Phycodes radiata is a significant pest of fig trees, causing extensive damage to fig orchards in the Semnan region of Iran in recent years. egg masses of P. radiata were collected from four Ficus carica cultivars, Zard Semnan, Ghermez Semnan, Zard Garmsar, and Ficus sp., and were subsequently reared under laboratory conditions. The study investigated the biological parameters of P. radiata when fed on four different fig cultivars. The feeding index parameters were significantly higher in the Zard Semnan cultivar than in the others. Hemocyte types observed in the larval hemolymph included prohemocytes, plasmatocytes, granulocytes, and oenocytoids, as identified via light microscopy. The pathogenicity of five isolates of entomopathogenic fungi: three isolates of Beauveria bassiana (B1, B2, and B3), one isolate of Metarhizium anisopliae, and one isolate of Lecanicillium muscarium were assessed against P. radiata larvae. The larvae were directly immersed in the fungal suspension for 6 seconds. Control larvae were treated similarly with Tween 80 (0.01%) and distilled water. Larval mortality was highest with the B2, B1, and B3 isolates, respectively. To evaluate hemocyte density in response to pathogenic fungi, fungal spores were injected into insect hemolymph, and hemocyte type changes were recorded at 1, 3, 6, 12, 24, 48, and 72 hours post-injection. The most pronounced effects were observed with the B1 and B2 isolates at 3 and 6 hours post-injection. Overall, the findings indicate that entomopathogenic fungi can effectively disrupt the growth and defense mechanisms of P. radiata, leading to impaired development and increased larval mortality.

Asian corn borer, Ostrinia furnacalis Guenée (Lepidoptera: Crambidae), is a major pest in corn production, and its management remains a significant challenge. Current control methods, which rely heavily on synthetic chemical pesticides, are environmentally detrimental and unsustainable, necessitating the development of eco-friendly alternatives. This study investigates the potential of the entomopathogenic nematode Steinernema carpocapsae as a biological control agent for O. furnacalis pupae, focusing on its infection efficacy and the factors influencing its performance. We conducted a series of laboratory experiments to evaluate the effects of distance, pupal developmental stage, soil depth, and light conditions on nematode attraction, pupal mortality and sublethal impacts on pupal longevity and oviposition. Results demonstrated that S. carpocapsae exhibited the highest attraction to pupae at a 3 cm distance, with infection declining significantly at greater distances. Younger pupae (<12 h old), were more attractive to nematodes than older pupae, and female pupae were preferred over males. Nematode infection was highest on the head and thorax of pupae, with a significant reduction in infection observed after 24 h. Infection caused 100% mortality in pupae within 2 cm soil depth, though efficacy was reduced under light conditions. Sublethal effects included a significant reduction in the longevity of infected adults and a decrease in the number of eggs laid by infected females compared to controls. These findings underscore the potential of S. carpocapsae as an effective biocontrol agent for sustainable pest management in corn production, offering a viable alternative to chemical pesticides.

The oriental armyworm, Mythimna separata (Walker), is a highly migratory pest known for its sudden larval outbreaks, which result in severe crop losses. These unpredictable surges pose significant challenges for timely and accurate monitoring, as conventional methods are labour-intensive and prone to errors. To address these limitations, this study investigates the use of machine learning for automated and precise identification of M. separata larval instars. A total of 1577 larval images representing different instar were analysed for geometric, colour, and texture features. Additionally, larval weight was predicted using 13 regression models. Instar identification was conducted using Support Vector Classifier (SVC), Random Forest, and Multi-Layer Perceptron. Key feature contributing to classification accuracy were subsequently identified through permutation feature importance analysis. The results demonstrated the potential of machine learning for automating instar identification with high efficiency and accuracy. Predicted larval weight emerged as a key feature, significantly enhancing the performance of all identification models. Among the tested approaches, BaggingRegressor exhibited the best performance for larval weight prediction (R2 = 98.20%, RMSE = 0.2313), while SVC achieved the highest instar identification accuracy (94%). Overall, the integration of larval weight with other image-derived features proved to be a highly effective strategy. This study demonstrates the efficacy of machine learning in enhancing pest monitoring systems by providing a scalable and reliable framework for precise pest management. The proposed methodology significantly improves larval instar identification accuracy and efficiency, offering actionable insights for implementing targeted biological and chemical control strategies.

