytosanitary treatment [...] Read more.
Bactrocera dorsalis is a major pest that causes serious damage to many fruits. Although phytosanitary treatment methods have been developed for Bactrocera control, there is a lack of information related to the gene expression pattern of B. dorsalis subjected to phytosanitary treatment conditions. Prior to quantitative reverse transcription polymerase chain reaction analysis of the most stable reference genes in B. dorsalis (Diptera: Tephritidae), B. dorsalis third-instar larvae were exposed to various phytosanitary treatments; seven candidate reference genes (18S, G6PDH, GAPDH, RPL-13, RPL-32, RPS-3, and α-Tub) were amplified and their expression stabilities were evaluated using geNorm, NormFinder, BestKeeper, and RefFinder algorithms. Different reference genes were found under different stress conditions. G6PDH was the most stable gene after heat treatment. After cold treatment, α-Tub exhibited the highest expression stability. G6PDH expression stability was the highest after fumigation with methyl bromide. RPL-32 showed the highest expression stability after irradiation treatment. Collectively, RefFinder analysis results revealed G6PDH and RPL-32 as the most suitable genes for analyzing phytosanitary treatment in B. dorsalis. This study provides an experimental basis for further gene expression analyses in B. dorsalis subjected to various phytosanitary treatments, which can aid in the development of novel phytosanitary treatments against insect pests. Full article
(This article belongs to the Section Insect Pest and Vector Management)
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14 pages, 3589 KiB  
Article
Effects of Aqueous Extracts of Endophyte-Infected Grass Achnatherum inebrians on Growth and Development of Pea Aphid Acyrthosiphon pisum
by Yaling Ma, Chunjie Li and James F. White
Insects 2021, 12(10), 944; https://doi.org/10.3390/insects12100944 - 18 Oct 2021
Cited by 2 | Viewed by 1975
Abstract
The pea aphid Acyrthosiphon pisum has a worldwide distribution and causes serious losses for agricultural production. Drunken horse grass Achnatherum inebrians is a widely distributed perennial poisonous grass on the grasslands of Northern and Northwestern China. The present study focused on contact toxicity [...] Read more.
The pea aphid Acyrthosiphon pisum has a worldwide distribution and causes serious losses for agricultural production. Drunken horse grass Achnatherum inebrians is a widely distributed perennial poisonous grass on the grasslands of Northern and Northwestern China. The present study focused on contact toxicity activity of aqueous extracts of endophyte-infected (E+) and endophyte-free (E−) A. inebrians in different growth periods of pea aphids, and the growth and development of two color morphs of F1 generation nymphs. Both of the color morphs had development durations in E+ treatments that tended to be longer at 1st, 2nd, 3rd, and 4th instars than E− and control (CK). The E+ treated aphids also showed decreased weights at maturity with over all lower mean relative growth rates (MRGR). Aphid survival of E+ treated aphids was lower than that of E− and CK at all growth periods. Seeding stage E+ extracts showed a greater propensity for negatively affecting aphids than did E+ extract at maturity and the yellowing stage. These results show that extracts from endophyte-containing plants may contain compounds that may be used to control insects. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
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13 pages, 2633 KiB  
Article
Air Temperature and Humidity at the Bottom of Desert Wolf Spider Burrows Are Not Affected by Surface Conditions
by Irene Steves, Pedro Berliner and Berry Pinshow
Insects 2021, 12(10), 943; https://doi.org/10.3390/insects12100943 - 18 Oct 2021
Cited by 4 | Viewed by 2716
Abstract
Burrows are animal-built structures that can buffer their occupants against the vagaries of the weather and provide protection from predators. We investigated whether the trapdoors of wolf spider (Lycosa sp.; temporary working name "L. hyraculus") burrows in the Negev Desert serve to [...] Read more.
Burrows are animal-built structures that can buffer their occupants against the vagaries of the weather and provide protection from predators. We investigated whether the trapdoors of wolf spider (Lycosa sp.; temporary working name "L. hyraculus") burrows in the Negev Desert serve to maintain favorable environmental conditions within the burrow by removing trapdoors and monitoring the ensuing temperature and relative humidity regime within them. We also monitored the behavioral responses of “L. hyraculus” to trapdoor removal at different times of the day and in different seasons. “L. hyraculus” often spun silk mesh in their burrow entrances in response to trapdoor removal during the day, possibly to deter diurnal predators. The frequency of web-spinning peaked on summer mornings, but spiders began spinning webs sooner after trapdoor removal later in the day. In addition, we monitored temperature and relative humidity in artificial burrows in the summer during the morning and at midday. At noon, air temperature (Ta) at the bottom of open burrows increased by <1 °C more than in covered burrows, but water vapor pressure in burrows did not change. The relatively small increase in Ta in uncovered burrows at midday can probably be ascribed to the penetration of direct solar radiation. Thus, air temperature and humidity at the bottom of the burrow are apparently decoupled from airflow at the surface. Full article
(This article belongs to the Special Issue Arthropods in Desert Ecosystems)
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23 pages, 7232 KiB  
Review
Immature Insect Assemblages from the Early Cretaceous (Purbeck/Wealden) of Southern England
by Robert A. Coram and Edmund A. Jarzembowski
Insects 2021, 12(10), 942; https://doi.org/10.3390/insects12100942 - 17 Oct 2021
Cited by 4 | Viewed by 2840
Abstract
The record of immature insects from the non-marine Purbeck and Wealden groups (Lower Cretaceous) of southern England is reviewed and expanded. Fossils of adult terrestrial insects are locally common, but terrestrial immature remains are restricted to transported hemipterans, most of which are sessile [...] Read more.
