Glyphosate decreases survival, increases fecundity, and alters the microbiome of the natural predator Harmonia axyridis (ladybird beetle).

Glyphosate is a widely-used herbicide that shows toxicity to non-target organisms. The predatory natural enemy Harmonia axyridis may ingest glyphosate present in pollen and aphid prey. The present study characterized the responses of adult H. axyridis to environmentally relevant concentrations of glyphosate (5, 10, and 20 mg/L) for one or five days. There were no obvious effects on adult H. axyridis survival rates or fecundity in response to 5 or 10 mg/L glyphosate. However, exposure to 20 mg/L glyphosate significantly reduced the survival rate and increased fecundity. Analysis of the adult H. axyridis microbiota with 16S rRNA sequencing demonstrated changes in the relative and/or total abundance of specific taxa, including Serratia, Enterobacter, Staphylococcus, and Hafnia-Obesumbacterium. These changes in symbiotic bacterial abundance may have led to changes in survival rates or fecundity of this beetle. This is the first report of herbicide-induced stimulation of fecundity in a non-target predatory natural enemy, reflecting potentially unexpected risks of glyphosate exposure in adult H. axyridis. Although glyphosate resistant crops have been widely planted, the results of this study indicate a need to strengthen glyphosate management to prevent over-use, which could cause glyphosate toxicity and threaten environmental and human health.

Assessment of the risk of imidaclothiz to the dominant aphid parasitoid Binodoxys communis (Hymenoptera: Braconidae).

The neonicotinoid of imidaclothiz insecticide with low resistance and high efficiency, has great potential for application in pest control in specifically cotton field. In this systematically evaluate the effects of sublethal doses of imidaclothiz (LC10: 11.48 mg/L; LC30: 28.03 mg/L) on the biology, transcriptome, and microbiome of Binodoxys communis, the predominant primary parasitic natural enemy of aphids. The findings indicated that imidaclothiz has significant deleterious effects on the survival rate, parasitic rate, and survival time of B. communis. Additionally, there was a marked reduction in the survival rate and survival time of the F1 generation, that is, the negative effect of imidaclothiz on B. communis was continuous and trans-generational. Transcriptome analysis revealed that imidaclothiz treatment elicited alterations in the expression of genes associated with energy and detoxification metabolism. In addition, 16S rRNA analysis revealed a significant increase in the relative abundance of Rhodococcus and Pantoea, which are associated with detoxification metabolism, due to imidaclothiz exposure. These findings provide evidence that B. communis may regulate gene expression in conjunction with symbiotic bacteria to enhance adaptation to imidaclothiz. Finally, this study precise evaluation of imidaclothiz's potential risk to B. communis and provides crucial theoretical support for increasing the assessment of imidaclothiz in integrated pest management.

Sublethal toxicity of sulfoxaflor to parasitoid Binodoxys communis Gahan.

Integrated pest management is focused on combining biological and chemical controls. There is evidence of a negative impact of neonicotinoids on biological control, however, sulfoxaflor (SFX), a novel insecticide, its impact on parasitoid natural predator remain limited. Binodoxys communis is an important parasitic natural enemy of Aphis gossypii, which may have direct and indirect toxicity from the insecticides and aphids. Understanding the potential threat of SFX to B. communis is therefore essential to integrated pest management and the conservation of parasitoids. Here, the effects of sublethal doses of SFX on B. communis larvae and adults are presented for the first time. Sublethal SFX doses had a significant negative effect on the survival rate, adult life span, duration of development, and rate of parasitism. Moreover, exposure to sublethal SFX doses also had adverse effects on the biological performance of the next generation of B. communis. Based on the transcriptome analysis, the expression of genes involved in fatty acid metabolism, glycerolipid metabolism, glycerophospholipid metabolism, peroxidase, lysosomes, glutathione metabolism, drug metabolism, and CYP450 were significantly shifted by sublethal SFX exposure. These results indicate that sublethal SFX doses might adversely affect the biological performance of B. communis by altering gene expression related to the function of detoxification systems and energy metabolism. In conclusion, considering the beneficial ecological services of provided by parasitoids and the negative effects of sulfoxaflor across a greater usage scale, we emphasize the importance to optimize pesticide applications in IPM packages, in order to ensure the safety and survival of natural pest parasitoids.

