Migratoria Manilensis Research Articles

MaAzaR Influences Virulence of Metarhizium acridum against Locusta migratoria manilensis by Affecting Cuticle Penetration.

The entomopathogenic fungus (EPF) Metarhizium acridum is a typical filamentous fungus and has been used to control migratory locusts (Locusta migratoria manilensis). This study examines the impact of the Zn(II)2Cys6 transcription factor, MaAzaR, in the virulence of M. acridum. Disruption of MaAzaR (ΔMaAzaR) diminished the fungus's ability to penetrate the insect cuticle, thereby decreasing its virulence. The median lethal time (LT50) for the ΔMaAzaR strain increased by approximately 1.5 d compared to the wild-type (WT) strain when topically inoculated, simulating natural infection conditions. ΔMaAzaR compromises the formation, turgor pressure, and secretion of extracellular hydrolytic enzymes in appressoria. However, the growth ability of ΔMaAzaR within the hemolymph is not impaired; in fact, it grows better than the WT strain. Moreover, RNA-sequencing (RNA-Seq) analysis of ΔMaAzaR and WT strains grown for 20 h on locust hindwings revealed 87 upregulated and 37 downregulated differentially expressed genes (DEGs) in the mutant strain. Pathogen-host interaction database (PHI) analysis showed that about 40% of the total DEGs were associated with virulence, suggesting that MaAzaR is a crucial transcription factor that directly regulates the expression of downstream genes. This study identifies a new transcription factor involved in EPF cuticle penetration, providing theoretical support and genetic resources for the developing highly virulent strains.

Design and Experiment of Bionic Straw-Cutting Blades Based on Locusta Migratoria Manilensis

Aimed at addressing the problems of the existing straw choppers on combine harvesters, such as a large cutting resistance and poor cutting effect, combined with bionic engineering technology and biological characteristics, a bionic model was used to extract the characteristics of the cutting blades of locusta migratoria manilensis’s upper jaw. A 3D point cloud reconstruction and machine vision methods were used to fit the polynomial curve of the blade edge using Matlab 2016. A straw-cutting process was simulated using the discrete element method, and the cutting effect of the bionic blade was verified. Cutting experiments with rice straws were conducted using a physical property tester, and the cutting resistance of straw to bionic blades and general blades was compared. On the whole, the average cutting force of the bionic blades was lower than that of the general blades. The average cutting force of the bionic blade was 18.74~38.23% lower than that of a smooth blade and 1.63~25.23% lower than that of a serrated blade. Similarly, the maximum instantaneous cutting force of the bionic blade was reduced by 2.30~2.89% compared with the general blade, which had a significant drag reduction effect. By comparing the time–force curves of different blades’ cutting processes, it was determined that the drag-reducing effect of the bionic blade lies in shortening the straw rupture time. The larger the contact area between the blade and the straw, the more uniform the cutting morphology of the straw after cutting. Field experiment results indicate that the average power consumption of a straw chopper partially installed with bionic blades was 5.48% lower than one with smooth blades, measured using a wireless torque analysis module. In this research study, the structure of the straw chopper of an existing combine harvester was improved based on the bionic principle, which reduced resistance when cutting crop straw, thus reducing the power consumption required by the straw chopper and improving the effectiveness and stability of the blades.

The immune response of Locusta migratoria manilensis at different times of infection with Paranosema locustae.

Paranosema locustae is an entomopathogenic microsporidia with promising potential for controlling agricultural pests, including Locusta migratoria manilensis. However, it has the disadvantage of having a slow insecticidal rate, and how P. locustae infection impacts the host immune response is currently unknown. The present study investigated the effect of P. locustae on the natural immune response of L. migratoria and the activities of enzymes that protect against oxidative stress. Infection with P. locustae increased the hemocytes and nodulation number of L. migratoria at the initial stage of infection. The hemocyte-mediated modulation of immune response was also affected by a decrease in the number of hemocytes 12 days postinfection. Superoxide dismutase activity in locusts increased in the early stages of infection but decreased in the later stages, whereas the activities of peroxidase (POD) and catalase (CAT) showed opposite trends may be due to their different mechanisms of action. Furthermore, the transcription levels of mRNA of antimicrobial peptide-related genes and phenoloxidase activity in hemolymph in L. migratoria were suppressed within 15 days of P. locustae infection. Overall, our data suggest that P. locustae create a conducive environment for its own proliferation in the host by disrupting the immune defense against it. These findings provide useful information for the potential application of P. locustae as a biocontrol agent.