The record of immature insects from the non-marine Purbeck and Wealden groups (Lower Cretaceous) of southern England is reviewed and expanded. Fossils of adult terrestrial insects are locally common, but terrestrial immature remains are restricted to transported hemipterans, most of which are sessile nymphs or puparia resembling those of extant whiteflies (Aleyrodidae). Remains of immature aquatic insects are more diverse and comprise the extant orders Plecoptera, Ephemeroptera, Odonata, Trichoptera, Hemiptera and Diptera. The Trichoptera are represented by larval cases constructed from a variety of materials corresponding to several ichnogenera. The Wealden immature insects were preserved in predominantly freshwater fluvial settings, whereas the Purbeck ones occur in lagoonal palaeoenvironments, ranging in salinity from brackish to hypersaline. The composition of aquatic immature insect faunas in the latter offers potential for palaeosalinity analysis, although there are complicating factors relating to habitat stability. Uncommon trace fossils such as beetle borings in wood provide evidence of immature insects not represented by body fossils. Full article
(This article belongs to the Special Issue The Fossil Record of Immature Insects)
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11 pages, 1098 KiB  
Article
Parasite Prevalence May Drive the Biotic Impoverishment of New England (USA) Bumble Bee Communities
by Anne L. Averill, Andrea V. Couto, Jeremy C. Andersen and Joseph S. Elkinton
Insects 2021, 12(10), 941; https://doi.org/10.3390/insects12100941 - 16 Oct 2021
Cited by 11 | Viewed by 2759
Abstract
Numerous studies have reported a diversity of stressors that may explain continental-scale declines in populations of native pollinators, particularly those in the genus Bombus. However, there has been little focus on the identification of the local-scale dynamics that may structure currently impoverished [...] Read more.
Numerous studies have reported a diversity of stressors that may explain continental-scale declines in populations of native pollinators, particularly those in the genus Bombus. However, there has been little focus on the identification of the local-scale dynamics that may structure currently impoverished Bombus communities. For example, the historically diverse coastal-zone communities of New England (USA) now comprise only a few species and are primarily dominated by a single species, B. impatiens. To better understand the local-scale factors that might be influencing this change in community structure, we examined differences in the presence of parasites in different species of Bombus collected in coastal-zone communities. Our results indicate that Bombus species that are in decline in this region were more likely to harbor parasites than are B. impatiens populations, which were more likely to be parasite-free and to harbor fewer intense infections or co-infections. The contrasting parasite burden between co-occurring winners and losers in this community may impact the endgame of asymmetric contests among species competing for dwindling resources. We suggest that under changing climate and landscape conditions, increasing domination of communities by healthy, synanthropic Bombus species (such as B. impatiens) may be another factor hastening the further erosion of bumble bee diversity. Full article
(This article belongs to the Section Insect Ecology, Diversity and Conservation)
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11 pages, 1249 KiB  
Review
Hemp Pest Spectrum and Potential Relationship between Helicoverpa zea Infestation and Hemp Production in the United States in the Face of Climate Change
by Olufemi S. Ajayi and Michelle Samuel-Foo
Insects 2021, 12(10), 940; https://doi.org/10.3390/insects12100940 - 15 Oct 2021
Cited by 16 | Viewed by 8468
Abstract
There has been a resurgence in the cultivation of industrial hemp, Cannabis sativa L., in the United States since its recent legalization. This may facilitate increased populations of arthropods associated with the plant. Hemp pests target highly marketable parts of the plant, such [...] Read more.
There has been a resurgence in the cultivation of industrial hemp, Cannabis sativa L., in the United States since its recent legalization. This may facilitate increased populations of arthropods associated with the plant. Hemp pests target highly marketable parts of the plant, such as flowers, stalks, and leaves, which ultimately results in a decline in the quality. Industrial hemp can be used for several purposes including production of fiber, grain, and cannabidiol. Thus, proper management of pests is essential to achieve a substantial yield of hemp in the face of climate change. In this review, we provide updates on various arthropods associated with industrial hemp in the United States and examine the potential impact of climate change on corn earworm (CEW) Helicoverpa zea Boddie, a major hemp pest. For example, temperature and photoperiod affect the development and diapause process in CEW. Additionally, drought can lead to a reduction in hemp growth. Host plant diversity of CEW may prevent populations of the pest from reaching outbreak levels. It is suggested that hemp varieties resistant to drought, high soil salinity, cold, heat, humidity, and common pests and diseases should be selected. Ongoing research on effective management of CEW in hemp is critical. Full article
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18 pages, 3227 KiB  
Article
GOBP1 from the Variegated Cutworm Peridroma saucia (Hübner) (Lepidoptera: Noctuidae) Displays High Binding Affinities to the Behavioral Attractant (Z)-3-Hexenyl acetate
by Ya-Lan Sun, Jun-Feng Dong, Yue-Qin Song and Shao-Li Wang
Insects 2021, 12(10), 939; https://doi.org/10.3390/insects12100939 - 15 Oct 2021
Cited by 8 | Viewed by 2363
Abstract
The variegated cutworm Peridroma saucia (Hübner) is a worldwide pest that causes serious damage to many crops. To recognize sex pheromones and host plant volatiles, insects depend on olfactory chemoreception involving general odorant-binding proteins (GOBPs). In this study, PsauGOBP1 was cloned from the [...] Read more.
