Bacterial endosymbionts are ubiquitous in insects and play a critical role in host ecology, including adaptability to thermal extremes. The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a major agricultural pest in China that harbours diverse microbial symbionts. However, the contribution of Arsenophonus, a key secondary symbiont in A. gossypii, to the host's thermal tolerance remains poorly understood. In this study, we used antibiotics to eliminate Arsenophonus from A. gossypii and evaluated the effects on host thermal tolerance by comparing the life-history traits of an Arsenophonus-infected line (A-infected) and an antibiotic-cured, Arsenophonus-deleted line (A-deleted) across a temperature gradient (26-35 °C). Our results revealed that while host performance declined for both lines as temperatures increased, the magnitude of these fitness costs was significantly modulated by infection status. No significant differences in fitness parameters were observed at 26 °C or 29 °C. Furthermore, at 32 °C, the A-infected line exhibited significantly extended adult longevity compared with the A-deleted line. Under extreme heat stress (35 °C), the infected line surpassed the cured line in both longevity and fecundity. These results confirm the dependency of A. gossypii on Arsenophonus for a conditional fitness advantage at high temperatures, effectively broadening its thermal niche. Ultimately, this symbiont-mediated heat tolerance provides new insight regarding the ecological resilience and population stability of this pest in warming agricultural environments.

Hippodamia variegata (Coleoptera: Coccinellidae) is an important predator of the cotton aphid, Aphis gossypii, and it plays an important role in its biological control. However, widespread use of neonicotinoid insecticides such as imidacloprid may exert sublethal effects on non-target natural enemies. In this study, we evaluated the impact of sublethal imidacloprid exposure on the olfactory behavior of H. variegata and explored the underlying molecular mechanisms. Adult beetles were fed cotton aphids treated with imidacloprid at 3.93 mg a.i./L (LC20) and 13.62 mg a.i./L (LC50), and their olfactory responses to aphid-infested versus uninfested cotton leaves were assessed using a Y-tube olfactometer. In parallel, transcriptomic profiling was conducted on the antennae and brain tissues of adult male and female beetles from both control and treatment groups, followed by GO/KEGG enrichment analyses and qRT-PCR validation of candidate genes. Finally, RNA interference (RNAi) was used to functionally verify the roles of selected odorant-binding protein (OBP) genes in the sublethal effects observed. Y-tube assays showed that control adults exhibited significant attraction to aphid-infested cotton plants, whereas beetles of both sexes exposed to LC20 and LC50 imidacloprid lost this olfactory preference. Transcriptomic analyses revealed extensive differential gene expression in the antennae and brains of beetles treated with LC20 and LC50 compared with the control group, with differentially expressed genes significantly enriched in pathways associated with metabolic processes, ribosomes, RNA transport, and neural signaling. Notably, several olfaction and neural function-related genes, including Obp2, Obp7, Obp8, Obp10, Ten-m, and Nlg4, were significantly downregulated after imidacloprid exposure, and these patterns were confirmed by qRT-PCR. RNAi-mediated silencing of Obp2, Obp7, Obp8, and Obp10, which significantly reduced transcript levels and eliminated the olfactory preference for aphid-infested cotton plants in behavioral assays, supporting their essential roles in prey-related odor perception. Overall, our findings demonstrate that sublethal imidacloprid exposure impaired olfactory function in H. variegata and was associated with transcriptional disruptions in olfactory and neural signaling pathways, which may compromise its efficiency as a biological control agent. These results highlight the need to consider sublethal ecological risks of insecticide use and to optimize pesticide application strategies to better align with integrated pest management programs.

Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is an aphid parasitoid capable of developing in a wide range of pest aphids. Currently, laboratory rearing of B. communis in China mainly depends on the cotton aphid Aphis gossypii Glover (Hemiptera: Aphididae)-cotton system. Although technically reliable, this method entails high labor demands, extensive space requirements, and overall elevated costs. To identify a more efficient aphid-plant combination for mass rearing of B. communis, we evaluated this parasitoid's developmental performance, population growth, and rearing cost-effectiveness on four aphid-plant combinations: A. gossypii-cotton (Ago-Cot), A. gossypii-zucchini (Ago-Zuc), bean aphid Aphis fabae Scopoli (Hemiptera: Aphididae)-faba bean (Afa-FB), and greenbug Schizaphis graminum (Rondani) (Hemiptera: Aphididae)-wheat (Sgr-W). The Afa-FB and Sgr-W combinations shortened the developmental time of B. communis from larva to adult. Analysis of age-stage, two-sex life table showed that female parasitoids reared on Afa-FB reached their peak reproductive value earlier and reproduced at a higher level than those reared on the other three combinations, indicating enhanced reproductive potential. Comparative evaluation of rearing cycles further revealed that parasitizing A. fabae reared on faba bean supported rapid and consistently high rates of mummy formation, along with the highest rate of parasitism (38.68 ± 0.69%), highlighting the strong parasitic potential of the Afa-FB combination. Moreover, cost analysis indicated that, compared with the other three combinations, Afa-FB produced the highest number of mummies and had the lowest total material and labor costs (9.18 USD per 10,000 mummies), offering economic advantages. In conclusion, the Afa-FB combination represents a promising approach for more efficient mass rearing of B. communis.