Serine protease inhibitors LmSPN2 and LmSPN3 co-regulate embryonic diapause in Locusta migratoria manilensis (Meyen) via the Toll pathway

Female adults of the migratory locust, Locusta migratoria manilensis (Meyen), can sense seasonal photoperiod changes, which induces embryonic diapause as a key strategy to overwinter. Serine protease inhibitor genes (SPNs) were thought to play key roles during diapause, while few SPNs were functionally characterized. LmSPN2 was one of those genes differentially expressed between diapause and non-diapause eggs; however, its biological function remained to be explored. So, we conducted RNAi knockdown of LmSPN2, resulting in a significant decrease of the egg diapause rate by 29.7%. Using yeast two-hybrid assays, co-immunoprecipitation, and pull-down methods, we found an interaction between LmSPN2 and LmSPN3, which was proved to be mediated by a glutamate (E331) binding site of LmSPN2. RNAi knockdown of LmSPN3 resulted in a significant increase in diapause rate by 14.6%, indicating an inverse function of LmSPN2 and LmSPN3 on diapause regulation. Double knockdown of two SPN genes resulted in a 26.4% reduction in diapause rate, indicating that LmSPN2 was the dominant regulatory signal. Moreover, we found four Toll pathway genes (easter, spätzle, pelle, and dorsal) upregulated significantly after the knockdown of LmSPN2 while downregulated after the knockdown of LmSPN3. Therefore, we speculate that two SPNs regulate diapause through the Toll pathway. Our results indicated that LmSPN2 positively regulates locust egg entry into diapause, while LmSPN3 is a negative regulator of embryonic commitment to diapause. Their interaction is mediated by the binding site of E331 and influences egg diapause through the Toll pathway. This mechanistic understanding of diapause regulation expands our understanding of insect developmental regulation and provides functional targets for developing locust management strategies.

RNAi-mediated CrebA silencing inhibits reproduction and immunity in Locusta migratoria manilensis

Locusta migratoria manilensis is a major agricultural pest that causes severe direct and indirect damage to several crops. Thus, to provide a theoretical foundation for pest control, the role of CrebA in the reproduction and immune regulation of L. migratoria was investigated. CrebA is a bZIP transcription factor that critically regulates intracellular protein secretion. In this study, CrebA was widely expressed in the brain, fat body, integument, midgut, and reproductive tissues of different maturity stages of adult locusts, especially in the female fat body. RNA interfering (RNAi)-mediated silencing of CrebA inhibited locusts ovarian development, and key reproduction gene expressions, Vgs, VgRs, Chico, and JHAMT were downregulated. After the locusts were injected with Micrococcus luteus or Escherichia coli, M. luteus activated lysozyme expression, while the E. coli activated both phenol oxidase cascade and lysozyme expression. Furthermore, both bacteria stimulated the upregulation of the antimicrobial peptide genes DEF3 and DEF4. However, CrebA silencing is fatal to locusts infection with E. coli, with a mortality rate of up to 96.3%, and resulted in a significant decrease in the expression of DEF3 and DEF4 and changes in the activities of phenol oxidase and lysozyme of locusts infected by bacteria. Collectively, CrebA may be involved in diverse biological processes, including reproduction and immunity. CrebA inhibited locusts reproduction by regulating JH signaling pathway and inhibits the expression of immune genes TLR6, IMD, and AMPs. These results demonstrate CrebA seems to play a crucial role in reproduction and innate immunity.

Rapid detection of insect pest with CRISPR‐Cas13a‐Based Lateral Flow Strip: Using Locusta migratoria manilensis

