Insects

15 pages, 2947 KiB

Open AccessArticle

Neem and Gliricidia Plant Leaf Extracts Improve Yield and Quality of Leaf Mustard by Managing Insect Pests’ Abundance Without Harming Beneficial Insects and Some Sensory Attributes

by Rowland Maganizo Kamanga, Salifu Bhikha, Felix Dalitso Kamala, Vincent Mgoli Mwale, Yolice Tembo and Patrick Alois Ndakidemi

Insects 2025, 16(2), 156; https://doi.org/10.3390/insects16020156 - 3 Feb 2025

Abstract

Production and consumption of vegetable crops has seen a sharp increase in the recent past owing to an increasing recognition of their nutraceutical benefits. In tandem, there has been unwarranted application of agrochemicals such as insecticides to enhance productivity and vegetable quality, at [...] Read more.

Production and consumption of vegetable crops has seen a sharp increase in the recent past owing to an increasing recognition of their nutraceutical benefits. In tandem, there has been unwarranted application of agrochemicals such as insecticides to enhance productivity and vegetable quality, at the cost of human health, and fundamental environmental and ecosystem functions and services. This study was conducted to evaluate the efficacy of neem and gliricidia botanical extracts in managing harmful insect pest populations in leaf mustard. Our results report that neem and gliricidia plant extracts enhance the yield and quality of leaf mustard by reducing the prevalence and feeding activity of harmful insect pests in a manner similar to synthetic insecticides. Some of the key insect pests reduced were Lipaphis erysimi, Pieris oleracea, Phyllotreta Cruciferae, Melanoplus sanguinipes, and Murgantia histrionica. However, compared to synthetic insecticides, neem and gliricidia plant extracts were able to preserve beneficial insects such as the Coccinellidae spp., Trichogramma minutum, Araneae spp., Lepidoptera spp., and Blattodea spp. Furthermore, plant extracts did not significantly alter sensory attributes, especially taste and odor, whereas the visual appearance of leaf mustard was greater in plants sprayed with neem and synthetic insecticides. Physiologically, plant extracts were also able to significantly lower leaf membrane damage as shown through the electrolyte leakage assay. Therefore, these plant extracts represent promising pesticidal plant materials and botanically active substances that can be leveraged to develop environmentally friendly commercial pest management products. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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15 pages, 6174 KiB

Open AccessArticle

Impact of Temperature Variation on the Biological Traits and Lifecycle of Spodoptera exigua (Lepidoptera: Noctuidae): A Meta-Analysis Approach

by Honghua Zhang, Danping Xu, Xingqi Deng, Zhiqian Liu, Zhipeng He, Junhao Wu and Zhihang Zhuo

Insects 2025, 16(2), 155; https://doi.org/10.3390/insects16020155 - 3 Feb 2025

Abstract

Spodoptera exigua is a pest of considerable economic importance; however, detailed research into its ecological adaptability in newly invaded habitats is limited. This research performed a comprehensive analysis of the life history characteristics of S. exigua under varying temperature, photoperiod, and humidity conditions. [...] Read more.

Spodoptera exigua is a pest of considerable economic importance; however, detailed research into its ecological adaptability in newly invaded habitats is limited. This research performed a comprehensive analysis of the life history characteristics of S. exigua under varying temperature, photoperiod, and humidity conditions. A total of 264 studies that met the inclusion criteria were included in the analysis, and the data were examined using random-effects model, fixed-effects model, and meta-regression analysis techniques. The findings reveal that when temperatures exceed 20 °C, several biological parameters of S. exigua significantly increase, with the highest biological activity observed at 33 °C. As temperature rises, the duration of each developmental phase significantly decreases, accompanied by a reduction in the average number of eggs produced by females and a shorter pre-oviposition period. In addition, the pupal development period is shortened, resulting in a longer adult lifespan. By considering environmental variables such as temperature, photoperiod, and relative humidity, we identified the optimal conditions for the survival of each developmental stage of S. exigua. These results provide a foundation for predicting the population dynamics of this pest and contribute to the development of more effective pest control strategies. Full article

(This article belongs to the Special Issue Corn Insect Pests: From Biology to Control Technology)

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15 pages, 5461 KiB

Open AccessArticle

Identification of Fatty Acid Synthase in Arma chinensis and Its Expression Profiles in Response to Starvation

by Le Ma, Hongmei Cheng, Changjin Lin, Luyao Fu, Dianyu Liu, Yu Chen, Zhihan Su, Xiaoyu Yan, Wenyan Xu, Xiaolin Dong and Chenxi Liu

Insects 2025, 16(2), 154; https://doi.org/10.3390/insects16020154 - 3 Feb 2025

Abstract

Fatty acids are the main form of energy production and storage in insects, and fatty acid synthase (FAS) plays a major role in this process. Arma chinensis is a natural enemy used in China to control agricultural pests. While its whole genome has [...] Read more.