The tomato leafminer, Phthorimaea absoluta (synonym Tuta absoluta Meyrick, 1917), is a transboundary plant pest that poses a serious threat to global tomato cultivation and production, with significant negative social and environmental impact from increased insecticide usage for its management. We present three P. absoluta draft mitochondrial genomes (mitogenomes) from Malawi and South Africa, thereby increasing the mitogenome resources for this invasive agricultural pest. Comparative analysis with Spain, China, and Kenya samples revealed at least seven maternal lineages across its current invasive ranges, supporting multiple introductions as a major factor for the spread of invasive populations. Mitogenome results therefore identified unexpected diversity as compared to the use of the partial mitochondrial cytochrome oxidase subunit I (mtCOI/cox1) gene marker for the inference of P. absoluta invasion biology. The whole-genome sequencing approach further identified alternative mitochondrial DNA (mtDNA) gene regions necessary to improve diversity estimates, and enables concurrent characterisation of insecticide resistance genes. Characterisation of the VSSG (Para) and AChE-1/ace-1 gene profiles that underpin pyrethroid and organophosphate (OP) resistances, respectively, confirmed co-introductions of pyrethroid and OP resistance genes into Malawian and South African populations. Our study highlights the need for additional P. absoluta mitogenome resources, especially from native populations that is needed for more accurate interpretations of introduction pathways and the development of future sustainable management strategies.

Land use change has significantly altered most ecosystem functioning, such as nutrition provisioning, water flows and pollination services. So far, the impact of land use change on the dietary diversity of predatory insects has remained largely unexplored. In this study, we explored the prey composition of reared yellow-legged hornets Vespa velutina Lepeletier (Hymenoptera: Vespidae) in landscapes with a gradient of surrounding green lands, using metabarcoding of feces eliminated by larvae. The hornets primarily fed upon insects, with dipterans, coleopterans, lepidopterans, hemipterans, hymenopterans, and orthopterans being the dominant prey groups. The percentage of green lands had a significantly positive effect on prey richness at a spatial scale of 1500 m, but no effect on Shannnon index of the prey community. Meanwhile, the green lands had significantly positive effects on richness of coleopteran prey and lepidopteran prey, but no significant effect on richness of dipteran prey, hemipteran prey, hymenopteran prey, or orthopteran prey. In terms of beta diversity, the percentage of green lands explained the dissimilarity of prey communities among landscapes, whereas local factors, such as the distance to green lands and the distance to buildings, did not explain the dissimilarity. Our study indicated that the green lands in the landscape positively affected the dietary diversity of reared yellow-legged hornets, but this effect varied among different taxonomic groups of prey.

The gut pH plays crucial roles in diet preference, habitat choice, insect fitness, and insect-microbial relationships. It significantly impacts enzyme activity efficiency, as well as the internalisation and efficacy of pesticides. Without a comprehensive understanding of the gut environment, potential pest management strategies cannot be fully optimised.

This study investigates the gut pH of the globally invasive pest insect Western flower thrips Frankliniella occidentalis, and the effect its Gram-negative symbiotic gut bacterium BFo2 has on pH modulation. Indicator dyes were fed to F. occidentalis and the gut pH was found to vary between 6 and 7. In general, the larval and adult guts appear to have a pH of between 6 and 6.5; however, the posterior gut of some adults appears to be closer to 7. This almost neutral pH offers a favourable environment for the neutrophilic symbiotic BFo2. The ability of BFo2 isolates to buffer pH towards neutral was also observed during in vitro culture using broths at different pH values.

This paper also discusses the implications of this gut environment on dsRNAi delivery. By laying the foundation for understanding how gut pH can be leveraged to enhance current pest management strategies, this study particularly benefits research aimed at optimising the delivery of lethal dsRNA through symbiont-mediated RNAi to Western flower thrips in pest management programs.