AbstractThe Clustered Regularly Interspaced Short Palindromic Repeats‐associated (CRISPR‐Cas) system has been used as a powerful diagnostic tool because of its trans‐cleavage ability to accurately recognize and cleave specific nucleic acid targets. However, its application in insect pest detection has rarely been reported. The aim of the current study was to develop a new molecular identification method for insect based on CRISPR‐Cas13a system. In this study, we have developed a highly specific and sensitive detection system that combines polymerase chain reaction, CRISPR‐Cas13a system and lateral flow dipstick (PCR‐Cas13a‐LFD) to rapidly detect the presence of Locusta migratoria manilensis (Orthoptera: Acrididae) DNA and discriminate it from other species, by using material from different stages of development. A pair of specific primers and crRNA were designed based on the Gene DEAD‐box DDX10 mRNA sequence. For visual readout, a FAM‐RNA‐biotin reporter was used for detection. The CRISPR‐Cas13a‐based detection method utilizes the visual identification of L. migratoria manilensis at different developmental stages or with the use of incomplete samples. The test results could be distinguished within 2 h. The sensitivity of the PCR‐Cas13a‐LFD detection system reached 0.1 ng/μL, a 10‐fold increase compared with that of the PCR with electrophoresis. The LFD coupled with CRISPR‐Cas13a (Cas13a‐LFD) is promising for the portable, onsite and fast identification of insect pests. This study provides a reference for the development of a new method for insect identification.

Study of species richness of grasshopper (ordo orthoptera) in Beriri Jarak, Lombok Island, Indonesia

The number of species of grasshoppers (Orthoptera) in Indonesia is very large, but the successfully identified species still need improvement. It then causes many of the existing species to be identified. This study aimed to determine the grasshopper species (Orthoptera) types in the Hamlet of Otak Kebon, Beriri Jarak Village. This exploratory, descriptive research uses a qualitative approach. Sampling was carried out in May 2022 in three habitat types: gardens, fields, and rice fields. Absolute and relative methods were carried out in sampling. The samples obtained were then identified using field guides and available literature to obtain existing species richness data. The results showed that there were 15 species, namely: Valanga nigricornis, Conozoa hyaline, Oedaleus infernalis, Chorthippus brunneus, Trimerotropis pallidipennis, Chorthippus albomarginatus, Ceracris kiangsu, Melanoplus bispinosus, L. migratoria manilensis Meyen, Trimerotropis occulens, Locusta migratoria, Austracris guttulosa, Atractomorpha crenulate, Leptophyes punctatissima, and Gryllus bimaculatus. The species found belong to two suborders, namely Caelifera and Ensifera. The species are divided into four families: Acrididae, Pyrgomorphidae, Tettigoniidae, and Gryllidae. The Acrididae family dominates the existing species. In addition, 13 species were also found that still needed to be recorded in previous studies, bringing the total to 43 species.

Comparison of Gut Bacterial Communities of Locusta migratoria manilensis (Meyen) Reared on Different Food Plants.

Simple SummaryAlthough locusts can cause major agricultural damage, they also constitute a valuable food resource. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. There are apparent differences in the capacity of locusts to adapt to different food plants. To elucidate the effect of different food plants (i.e., goosegrass, maize leaves, soybean leaves, and pakchoi) on the growth and development of L. migratoria manilensis, the gut bacterial community composition of L. migratoria manilensis fifth instars fed on different plants was analyzed by high-throughput sequencing. Gut bacterial communities were affected by food plants and may play an essential role in host adaption. Feeding on different food plants has significant effects on the growth and development of L. migratoria manilensis. The present study establishes a theoretical foundation for studying the interplay between gut bacteria structure and L. migratoria manilensis adaptation.Locusts, in particular Locusta migratoria manilensis (Meyen), have been associated with major damages in agriculture, forestry, and animal husbandry in China. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. It has been demonstrated that microorganisms inhabiting the insect gut impact nutrition, development, defense, and reproduction of the insect host. The aim of the present study was to search for the adaptation mechanism of L. migratoria manilensis feeding on four different food plants (goosegrass, maize leaves, soybean leaves, and pakchoi) and explore changes in the gut bacterial community structure of the insect at the fifth instar nymph stage. Proteobacteria and Firmicutes were the dominant phyla, whereas Kluyvera, Enterobacter, Pseudocitrobacter, Klebsiella, Cronobacter, Citrobacter, Lactococcus, and Weissella were the dominant genera in the gut of L. migratoria manilensis. Principal component analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the gut microbiota structure of L. migratoria manilensis fed on different food plants. Moreover, functional prediction analysis revealed that metabolic and cellular processes were the most enriched categories. Within the category of metabolic processes, the most enriched pathways were carbohydrate transport and metabolism; amino acid transport and metabolism; translation, ribosomal structure, and biogenesis; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; and energy production and conversion. Collectively, the present results revealed that the structure of gut bacterial communities in L. migratoria manilensis fed on different food plants is impacted by food plants, which may play an essential part in the adaptation of the host.