The variegated cutworm Peridroma saucia (Hübner) is a worldwide pest that causes serious damage to many crops. To recognize sex pheromones and host plant volatiles, insects depend on olfactory chemoreception involving general odorant-binding proteins (GOBPs). In this study, PsauGOBP1 was cloned from the adult antennae of P. saucia. RT-qPCR and Western-blot analysis showed that PsauGOBP1 was specifically and equally expressed in the adult antennae of both females and males. Fluorescence competitive-binding assays with sex pheromones and host plant volatiles demonstrated that PsauGOBP1 bound to six host plant volatiles: (Z)-3-hexenyl acetate (KD = 4.0 ± 0.1 μM), citral (KD = 5.6 ± 0.4 μM), farnesol (KD = 6.4 ± 0.6 μM), nonanal (KD = 6.8 ± 0.3 μM), (Z)-3-hexen-1-ol (KD = 8.5 ± 0.6 μM), and benzaldehyde (KD = 9.4 ± 0.5 μM). Electroantennogram recordings with the six host plant volatiles indicated that (Z)-3-hexenyl acetate elicited the strongest responses from both male and female antennae. Further bioassays using Y-tube olfactometers showed that (Z)-3-hexenyl acetate was attractive to adult P. saucia of both sexes. These results suggest that PsauGOBP1 might be involved in detecting host plant volatiles and that (Z)-3-hexenyl acetate might serve as a potential attractant for the biological control of P. saucia. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
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18 pages, 1235 KiB  
Article
Full-Length SMRT Transcriptome Sequencing and SSR Analysis of Bactrocera dorsalis (Hendel)
by Huili Ouyang, Xiaoyun Wang, Xialin Zheng, Wen Lu, Fengping Qin and Chao Chen
Insects 2021, 12(10), 938; https://doi.org/10.3390/insects12100938 - 14 Oct 2021
Cited by 10 | Viewed by 2447
Abstract
Bactrocera dorsalis (Hendel), as one of the most notorious and destructive invasive agricultural pests in the world, causes damage to over 250 different types of fruits and vegetables throughout tropical and subtropical areas. PacBio single-molecule real-time (SMRT) sequencing was used to generate the [...] Read more.
Bactrocera dorsalis (Hendel), as one of the most notorious and destructive invasive agricultural pests in the world, causes damage to over 250 different types of fruits and vegetables throughout tropical and subtropical areas. PacBio single-molecule real-time (SMRT) sequencing was used to generate the full-length transcriptome data of B. dorsalis. A total of 40,319,890 subreads (76.6 Gb, clean reads) were generated, including 535,241 circular consensus sequences (CCSs) and 386,916 full-length non-concatemer reads (FLNCs). Transcript cluster analysis of the FLNC reads revealed 22,780 high-quality reads (HQs). In total, 12,274 transcripts were functionally annotated based on four different databases. A total of 1978 SSR loci were distributed throughout 1714 HQ transcripts, of which 1926 were complete SSRs and 52 were complex SSRs. Among the total SSR loci, 2–3 nucleotide repeats were dominant, occupying 83.62%, of which di- and tri- nucleotide repeats were 39.38% and 44.24%, respectively. We detected 105 repeat motifs, of which AT/AT (50.19%), AC/GT (39.15%), CAA/TTG (32.46%), and ACA/TGT (10.86%) were the most common in di- and tri-nucleotide repeats. The repeat SSR motifs were 12–190 bp in length, and 1638 (88.02%) were shorter than 20 bp. According to the randomly selected microsatellite sequence, 80 pairs of primers were designed, and 174 individuals were randomly amplified by PCR using primers. The number of primers that had amplification products with clear bands and showed good polymorphism came to 41, indicating that this was a feasible way to explore SSR markers from the transcriptomic data of B. dorsalis. These results lay a foundation for developing highly polymorphic microsatellites for researching the functional genomics, population genetic structure, and genetic diversity of B. dorsalis. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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26 pages, 2618 KiB  
Article
The Structure of the Endophallus Is a New Promising Feature and a Key to Study of Taxonomy of the Subgenus Metallotimarcha of the Genus Timarcha (Coleoptera, Chrysomelidae) in the Caucasus
by Andrzej Bieńkowski
Insects 2021, 12(10), 937; https://doi.org/10.3390/insects12100937 - 14 Oct 2021
Cited by 1 | Viewed by 2215
Abstract
A comparative morphological study of the members of the subgenus Metallotimarcha revealed that Caucasian Timarcha hummelii is a separate species, which differs from European members of the subgenus (T. metallica, T. corinthia, T. gibba) by the internal structure of male aedeagus, [...] Read more.
