Ectropis grisescens Warren and Ectropis obliqua (Prout) are two morphologically similar sibling species with overlapping ranges. In this study, manipulative laboratory experiments were conducted to examine the possibility of reproductive interference in sympatric populations of E. grisescens and E. obliqua and the potential consequences of the mating interaction. Our results showed that the presence of males or females of different species could incur mating interference and significant reduction of F1 offspring. The reduction was not significant relevant to the initial relative abundance of E. grisescens and E. obliqua. Detailed observations of mating opportunity showed that female mating frequencies of both species were not significantly affected by the absolute species density, but the mating success of E. obliqua females with conspecific males depended on species ratio. In addition, adding males to the other species resulted in lower number of offspring suggesting that the males’ behaviour might be linked with mating interference. Males of both E. grisescens and E. obliqua could interfere the intraspecific mating of the other species, but the impact of the mating interference differed. These combined data indicated that asymmetric reproductive interference existed in E. grisescens and E. obliqua under laboratory conditions, and the offspring of the mixed species were significantly reduced. The long term outcome of this effect is yet to be determined since additional reproductive factors such as oviposition rate and progeny survival to adulthood may reduce the probability of demographic displacement of one species by the other in overlapping niches.

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.

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.

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.

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.

The olive black scale, Saissetia oleae (Olivier), is a significant pest of olive crops worldwide. The developmental, reproductive, and population growth parameters of S. oleae were evaluated under five constant temperature conditions (18°C to 33°C). Developmental durations significantly decreased with increasing temperatures. Female lifespan decreased from 161.6 days at 18°C to 104.3 days at 33°C, while male lifespan decreased from 96.8 days at 18°C to 49.4 days at 33°C. The highest sex ratio (proportion of females) of 0.35 was observed at 30°C, with pre-adult survival rates of 63%, while survival rates dropped to 28% at 18°C. Parthenogenesis was not observed in females. The total pre-oviposition and post-oviposition periods decreased with increasing temperature, with the longest oviposition period at 33°C (49.6 days). Maximum fecundity was recorded at 33°C (379.0 eggs/female), followed by 30°C (298.6 eggs/female), and decreased sharply at 18°C (90.1 eggs/female). The intrinsic rate of increase (r) was highest at 30 and 33°C (0.038 d⁻1), while the net reproductive rate (R0) peaked at 30°C (104.5 offspring/female). The predicted fecundity of the next generation showed significant potential growth at 27 and 30°C, with the population increasing 65.3 times at 30°C and 39.4 times at 27°C. The developmental threshold for S. oleae was highest for first-instar nymphs (7.58°C), while second-instar nymphs had lower thresholds (1.09–1.65°C), with total pre-adult development requiring 1250 degree-days for both males and females. These findings underscore the significant impact of temperature on the development and reproduction of S. oleae, with implications for pest management in olive orchards.

Aphids are important pests of cereal crops and cause economically significant damage through direct feeding and the transmission of plant viruses. In Europe, the aphid species of greatest concern are the grain aphid (Sitobion avenae Fabricius) and the bird cherry-oat aphid, (Rhopalosiphum padi Linnaeus). Often, cereal crops are dominated by a small number of prolific clonal populations and these populations can differ in phenotypic traits of agricultural importance. There are two heritable factors that influence aphid phenotype: aphid genetic diversity and the presence of endosymbionts.

Here, multiple cereal aphid populations are used to determine how heritable factors influence aphid phenotype. Several agriculturally important phenotypic traits are examined, and both endosymbiont- and genotype-derived phenotypes are identified. For S. avenae, aphid genotype influences all phenotypic traits assessed, and association with the facultative endosymbiont Regiella insecticola influences alate morph production with co-infection of R. insecticola and Fukatsuia symbiotica increasing reproductive output. For R. padi, adult aphid morph (apterous or alate) is the key driver behind reproductive output, with a genotype × morph effect also found to influence development time.

Overall, these results provide insight into the biological drivers behind phenotypic diversity in agriculturally important aphid species. Being able to associate heritable factors with key phenotypes can generate biological insights into the processes underpinning the dominance of specific aphid clones and can be used to develop pest and disease management strategies based around the phenotypic risk of the aphid populations present.

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.

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.

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.

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.

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.

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.

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.