Exposure to flupyradifurone affect health of biocontrol parasitoid Binodoxys communis (Hymenoptera: Braconidae) via disrupting detoxification metabolism and lipid synthesis.

Assessing the potential effects of insecticides on beneficial biological control agents is key to facilitating the success of integrated pest management (IPM) approaches. Flupyradifurone (FPF) is a novel neonicotinoid insecticide that is replacing traditional neonicotinoids over a large geographical range to control pests. Binodoxys communis, is the dominant parasitic natural enemy of aphids. To date, no reports have addressed sublethal effects of FPF on B. communis. In this study, the lethal and sublethal effects of FPF on B. communis were investigated by indirect exposure to larvae and direct exposure to adults. Results showed that the sublethal LC10 and LC25 of FPF had negative effects on the biological parameters of B. communis, including significantly reducing survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonging the developmental stages from egg to cocoons. In addition, we observed a transgenerational effect of FPF on the next generation (F1). RNA-Seq transcriptomic analysis identified a total of 1429 differentially expressed genes (DEGs) that were significantly changed between FPF-treated and control groups. These DEGs are mainly enriched in metabolic pathways such as peroxisomes, glutamate metabolism, carbon metabolism, fatty acid metabolism, and amino acid metabolism. This report is the first comprehensive evaluation of how FPF effects B. communis, which adds to the methods of assessing pesticide exposure in parasitic natural enemies. We speculate that the significant changes in pathways, especially those related to lipid synthesis, may be the reason for weakened parasitoid biocontrol ability. The present study provides new evidence for the toxic effects and environmental residue risk of FPF.

Response of the Pardosa astrigera bacterial community to Cry1B protein.

While genetically modified (GM) crops bring economic benefits to human beings, their impact on non-target organisms has become an important part of environmental safety assessments. Symbiotic bacteria play an important role in eukaryotic biological functions and can adjust host communities to adapt to new environments. Therefore, this study examined the effects of Cry1B protein on the growth and development of non-target natural enemies of Pardosa astrigera (L. Koch) from the perspective of symbiotic bacteria. Cry1B protein had no significant effect on the health indicators of P. astrigera (adults and 2nd instar spiderlings). 16S rRNA sequencing results revealed that Cry1B protein did not change the symbiotic bacteria species composition of P. astrigera, but did reduce the number of OTU and species diversity. In 2nd instar spiderlings, neither the dominant phylum (Proteobacteria) nor the dominant genus (Acinetobacter) changed, but the relative abundance of Corynebacterium-1 decreased significantly; in adult spiders, the dominant bacteria genera of females and males were different. The dominant bacterial genera were Brevibacterium in females and Corynebacterium-1 in males, but Corynebacterium-1 was the dominant bacteria in both females and males feeding on Cry1B. The relative abundance of Wolbachia also increased significantly. In addition, bacteria in other genera varied significantly by sex. KEGG results showed that Cry1B protein only altered the significant enrichment of metabolic pathways in female spiders. In conclusion, the effects of Cry1B protein on symbiotic bacteria vary by growth and development stage and sex.

Transgenic cotton expressing Cry1B protein has no adverse effect on predatory insect Propylea Japonica.

The lady beetle Propylea japonica is a dominant natural predator of insect pests in farmland ecosystems and an important non-target indicator insect for the environmental safety assessment of GM crops. The commercial cultivation of GM crops may cause P. japonica to frequently be exposed to the Bt protein environment. In this study, the biological characteristics, enzyme activity, and expression levels of detoxification and metabolism in P. japonica were studied after Cry1B protein treatment. No significant differences were observed in developmental duration, emergence rate, or body weight at different ages after feeding larvae 0.5 mg/mL of Cry1B protein compared with the control. Furthermore, there were no significant differences in the activities of glutathione S-transferase (GST), catalase (CAT), and peroxidase (POD) after feeding 0.25 mg/mL and 0.5 mg/mL Cry1B protein. However, when the concentration of Cry1B protein increased to 1.0 mg/mL, the activities of the GST, CAT, and POD increased significantly. Compared with the control group, there were no significant differences in the expression levels of most detoxification metabolism related genes; only a few genes had changed expression levels at the individual concentrations (CYP345B1, CYP4Q2, CYP9F2, GST, and microsomal GST). Overall, these results suggest that Cry1B protein has little or no effect on the biological characteristics of P. japonica. Genes related to enzyme activity and detoxification are differentially expressed at high concentration stimulation. Therefore, this research suggests that the potential risks of Cry1B for the predator P. japonica are negligible.