A comparative morphological study of the members of the subgenus Metallotimarcha revealed that Caucasian Timarcha hummelii is a separate species, which differs from European members of the subgenus (T. metallica, T. corinthia, T. gibba) by the internal structure of male aedeagus, namely, manubrium of the endophallus. Morphology of manubrium is described for all species of the subgenus. External characters and the shape of male aedeagus do not permit separating the members of the subgenus distinctly. Examination of both external characters and endophallus structure in the specimens from the Caucasus revealed that T. armeniaca and T. hummelii starcki are the synonyms of T. hummelii hummelii, but not separate species or subspecies. Neotypes of T. hummelii and T. armeniaca are designated. Syntypes of T. hummelii starcki are examined. The key to the species for the subgenus Metallotimarcha is compiled. Full article
(This article belongs to the Section Insect Systematics, Phylogeny and Evolution)
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16 pages, 1634 KiB  
Article
A Small-Scale Analysis of Elevational Species Richness and Beta Diversity Patterns of Arthropods on an Oceanic Island (Terceira, Azores)
by Jan Peter Reinier de Vries, Emiel van Loon and Paulo A. V. Borges
Insects 2021, 12(10), 936; https://doi.org/10.3390/insects12100936 - 14 Oct 2021
Cited by 9 | Viewed by 3047
Abstract
We present an analysis of arthropod diversity patterns in native forest communities along the small elevation gradient (0–1021 m a.s.l.) of Terceira island, Azores (Portugal). We analysed (1) how the alpha diversity of Azorean arthropods responds to increasing elevation and (2) differs between [...] Read more.
We present an analysis of arthropod diversity patterns in native forest communities along the small elevation gradient (0–1021 m a.s.l.) of Terceira island, Azores (Portugal). We analysed (1) how the alpha diversity of Azorean arthropods responds to increasing elevation and (2) differs between endemic, native non-endemic and introduced (alien) species, and (3) the contributions of species replacement and richness difference to beta diversity. Arthropods were sampled using SLAM traps between 2014 and 2018. We analysed species richness indicators, the Hill series and beta diversity partitioning (species replacement and species richness differences). Selected orders (Araneae, Coleoptera, Hemiptera and Psocoptera) and endemic, native non-endemic and introduced species were analysed separately. Total species richness shows a monotonic decrease with elevation for all species and Coleoptera and Psocoptera, but peaks at mid-high elevation for Araneae and endemic species. Introduced species richness decreases strongly with elevation especially. These patterns are most likely driven by climatic factors but also influenced by human disturbance. Beta diversity is, for most groups, the main component of total (gamma) diversity along the gradient but shows no relation with elevation. It results from a combined effect of richness decrease with elevation and species replacement in groups with many narrow-ranged species. Full article
(This article belongs to the Collection Insects in Mountain Ecosystems)
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17 pages, 4649 KiB  
Article
Knockdown of Vacuolar ATPase Subunit G Gene Affects Larval Survival and Impaired Pupation and Adult Emergence in Henosepilachna vigintioctopunctata
by Jie Zeng, Wei-Nan Kang, Lin Jin, Ahmad Ali Anjum and Guo-Qing Li
Insects 2021, 12(10), 935; https://doi.org/10.3390/insects12100935 - 14 Oct 2021
Cited by 6 | Viewed by 2367
Abstract
The vATPase holoenzyme consists of two functional subcomplexes, the cytoplasmic (peripheral) V1 and the membrane-embedded V0. Both V1 and V0 sectors contain eight subunits, with stoichiometry of A3B3CDE3FG3H in V [...] Read more.