Suppression of yolk formation, oviposition and egg quality of locust (Locusta migratoria manilensis) infected by Paranosema locustae.

Locusta migratoria manilensis is one of the most important agricultural pests in China. The locust has high fecundity and consumes large quantities of food, causing severe damage to diverse crops such as corn, sorghum, and rice. Immunity against pathogens and reproductive success are two important components of individual fitness, and many insects have a trade-off between reproduction and immunity when resources are limited, which may be an important target for pest control. In this study, adult females L. migratoria manilensis were treated with different concentrations (5 × 106 spores/mL or 2 × 107 spores/mL) of the entomopathogenic fungus Paranosema locustae. Effects of input to immunity on reproduction were studied by measuring feeding amount, enzyme activity, vitellogenin (Vg) and vitellogenin receptor (VgR) production, ovary development, and oviposition amount. When infected by P. locustae, feeding rate and phenol oxidase and lysozyme activities increased, mRNA expression of Vg and VgR genes decreased, and yolk deposition was blocked. Weight of ovaries decreased, with significant decreases in egg, length and weight.Thus, locusts used nutritive input required for reproduction to resist invasion by microsporidia. This leads to a decrease in expression of Vg and VgR genes inhibited ovarian development, and greatly decreased total fecundity. P. locustae at 2 × 107 spores/mL had a more obvious inhibitory effect on the ovarian development in migratory locusts. This study provides a detailed trade-off between reproduction and immune input of the female, which provides a reliable basis to find pest targets for biological control from those trade-off processes.

Biodegradation of Gramineous Lignocellulose by Locusta migratoria manilensis (Orthoptera: Acridoidea)

Exploring an efficient and green pretreatment method is an important prerequisite for the development of biorefinery. It is well known that locusts can degrade gramineous lignocellulose efficiently. Locusts can be used as a potential resource for studying plant cell wall degradation, but there are few relative studies about locusts so far. Herein, some new discoveries were revealed about elucidating the process of biodegradation of gramineous lignocellulose in Locusta migratoria manilensis. The enzyme activity related to lignocellulose degradation and the content of cellulose, hemicellulose, and lignin in the different gut segments of locusts fed corn leaves were measured in this study. A series of characterization analyses were conducted on corn leaves and locust feces, which included field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction pattern (XRD), and thermogravimetric (TG) analysis. These results showed that the highest activities of carboxymethyl cellulase (CMCase), filter paper cellulase (FPA), and xylanase were obtained in the foregut of locusts, which strongly indicated that the foregut was the main lignocellulose degradation segment in locusts; furthermore, the majority of nutritional components were absorbed in the midgut of locusts. The activity of CMCase was significantly higher than that of xylanase, and manganese peroxidase (MnPase) activity was lowest, which might be due to the basic nutrition of locusts being cellulose and hemicellulose and not lignin based on the results of FE-SEM, FTIR, XRD, and TG analysis. Overall, these results provided a valuable insight into lignocellulosic degradation mechanisms for understanding gramineous plant cell wall deconstruction and recalcitrance in locusts, which could be useful in the development of new enzymatic pretreatment processes mimicking the locust digestive system for the biochemical conversion of lignocellulosic biomass to fuels and chemicals.

Effect of antipyretic phenidone on the nodulation response and mortality of locust infected with fungus

The use of eicosanoids biosynthesis inhibitors (EBIs) as immune disruptors in host-pathogen interaction is a promising tool in insect pest control. In this study, co-applying the dual cyclooxygenase (COX) and lipoxygenase (LOX) inhibitor phenidone (104 µg/larva) with the entomopathogen Beauveria bassiana (108 spores/mL) on Locusta migratoria manilensis, sharply declined the nodulation response. The reduction of nodulation response by phenidone proved that the dual COX/LOX is involved in nodules formation in L. migratoria manilensis. We investigated the effect of the antipyretic drug on the fungus virulence under different thermal conditions (thermoregulation and non-thermoregulation). Interestingly, a significant increase in the mortality rate of fungus-phenidone treated locusts was recorded. The drug suppressed the therapeutic effect of thermoregulation in infected locusts combined with phenidone tailoring a mortality rate of 70% by 14 days post-infection. Whereas 40% of the mortality rate was observed in those infected locusts under the same thermal condition but not treated with phenidone. These findings indicated that phenidone can cripple the immune defense of L. migratoria manilensis and additionally increase the virulence of B. bassiana under certain ecological conditions.