Transgenic insect-resistant Bt cotton expressing Cry1Ac/1Ab does not harm the insect predator Geocoris pallidipennis.

The large-scale commercial cultivation of genetically modified (GM) cotton has brought significant economic and environmental benefits. However, GM crops must undergo strict environmental monitoring and long-term observation. An important natural enemy insect in cotton fields, Geocoris pallidipennis, can ingest the Bt protein expressed in GM cotton by feeding on herbivorous insects that feed on the cotton. However, the potential risk of GM cotton to G. pallidipennis is still unclear. We here evaluated the effects of Bt cotton expressing the Cry1Ac/1Ab protein on nymphs and adults G. pallidipennis. Cry1Ac protein was detected in the midgut of the cotton bollworm, Helicoverpa armigera, after it ingested Bt cotton, and in the midgut of G. pallidipennis nymphs and adults preying on Bt-fed H. armigera. However, the survival rate, growth, development, and fecundity of G. pallidipennis were not adversely affected. Furthermore, G. pallidipennis cadherins, and those genes related to detoxification, antioxidant activity, nutrient utilization, and immune function were not differentially expressed in response to Cry1Ac exposure. Finally, we showed that Cry1Ac could not bind to brush border membrane vesicles (BBMV) proteins in G. pallidipennis nymphs or adults. In summary, these results indicate that the potential negative effect of transgenic Cry1Ac/1Ab cotton on the insect redator G. pallidipennis is negligible.

Knockdown of cytochrome P450 gene CYP6AB12 based on nanomaterial technology reduces the detoxification ability of Spodoptera litura to gossypol.

In insects, cytochrome P450 monooxygenases (P450s or CYPs) play an important role in the detoxification and metabolism of exogenous plant allelochemicals. In this study, a P450 gene CYP6AB12 was identified and characterized from Spodoptera litura. The cDNA contains an open reading frame (ORF) encoding 511 amino acid residues. CYP6AB12 was expressed at different ages of S. litura, with the highest levels found in the third and fourth instar larvae. Its highest expression was found in the midgut and fat body of fourth instar larvae fed with gossypol. Moreover, these expression levels were substantially increased compared with those from larvae fed with control diet. Gene silencing was then conducted by smearing dsRNA mixed with nanomaterials onto the cuticle. CYP6AB12 expression was significantly decreased in the midgut and fat body, and the net weight increase was substantially lower than that of the control group, indicating that the treatment group had more sensitivity to gossypol than the control. These results reveal that CYP6AB12 plays an important role in the detoxification and metabolism of gossypol, thus further confirming that P450s have a broad ability to detoxify and metabolize plant allelochemicals. It provides an important molecular basis for the exploration of detoxification metabolism and pest control of S. litura.

Dynamic transcriptome analysis and Methoprene-tolerant gene knockdown reveal that juvenile hormone regulates oogenesis and vitellogenin synthesis in Propylea Japonica.

Propylea japonica has been regarded as one of the most remarkable natural enemies against aphid in China. However, the mechanism of juvenile hormone (JH) regulation of reproduction in P. japonica is still unclear. In this study, we investigated the JH titers of P. japonica and the development of the ovaries. We selected the six different developmental stages of ladybeetle females for transcriptome sequencing. We identified 583 genes involved in insect reproduction regulation, including 107 insect hormone synthesis signaling pathway-related genes and 476 nutrition-sensing signaling pathway-related genes. Transcriptome analysis indicated that a large number JH synthesis- and metabolism-related enzyme genes and some potential nutrient signal sensing- and transduction-related genes were significantly differentially expressed during P. japonica development. We investigated the effects of Met gene silencing on the reproduction of female adults and found that the ovarian maturation, vitellogenesis, and follicular epithelium development in the dsMet treatment group were significantly inhibited.

Molecular Evidence that Lysiphlebia japonica Regulates the Development and Physiological Metabolism of Aphis gossypii.