Crop diversification is a promising strategy to strengthen pest control services in agricultural landscapes. Diversifying crops may limit pests through host crop dilution or by enhancing top-down control by their enemies. However, crop diversification may also benefit generalist pests through higher resource continuity. Using a large-scale dataset encompassing 742 landscapes across 13 countries, we assessed the impact of landscape-scale crop diversity on the abundance of natural enemies, the potential for biological control, and insect pest abundance. Crop diversification did not increase the overall abundance of natural enemies or the potential for biological pest control. Instead, crop diversity primarily favoured the abundance of specialist natural enemies and pests in highly simplified landscapes, an effect that was reduced in landscapes with high proportions of semi-natural habitats. Lastly, low proportions of host crops in the landscape were associated with higher abundances of natural enemies. Taken together, our results indicate that crop diversification is not a 'one size fits all' strategy to control agricultural pests, and that other landscape characteristics, such as high amounts of semi-natural habitats, must be considered to enhance biological pest control services.

IntroductionThe cotton aphid, Aphis gossypii Glover, is a globally significant agricultural pest that harbors diverse microbial symbionts. Beyond their well-known roles in nutrition, these microbial partners are increasingly recognized for their potential to modulate host detoxification pathways and influence insecticide susceptibility. While sulfoxaflor is a primary insecticide for controlling A. gossypii, the extent to which the predominant secondary symbiont, Arsenophonus, mediates susceptibility to this chemical remains largely unexplored.MethodsIn this study, we investigated the role of Arsenophonus in modulating host sulfoxaflor susceptibility and the underlying molecular mechanisms. We established an Arsenophonus-infected A. gossypii line (A-infected) and an antibiotic-cured, Arsenophonus-deleted line (A-deleted). To ensure identical genetic backgrounds and eliminate residual antibiotic effects, the A-deleted line was maintained for 10 generations under antibiotic-free conditions, with symbiont status confirmed by PCR and 16S rRNA sequencing. We then compared sulfoxaflor susceptibility, analyzed protein levels of detoxification enzymes, performed comparative transcriptomic analysis, and validated key candidate genes using RNA interference (RNAi).Results and discussionBioassays revealed that the elimination of Arsenophonus significantly increased susceptibility to sulfoxaflor. This hypersensitivity was metabolically associated with reduced protein levels of mixed-function oxidases (MFOs) and glutathione S-transferases (GSTs). Comparative transcriptomic analysis identified multiple differentially expressed cytochrome P450 genes, including CYP380C44, CYP380C45, CYP6J1, CYP6CY14, CYP6CY21, CYP4CJ1, and CYP4C1. Functional verification demonstrated that RNAi-mediated silencing of CYP380C44 in the A-infected line significantly increased sulfoxaflor mortality. Collectively, our findings demonstrate that the secondary symbiont Arsenophonus modulates the host response to sulfoxaflor by regulating P450-mediated metabolic pathways. Identifying CYP380C44 as a critical effector gene highlights the Arsenophonus-P450 axis as a potential molecular target for developing novel pest control strategies that exploit symbiotic vulnerabilities