The vATPase holoenzyme consists of two functional subcomplexes, the cytoplasmic (peripheral) V1 and the membrane-embedded V0. Both V1 and V0 sectors contain eight subunits, with stoichiometry of A3B3CDE3FG3H in V1 and ac8c’c”def(Voa1p) in V0 respectively. However, the function of G subunit has not been characterized in any non-Drosophilid insect species. In the present paper, we uncovered that HvvATPaseG was actively transcribed from embryo to adult in a Coleopteran pest Henosepilachna vigintioctopunctata. Its mRNA levels peaked in larval hindgut and Malpighian tubules. RNA interference (RNAi)-mediated knockdown of HvvATPaseG significantly reduced larval feeding, affected chitin biosynthesis, destroyed midgut integrity, damaged midgut peritrophic membrane, and retarded larval growth. The function of Malpighian tubules was damaged, the contents of glucose, trehalose, lipid, total soluble amino acids and protein were lowered and the fat bodies were lessened in the HvvATPaseG RNAi larvae, compared with those in the PBS- and dsegfp-fed beetles. In contrast, the amount of glycogen was dramatically increased in the HvvATPaseG depletion ladybirds. As a result, the development was arrested, pupation was inhibited and adult emergence was impaired in the HvvATPaseG hypomorphs. Our results demonstrated that G subunit plays a critical role during larval development in H. vigintioctopunctata. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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15 pages, 2209 KiB  
Article
Monitoring Mitochondrial Function in Aedes albopictus C6/36 Cell Line during Dengue Virus Infection
by María E. Santana-Román, Paola Maycotte, Salvador Uribe-Carvajal, Cristina Uribe-Alvarez, Nayeli Alvarado-Medina, Mohsin Khan, Aleem Siddiqui and Victoria Pando-Robles
Insects 2021, 12(10), 934; https://doi.org/10.3390/insects12100934 - 14 Oct 2021
Cited by 8 | Viewed by 3231
Abstract
Aedes aegypti and Aedes albopictus mosquitoes are responsible for dengue virus (DENV) transmission in tropical and subtropical areas worldwide, where an estimated 3 billion people live at risk of DENV exposure. DENV-infected individuals show symptoms ranging from sub-clinical or mild to hemorrhagic fever. [...] Read more.
Aedes aegypti and Aedes albopictus mosquitoes are responsible for dengue virus (DENV) transmission in tropical and subtropical areas worldwide, where an estimated 3 billion people live at risk of DENV exposure. DENV-infected individuals show symptoms ranging from sub-clinical or mild to hemorrhagic fever. Infected mosquitoes do not show detectable signs of disease, even though the virus maintains a lifelong persistent infection. The interactions between viruses and host mitochondria are crucial for virus replication and pathogenicity. DENV infection in vertebrate cells modulates mitochondrial function and dynamics to facilitate viral proliferation. Here, we describe that DENV also regulates mitochondrial function and morphology in infected C6/36 mosquito cells (derived from Aedes albopictus). Our results showed that DENV infection increased ROS (reactive oxygen species) production, modulated mitochondrial transmembrane potential and induced changes in mitochondrial respiration. Furthermore, we offer the first evidence that DENV causes translocation of mitofusins to mitochondria in the C6/36 mosquito cell line. Another protein Drp-1 (Dynamin-related protein 1) did not localize to mitochondria in DENV-infected cells. This observation therefore ruled out the possibility that the abovementioned alterations in mitochondrial function are associated with mitochondrial fission. In summary, this report provides some key insights into the virus–mitochondria crosstalk in DENV infected mosquito cells. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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16 pages, 964 KiB  
Review
Biodiversity in and around Greenhouses: Benefits and Potential Risks for Pest Management
by Gerben J. Messelink, Jérôme Lambion, Arne Janssen and Paul C. J. van Rijn
Insects 2021, 12(10), 933; https://doi.org/10.3390/insects12100933 - 14 Oct 2021
Cited by 19 | Viewed by 4907
Abstract
One of the ecosystem services of biodiversity is the contribution to pest control through conservation and stimulation of natural enemies. However, whether plant diversity around greenhouses is beneficial or a potential risk is heavily debated. In this review, we argue that most greenhouse [...] Read more.
One of the ecosystem services of biodiversity is the contribution to pest control through conservation and stimulation of natural enemies. However, whether plant diversity around greenhouses is beneficial or a potential risk is heavily debated. In this review, we argue that most greenhouse pests in temperate climates are of exotic origin and infest greenhouses mainly through transportation of plant material. For indigenous pests, we discuss the potential ways in which plant diversity around greenhouses can facilitate or prevent pest migrations into greenhouses. As shown in several studies, an important benefit of increased plant diversity around greenhouses is the stimulation of indigenous natural enemies that migrate to greenhouses, where they suppress both indigenous and exotic pests. How this influx can be supported by specific plant communities, plant characteristics, and habitats while minimising risks of increasing greenhouse pest densities, virus transmission, or hyperparasitism needs further studies. It also requires a better understanding of the underlying processes that link biodiversity with pest management. Inside greenhouses, plant biodiversity can also support biological control. We summarise general methods that growers can use to enhance pest control with functional biodiversity and suggest that it is particularly important to study how biodiversity inside and outside greenhouses can be linked to enhancement of biological pest control with both released and naturally occurring species of natural enemies. Full article
(This article belongs to the Special Issue Greenhouse Pest Management)
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12 pages, 1870 KiB  
Article
How to Count Bugs: A Method to Estimate the Most Probable Absolute Population Density and Its Statistical Bounds from a Single Trap Catch
by Ksenia S. Onufrieva and Alexey V. Onufriev
Insects 2021, 12(10), 932; https://doi.org/10.3390/insects12100932 - 13 Oct 2021
Cited by 5 | Viewed by 4445
Abstract
Knowledge of insect population density is crucial for establishing management and conservation tactics and evaluating treatment efficacies. Here, we propose a simple and universal method for estimating the most probable absolute population density and its statistical bounds. The method is based on a [...] Read more.
