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15 pages, 4092 KiB

Open AccessArticle

A Chemosensory Protein Detects Antifeedant in Locust (Locusta migratoria)

by Xingcong Jiang, Haozhi Xu, Nan Zheng, Xuewei Yin and Long Zhang

Insects 2021, 12(1), 1; https://doi.org/10.3390/insects12010001 - 23 Dec 2020

Cited by 10 | Viewed by 2821

Abstract

Chemosensory system is vitally important for animals to select food. Antifeedants that herbivores encounter can interfere with feeding behavior and exert physiological effects. Few studies have assessed the molecular mechanisms underlying the chemoreception of antifeedants. In this study, we demonstrated that a chemosensory [...] Read more.

Chemosensory system is vitally important for animals to select food. Antifeedants that herbivores encounter can interfere with feeding behavior and exert physiological effects. Few studies have assessed the molecular mechanisms underlying the chemoreception of antifeedants. In this study, we demonstrated that a chemosensory protein (CSP) in Locusta migratoria is involved in detecting an antifeedant. This CSP, LmigEST6 (GenBank Acc. No. AJ973420), we named as LmigCSPIII, expressed in sensory organs where chemosensilla are widely distributed. Fluorescent binding experiments indicated that LmigCSPIII exhibits high binding affinity to α-amylcinnamaldehyde (AMCAL), a natural compound from non-host plant. This compound was subsequently demonstrated to be an effective antifeedant to locusts in feeding bioassay. By injection of double-stranded RNA (dsRNA) of LmigCSPIII, we generated LmigCSPIII knockdown locusts. The feeding behaviour assays demonstrated that the LmigCSPIII knockdown locusts had reduced sensitivity to the antifeedant but showed no changes in their physiological development or food consumption. Therefore, we inferred that this chemosensory protein is involved in antifeedant detection. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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8 pages, 2088 KiB

Open AccessCommunication

Plagues of Desert Locusts: Very Low Invasion Risk to China

by Yun-Ping Wang, Ming-Fei Wu, Pei-Jiong Lin, Yao Wang, Ai-Dong Chen, Yu-Ying Jiang, Bao-Ping Zhai, Jason W. Chapman and Gao Hu

Insects 2020, 11(9), 628; https://doi.org/10.3390/insects11090628 - 11 Sep 2020

Cited by 15 | Viewed by 3702

Abstract

Recently, the most serious upsurge of the desert locust (Schistocerca gregaria) in the last 25 years is spreading across eastern Africa and southwestern Asia. Parts of the desert locust ‘invasion area’, namely the northern border areas of Pakistan and India, are [...] Read more.

Recently, the most serious upsurge of the desert locust (Schistocerca gregaria) in the last 25 years is spreading across eastern Africa and southwestern Asia. Parts of the desert locust ‘invasion area’, namely the northern border areas of Pakistan and India, are very close to China, and whether locust swarms will invade China is of wide concern. To answer this question, we identified areas of potentially suitable habitat for the desert locust within China based on historical precipitation and temperature data, and found that parts of Xinjiang and Inner Mongolia provinces could provide ephemeral habitat in summer, but these places are remote from any other desert locust breeding areas. New generation adults of the desert locust in Pakistan and India present since April led to swarms spreading into the Indo-Pakistan border region in June, and so we examined historical wind data for this period. Our results showed that winds at the altitude of locust swarm flight blew eastward during April–June, but the wind speeds were quite slow and would not facilitate desert locust eastward migration over large distances. Simulated trajectories of desert locust swarms undertaking 10-day migrations mostly ended within India. The most easterly point of these trajectories just reached eastern India, and this is very close to the eastern border of the invasion area of desert locusts described in previous studies. Overall, the risk that the desert locust will invade China is very low. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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17 pages, 4271 KiB

Open AccessArticle

ResNet-Locust-BN Network-Based Automatic Identification of East Asian Migratory Locust Species and Instars from RGB Images

by Sijing Ye, Shuhan Lu, Xuesong Bai and Jinfeng Gu

Insects 2020, 11(8), 458; https://doi.org/10.3390/insects11080458 - 22 Jul 2020

Cited by 27 | Viewed by 6765

Abstract

Locusts are agricultural pests found in many parts of the world. Developing efficient and accurate locust information acquisition techniques helps in understanding the relation between locust distribution density and structural changes in locust communities. It also helps in understanding the hydrothermal and vegetation [...] Read more.