Omnidirectional Jump Control of a Locust-Computer Hybrid Robot.

Jumping locomotion is critical for microrobots to overcome obstacles. Among the microjumping robots, the development of an omnidirectional jumping mechanism is challenging. To avoid the complicated microfabrication process, we present an insect-computer hybrid robot by controlling the locomotions of an Oriental Migratory Locust (Locusta migratoria manilensis, Meyen 1835). The insect-computer hybrid robot achieves repetitive omnidirectional jumps of ∼100 mm high. A series of experiments on jumping control, turning control, and collaborative directional jumping control are carried out. We also demonstrate the implementation of a wireless stimulator backpack that provides remote locomotion control, which transforms the insect into a hybrid robot. Moreover, a feedback jump control system is subsequently presented. The results indicate that the hybrid robot could easily achieve an omnidirectional jump and maintain body righting after landing. This robot is well-suited for applications that require locomotion on uneven terrains, such as environmental surveillance and search and rescue.

Isolation, Identification and Insecticidal Activity of the Secondary Metabolites of Talaromyces purpureogenus BS5.

The fungal strain BS5 was isolated from a soil sample collected in the Tibetan Plateau, which displayed good insecticidal activity and was identified as Talaromyces purpureogenus based on morphological and molecular analysis. This study aimed to evaluate the insecticidal activity and identify the active compound of the strain BS5 against the locust Locusta migratoria manilensis. The insecticidal activity of the fermented broth of BS5 was at 100% after 7 days against locusts. We extracted the fermented broth of BS5 and then evaluated the insecticidal activity of the extracts against locusts. The ethyl acetate extract exhibited promising activity levels with an LC50 value of 1077.94 μg/mL and was separated through silica gel column chromatography. The UPLC-Q-Exactive Orbitrap/MS system was employed to analyze the active fraction Fr2.2.2 (with an LC50 value of 674.87 μg/mL), and two compounds were identified: phellamurin and rubratoxin B.

Old pesticide, new use: Smart and safe enantiomer of isocarbophos in locust control

Locust plagues are still worldwide problems. Selecting active enantiomers from current chiral insecticides is necessary for controlling locusts and mitigating the pesticide pollution in agricultural lands. Herein, two enantiomers of isocarbophos (ICP) were separated and the enantioselectivity in insecticidal activity against the pest Locusta migratoria manilensis (L. migratoria) and mechanisms were investigated. The significant difference of LD50 between (+)-ICP (0.609 mg/kg bw) and (−)-ICP (79.412 mg/kg bw) demonstrated that (+)-ICP was a more effective enantiomer. The enantioselectivity in insecticidal activity of ICP enantiomers could be attributed to the selective affinity to acetylcholinesterase (AChE). Results of in vivo and in vitro assays suggested that AChE was more sensitive to (+)-ICP. In addition, molecular docking showed that the -CDOKER energies of (+)-ICP and (−)-ICP were 25.6652 and 24.4169, respectively, which suggested a stronger affinity between (+)-ICP and AChE. Significant selectivity also occurred in detoxifying enzymes activities (carboxylesterases (CarEs) and glutathione S-transferases (GSTs)) and related gene expressions. Suppression of detoxifying enzymes activities with (+)-ICP treatment suggested that (−)-ICP may induce the detoxifying enzyme-mediated ICP resistance. A more comprehensive understanding of the enantioselectivity of ICP is necessary for improving regulation and risk assessment of ICP.

Molecular Identification and Immunity Functional Characterization of Lmserpin1 in Locusta migratoria manilensis.