Fatty acids are the main form of energy production and storage in insects, and fatty acid synthase (FAS) plays a major role in this process. Arma chinensis is a natural enemy used in China to control agricultural pests. While its whole genome has been assembled, its FAS genes remain undescribed. Herein, we aim to identify the FAS genes of A. chinensis and explore their expression during starvation. Phylogenetic analysis identified nine FAS genes (ArmaFas1–ArmaFas9). During the predatory developmental stages, ArmaFas9 expression gradually increased from the 2nd to the 4th instar, peaking at the 5th instar and plateauing at the adult stage. Female adults exhibited the highest expression of ArmaFas9 in their fat body and the lowest expression in their salivary glands, whereas male adults demonstrated the opposite pattern. ArmaFas9 expression was negatively correlated with starvation duration. Compared to the controls, starved adult females exhibited a downward expression trend, whereas starved adult males demonstrated an initial increase, followed by a downward trend after 7 days. Starvation and refeeding increased ArmaFas9 expression. These results demonstrate the important role of ArmaFas9 in A. chinensis growth and development, providing a basis for further studies on lipid synthesis in predatory bugs. Full article

(This article belongs to the Section Insect Molecular Biology and Genomics)

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14 pages, 1972 KiB

Open AccessArticle

Methyl Jasmonate Enhances the Resistance of Populus alba var. pyramidalis Against Anoplophora glabripennis (Coleoptera: Cerambycidae)

by Pengpeng Shao, Jiayu Luo, Rui Zhang, Jianfeng Liu, Dandan Cao, Zhi Su and Jianrong Wei

Insects 2025, 16(2), 153; https://doi.org/10.3390/insects16020153 - 3 Feb 2025

Abstract

Populus alba var. pyramidalis (PaP) is a very important and main planted tree species in northwestern China. However, it has been threatened by Asian longhorned beetle Anoplophora glabripennis (ALB) infestation. A feasible way to protect PaP is by improving its own insect resistance [...] Read more.

Populus alba var. pyramidalis (PaP) is a very important and main planted tree species in northwestern China. However, it has been threatened by Asian longhorned beetle Anoplophora glabripennis (ALB) infestation. A feasible way to protect PaP is by improving its own insect resistance ability. In order to achieve this goal, we first checked whether ALB could induce the defense system of PaP by comparing the ALB-attracted volatiles of PaP before and after ALB infestation through the collection and identification of volatiles by gas chromatography–mass spectrometry (GC-MS). We found that attractant volatiles (Z)-3-hexenol (Z3H) and (Z)-3-hexen-1-yl acetate (Z3HA) decreased by 72.99% and 74.53% after ALB infestation, respectively. Then, the contents of the plant hormones salicylic acid (SA), jasmonic acid (JA), methyl salicylate (MeSA), and methyl jasmonate (MeJA) and the defense substances hydrogen peroxide (H₂O₂), peroxidase (POD), and total superoxide dismutase (T-SOD) in the phloem of PaP were determined before and after ALB infestation by high-performance liquid chromatography–mass spectrometry (HPLC-MS) and a manufacturer’s kit, respectively. The results showed that the quantities of SA decreased, but JA and MeJA increased by 2.1 times and 3.02 times, respectively, and the increase in H₂O₂ and POD was also significant. Therefore, we hypothesized that MeJA might be closely related to the induced ALB resistance of PaP. Further exogenous spraying of MeJA on PaP showed that the feeding and oviposition of ALB adults were significantly decreased on PaP, confirming that MeJA could improve PaP’s resistance against ALB. The concentration effect showed that 10⁻⁴ mol/L of MeJA treatment induced the strongest results. Our results clearly demonstrated the response of a poplar species to a wood borer infestation and provide an alternative method to protect PaP in the future. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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19 pages, 9936 KiB

Open AccessArticle

Identification of Candidate Olfactory Genes in the Antennal Transcriptome of Loxostege sticticalis Trapped by Three Different Sex Pheromone Blends

by Mengke Zhang, Sumei Zhao, Zhiping Xue, Jiaying Sun, Jiangning Hao, Fengzhi Deng, Junxia Huang, Caroline Du and Yongjun Du

Insects 2025, 16(2), 152; https://doi.org/10.3390/insects16020152 - 3 Feb 2025

Abstract

Insects sense intraspecific or interspecific information about the chemical substances in the habitat through the sensitive olfactory system to carry out foraging, mating, oviposition, and other activities. The antennae serve as the primary olfactory organs in insects. The olfactory process involves the participation [...] Read more.