Locusts are agricultural pests found in many parts of the world. Developing efficient and accurate locust information acquisition techniques helps in understanding the relation between locust distribution density and structural changes in locust communities. It also helps in understanding the hydrothermal and vegetation growth conditions that affect locusts in their habitats in various parts of the world as well as in providing rapid and accurate warnings on locust plague outbreak. This study is a preliminary attempt to explore whether the batch normalization-based convolutional neural network (CNN) model can be applied used to perform automatic classification of East Asian migratory locust (AM locust), Oxya chinensis (rice locusts), and cotton locusts. In this paper, we present a way of applying the CNN technique to identify species and instars of locusts using the proposed ResNet-Locust-BN model. This model is based on the ResNet architecture and involves introduction of a BatchNorm function before each convolution layer to improve the network’s stability, convergence speed, and classification accuracy. Subsequently, locust image data collected in the field were used as input to train the model. By performing comparison experiments of the activation function, initial learning rate, and batch size, we selected ReLU as the preferred activation function. The initial learning rate and batch size were set to 0.1 and 32, respectively. Experiments performed to evaluate the accuracy of the proposed ResNet-Locust-BN model show that the model can effectively distinguish AM locust from rice locusts (93.60% accuracy) and cotton locusts (97.80% accuracy). The model also performed well in identifying the growth status information of AM locusts (third-instar (77.20% accuracy), fifth-instar (88.40% accuracy), and adult (93.80% accuracy)) with an overall accuracy of 90.16%. This is higher than the accuracy scores obtained by using other typical models: AlexNet (73.68%), GoogLeNet (69.12%), ResNet 18 (67.60%), ResNet 50 (80.84%), and VggNet (81.70%). Further, the model has good robustness and fast convergence rate. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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10 pages, 1156 KiB

Open AccessArticle

Migratory Take-Off Behaviour of the Mongolian Grasshopper Oedaleus asiaticus

by Yun-Ping Wang, Xiong-Bing Tu, Pei-Jiong Lin, Shuang Li, Chao-Min Xu, Xin-Qiao Wang, Don R. Reynolds, Jason Chapman, Ze-Hua Zhang and Gao Hu

Insects 2020, 11(7), 416; https://doi.org/10.3390/insects11070416 - 4 Jul 2020

Cited by 5 | Viewed by 3478

Abstract

Oedaleus asiaticus is one of the dominant species of grasshoppers in the rangeland on the Mongolian plateau, and a serious pest, but its migratory behavior is poorly known. We investigated the take-off behavior of migratory O. asiaticus in field cages in the inner [...] Read more.

Oedaleus asiaticus is one of the dominant species of grasshoppers in the rangeland on the Mongolian plateau, and a serious pest, but its migratory behavior is poorly known. We investigated the take-off behavior of migratory O. asiaticus in field cages in the inner Mongolia region of northern China. The species shows a degree of density-dependent phase polyphenism, with high-density swarming populations characterized by a brown morph, while low-density populations are more likely to comprise a green morph. We found that only 12.4% of brown morphs engaged in migratory take-off, and 2.0% of green morphs. Migratory grasshoppers took off at dusk, especially in the half hour after sunset (20:00–20:30 h). Most emigrating individuals did not have any food in their digestive tract, and the females were mated but with immature ovaries. In contrast, non-emigrating individuals rarely had empty digestive tracts, and most females were mated and sexually mature. Therefore, it seems clear that individuals prepare for migration in the afternoon by eliminating food residue from the body, and migration is largely restricted to sexually immature stages (at least in females). Furthermore, it was found that weather conditions (particularly temperature and wind speed at 15:00 h) in the afternoon had a significant effect on take-off that evening, with O. asiaticus preferring to take off in warm, dry and calm weather. The findings of this study will contribute to a reliable basis for forecasting migratory movements of this pest. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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Review