Simple SummaryInsect serpins play a vital role in the defense mechanism of insects, especially in the Toll pathway and PPO (prophenoloxidase) cascade. In this study, we provided an answer to the open question of whether serpin1 was involved in the humoral immune responses of Locusta migratoria manilensis. We identified a new Lmserpin1 gene from L. migratoria manilensis and investigated its expression profiles in all examined stages and tissues. Meanwhile, by interfering with Lmserpin1 gene, we examined the mortality of L. migratoria manilensis under Metarhizium anisopliae infection, as well as the activities of protective enzymes and detoxifying enzymes and the expression level of three immune-related genes (PPAE (prophenoloxidase-activating enzyme), PPO, and defensin). The results indicated that Lmserpin1 gene up-regulated the immune responses of L. migratoria manilensis and inhibited the infection of M. anisopliae. Our results are of great importance for better understanding of the mechanism characterization of Lmserpin1 in L. migratoria manilensis.Serine protease inhibitors (Serpins) are a broadly distributed superfamily of proteins that exist in organisms with the role of immune responses. Lmserpin1 gene was cloned firstly from Locusta migratoria manilensis and then was detected in all tested stages from eggs to adults and six different tissues through qRT-PCR analysis. The expression was significantly higher in the 3rd instars and within integument. After RNAi treatment, the expression of Lmserpin1 was significantly down-regulated at four different time points. Moreover, it dropped significantly in the fat body and hemolymph at 24 h after treatment. The bioassay results indicated that the mortality of L. migratoria manilensis treated with dsSerpin1 + Metarhizium was significantly higher than the other three treatments. Furthermore, the immune-related genes (PPAE, PPO, and defensin) treated by dsSerpin1 + Metarhizium were significantly down-regulated compared with the Metarhizium treatment, but the activities of phenoloxidase (PO), peroxidase (POD), superoxide dismutase (SOD), glutathione S-transferase (GST), and multifunctional oxidase (MFO) were fluctuating. Our results suggest that Lmserpin1 plays a crucial role in the innate immunity of L. migratoria manilensis. Lmserpin1 probably took part in regulation of melanization and promoted the synthesis of antimicrobial peptides (AMPs).

HYD3, a conidial hydrophobin of the fungal entomopathogen Metarhizium acridum induces the immunity of its specialist host locust

Conidial hydrophobins in fungal pathogens of plants, insects, and humans are required for fungal attachment and are associated with high virulence. They are believed to contribute to the pathogenesis of infection by preventing immune recognition. Here, we refute this generalisation offering a more nuanced analysis. We show that MacHYD3, a hydrophobin located on the conidial surface of the specialist entomopathogenic fungus Metarhizium acridum (narrow host range, kills only locusts and grasshoppers), activates specifically the humoral and cellular immunity of its own host insect, Locusta migratoria manilensis (Meyen) but not that of other non-host insects. When topically applied to the cuticle, purified MacHYD3 improved the resistance of locusts to both specialist and generalist fungal pathogens (wide host range) but had no effect on the fungal resistance of other insects, including Spodoptera frugiperda and Galleria mellonella. Hydrophobins extracted from the generalist fungal pathogens M. anisopliae and Beauveria bassiana had no effect on the resistance of locusts to fungal infection. Thus, the host locust has evolved to recognize the conidial hydrophobin of its specialist fungal pathogen, whereas conidial hydrophobins from generalist fungi are able to evade recognition. Our results distinguish the immunogenic potential of conidial hydrophobins between specialist and generalist fungi.

Land use/cover changes in the Oriental migratory locust area of China: Implications for ecological control and monitoring of locust area

The Oriental migratory locust (Locusta migratoria manilensis) is a threat to agriculture in China. The locust area is defined as an area possessing a suitable breeding habitat for this locust and has a locust outbreak at least once per decade. Ecological control of the locust area is an effective approach to manage locust with minimal environmental degradation. The formation and dynamic changes of locust areas are greatly affected by land use/cover changes (LUCC). Clarifying the LUCC in the locust area is significant for implementing rational ecological control strategies and detecting timely potential locust areas. This paper proposed a patch-based habitat suitability assessment (PHSA) method for nationwide locust area extraction. Then, a multi-temporal binary coding method was used to detect the locust area dynamic changes from 1995 to 2017. Subsequently, the relationship between LUCC and the extinction and formation of locust areas in different ecotypes was quantitatively investigated. Results show that the area of the locust area has greatly reduced over the past 20 years, and the distribution range has a large degree of temporal and spatial variation. The extinction of the locust area is closely related to the LUCC from cropland and wetland to woodland and artificial surface. It is also related to changes from grassland to cropland and woodland. The newly formed locust area shows opposite LUCC trends. These results provide practical strategies and guidance for ecological control and early monitoring of locust areas. They are instrumental in reducing pesticide use and achieving more sustainable agriculture.