Insects sense intraspecific or interspecific information about the chemical substances in the habitat through the sensitive olfactory system to carry out foraging, mating, oviposition, and other activities. The antennae serve as the primary olfactory organs in insects. The olfactory process involves the participation of many proteins, such as odorant-binding proteins (OBPs) and odorant receptors (ORs), but ORs play a central role in olfactory specificity and sensitivity. The beet webworm, Loxostege sticticalis, is an omnivorous agricultural pest that endangers crops and poses a significant risk to the agricultural and animal husbandry production in northern China. In this study, Illumina sequencing was conducted on the antennal transcriptome of male L. sticticalis trapped by three different sex pheromone blends. A total of 10,320 DEGs were identified, from which 46 candidate olfactory genes were selected for further analysis. These candidate olfactory genes comprise 13 odorant receptors, 6 ionotropic receptors (IRs), 3 gustatory receptors (GRs), 12 odorant-binding proteins, and 13 chemosensory proteins (CSPs). In summary, we analyzed the antennal transcriptome of male L. sticticalis trapped by three different sex pheromone blends and identified several candidate olfactory genes. This discovery offers a foundation for further molecular-level investigations into the olfactory system of L. sticticalis. Full article

(This article belongs to the Section Insect Molecular Biology and Genomics)

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23 pages, 7686 KiB

Open AccessArticle

Phylogenetics and Evolutionary Dynamics of Yunnan Acrididae Grasshoppers Inferred from 17 New Mitochondrial Genomes

by Keyao Zhang, Jing Song, Junhui Lu, Lu Zhao, Weian Deng, Delong Guan and Benyong Mao

Insects 2025, 16(2), 151; https://doi.org/10.3390/insects16020151 - 3 Feb 2025

Abstract

Yunnan Province, a global biodiversity hotspot, hosts a diverse array of Acrididae grasshoppers essential for ecosystem dynamics and agriculture. To elucidate the phylogenetic relationships and evolutionary history of this group, we sequenced and analyzed complete mitochondrial genomes from 17 Acrididae species endemic to [...] Read more.

Yunnan Province, a global biodiversity hotspot, hosts a diverse array of Acrididae grasshoppers essential for ecosystem dynamics and agriculture. To elucidate the phylogenetic relationships and evolutionary history of this group, we sequenced and analyzed complete mitochondrial genomes from 17 Acrididae species endemic to Yunnan, with genome lengths ranging from 15,403 to 15,943 base pairs. These data were integrated with mitochondrial sequences from 46 additional species to construct comprehensive phylogenetic trees. The maximum-likelihood tree identified four major clades with robust support (bootstrap values > 90%), revealing significant lineage diversification during the Early Eocene (51.94 million years ago, Mya) and subsequent radiations in the Miocene (~20 Mya) and Pliocene (~5 Mya). These divergence times correlate with major geological events and climatic shifts in the region, such as the uplift of the Tibetan Plateau and the intensification of the Asian monsoon. Notably, several species within the Coptacrinae and Oxyinae subfamilies, particularly Pseudodotraulia cornuata and Spathosternum prasiniferum, were found to be polyphyletic, indicating the necessity for taxonomic revisions. Further cluster analyses of codon usage bias and genetic distance support these taxonomic revisions within Acrididae. This robust phylogenetic framework underpins conservation strategies aimed at preserving Yunnan’s rich grasshopper biodiversity and informs updates to their phylogeny. Full article

(This article belongs to the Special Issue Revival of a Prominent Taxonomy of Insects)

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22 pages, 6932 KiB

Open AccessArticle

A Genome-Wide Analysis of Nuclear Mitochondrial DNA Sequences (NUMTs) in Chrysomelidae Species (Coleoptera)

by Yeyan He, Siqin Ge and Hongbin Liang

Insects 2025, 16(2), 150; https://doi.org/10.3390/insects16020150 - 2 Feb 2025

Abstract

Nuclear mitochondrial DNA sequences (NUMTs) are mitochondrial DNA fragments in the nuclear genome, and their unclear distribution in Chrysomelidae species hinders the selection of accurate molecular markers for species identification and phylogenetic analysis. Our study presents a genome-wide survey of NUMTs in 32 [...] Read more.

Nuclear mitochondrial DNA sequences (NUMTs) are mitochondrial DNA fragments in the nuclear genome, and their unclear distribution in Chrysomelidae species hinders the selection of accurate molecular markers for species identification and phylogenetic analysis. Our study presents a genome-wide survey of NUMTs in 32 Chrysomelidae species. Filtering strategies based on sequence length and open reading frame (ORF) features were employed to identify mitochondrial protein-coding genes (PCGs) minimally affected by NUMTs. Phylogenetic relationships were inferred from both mitochondrial PCG datasets and a COX1 dataset containing NUMTs. Our results show that NUMTs are chromosomally specific, species-specific, and widely distributed. ATP8, COX1, ND1, and ND4 are identified as relatively reliable molecular markers. Phylogenetic analysis is influenced by NUMTs and other factors such as sequence type and saturation. A total of 66 independent COX1 gene nuclear integration events were estimated across 32 species, mostly from distinct mitochondrial lineages. These findings suggest that NUMTs reflect key evolutionary processes such as gene flow and mitochondrial lineage diversification. Their prevalence emphasizes the need for refined molecular markers in species identification and phylogenetic analysis, while also highlighting the importance of NUMTs in understanding mitochondrial DNA integration and their contribution to species’ evolutionary history. Full article