Lysiphlebia japonica Ashmead (Hymenoptera, Braconidae) is an endophagous parasitoid and Aphis gossypii Glover (Hemiptera, Aphididae) is a major pest in cotton. The relationship between insect host-parasitoids and their hosts involves complex physiological, biochemical and genetic interactions. This study examines changes in the development and physiological metabolism of A. gossypii regulated by L. japonica. Our results demonstrated that both the body length and width increased compared to non-parasitized aphids. We detected significantly increases in the developmental period as well as severe reproductive castration following parasitization by L. japonica. We then used proteomics to characterize these biological changes, and when combined with transcriptomes, this analysis demonstrated that the differential expression of mRNA (up or downregulation) captured a maximum of 48.7% of the variations of protein expression. We assigned these proteins to functional categories that included immunity, energy metabolism and transport, lipid metabolism, and reproduction. We then verified the contents of glycogen and 6-phosphate glucose, which demonstrated that these important energy sources were significantly altered following parasitization. These results uncover the effects on A. gossypii following parasitization by L. japonica, additional insight into the mechanisms behind insect-insect parasitism, and a better understanding of host-parasite interactions.

Integrated Omics Analysis Reveals Key Pathways in Cotton Defense against Mirid Bug (Adelphocoris suturalis Jakovlev) Feeding.

The recent dominance of Adelphocoris suturalis Jakovlev as the primary cotton field pest in Bt-cotton-cultivated areas has generated significant interest in cotton pest control research. This study addresses the limited understanding of cotton defense mechanisms triggered by A. suturalis feeding. Utilizing LC-QTOF-MS, we analyzed cotton metabolomic changes induced by A. suturalis, and identified 496 differential positive ions (374 upregulated, 122 downregulated) across 11 categories, such as terpenoids, alkaloids, phenylpropanoids, flavonoids, isoflavones, etc. Subsequent iTRAQ-LC-MS/MS analysis of the cotton proteome revealed 1569 differential proteins enriched in 35 metabolic pathways. Integrated metabolome and proteome analysis highlighted significant upregulation of 17 (89%) proteases in the α-linolenic acid (ALA) metabolism pathway, concomitant with a significant increase in 14 (88%) associated metabolites. Conversely, 19 (73%) proteases in the fructose and mannose biosynthesis pathway were downregulated, with 7 (27%) upregulated proteases corresponding to the downregulation of 8 pathway-associated metabolites. Expression analysis of key regulators in the ALA pathway, including allene oxidase synthase (AOS), phospholipase A (PLA), allene oxidative cyclase (AOC), and 12-oxophytodienoate reductase3 (OPR3), demonstrated significant responses to A. suturalis feeding. Finally, this study pioneers the exploration of molecular mechanisms in the plant-insect relationship, thereby offering insights into potential novel control strategies against this cotton pest.

Comparative transcriptome and proteome reveal the unique genes and proteins of female parasitic wasps, Lysiphlebia japonica Ashmead.

BACKGROUND: Lysiphlebia japonica Ashmead (Hymenoptera, Braconidae) is an endophagous parasitoid wasp and its host, Aphis gossypii Glover (Hemiptera, Aphididae) is a major cotton pest. L. japonica affects the growth and fatty acid metabolism of cotton aphids after parasitization and has been widely used as a biocontrol agent. However, there are currently few reports about the molecular characteristics of L. japonica, especially the differences between male and female. RESULTS: In this study, using transcriptome and proteome analysis of the abdomen of female and male parasitic wasps, respectively, we obtained a total of 27,169 DEGs and 1,194 DEPs, then a total of 909 positively correlated high-expression proteins and genes were obtained by combined omics analysis. Subsequently, 20 differentially expressed abdomen specific proteins were selected for validation by RT-qPCR and Multiple Reaction Monitoring (MRM) protein verification. The result of RT-qPCR demonstrated that all 20 genes were highly expressed in the abdomen of females, and five target proteins with unique peptide fragments and identification profiles were identified by MRM, which were venom protease, tropomyosin, lipase member I, venom serine carboxypeptidase and calreticulin, respectively. CONCLUSION: Overall, these results provided molecular resources for the differences between males and females in L. japonica and the screened 20 abdomen specific proteins were verified to demonstrate the validity of the data, which offered important molecular data resources for further studies on the related functional genes of parasitic wasps and the mechanism of parasitoids regulating the growth of aphids. © 2023 Society of Chemical Industry.