There is interest in exploring biodegradable chemicals, e.g. sex pheromones, in behaviour manipulation to control the polyphagous mirid species Helopeltis bakeri Poppius. Understanding this insect pest’s reproductive behaviour is critical for identifying and isolating semiochemicals. H. bakeri rate of sexual maturation was determined by identifying the time the winged adult changed colour after the 5th and final nymphal form. We verified that there was no significant difference in the rate of colour change for both sexes. Copulation lasted an average of 167.0 ± 77.1 min and was observed on mating pairs >72 h old from the time of final molt. Close-range copulation behaviour of H. bakeri was recorded using the Behavioral Observation Research Interactive Software, and sequential behaviour analysis was performed by creating adjacency matrices. The ethograms revealed the absence of specific calling behaviour from either of the sexes. However, the male’s active pursuit of the female may indicate the latter’s role in releasing sex attractants. Using a wind tunnel, it was observed that the number of male visitations of 96-h to 120-h-old females significantly differed from the attraction in younger females (p < 0.05) and peaked from 2:00 PM to 12:00 AM. This supports the crepuscular nature of this mirid species. The difference in the sex maturation age and maximum male attraction implies that the secretion of sex attractant could happen after the completion of development, i.e. the exhibition of colour dimorphism.

Diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), a globally distributed insect, is a major pest of crucifer crops due to its adaptability to diverse climates. In Argentina, its distribution spans three regions: a core area in the northeast and central-east where it persists year-round, a southwestern region with seasonal migrations, and an intermediate zone with variable year-round persistence. Across these areas, it is the primary pest of Brassica crops. In the central-east, the availability of year-round Brassicaceae crops and wild species indicates that seasonality is not linked to food scarcity. While studies have examined this relationship elsewhere, thermal thresholds vary among populations, and limited data on South American populations highlight the need for localised research. This study evaluated thermal thresholds for P. xylostella populations in central Argentina, focusing on temperature’s effects on fecundity, fertility, development, and survival. We found that temperatures outside the optimal range (15–23°C) significantly reduced survival, with no individuals surviving at 5 or 30°C. Linear and non-linear models accurately described the relationship between temperature and pest development. Using cumulative degree-days, we mapped potential P. xylostella generations across central Argentina. This research provides the first comprehensive analysis of P. xylostella thermal biology in temperate Argentina, emphasising temperature’s critical role in its development. The findings offer valuable insights for climate-specific pest management strategies and enhance understanding of insect population dynamics in agricultural ecosystems, contributing to more sustainable control practices.

Cathepsin B (CTSB) is a cysteine protease that is widely found in eukaryotes and plays a role in insect growth, development, digestion, metamorphosis, and immunity. In the present study, we examined the role of CTSB in response to environmental stresses in Myzus persicae Sulzer (Hemiptera: Aphididae). Six MpCTSB genes, namely MpCTSB-N, MpCTSB-16D1, MpCTSB-3098, MpCTSB-10270, MpCTSB-mp2, and MpCTSB-16, were identified and cloned from M. persicae. The putative proteins encoded by these genes contained three conserved active site residues, i.e. Cys, His, and Asn. A phylogenetic tree analysis revealed that the six MpCTSB proteins of M. persicae were highly homologous to other Hemipteran insects. Real-time polymerase chain reaction revealed that the MpCTSB genes were expressed at different stages of M. persicae and highly expressed in winged adults or first-instar nymphs. The expression of nearly all MpCTSB genes was significantly upregulated under different environmental stresses (38°C, 4°C, and ultraviolet-B). This study shows that MpCTSB plays an important role in the growth and development of M. persicae and its resistance to environmental stress.