(This article belongs to the Section Insect Molecular Biology and Genomics)

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13 pages, 272 KiB

Open AccessArticle

Exploiting Trap Type and Color for Monitoring Macadamia Felted Coccid Acanthococcus ironsidei (Williams) and Associated Parasitic Wasps in Macadamia Orchards in Hawai’i

by Angelita L. Acebes-Doria and Pascal O. Aigbedion-Atalor

Insects 2025, 16(2), 149; https://doi.org/10.3390/insects16020149 - 2 Feb 2025

Abstract

Acanthococcus ironsidei (Williams) (Hemiptera: Eriococcidae) is an invasive pest of macadamia, Macadamia integrifolia, in Hawai’i, causing death to macadamia trees and decreased nut productivity. Monitoring relies on wrapping double-sided sticky tapes over tree branches to trap dispersing crawlers (i.e., mobile immature stage), [...] Read more.

Acanthococcus ironsidei (Williams) (Hemiptera: Eriococcidae) is an invasive pest of macadamia, Macadamia integrifolia, in Hawai’i, causing death to macadamia trees and decreased nut productivity. Monitoring relies on wrapping double-sided sticky tapes over tree branches to trap dispersing crawlers (i.e., mobile immature stage), but this is tedious for growers, especially in large orchards. From September to November 2022 and December 2022 to February 2023, at two commercial macadamia orchards on Hawai’i Island, the use of colored sticky cards was assessed for improving the monitoring of A. ironsidei and to investigate the Hymenopteran parasitoid complex that inhabits macadamia canopies. At each study site, four different colored sticky cards (yellow, lime green, dark green, and white) were placed on the lower canopy of five trees, and on each tree, a transparent double-sided sticky tape was deployed. At bi-weekly intervals, the sticky cards were replaced and re-randomized on each tree, and the double-sided sticky tapes were replaced. The results showed that the sticky cards captured both A. ironsidei crawlers and (winged) male adults, while the double-sided sticky tapes captured only crawlers. The trap color did not have significant effects on the captures of A. ironsidei male adults at the sites, while the captures of crawlers on sticky cards were lowest on the dark green sticky traps at one site. The captures of A. ironsidei adult males on white sticky traps were generally correlated with the number of crawlers captured on the double-sided sticky tapes. The parasitoid complex captured had disparities in the attraction to color; however, the yellow, lime green and dark green colors were seemingly more effective for monitoring Encarsia lounsburyi (Berlese & Paoli), a reported parasitoid of A. ironsidei. These results have useful practical implications for improved monitoring of A. ironsidei crawlers, male adults and associated natural enemies. Full article

(This article belongs to the Special Issue Resilient Tree Nut Agroecosystems under Changing Climate)

14 pages, 2199 KiB

Open AccessArticle

Identification of Bed Bugs from Comoros, Using Morphological, Matrix-Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry, and Molecular Biology Tools, and the Detection of Associated Bacteria

by Saidou Ahamada M’madi, Adama Zan Diarra, Jean-Michel Bérenger, Bouthaina Hasnaoui and Philippe Parola

Insects 2025, 16(2), 148; https://doi.org/10.3390/insects16020148 - 2 Feb 2025

Abstract

After virtually disappearing from domestic dwellings in the Western world at the end of the Second World War, bed bugs have re-emerged in recent years. Few studies, however, have been carried out on these insects in tropical islands. In this study, we focussed [...] Read more.

After virtually disappearing from domestic dwellings in the Western world at the end of the Second World War, bed bugs have re-emerged in recent years. Few studies, however, have been carried out on these insects in tropical islands. In this study, we focussed on describing bed bug specimens collected from dwellings in a high-altitude village in Grande Comore, an island in the Comoros, in the Indian Ocean. We also aimed to detect the bacteria associated with them. Using MALDI-TOF MS coupled with molecular biology, we were able to confirm that the C. hemipterus species (the tropical bug) was the bug infesting these homes. Interestingly, the results also show that MALDI-TOF MS can differentiate between the developmental stages of bed bugs (immature and adult). Screening for bacteria was carried out using qPCR, regular PCR, and sequencing, with only Wolbachia DNA being found. Widespread surveys throughout the country are needed to ascertain the level of bed bug infestation, with a view to implementing appropriate control measures. Full article

(This article belongs to the Section Medical and Livestock Entomology)

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8 pages, 651 KiB

Open AccessCommunication

A Pre-Exposure to Male-Specific Compound γ-Hexalactone Reduces Oviposition in Bactrocera oleae (Rossi) (Diptera: Tephritidae) Under Laboratory Conditions

by Sergio López, Clàudia Corbella-Martorell, Elisa Tarantino and Carmen Quero

Insects 2025, 16(2), 147; https://doi.org/10.3390/insects16020147 - 1 Feb 2025

Abstract

The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is regarded as the most harmful pest insect for olive trees worldwide. In order to control olive fruit fly populations and mitigate the damage and economic losses they produce, the development of novel strategies [...] Read more.