Knowledge of insect population density is crucial for establishing management and conservation tactics and evaluating treatment efficacies. Here, we propose a simple and universal method for estimating the most probable absolute population density and its statistical bounds. The method is based on a novel relationship between experimentally measurable characteristics of insect trap systems and the probability to catch an insect located a given distance away from the trap. The generality of the proposed relationship is tested using 10 distinct trapping datasets collected for insects from 5 different orders and using major trapping methods, i.e., chemical-baited traps and light. For all datasets, the relationship faithfully (R¯=0.91) describes the experiment. The proposed approach will take insect detection and monitoring to a new, rigorously quantitative level. It will improve conservation and management, while driv-ing future basic and applied research in population and chemical ecology. Full article
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19 pages, 4011 KiB  
Article
Silencing of Aquaporin Homologue Accumulates Uric Acid and Decreases the Lifespan of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae)
by Yulica Santos-Ortega and Nabil Killiny
Insects 2021, 12(10), 931; https://doi.org/10.3390/insects12100931 - 13 Oct 2021
Cited by 3 | Viewed by 2799
Abstract
The Asian citrus psyllid, Diaphorina citri Kuwayama is devastating the citrus industry worldwide. It transmits ‘Candidatus Liberibacter asiaticus’, the pathogen of Huanglongbing in citrus. RNA interference is an excellent tool for functional genomics and for screening target genes for pest control. [...] Read more.
The Asian citrus psyllid, Diaphorina citri Kuwayama is devastating the citrus industry worldwide. It transmits ‘Candidatus Liberibacter asiaticus’, the pathogen of Huanglongbing in citrus. RNA interference is an excellent tool for functional genomics and for screening target genes for pest control. Herein, we silenced the aquaporin (AQP) gene (DcAQP) homologue in D. citri to study its functionality and whether it could be a good target for a control strategy. AQP is an integral membrane channel protein that aids in the rapid flux of water and other small solutes that move across the lipid membrane. In Hemiptera, it is well established that AQP plays important roles in adjusting to physiological challenges including (1) regulating osmotic stress between the gut lumen and hemolymph after imbibing large quantities of a low nitrogen, sugar-rich liquid diet; (2) avoiding or preventing dehydration and desiccation; and (3) surviving at elevated temperatures. The dsRNA-DcAQP was applied twice to nymphs of the 4th and 5th instars through a soaking technique. Silencing AQP caused a significant increase in nymph mortality. Emerged adults showed malformations and a shorter lifespan. Silencing DcAQP provoked alterations in some metabolites and increased the uric acid content in emerged adults. DcAQP could be a useful target to control D. citri. Full article
(This article belongs to the Collection Psyllid Vectors: From Genetics to Pest Integrated Management)
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20 pages, 3372 KiB  
Article
Characterizing Billbug (Sphenophorus spp.) Seasonal Biology Using DNA Barcodes and a Simple Morphometric Analysis
by Marian M. Rodriguez-Soto, Douglas S. Richmond, Ricardo A. Ramirez, Xi Xiong and Laramy S. Enders
Insects 2021, 12(10), 930; https://doi.org/10.3390/insects12100930 - 13 Oct 2021
Cited by 2 | Viewed by 2451
Abstract
Billbugs (Sphenophorus spp.) are a complex of grass-feeding weevil species that reduce the aesthetic and functional qualities of turfgrass. Effective billbug monitoring and management programs rely on a clear understanding of their seasonal biology. However, our limited understanding of regional variation in [...] Read more.
Billbugs (Sphenophorus spp.) are a complex of grass-feeding weevil species that reduce the aesthetic and functional qualities of turfgrass. Effective billbug monitoring and management programs rely on a clear understanding of their seasonal biology. However, our limited understanding of regional variation in the species compositions and seasonal biology of billbugs, stemming primarily from our inability to identify the damaging larval stage to species level, has hindered efforts to articulate efficient IPM strategies to growers. We used a combination of DNA barcoding methods and morphometric measures to begin filling critical gaps in our understanding of the seasonal biology of the billbug species complex across a broad geographic range. First, we developed a DNA barcoding reference library using cytochrome oxidase subunit 1 (COI) sequences from morphologically identified adult billbugs collected across Indiana, Missouri, Utah and Arizona. Next, we used our reference library for comparison and identification of unknown larval specimens collected across the growing season in Utah and Indiana. Finally, we combined our DNA barcoding approach with larval head capsule diameter, a proxy for developmental instar, to develop larval phenology charts. Adult COI sequences varied among billbug species, but variation was not influenced by geography, indicating that this locus alone was useful for resolving larval species identity. Overlaid with head capsule diameter data from specimens collected across the growing season, a better visualization of billbug species composition and seasonal biology emerged. This approach will provide researchers with the tools necessary to fill critical gaps in our understanding of billbug biology and facilitate the development of turfgrass pest management programs. Full article
(This article belongs to the Special Issue IPM in the Rhizosphere: Challenges, Discovery and Success)
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12 pages, 1254 KiB  
Article
Crude Extracts and Alkaloids Derived from Ipomoea-Periglandula Symbiotic Association Cause Mortality of Asian Citrus Psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae)
by Xue-Dong Chen, Navneet Kaur, David R. Horton, W. Rodney Cooper, Jawwad A. Qureshi and Lukasz L. Stelinski
Insects 2021, 12(10), 929; https://doi.org/10.3390/insects12100929 - 12 Oct 2021
Cited by 5 | Viewed by 3012
Abstract
Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important economic pest of citrus crops because it vectors the causal pathogen of huanglongbing (HLB; aka citrus greening). Population suppression of D. citri with insecticides has been disproportionally relied on for HLB management [...] Read more.
Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important economic pest of citrus crops because it vectors the causal pathogen of huanglongbing (HLB; aka citrus greening). Population suppression of D. citri with insecticides has been disproportionally relied on for HLB management and a greater diversity of more sustainable tools is needed. Periglandula spp. is a fungal endosymbiont (family Clavicipitaceae) that forms a mutualistic relationship with members of plants in family Convolvulaceae. This association results in the production of ergot alkaloids that were previously documented as having psyllicidal properties. We investigated the mortality and behavior of D. citri exposed to crude extracts from morning glories in the plant family Convolvulaceae, as well as synthetic ergot alkaloids. Nymphs and adults were exposed to the crude plant extracts from Periglandula positive species of Convolvulaceae, as well as five synthetic ergot alkaloids. Treatments were prepared by exposing clippings of citrus to 100 ng/µL of crude extract from Periglandula-positive species of Ipomoea (I. imperati, I. leptophylla, I. pandurata and I. tricolor), and Turbina corymbosa, and from one Periglandula-negative species (I. alba) (100 ng/µL). Mortality of adult and nymphal D. citri was significantly higher than the control after exposure to extracts from I. tricolor and I. imperati. The synthetic ergot alkaloids, lysergol (10–100 ng/µL), ergonovine maleate (100 ng/µL), agroclavine (10–100 ng/µL), and ergosine (10–100 ng/µL) increased mortality of D. citri nymphs, while ergosine (100 ng/µL) and agroclavine (100 ng/µL) increased mortality of adults compared to water controls. Fewer D. citri adults settled on plants treated with crude extracts or synthetic ergot alkaloids than on water controls at 48 h after release. D. citri that fed on citrus leaves treated with 10 ng/μL solution of crude extract from the Periglandula-positive species Ipomoea (I. imperati, I. leptophylla, I. pandurata, I. tricolor), and Turbina corymbosa excreted significantly less honeydew compared with a negative water control and extract from Periglandula-negative species (I. alba). Our results indicate that crude extracts and ergot alkaloids exhibit toxic and sub-lethal effects on D. citri that could be useful for management of this pest. Full article
(This article belongs to the Collection Psyllid Vectors: From Genetics to Pest Integrated Management)
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13 pages, 8010 KiB  
Article
Heat Shock Protein 70 Family in Response to Multiple Abiotic Stresses in the Silkworm
by Shou-Min Fang, Qian Zhang, Yu-Li Zhang, Gui-Zheng Zhang, Ze Zhang and Quan-You Yu
Insects 2021, 12(10), 928; https://doi.org/10.3390/insects12100928 - 12 Oct 2021
Cited by 17 | Viewed by 3047
Abstract
The 70 kDa heat shock proteins play important roles in protecting organisms against environmental stresses, which are divided into stress-inducible forms (HSP70s) and heat shock cognates (HSC70s). In this study, heat shock protein 70 family was identified in the whole genome of the [...] Read more.
The 70 kDa heat shock proteins play important roles in protecting organisms against environmental stresses, which are divided into stress-inducible forms (HSP70s) and heat shock cognates (HSC70s). In this study, heat shock protein 70 family was identified in the whole genome of the silkworm. Based on the known nomenclature and phylogenetic analysis, four HSP70s and five HSC70s were classified. Relatively, heat shock cognates were more conservative and were constitutively expressed in various tissues of the silkworm larvae. Under thermal (37 °C and 42 °C) and cold (2 °C) stresses, the expressions of HSP70–1, HSP70–2, and HSP70–3 were up-regulated, and the highest induction reached 4147.3, 607.1, and 1987.3 times, respectively. Interestingly, HSC70–1, HSC70–4, and HSC70–5 also showed slight induced expressions in the fat body and/or midgut under thermal stresses. In addition, the expression of HSP70–1 was induced by dichlorvos and phoxim insecticides, while most HSC70 genes were inhibited. The results suggested that stress-inducible forms play more important roles in adaptation to various stresses than HSC70s. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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16 pages, 1962 KiB  
Article
GC/TOF-MS-Based Metabolomics Reveals Altered Metabolic Profiles in Wood-Feeding Termite Coptotermes formosanus Shiraki Digesting the Weed Mikania micrantha Kunth
by Wenjing Wu, Yahui Hou, Shijun Zhang, Yong Chen, Wenhui Zeng and Zhiqiang Li
Insects 2021, 12(10), 927; https://doi.org/10.3390/insects12100927 - 11 Oct 2021
Cited by 1 | Viewed by 2157
Abstract
Effective approaches to exploiting the biomass of the abundant invasive weed Mikania micrantha Kunth are limited. Termites have been a focus of significant attention as mediators of biomass-processing owing to their ability to digest lignocellulose. Here, the GC/TOF-MS approach was employed to assess [...] Read more.