Jump to: Research

36 pages, 6108 KiB

Open AccessReview

Application of Remote Sensing Data for Locust Research and Management—A Review

by Igor Klein, Natascha Oppelt and Claudia Kuenzer

Insects 2021, 12(3), 233; https://doi.org/10.3390/insects12030233 - 9 Mar 2021

Cited by 36 | Viewed by 8411

Abstract

Recently, locust outbreaks around the world have destroyed agricultural and natural vegetation and caused massive damage endangering food security. Unusual heavy rainfalls in habitats of the desert locust (Schistocerca gregaria) and lack of monitoring due to political conflicts or inaccessibility of [...] Read more.

Recently, locust outbreaks around the world have destroyed agricultural and natural vegetation and caused massive damage endangering food security. Unusual heavy rainfalls in habitats of the desert locust (Schistocerca gregaria) and lack of monitoring due to political conflicts or inaccessibility of those habitats lead to massive desert locust outbreaks and swarms migrating over the Arabian Peninsula, East Africa, India and Pakistan. At the same time, swarms of the Moroccan locust (Dociostaurus maroccanus) in some Central Asian countries and swarms of the Italian locust (Calliptamus italicus) in Russia and China destroyed crops despite developed and ongoing monitoring and control measurements. These recent events underline that the risk and damage caused by locust pests is as present as ever and affects 100 million of human lives despite technical progress in locust monitoring, prediction and control approaches. Remote sensing has become one of the most important data sources in locust management. Since the 1980s, remote sensing data and applications have accompanied many locust management activities and contributed to an improved and more effective control of locust outbreaks and plagues. Recently, open-access remote sensing data archives as well as progress in cloud computing provide unprecedented opportunity for remote sensing-based locust management and research. Additionally, unmanned aerial vehicle (UAV) systems bring up new prospects for a more effective and faster locust control. Nevertheless, the full capacity of available remote sensing applications and possibilities have not been exploited yet. This review paper provides a comprehensive and quantitative overview of international research articles focusing on remote sensing application for locust management and research. We reviewed 110 articles published over the last four decades, and categorized them into different aspects and main research topics to summarize achievements and gaps for further research and application development. The results reveal a strong focus on three species—the desert locust, the migratory locust (Locusta migratoria), and the Australian plague locust (Chortoicetes terminifera)—and corresponding regions of interest. There is still a lack of international studies for other pest species such as the Italian locust, the Moroccan locust, the Central American locust (Schistocerca piceifrons), the South American locust (Schistocerca cancellata), the brown locust (Locustana pardalina) and the red locust (Nomadacris septemfasciata). In terms of applied sensors, most studies utilized Advanced Very-High-Resolution Radiometer (AVHRR), Satellite Pour l’Observation de la Terre VEGETATION (SPOT-VGT), Moderate-Resolution Imaging Spectroradiometer (MODIS) as well as Landsat data focusing mainly on vegetation monitoring or land cover mapping. Application of geomorphological metrics as well as radar-based soil moisture data is comparably rare despite previous acknowledgement of their importance for locust outbreaks. Despite great advance and usage of available remote sensing resources, we identify several gaps and potential for future research to further improve the understanding and capacities of the use of remote sensing in supporting locust outbreak- research and management. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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23 pages, 2012 KiB

Open AccessReview

Distribution Patterns of Grasshoppers and Their Kin over the Eurasian Steppes

by Michael G. Sergeev

Insects 2021, 12(1), 77; https://doi.org/10.3390/insects12010077 - 15 Jan 2021

Cited by 26 | Viewed by 6724

Abstract

The main aims of this paper are to reveal general patterns of Orthoptera distribution in the Eurasian steppes, to evaluate long-term trends of changes in distribution of taxa and populations, and to estimate the potential for population changes relative to human activity and [...] Read more.