The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is regarded as the most harmful pest insect for olive trees worldwide. In order to control olive fruit fly populations and mitigate the damage and economic losses they produce, the development of novel strategies to control the olive fruit fly within an integrated pest management scope has become a major concern. Here we show that a 24-h pre-exposure to the male-specific γ-hexalactone significantly reduces the oviposition on an artificial substrate. The number of eggs per female laid by those females pre-exposed to 1 mg of γ-hexalactone was significantly reduced (6.8 ± 6.1 eggs/female) in comparison to naïve (i.e., non-exposed) females (22.4 ± 10.9 eggs/female), yielding a mean oviposition activity index (OAI) of −0.56 ± 0.22. Contrarily, no significant effect was observed when females were pre-exposed to 0.5 mg of compound, even though the number of eggs per female (14.2 ± 6.3) was lower than that of naïve females, resulting in a mean OIA of −0.24 ± 0.17. Overall, this research represents a preliminary basis for delving into the potential of γ-hexalactone for being used as an oviposition disruptant, albeit further research is still required to address this issue. Full article

(This article belongs to the Special Issue Biology and Management of Tephritid Fruit Flies)

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16 pages, 6821 KiB

Open AccessArticle

Exploring Bacterial Communities and Functions in Phytophagous Halyomorpha halys and Predatory Arma chinensis

by Hongmei Cheng, Xiaoyu Yan, Changjin Lin, Yu Chen, Le Ma, Luyao Fu, Xiaolin Dong and Chenxi Liu

Insects 2025, 16(2), 146; https://doi.org/10.3390/insects16020146 - 1 Feb 2025

Abstract

The phytophagous Halyomorpha halys (Hemiptera: Pentatomidae) is a global agricultural pest that damages many crops. Conversely, the predatory Arma chinensis (Hemiptera: Pentatomidae) shows promise as a biological control agent against lepidopteran and coleopteran pests. Halyomorpha halys and A. chinensis are closely related species [...] Read more.

The phytophagous Halyomorpha halys (Hemiptera: Pentatomidae) is a global agricultural pest that damages many crops. Conversely, the predatory Arma chinensis (Hemiptera: Pentatomidae) shows promise as a biological control agent against lepidopteran and coleopteran pests. Halyomorpha halys and A. chinensis are closely related species with different feeding habits, as confirmed via genomic and morphological analyses. However, no study investigating the implications of these differences has been reported. Herein, 16S rRNA sequencing technology was employed to analyze the microbiota diversity and function in different tissues (salivary glands, gut, sperm, and ovaries) of H. halys and A. chinensis to elucidate these differences from a microbial perspective. Additionally, the adult male-to-female ratio in A. chinensis organs was statistically similar, while that in H. halys was not. Based on the dominance of the symbionts in the two bug species, we inferred that Sodalis is involved in reproduction and digestion in A. chinensis, while Spiroplasma and Pantoea play essential roles in H. halys reproduction and digestion. We analyzed the data on the microbial diversity of two bug species, laying a foundation for further understanding microbial symbiosis in A. chinensis and H. halys, which may inform the development of biological control strategies. Full article

(This article belongs to the Section Insect Behavior and Pathology)

18 pages, 673 KiB

Open AccessArticle

Seasonal and Spatial Distribution of Fall Armyworm Larvae in Maize Fields: Implications for Integrated Pest Management

by Karimou Zanzana, Antonio Sinzogan, Ghislain T. Tepa-Yotto, Elie Dannon, Georg Goergen and Manuele Tamò

Insects 2025, 16(2), 145; https://doi.org/10.3390/insects16020145 - 1 Feb 2025

Abstract

The fall armyworm (FAW), Spodoptera frugiperda, a major pest in maize production, was assessed for its temporal and spatial distribution in maize fields during both the dry and rainy seasons of 2021 and 2022 in two agroecological regions in Benin (zone 6 [...] Read more.