Data from three and half years’ nightly light-trap catches of 25 Afrotropical ant species were examined by Fourier analysis. Between 8 and 72 % of the seven-day-moving-average logarithmically transformed catches were accounted for by two to four terms. All 25 species showed significant annual periodicity and all, but Dorylus fulvus and Camponotus foraminosus, six monthly. Four species had wavelengths of between two and four years, and Tapinoma melanocephalum of 289 days. Twenty-three species showed two peak catches annually, contemporaneous with the two rainy seasons, with the higher peak corresponding with the main rains for 21 of them, while D. fulvus and C. foraminosus had single annual peaks during the main rains. Catches of 14 species with lunar periodicities were lowest around full moon and highest near new moon, contrasting with Hypoponera dulcis and Plagiolepis brunni whose catches were highest at full moon, and near the first quarter, respectively. Gynes and males of eight species were sufficiently numerous for comparisons of their separate responses to lunar illuminance. Catches of males peaked ca. six and three days later than gynes for Tapinoma cf. carininotum and Tetramorium aculeatum, respectively; whereas males of Crematogaster africana, Cr. depressa, Tetramorium sericeiventre, Oecophylla longinoda, Tapinoma melanocephalum, and Technomyrmex andrei peaked from ca. one to six days earlier than their respective gynes.

Influenced by human activities, microplastics (MPs) are widely distributed in terrestrial ecosystems. However, their ecotoxicity remains unclear. Therefore, we assessed the ecotoxicity of polyamide microplastics (PA-MPs) by investigating their toxic effects on the model insect, the silkworms Bombyx mori (Lepidoptera: Bombycidae). In this study, fifth-instar silkworm larvae were fed mulberry leaves treated with PA-MPs for 120 hours, but no changes in mortality rates were observed. However, the body weight, pupal weight, cocoon weight, egg laying amount, and cocoon shell weight in F0 generation silkworms were significantly reduced. This indicates that PA-MPs have sublethal effects on silkworms. To further investigate the effects of PA-MPs on the offspring of silkworms, we applied the age-stage, two-sex life table analysis. We found that in the PA-MPs treatment group, the duration of the larval and pupal stages of F1 generation silkworms was significantly prolonged, while the lifespan of the adults and total longevity were shortened. Meanwhile, the life history parameters (sxj, exj, lx, fxj, lxmx, and vxj values) and population parameters (R0, λ, r, and T) of F1 generation silkworms in the PA-MPs treatment group were also lower than control. This indicates that PA-MPs have transgenerational effects, affecting the growth, development, and reproduction of F1 generation silkworms. Our research findings demonstrate the sublethal and transgenerational effects of PA-MPs on silkworms, providing evidence for their ecotoxicity.

Sensory neuron membrane protein (SNMP) gene play a crucial role in insect chemosensory systems. However, the role of SNMP in the host searching behaviour of Rhopalosiphum padi (Hemiptera: Aphididae), a highly destructive pest of cereal crops, has not been clearly understood. Our previous research has shown that three wheat volatile organic compounds (VOCs) – (E)-2-hexenol, linalool, and octanal can attract R. padi, but the involvement of SNMP in the aphid’s olfactory response to these wheat VOCs has not to be elucidated. In this study, only one SNMP gene was cloned and characterised from R. padi. The results revealed that the SNMP belongs to the SNMP1 subfamily and was named RpadSNMP1. RpadSNMP11 was predominantly expressed in the antennae of the aphid, with significantly higher expression levels observed in winged forms, indicating that it is involved in olfactory responses of R. padi. RpadSNMP1 expression was significantly up-regulated following starvation, and the expression of this gene showed a decreasing trend after 24 h of aphid feeding. Functional analysis through RpadSNMP1 knockdown demonstrated a significant decrease in R. padi’s ability to search for host plants. The residence time of R. padi injected with dsRpadSNMP1 significantly shortened in response to (E)-2-hexenol, linalool and octanal according to the four-arm olfactometer, indicating the crucial role of RpadSNMP1 in mediating the aphid’s response to these wheat VOCs. Molecular docking suggested potential binding interactions between RpadSNMP1 and three wheat VOCs. Overall, these findings provided evidence for the involvement of RpadSNMP1 in host plant searching and lay a foundation for developing new methods to control this destructive pest.