Helicoverpa armigera is an important polyphagous pest causing substantial crop losses. The sterile insect technique (SIT) is an effective, environmentally friendly strategy for suppressing pest populations. We assessed dose-dependent effects of pupal X-ray irradiation (50-400 Gy; five doses) on male development and reproduction and then identified irradiation-responsive genes in adult testes. In our research, irradiation at 50-400 Gy did not affect parental male emergence or mating, nor the pre-oviposition and oviposition periods of non-irradiated females after mating. However, male deformity increased with dose and longevity was significantly shortened. Female fecundity and F1 egg hatchability declined markedly, and complete egg sterility was achieved at 400 Gy. Parental irradiation also impaired F1 performance by prolonging developmental duration, reducing emergence, shortening adult longevity, and decreasing reproduction. Specifically, at 200 Gy, F1 female and male longevity decreased to 10.23 d and 8.42 d, respectively, whereas it was 17.99 d and 19.43 d in the control. In addition, fecundity was reduced to 303.95 progeny per female compared with 1043.74 in the control. F2 egg hatchability also decreased with increasing irradiation dose. Testis transcriptome analysis identified 283 differentially expressed genes (DEGs) at 200 Gy compared with the control (147 up-regulated, 136 down-regulated) and 230 DEGs at 400 Gy (176 up-regulated, 54 down-regulated). Enrichment analyses indicated that 200 Gy mainly suppressed genes associated with chromosome organization/replication and core metabolism, whereas 400 Gy predominantly induced detoxification metabolism and immune response pathways. Thus, our findings indicate that 200 Gy appears to be a suitable sub-sterilizing dose and the transcriptomic data provides candidate targets for optimizing SIT in H. armigera.

Intercropping is a promising strategy for ecologically based pest management in field crops. However, its effects on pest suppression and crop yield vary across species combinations, requiring experiments to identify contextspecific driving principles and guide practical application. We evaluated the effects of intercropping cotton with spring wheat or maize on pest suppression and yield. Aphid and natural enemy populations were monitored in intercropped and sole cotton, and predation activity was assessed using cotton bollworm egg cards. Cotton yield was also measured. Aphid densities on cotton were 63 % lower in both cotton-wheat and cotton-maize than in sole cotton in 2023, and 24 % and 29 % lower in cotton-wheat and cotton-maize than in sole cotton in 2024. No significant difference was observed in cotton aphid control between the two intercrops in either year. Ladybeetle densities during early cotton aphid population build-up were higher in the two intercrops than in sole cotton. The predation rate on cotton bollworm eggs was 10 % - 178 % higher in intercrops with wheat and maize. Cotton yield was 18 % higher in cotton-wheat but 18 % lower in cotton-maize than in sole cotton. Different strength of interspecific plant competition is the likely key driver for the difference in yield impact of the two companion species. We conclude that both spring wheat and maize enhance natural enemies and reduce aphid populations in cotton, but only intercropping with wheat enhanced cotton yield. Results indicate that cotton-cereal intercropping is a robust strategy to suppress cotton aphid and reduce reliance on insecticides, but interspecific plant competition needs to be considered to ensure cotton yield.

Neoseiulus bicaudus Wainstein (Acari: Phytoseiidae), an important natural enemy of spider mites, is commonly reared on Tyrophagus putrescentiae Schrank (Acari: Acaridae) as a food source. As learning behavior enhances insect foraging efficiency, this study investigated the effects of learning behavior on the predation of Tetranychus turkestani Ugarov et Nikolskii (Acari: Tetranychidae) by N. bicaudus, by evaluating the effects of learning frequency and reward status on olfactory response and memory retention. The influence of learning experiences at different developmental stages on predation capacity as adults was also assessed, alongside the effect of learning behavior on control efficacy against Te. turkestani. Results showed that 4-nonreward learning enabled N. bicaudus to form memories lasting 0.5 h with olfactory behavioral changes, while 4-reward learning induced stable memory persisting 72 h and a significant olfactory preference for Te. Turkestani. This preference lasted at least 0.5 h and was not induced by nonreward learning. Learning experiences during the larval, deutonymphal, and female adult stages significantly increased the attack rate and prey handling time of female N. bicaudus. Among these groups, the female adult learning and larval learning groups showed the most significant predation efficiency, with maximum daily consumption of 17.54 and 19.61 prey individuals, respectively. Field trials confirmed that N. bicaudus trained through learning exhibited enhanced biological control efficacy. In conclusion, incorporating targeted learning into large-scale rearing enhances N. bicaudus's sensitivity to target prey, thereby improving biological control efficacy.