The fall armyworm (FAW), Spodoptera frugiperda, a major pest in maize production, was assessed for its temporal and spatial distribution in maize fields during both the dry and rainy seasons of 2021 and 2022 in two agroecological regions in Benin (zone 6 and 8). Zone 6 (AEZ 6) “called zone of terre de barre” (Southern and Central Benin) consisted of ferralitic soils, a Sudano-Guinean climate (two rainy seasons alternating with two dry seasons) with a rainfall ranging between 800 and 1400 mm of rainfall per year; while zone 8 (AEZ 8) called “fisheries region” (Southern Benin” is characterized by coastal gleysols and arenosols with a Sudano-Guinean climate and a rainfall of 900–1400 mm of rainfall per year. In this study, 30 and 50 maize plants were randomly sampled using a “W” pattern during the dry and rainy seasons, respectively. Larval density, larval infestation rates, and damage severity were monitored over time. Taylor’s power law and the mean crowding aggregation index were applied to evaluate the dispersion patterns of the larvae. The results indicate a higher larval infestation rate and larval density in AEZ 8 compared to AEZ 6 during the dry season. In the rainy season, while the percentage of damaged plants was higher in AZE 8, no significant differences in larval density between the two zones were observed. The dispersion analysis revealed moderate aggregation (aggregation index = 1.25) with a basic colony of 2.08 larvae, i.e., an average initial cluster of 2.08 larvae observed per plant, reflecting the aggregation oviposition behavior of FAW. This study provides valuable monitoring data on the FAW’s distribution, offering insights for further research on population dynamics and developing predictive models for integrated pest management strategies. Full article

(This article belongs to the Section Insect Pest and Vector Management)

11 pages, 590 KiB

Open AccessReview

Advances and Current Status in the Use of Cuticular Hydrocarbons for Forensic Entomology Applications

by David Stewart-Yates, Garth L. Maker, Stefano D’Errico and Paola A. Magni

Insects 2025, 16(2), 144; https://doi.org/10.3390/insects16020144 - 1 Feb 2025

Abstract

Cuticular hydrocarbons (CHCs) are long-chain lipids found on the exoskeletons of insects, serving primarily as a protective barrier against water loss and environmental factors. In the last few decades, the qualitative and quantitative analysis of CHCs, particularly in blow flies, has emerged as [...] Read more.

Cuticular hydrocarbons (CHCs) are long-chain lipids found on the exoskeletons of insects, serving primarily as a protective barrier against water loss and environmental factors. In the last few decades, the qualitative and quantitative analysis of CHCs, particularly in blow flies, has emerged as a valuable tool in forensic entomology, offering promising potential for species identification and age estimation of forensically important insects. This review examines the current application of CHC analysis in forensic investigations and highlights the significant advancements in the field over the past few years. Studies have demonstrated that CHC profiles vary with insect development, and while intra-species variability exists due to factors such as age, sex, geographical location, and environmental conditions, these variations can be harnessed to refine post-mortem interval (PMI) estimations and improve the accuracy of forensic entomological evidence. Notably, CHC analysis can also aid in distinguishing between multiple generations of insects on a body, providing insights into post-mortem body movement and aiding in the interpretation of PMI in complex cases. Furthermore, recent studies have investigated the variability and degradation of CHCs over time, revealing how environmental factors—such as temperature, humidity, UV light exposure, and toxicological substances—affect CHC composition, providing valuable insights for forensic investigations. Despite the promise of CHC profiling, several challenges remain, and this review also aims to highlight future research directions to enhance the reliability of this technique in forensic casework. Full article

(This article belongs to the Section Role of Insects in Human Society)

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15 pages, 44211 KiB

Open AccessFeature PaperArticle

Immature Stages and Breeding Behaviour of the Hollyhock Weevil–Rhopalapion longirostre (Olivier 1807) (Coleoptera, Brentidae, Apioninae)

by Rafał Gosik

Insects 2025, 16(2), 143; https://doi.org/10.3390/insects16020143 - 1 Feb 2025

Abstract

Since the 1960s, the range of Rhopalapion longirostre has rapidly expanded from central Asia to almost all of Europe; it has also been introduced to North America. This expansion is an expression of this weevil’s response to climate change. The phenology of Rhopalapion [...] Read more.

Since the 1960s, the range of Rhopalapion longirostre has rapidly expanded from central Asia to almost all of Europe; it has also been introduced to North America. This expansion is an expression of this weevil’s response to climate change. The phenology of Rhopalapion has been comprehensively described. Its feeding and development are associated with plants from the genus Alcea. Even though more than 300 scientific papers have been written on various aspects of R. longirostre, its immatures and certain kinds of behaviours have yet to be described. The aims of this study were (1) to provide new information on the biology of this species, in particular with regard to the morphology of the preimaginal stages, and (2) to present new observations of its reproductive and developmental behaviour. A total of 73 larvae and 67 pupae were collected from 20 hollyhock plants. Of these, 21 mature larvae and 42 pupae (21 male and 21 female) were measured and described morphologically. The descriptions of both larvae and pupae revealed a number of original features, not previously observed on known immatures of Brentidae. The sympatric development of caterpillars of Pexicopia malvella (Hübner, (1805)) in hollyhock fruit was recorded as a pathogenic factor limiting the numbers of R. longirostre. Full article

(This article belongs to the Section Insect Behavior and Pathology)

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12 pages, 1085 KiB

Open AccessArticle

Impact of Rearing Substrates on Black Soldier Fly Growth and Fertility: A Semi-Industrial Scale Study to Optimize Egg Collection

by Qi-Hui Zhang and Nalini Puniamoorthy

Insects 2025, 16(2), 142; https://doi.org/10.3390/insects16020142 - 1 Feb 2025

Abstract

Juvenile environments can influence adult phenotypes in holometabolous insects. This study examines the effects of larval rearing substrates on the reproductive outcomes of Black Soldier Flies (BSFs) at a semi-industrial scale. Larvae were reared on five substrates. Larval growth, adult size, and reproductive [...] Read more.