Hymenopteran parasitoids are an understudied group of insects despite being important in biological control programs globally. Little is known about the ability of parasitoids to control the passionvine hopper (Scolypopa australis (Walker); PVH), which was introduced to New Zealand (NZ) in the 1800s and has since become a major economic pest of kiwifruit. However, in their native Australia, this species has not reached pest status, likely due to the presence of associated parasitoids. Understanding the ecology of parasitoids associated with PVH in their native range is a critical step in identifying potential biological control agents that could be used in NZ. In this study, PVH presence and occupancy on different plant species was determined and the PVH parasitoid fauna of NZ compared with the Australian fauna. Collections were undertaken in and around Melbourne, Australia, between December 2021 and May 2023 in public and private gardens, roadside verges and parklands. Parasitoids were reared from the nymphs and eggs of PVH and identified. Ten species of parasitoid were discovered to parasitise PVH, eight of which were new host records. Three parasitoids, Dryinus koebelei, Neodryinus nelsoni, and Neodryinus koebelei, were reared from PVH nymphs and seven parasitoids were reared from PVH eggs: Ablerus sp., Anastatus sp., Centrodora sp., Cheilonoeurus sp., Ooencyrtus sp., and unknown species belonging to the families Figitidae and Platygastridae. These new data have made a significant contribution to understanding the ecology of PVH in their native range.

Bombyx mori Tryptophanyl-tRNA synthetase (BmWARS) belongs to the family of Ic-like aminoacyl-tRNA synthetases (aaRSs), whose specific recognition of the substrate Trp, tRNA, maintains the fidelity of protein synthesis. In this study, BmWARS was cloned and characterized from the midgut of the silkworm, Bombyx mori, resulting in an open reading frame (ORF) with a full length of 1,149 bp, which can encode 382 Aa. BmWARS is localized in the cytoplasm, and is expressed in all tissues of the silkworm, with higher expression in the testis, ovary, silk gland and malpighian tubule. The expression of BmWARS was significantly up-regulated in the midgut and silk gland after infection with Bombyx mori nuclear polyhedrosis virus (BmNPV). In addition, overexpression of BmWARS inhibited BmNPV infection and replication extremely significantly, while interference with BmWARS expression promoted BmNPV infection and replication. Analysis of the immune pathways in which BmWARS may be involved revealed that the expression of the key genes of the PI3K-Akt pathway, BmPI3K, BmAkt, BmPDK1, BmeIF4E, BmS6, and p-Akt protein was significantly reduced, whereas the expression of BmPTEN, BmFoxO, and BmCaspase9 was significantly increased in the cells that overexpressed BmWARS and were infected with BmNPV. Meanwhile, the results of the study interfering with the expression of BmWARS were completely opposite to those of the study overexpressing BmWARS. This is the first report that BmWARS has antiviral effects in Bombyx mori. Moreover, BmWARS inhibits BmNPV infection and replication in Bombyx mori cells by promoting apoptosis and inhibiting cell proliferation.

Aphis gossypii Glover (Hemiptera: Aphididae) is a significant pest of Capsicum annuum (Solanales: Solanaceae) and exhibits intraspecific differentiation within populations. To investigate the adaptability of Hap3 and Hap17 A. gossypii to various C. annuum varieties, including ‘Lvzhou101’ (LZ), ‘Lashen’ (LA), ‘Saierweilvtianjiao’ (SE), ‘Haimaihongri’ (HM), ‘Chaotianjiao’ (CT), and ‘Luosijiangjun’ (LS), we employed life tables to analyse growth and population parameters post-feeding and conducted petri dish host choice experiments to assess the host plant preference of A. gossypii. Survival rates of A. gossypii varied significantly across C. annuum varieties. Notably, Hap3 and Hap17 thrived on ‘LZ’ but failed to establish populations on ‘LA’. The net reproductive rate (R0), average generation time (T), and intrinsic rate of increase (rm) differed markedly between Hap3 and Hap17 across C. annuum varieties. Feeding on ‘LZ’ resulted in a significantly higher R0 value (26.49) for Hap3 relative to other varieties. The T (7.60 days) and rm (0.27) values for Hap3 on ‘SE’ were superior to those observed on other C. annuum varieties. These findings indicate that ‘SE’ is the optimal host for Hap3 growth, while ‘LZ’ best supports Hap17. Both haplotypes exhibited the lowest adaptability to ‘LA’. Therefore, the utilisation capacity of A. gossypii populations on C. annuum demonstrates differentiation, and the resistance levels among C. annuum varieties to A. gossypii vary. This differentiation can inform targeted management strategies for aphid infestations on pepper crops.