The main aims of this paper are to reveal general patterns of Orthoptera distribution in the Eurasian steppes, to evaluate long-term trends of changes in distribution of taxa and populations, and to estimate the potential for population changes relative to human activity and global warming trends. The main publications concerning diversity and distribution of these insects over the steppes are analyzed. The fauna of the Eurasian steppes includes more than 440 species of Orthoptera. The general distribution of grasshoppers and their kin in the Eurasian steppes reflects their common associations with different grasslands. The species richness increases from the relatively cold forest-steppes to the semi-deserts with their warm summer. There are some endemic or subendemic taxa, including the tribe Onconotini (Tettigoniidae). The populations’ distribution of Orthoptera is also analyzed. The populations of native Orthoptera extend through all the herbaceous landscapes. Under these conditions, the interrelating of colonies of each species may result in great abundance. The population distribution of three species locusts (Locusta migratoria, Calliptamus italicus, Dociostaurus maroccanus) is also discussed. Some notable changes of their populations’ distribution and dynamics are characterized. The situation with rare Orthoptera is estimated. Retrospective and prospective of the steppe fauna of Orthoptera are discussed. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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10 pages, 1620 KiB

Open AccessReview

Locust Bacterial Symbionts: An Update

by Omer Lavy, Uri Gophna, Eran Gefen and Amir Ayali

Insects 2020, 11(10), 655; https://doi.org/10.3390/insects11100655 - 24 Sep 2020

Cited by 17 | Viewed by 4160

Abstract

As one of the world’s most infamous agricultural pests, locusts have been subjected to many in-depth studies. Their ability at one end of their behavioral spectrum to live as solitary individuals under specific conditions, and at the other end of the spectrum to [...] Read more.

As one of the world’s most infamous agricultural pests, locusts have been subjected to many in-depth studies. Their ability at one end of their behavioral spectrum to live as solitary individuals under specific conditions, and at the other end of the spectrum to form swarms of biblical scale, has placed them at the focus of vast research efforts. One important aspect of locust ecology is that of their interactions with the bacteria that reside in and on them. Although this aspect of locust ecology has been little studied relative to the mainstream locust research, these bacteria have been shown both to affect locust immunity and to participate in maintaining swarm integrity through the secretion of attractant volatiles. The interaction between locusts and their bacteria seems, however, to be bi-directional, with the bacteria themselves, as recently shown, being influenced by their host’s swarming tendencies. This seems to be a consequence of the bacterial composition in the locust’s gut, reproductive organs, and integument undergoing change with the change in their host’s behavior. In this review we describe the current state of knowledge of the locust–bacteria interactions (data exists mainly for the desert and the migratory locusts), as well as highlighting some newly-gained understanding; and offer perspectives for future research. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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18 pages, 9481 KiB

Open AccessReview

Control of Pest Grasshoppers in North America

by Wahid H. Dakhel, Stefan T. Jaronski and Scott Schell

Insects 2020, 11(9), 566; https://doi.org/10.3390/insects11090566 - 24 Aug 2020

Cited by 18 | Viewed by 9586

Abstract

Grasshoppers (Orthoptera: Acrididae) frequently inflict damage on millions of hectares of western rangelands and crops. The main method of controlling grasshopper outbreaks consists of covering their infestations with chemical insecticides. Although it is relatively cheap, fast, and efficient, chemical control bears serious risks [...] Read more.

Grasshoppers (Orthoptera: Acrididae) frequently inflict damage on millions of hectares of western rangelands and crops. The main method of controlling grasshopper outbreaks consists of covering their infestations with chemical insecticides. Although it is relatively cheap, fast, and efficient, chemical control bears serious risks to human health, non-target organisms, and the environment. To overcome this challenge, biological control is a less environmentally hazardous alternative to traditional, synthetic insecticides. This paper reviews strategies that could be used as effective ways to control such pests with a special focus on effective bait formulations that might provide a key model in developing biological control strategies for the grasshopper population. Full article

(This article belongs to the Special Issue Locusts and Grasshoppers: Biology, Ecology and Management)

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