Juvenile environments can influence adult phenotypes in holometabolous insects. This study examines the effects of larval rearing substrates on the reproductive outcomes of Black Soldier Flies (BSFs) at a semi-industrial scale. Larvae were reared on five substrates. Larval growth, adult size, and reproductive performance were monitored, with a specific focus on egg production and hatching rates across 17 continuous egg collection days. Egg production was positively correlated with female body weight, while male body weight appeared to influence the egg production peak. Extended larval feeding stages and shorter non-feeding periods were associated with an earlier onset of egg-laying, suggesting life-history traits as predictors for reproductive timing. Diets high in carbohydrates but low in protein and fat positively influenced larval growth, egg production, and female body weight, while diets rich in both protein and carbohydrates negatively affected all measured parameters. Notably, higher fecundity did not necessarily correlate with fertility (i.e., more viable larvae for bioconversion), highlighting the need to optimize diets for both egg quantity and hatchability to maximize productivity. These findings provide valuable insights for optimizing larval nutrition and egg collection practices, enhancing reproductive efficiency and overall productivity in industrial BSF farming. Full article

(This article belongs to the Special Issue Unexplored Potentials of the Adult Black Soldier Fly: Behavioral Ecology, Reproductive Efficiency, and Ecological Contributions)

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14 pages, 3618 KiB

Open AccessArticle

Different Long-Term Nutritional Regimens of Drosophila melanogaster Shape Its Microbiota and Associated Metabolic Activity in a Sex-Specific Manner

by Repac Jelena, Trajković Jelena, Rakić Marija, Lunić Tanja, Savić Tatjana, Božić Bojan, Božić Nedeljković Biljana and Sofija Pavković-Lučić

Insects 2025, 16(2), 141; https://doi.org/10.3390/insects16020141 - 1 Feb 2025

Abstract

The dietary habits of fruit flies profoundly influence their fitness, morphology, and physiology yet the mechanisms underlying these effects remain incompletely understood. To address this gap, the relationship between dietary regimens and the composition and function of adult Drosophila melanogaster microbiota was investigated [...] Read more.

The dietary habits of fruit flies profoundly influence their fitness, morphology, and physiology yet the mechanisms underlying these effects remain incompletely understood. To address this gap, the relationship between dietary regimens and the composition and function of adult Drosophila melanogaster microbiota was investigated in the present study. The adult fly microbiota communities that were reared for long time on five different diets were characterized by means of 16S rRNA sequencing. Obtained results revealed distinct community structures associated with each dietary regimen, which was additionally corroborated through machine learning-based analysis. In general, sugar-rich diets correlate with microbial ecosystems of higher richness/diversity. Dominance of the phyla Proteobacteria and Firmicutes in the microbiota was confirmed irrespective of diet, with the varying proportions of the most abundant families: Acetobacteraceae, Lactobacillaceae, Moraxellaceae, Bradyrhizobiaceae, and Leucostonocaceae. Bacterial families of lower abundance also emerged as differentially present among the studied fly groups. Additionally, functional prediction provided initial clues into how nutrient availability might modulate the metabolic traits of adult fly microbiota in a sex-specific manner to meet host metabolic needs. Overall, the presented findings highlight the intricate interplay between diet, microbiota composition, and host phenotype in fruit flies, underscoring the importance of diet as a determinant of host-microbiota interactions. Full article

(This article belongs to the Section Insect Pest and Vector Management)

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13 pages, 2851 KiB

Open AccessArticle

Overwintering Strategies and Post-Diapause Female Reproduction Fitness in the Willow Leaf Beetle Plagiodera versicolora (Coleoptera: Chrysomelidae)

by Jian Yan, Lin Zhang, Mingxuan Xu, Xiaofeng Zhang and Lvquan Zhao

Insects 2025, 16(2), 140; https://doi.org/10.3390/insects16020140 - 1 Feb 2025

Abstract

Diapause, a survival strategy utilized by many insects under severe environmental conditions, can generate costs that potentially affect post-diapause development and reproduction. The willow leaf beetle, Plagiodera versicolora, overwinters as an adult. This study investigated the cold hardiness-hardiness and energy utilization of [...] Read more.