Binodoxys communis is a dominant endoparasitoid of aphids in cotton fields, yet empirical evidence on how temperature and humidity regulate its growth, development, and reproduction remains limited. To address this gap, we assessed the effects of both constant and fluctuating temperature, as well as various combinations of temperature and humidity, on the longevity, parasitism, and fecundity of this parasitoid. Our results revealed that adult longevity of B. communis was longer at 20 °C and 25 °C while significantly shortened at a high temperature (35 °C). Similarly, the parasitism rate, female ratio, emergence duration, and offspring longevity of the parasitoid were all superior at 20 °C and 25 °C compared to 15 °C and 35 °C. Moreover, the longevity of both male (6.96 ± 0.10 d) and female (6.88 ± 0.07 d) parasitoids was significantly extended at 25 °C and 60% RH. Temperature had a marked impact on the parasitic capability of parasitoids, with the number of Aphis gossypii parasitized daily by B. communis being significantly higher at 25 °C than at 15 °C and 35 °C. Nevertheless, humidity and the interaction between humidity and temperature had no significant influence on parasitic capacity. The parasitism of B. communis followed the Holling-II model, with the highest daily maximum parasitism observed at 25 °C. In conclusion, our study showed that 25 °C positively enhanced the fitness of B. communis, providing a valuable reference for indoor population expansion and field release of B. communis, potentially enhancing its effectiveness as a biological control agent against aphids.

Aphis gossypii is a highly polyphagous pest that causes substantial agricultural damage. Temperature and insecticides are two major abiotic stresses affecting their population abundance. Heat shock proteins play an essential role in cell protection when insects are exposed to environmental stresses. Three ApHsp70 genes were cloned from A. gossypii, and characterized their molecular features and expression profiles in response to temperature and insecticide stress. The deduced amino acid sequences of these proteins exhibited characteristic Hsp70 family signatures, and their tissue-specific expression patterns revealed their highest activity to be in the salivary glands under 35 °C. The temperature inductive assay further indicated that the expression of the three ApHsp70 genes was markedly upregulated under heat stress but not under cold shock. Furthermore, exposure to LC25 and LC50 concentrations of three insecticides triggered the upregulation of these ApHsp70 genes. The RNA interference (RNAi)-mediated suppression of ApHsp68 expression heightened cotton aphid's susceptibility to insecticides (acetamiprid and sulfoxaflor). Moreover, our study found that the sulfoxaflor-resistant strain of A. gossypii (Sul-R) displayed a higher survival rate compared with the sulfoxaflor-sensitive strain (Sul-S) under heat shock conditions. These results suggest that these three ApHsp70 genes play an essential role in response to both heat and insecticide stress.

Introduction:The cotton aphid Aphis gossypii is a significant polyphagous crop pest and has evolved a high level of resistance to neonicotinoids and other insecticides. Flavonoids, plant phytonutrients, have shown promise as natural insect deterrents and growth inhibitors. However, comprehensive evaluations of the effects of flavonoids on A. gossypii are currently lacking. Methods:In this study, we first evaluated the effects of seven flavonoids (kaempferol, genistein, daidzein, naringenin, rutin, luteolin, and apigenin) on aphid settling behavior using choice assays, followed by electrical penetration graph (EPG) recordings to assess their influence on feeding activity. We then measured honeydew excretion and conducted life table analysis under laboratory conditions to assess effects on growth and reproduction. Under greenhouse conditions, all seven flavonoids were tested for their inhibitory effects on A. gossypii population growth over 12 days. Based on the results, three effective flavonoids were selected for further testing at four concentrations (1×, 2×, 3×, and 4× of 1 μg/μL) to assess dose-dependent effects. Results:We found that all seven flavonoids significantly deterred aphid settling on host plants. Kaempferol, daidzein, naringenin, rutin, luteolin, and apigenin significantly reduced the total duration of phloem feeding and the proportion of time spent on phloem-related activities. And also, each of seven flavonoids reduced honeydew production compared to controls. In the laboratory, all flavonoids reduced adult longevity and fecundity, and kaempferol, genistein, daidzein, naringenin, luteolin and apigenin also reduced the net reproductive rate (R0), intrinsic rate of increase (rm), and finite rate of increase (λ). Naringenin, apigenin, and kaempferol significantly inhibited A. gossypii population growth in a dose-dependent manner over 12 days. Discussion:These results demonstrate that the seven flavonoids, especially naringenin, apigenin, and kaempferol tested provided effective management of A. gossypii populations by deterring host settling, reducing phloem feeding, honeydew production, and decreasing reproductive rates. This study highlights the potential of flavonoids as eco-friendly control agents against A. gossypii.