Effective approaches to exploiting the biomass of the abundant invasive weed Mikania micrantha Kunth are limited. Termites have been a focus of significant attention as mediators of biomass-processing owing to their ability to digest lignocellulose. Here, the GC/TOF-MS approach was employed to assess the effects of a diet composed of M. micrantha leaves on Coptotermes formosanus workers, with the growth performance of these workers also being assessed. The workers increased their dietary intake when fed M. micrantha leaves, with a concomitant gradual increase in mortality rate. A total of 62 differentially abundant metabolites and nine significantly affected pathways were found when comparing termites fed M. micrantha leaves to pinewood. Key metabolites, including carbohydrates, polyols, 4-hydroxyphenylacetic acid, and their related metabolic pathways, suggested that termites can digest and utilize M. micrantha-derived lignocellulose. However, changes in the tryptophan metabolism, tyrosine metabolism, and sphingolipid metabolism suggest an adverse effect of M. micrantha leaves on antioxidant activity and signal transduction in termites. Overall, this study identified the key metabolites and pathways associated with the response of these termites to dietary changes and the effect of M. micrantha on termites. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
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15 pages, 1739 KiB  
Article
Expression Levels of Detoxification Enzyme Genes from Dendroctonus armandi (Coleoptera: Curculionidae) Fed on a Solid Diet Containing Pine Phloem and Terpenoids
by Lulu Dai, Haiming Gao and Hui Chen
Insects 2021, 12(10), 926; https://doi.org/10.3390/insects12100926 - 11 Oct 2021
Cited by 12 | Viewed by 2006
Abstract
Bark beetles overcome the toxic terpenoids produced by pine trees by both detoxifying and converting them into a pheromone system. Detoxification enzymes such as cytochrome P450s, glutathione S-transferases, and carboxylesterases are involved in the ability of Dendroctonus armandi to adapt to its chemical [...] Read more.
Bark beetles overcome the toxic terpenoids produced by pine trees by both detoxifying and converting them into a pheromone system. Detoxification enzymes such as cytochrome P450s, glutathione S-transferases, and carboxylesterases are involved in the ability of Dendroctonus armandi to adapt to its chemical environment. Ten genes from these three major classes of detoxification enzymes were selected to study how these enzymes help D. armandi to respond to the host defenses. The expression profile of these detoxification enzyme genes was observed in adult beetles after feeding on different types of diet. Significant differences were observed between two types of seminatural diet containing the phloem of pines, and a purely artificial diet containing five monoterpenes ((−)-α-pinene, (−)-β-pinene, (+)-3-carene, (±)-limonene, and turpentine oil) also caused differential transcript levels in the detoxification enzyme genes. The results suggest that monoterpenes enter the beetles through different routes (i.e., respiratory and digestive systems) and cause the expression of different genes in response, which might be involved in pheromone metabolism. In addition, the xenobiotic metabolism in bark beetles should be considered as a system comprising multiple detoxifying enzymes. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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16 pages, 1194 KiB  
Article
Responses to Developmental Temperature Fluctuation in Life History Traits of Five Drosophila Species (Diptera: Drosophilidae) from Different Thermal Niches
by Tommaso Manenti, Anders Kjærsgaard, Toke Munk Schou, Cino Pertoldi, Neda N. Moghadam and Volker Loeschcke
Insects 2021, 12(10), 925; https://doi.org/10.3390/insects12100925 - 11 Oct 2021
Cited by 5 | Viewed by 3347
Abstract
Temperature has profound effects on biochemical processes as suggested by the extensive variation in performance of organisms across temperatures. Nonetheless, the use of fluctuating temperature (FT) regimes in laboratory experiments compared to constant temperature (CT) regimes is still mainly applied in studies of [...] Read more.
Temperature has profound effects on biochemical processes as suggested by the extensive variation in performance of organisms across temperatures. Nonetheless, the use of fluctuating temperature (FT) regimes in laboratory experiments compared to constant temperature (CT) regimes is still mainly applied in studies of model organisms. We investigated how two amplitudes of developmental temperature fluctuation (22.5/27.5 °C and 20/30 °C, 12/12 h) affected several fitness-related traits in five Drosophila species with markedly different thermal resistance. Egg-to-adult viability did not change much with temperature except in the cold-adapted D. immigrans. Developmental time increased with FT among all species compared to the same mean CT. The impact of FT on wing size was quite diverse among species. Whereas wing size decreased quasi-linearly with CT in all species, there were large qualitative differences with FT. Changes in wing aspect ratio due to FT were large compared to the other traits and presumably a consequence of thermal stress. These results demonstrate that species of the same genus but with different thermal resistance can show substantial differences in responses to fluctuating developmental temperatures not predictable by constant developmental temperatures. Testing multiple traits facilitated the interpretation of responses to FT in a broader context. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
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