Diapause, a survival strategy utilized by many insects under severe environmental conditions, can generate costs that potentially affect post-diapause development and reproduction. The willow leaf beetle, Plagiodera versicolora, overwinters as an adult. This study investigated the cold hardiness-hardiness and energy utilization of female P. versicolora, and their impact on post-diapause reproductive fitness. The supercooling point exhibited seasonal temperature variation, with the lowest points occurring in January and February, coinciding with the relatively lower ambient temperatures. Lipid content demonstrated a pronounced decline at the onset of diapause (from November to December) and stabilized from December to March. Glycogen content also showed a sharp decrease from November to January, subsequently stabilizing at relatively constant levels. In addition, trehalose content increased significantly when temperatures dropped (from November to January) and then decreased as temperatures rose (from January to March). There were no significant differences in the time from pairing to successful mating for post-diapause females compared with non-diapause females. However, mating duration and the pre-oviposition period for post-diapause individuals relative to non-diapause individuals increased, coupled with a reduction in the oviposition period, total number of eggs, number of egg clutches, and number of eggs per clutch; however, most importantly, there was no notable change in egg-hatching success. These results suggest that the cold-hardiness strategy of P. versicolora falls within the freeze-avoidance category, with energy usage predominantly reliant on lipids and carbohydrates during diapause initiation. Our findings also highlight that, although post-diapause females are capable of nutrient replenishment, the energetic demands of diapause result in considerable negative impacts on post-diapause female reproductive fitness. Full article

(This article belongs to the Special Issue Arthropod Reproductive Biology)

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14 pages, 2638 KiB

Open AccessArticle

Losses of Foliage to Defoliating Insects Increase with Leaf Damage Diversity Due to the Complementarity Effect

by Mikhail V. Kozlov and Vitali Zverev

Insects 2025, 16(2), 139; https://doi.org/10.3390/insects16020139 - 31 Jan 2025

Abstract

The functioning of ecosystems critically depends on biodiversity. However, the effects of herbivore diversity on plant damage caused by herbivore feeding remain underexplored. In this study, we tested the prediction that relative losses of foliage to defoliating insects increase with leaf damage diversity [...] Read more.

The functioning of ecosystems critically depends on biodiversity. However, the effects of herbivore diversity on plant damage caused by herbivore feeding remain underexplored. In this study, we tested the prediction that relative losses of foliage to defoliating insects increase with leaf damage diversity (LDD), and we also explored the mechanisms underlying the observed LDD patterns. We measured insect herbivory in 501 individuals of three deciduous woody species (Betula pubescens, Salix phylicifolia, and Vaccinium uliginosum) across 38 localities in north-western Russia, collected 8844 leaves damaged by defoliating insects, classifying the 21,073 feeding events observed in these leaves into 29 damage types. Overall, LDD significantly decreased with increasing latitude but showed no variation along elevation or pollution gradients. Herbivory weakly but significantly increased with increasing LDD, and a strong positive correlation between the rarefied number of leaf damage types and their evenness provided evidence for the complementarity effect underlying this herbivory increase, indicating that insects producing different leaf damage types differ in their resource use. Full article

(This article belongs to the Section Insect Ecology, Diversity and Conservation)

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15 pages, 1960 KiB

Open AccessArticle

Exploiting Plant–Natural Enemy Interactions: Selection and Evaluation of Plants for the Improvement of Biological Control

by Hipolito Cortez-Madrigal

Insects 2025, 16(2), 138; https://doi.org/10.3390/insects16020138 - 31 Jan 2025

Abstract

To identify and select wild plant species as a source of nectar and pollen for the conservation of natural enemies (NEs), with an emphasis on parasitic Hymenoptera, entomological samplings were carried out on the inflorescences of plants in the northwest of Michoacán, Mexico, [...] Read more.

To identify and select wild plant species as a source of nectar and pollen for the conservation of natural enemies (NEs), with an emphasis on parasitic Hymenoptera, entomological samplings were carried out on the inflorescences of plants in the northwest of Michoacán, Mexico, in 2020. The species were selected based on the number and diversity of NEs, flowering period, phytosanitary risks (pests), and ease of multiplication. Of more than 27 plant species, NEs were recorded in 24. The Eulophid family represented 74.14% of 23 families of parasitoids recorded, and in 19 of the 23 plant species with parasitoids, the eulophid family was the most prevalent. Thirteen plant species were selected; annual species such as Tithonia tubaeformis and Stevia serrata stand out. Among the shrubs, Senecio salignus and Baccharis salicifolia stand out, as do trees such as Viguiera quinqueradiata, Thouinia villosa and Buddleja parviflora. Serjania racemosa and Phytolacca icosandra stand out for their long flowering period (>5 months) and the wide diversity of beneficial entomofauna. They are plants that reproduce easily and have a low phytosanitary risk to crops. The presence of flowering plants in agroecosystems could attract and maintain NE populations, even before pests arrive, with predictable benefits for integrated pest management. Full article

(This article belongs to the Special Issue Advances in Research on Parasitoids for Biological Control of Agricultural Pests)

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