The Effect of Ground Type on the Jump Performance of Adults of the Locust Locusta migratoria manilensis: A Preliminary Study.

The jump performance of locusts depends on several physiological and environmental factors. Few studies have examined the effects of different ground types on the jump performance of locusts. Here, mature adult locusts (Locusta migratoria manilensis) were examined using a custom-developed measuring system to test their jump performance (including postural features, kinematics, and reaction forces) on three types of ground (sand, soil, and wood). Significant differences were primarily observed in the elevation angle at take-off, the tibial angle at take-off, and the component of the mass-specific reaction force along the aft direction of the insect body between wood and the other two ground types (sand and soil). Slippage of the tarsus and insertion of the tibia were often observed when the locusts jumped on sand and soil, respectively. Nevertheless, comparisons of the different parameters of jump initiation (i.e., take-off speed and mass-specific kinetic energy) did not reveal any differences among the three types of ground, indicating that locusts were able to achieve robust jump performance on various substrates. This study provides insights into the biomechanical basis of the locust jump on different types of ground and enhances our understanding of the mechanism underlying the locust jump.

Using an image segmentation and support vector machine method for identifying two locust species and instars

Locusts are agricultural pests around the world. To cognize how locust distribution density and community structure are related to the hydrothermal and vegetation growth conditions of their habitats and thereby providing rapid and accurate warning of locust invasions, it is important to develop efficient and accurate techniques for acquiring locust information. In this paper, by analyzing the differences between the morphological features of Locusta migratoria manilensis and Oedaleus decorus asiaticus, we proposed a semi-automatic locust species and instar information detection model based on locust image segmentation, locust feature variable extraction and support vector machine (SVM) classification. And we subsequently examined its applicability and accuracy based on sample image data acquired in the field. Locust image segmentation experiment showed that the proposed GrabCut-based interactive segmentation method can be used to rapidly extract images of various locust body parts and exhibits excellent operability. In a locust feature variable extraction experiment, the textural, color and morphological features of various locust body parts were calculated. Based on the results, eight feature variables were selected to identify locust species and instars using outlier detection, variable function calculation and principal component analysis. An SVM-based locust classification experiment achieved a semi-automatic detection accuracy of 96.16% when a polynomial kernel function with a penalty factor parameter c of 2 040 and a gamma parameter g of 0.5 was used. The proposed detection model exhibits advantages such as high applicability and accuracy when it is used to identify locust instars of L. migratoria manilensis and O. decorus asiaticus, and it can also be used to identify other species of locusts.

Estimating reed loss caused by Locusta migratoria manilensis using UAV-based hyperspectral data

Locusta migratoria manilensis has caused major damage to vegetation and crops. Quantitative evaluation studies of vegetation loss estimation from locust damage have seldom been found in traditional satellite-remote-sensing-based research due to insufficient temporal-spatial resolution available from most current satellite-based observations. We used remote sensing data acquired from an unmanned aerial vehicle (UAV) over a simulated Locusta migratoria manilensis damage experiment on a reed (Phragmites australis) canopy in Kenli District, China during July 2017. The experiment was conducted on 72 reed plots, and included three damage duration treatments with each treatment including six locust density levels. To establish the appropriate loss estimation models after locust damage, a hyperspectral imager was mounted on a UAV to collect reed canopy spectra. Loss components of six vegetation indices (RVI, NDVI, SAVI, MSAVI, GNDVI, and IPVI) and two “red edge” parameters (Dr and SDr) were used for constructing the loss estimation models. Results showed that: (1) Among the six selected vegetation indices, loss components of NDVI, MSAVI, and GNDVI were more sensitive to the variation of dry weight loss of reed green leaves and produced smaller estimation errors during the model test process, with RMSEs ranging from 8.8 to 9.1 g/m;. (2) Corresponding model test results based on loss components of the two selected red edge parameters yielded RMSEs of 27.5 g/m2 and 26.1 g/m2 for Dr and SDr respectively, suggesting an inferior performance of red edge parameters compared with vegetation indices for reed loss estimation. These results demonstrate the great potential of UAV-based loss estimation models for evaluating and quantifying degree of locust damage in an efficient and quantitative manner. The methodology has promise for being transferred to satellite remote sensing data in the future for better monitoring of locust damage of larger geographical areas.