C-type lectins (CTLs), a diverse family of pattern recognition receptors, are essential for immune recognition and pathogen clearance in invertebrates. TcCTL17 contains one carbohydrate recognition domain and three scavenger receptor Cys-rich domains. Spatial and temporal expression analysis revealed that TcCTL17 is highly expressed in early pupa, early adult stages, and the larval gut at 20 days. The recombinant TcCTL17 exhibited dose-dependent binding to lipopolysaccharides and peptidoglycans, Ca2+-dependent binding and agglutination of bacteria in vitro. Knocking down TcCTL17 before bacterial exposure reduced survival rates and increased bacterial loads in T. castaneum larvae, accompanied by decreased antimicrobial peptide expression and haemolymph phenoloxidase activity. Additionally, TcCTL17 RNA interference caused developmental abnormalities, affecting metamorphosis and fecundity, possibly by influencing the 20E, JH, and vitellogenin pathways. These findings underscore dual functions of TcCTL17 in immunity and development, making it a potential target for pest management.

Serotonin (5-hydroxytryptamine, 5-HT) is a key monoamine neurotransmitter in insects, which regulates neural functions and influences various developmental and physiological processes by binding to its receptors. In this study, we investigate the molecular characteristics, phylogenetic relationships, and expression patterns of the 5-HT7 receptor (Cf5-HT7) in Chrysopa formosa, with a focus on its potential involvement in developmental and diapause regulation. The Cf5-HT7 gene was identified and cloned from the C. formosa transcriptome, revealing an open reading frame of 1788 bp encoding a 596 amino acid protein. Sequence analysis confirmed that Cf5-HT7 is a typical class A G protein-coupled receptor, characterised by seven transmembrane domains and several post-translational modifications, including palmitoylation and N-glycosylation sites. Phylogenetic analysis revealed that Cf5-HT7 is most closely related to the 5-HT7 receptor from Chrysoperla carnea, with high conservation of key motifs involved in ligand binding and receptor activation. Expression analysis across different developmental stages of C. formosa showed that Cf5-HT7 is highly expressed in the first instar larvae, with significant upregulation observed during the prepupal stage. Under diapause-inducing conditions, Cf5-HT7 expression is modulated in a stage-specific manner, showing a marked decrease at the onset of diapause, followed by a significant increase during the mid-to-late diapause maintenance phase. These findings suggest that it plays a pivotal role in regulating development and diapause processes in C. formosa, offering new insights into the molecular mechanisms governing insect life cycle transitions. This study lays the groundwork for future research into the functional roles of 5-HT7 receptors in insect physiology and their potential applications in manipulating diapause.

Leaf epicuticular waxes play a crucial role in host selection of Spilosoma obliqua, Amsacta albistriga, Spodoptera litura, and Spilarctia luteum. The leaf epicuticular waxes of groundnut, soybean, mikania, and parthenium indicated the presence of 25 different n-alkanes (C14 to n-C36) and 15 free fatty acids (FFAs) (C12:0 to C22:0). All the chemical analysis and bioassays were conducted by using the standard protocols. The attraction index (AI %) and oviposition preference index (OPI %) of each pest species towards the combined-synthetic-mixtures of respective leaf wax chemicals (4 n-alkanes [n-C16, n-C18, n-C20, n-C22] + 4 FFAs [C14:0, C16:1, C16:0, C20:0]) were more preferred due to respective wax chemicals. The AI (%) and OPI (%) towards the said mixture (C3) of the selected host plants (groundnut > soybean > parthenium > mikania) were in the order of S. obliqua > S. litura > S. luteum > A. albistriga for better survival and growth of their neonates because of the respective amounts of leaf wax chemicals including other phytoconstituents. The said synthetic mixture in respective leaf equivalent amount (µg leaf−1) acted as the most preferred lure to develop baited trap and or groundnut as trap crop for soybean to support integrated pest management of such crops (groundnut and soybean). It also supports the use of such pest species as biocontrol agent for the exotic weeds (mikania and parthenium). This finding promotes sustainable pest and weed management for climate smart agriculture to maintain and sustain quality of our planet in the near future.