Diseases caused by vector-borne plant pathogens cause adverse impacts on yield resilience, food security, and farmer livelihoods, which are bound to aggravate under global change. Biological control is routinely discounted as a mitigation strategy for plant diseases, partially due to scarce and inconclusive empirical support. Here, using curated field survey data for 58 persistently or semi-persistently transmitted pathogens, we employ a multi-method approach to assess the role of resident (i.e., naturally occurring) biological control agents in these pathosystems. Our meta-analyses show how in planta pathogen incidence is strongly affected by vector abundance and infectivity. Meanwhile, biological control agent density negatively affects vector abundance and slows vector population build-up. Together, these relationships suggest that biological control lessens pathogen incidence by reducing vector abundance, though a paucity of data impedes direct, empirical demonstration of this effect. In particular, bipartite (mainly vector x pathogen) interactions have only been uncovered under field conditions for less than half of focal pathosystems. More so, just 5 % of studies simultaneously reported pathogen, vector, and biological control agent densities. Our study contests the long-standing dogma that arthropod-vectored pathogens cannot be mitigated through biological control, and accentuates how observational or manipulative field studies are imperative to grasp its full potential.

Roughly 40% of global agri-food production is lost to pests during an era when productivity gains are essential to humanity. Restoring farmland biodiversity for conservation biological control offers potential to secure win-win outcomes for yield and the environment. However, achieving this is hindered by gaps in our un-derstanding of agrobiodiversity, including a lack of data on the occurrence, identity, and interactions of farm-dwelling (plant, animal, microbial) biota. Limited interdisciplinary collaboration and weak policy frameworks exacerbate these is-sues. Comprehensive data capture using standardized metrics, universal proto-cols, farmer-scientist cooperation, and next-generation tools could consolidate the evidence base on which to reform farming practice. This will involve ecologists stepping outside their comfort zones to promote behavioral change and make ecological intensification a reality.

Chilo suppressalis is one of the most important rice pests worldwide, and chlorantraniliprole, abamectin, and methoxyfenozide have been widely used to control this pest in China. However, the control efficiency in the field has dramatically decreased in recent years. Therefore, assessing the impacts of different factors on C. suppressalis resistance is essential for maintaining control effectiveness and managing resistant populations. Herein, we investigated insecticide resistance and its potential influencing factors (biotic and abiotic factors) in C. suppressalis field populations, using bioassays and biochemical and molecular diagnostic approaches. The results showed that the resistance levels of most field populations of C. suppressalis have evolved to moderate-to-high levels to the tested insecticides. The toxicity correlation analysis indicated that there was a significant positive correlation between the resistance levels of abamectin and methoxyfenozide, whereas GST activity was positively correlated with abamectin and methoxyfenozide resistance in C. suppressalis. EST and P450 activities showed significantly positive correlation with the resistance of chlorantraniliprole and methoxyfenozide, while the increase in temperature enhanced EST enzyme activity and was positively correlated with the evolution of resistance to methoxyfenozide. Overall, our study provides a systematic understanding of the dynamic resistance status and its influencing factors of C. suppressalis to insecticides. These findings will help clarify the resistance levels and the influencing factors in the resistance development of C. suppressalis, providing a theoretical basis for the resistance management of this insect species.

Spider mites are globally distributed pests that cause significant damage to a wide range of crops. The use of predators for the control of pest mites is an effective and environmentally sustainable strategy. Stethorus punctillum Weise (Coleoptera: Coccinellidae), a well-known predator of spider mites, has been widely recognized as the primary natural enemy of pest mites in China. However, its pest control efficacy, particularly under field conditions, is not well known. In this study, we evaluated the biocontrol impact of S. punctillum on a key spider mite pest, Tetranychus urticae Koch (Acarina: Tetranychidae), through a combination of laboratory and field experiments. Laboratory assays showed that the predation rates in relation to the prey numbers were consistent with the Holling-II functional response model. The actually maximum predatory numbers of third-instars of S. punctillum, 3-day-old female adults, and male adults on the pest were 116.67, 181.67, and 166.67 mites per day, respectively, corresponding to the theoretically maximum values of 391.26, 498.07, and 413.95 mites per day individually. Field exclusion experiments demonstrated that both larval and adult stages of S. punctillum significantly suppressed spider mite populations’ growth across three different initial prey densities (80, 110, and 140 individuals for larvae; 100, 150, and 200 individuals for adults) on three economically important crops: maize, cotton, and apples. Within 96 h of their introduction, the pest population growth rate was reduced by 13.2–43.2% by larvae and 25.3–51.5% by adults of S. punctillum compared to predator-free control groups. These findings demonstrate that S. punctillum has a significant control efficacy on spider mite populations under both laboratory and field conditions, highlighting its potential as a promising biocontrol agent for integrated spider mite management in Northwest China.