Silencing the rhythm gene AgCLK-1 reduced feeding of Aphis gossypii.

The cotton aphid Aphis gossypii Glover is an important cotton pest, and means of controlling this insect is a primary research focus. Although biological rhythm is an important mechanism that regulates numerous insect processes and activities, its role in cotton aphid has not been elucidated. In the present study, four highly-expressed circadian rhythm genes were selected from the cotton aphid genome database and their physicochemical properties and protein structures were analyzed. These genes were in the Takeout, Timeless, and Timeless interacting-related families, and the corresponding proteins contained highly-conserved Swis and TIMELESS domains. Gene expression analysis at multiple developmental stages revealed differing expression patterns between the four genes. AgCLK-1 had the highest relative expression of the four, especially during the nymph period. Silencing AgCLK-1 caused a significant refusal of the cotton aphids to feed at 1, 3, and 5 d of treatment. These results demonstrated that AgCLK-1 played a key role in regulating the feeding behavior of cotton aphid. This new functional understanding provides novel insights into cotton aphid biology and suggests new targeting strategies for agricultural pest control.

Thripidae pest species community identification and population genetic diversity analyses of 2 dominant thrips in cotton fields of China.

Thrips are devastating pests for various crops, and they can rasp tender leaves, terminal buds, and flowers, which specifically causing huge economic losses to cotton production. However, there is very little knowledge about the species composition of thrips in mainland China, as well as the genetic structure of the thrips populations, particularly in the cotton-producing regions. In this study, thrips were collected from 40 geographical locations at 8 different provinces which representing majority cotton-producing belts in China, and mitochondrial cytochrome oxidase subunit I sequence was used to identify species composition and evaluate the genetic diversity of collected thrips individuals. Based on experimental results proven that overall, 10 and 8 species of thrips were identified in seedling and flowering stage respectively, which is corresponding dominant species are Thrip tabaci (Lindeman) and Frankliniella intonsa (Trybom). Genetically, 24 haplotypes were identified in 310 T. tabaci individuals from 10 locations, and 263 haplotypes were detected in 1,861 F. intonsa individuals from 40 locations. Hap1 (T. tabaci) is the most widely distributed haplotype among all the T. tabaci samples. Likewise, Hap 2 is the most widely distributed and abundant haplotype among all samples of F. intonsa. The genetic differentiation degrees of T. tabaci between SXYC population and other 9 populations were high, but its gene flow in these 10 regions was relatively low, which might be due to geographical barriers. The Mantel tests showed no correlation between genetic distance and geographic distance of the 2 thrip species. Demographic analysis results showed that both T. tabaci and F. intonsa experienced population expansion in China. Taken together, this study identifies the species composition of thrips in major cotton-producing regions at different growth periods and evaluates effects of geomorphology on the geographical distribution of haplotypes of dominant thrips T. tabaci and F. intonsa.

Sublethal acetamiprid affects reproduction, development and disrupts gene expression in Binodoxys communis.

At present, understanding of neonicotinoid toxicity in arthropods remains limited. We here evaluated the lethal and sublethal effects of acetamiprid in F0 and F1 generations of Binodoxys communis using a range of sublethal concentrations. The 10% lethal concentration (LC10) and half lethal concentration (LC25) of ACE had negative effects on the B. communis survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonged the duration of the developmental cycle. ACE also had intergenerational effects, with some biological indices affected in the F1 generation after pesticide exposure. Transcriptomic analysis demonstrated that differentially expressed genes were enriched in specific pathways including the amino acid metabolism, carbohydrate metabolism, energy metabolism, exogenous metabolism, signal transduction, and glutathione metabolism pathways. These results indicated strong contact toxicity of ACE to B. communis, which may inhibit their biological control capacity. These results improve our understanding of the toxicological mechanisms of parasitic natural enemies in response to insecticide exposure.

Effects of sublethal fipronil exposure on cross-generational functional responses and gene expression in Binodoxys communis.

The effective systemic insecticide fipronil is widely used on a variety of crops and in public spaces to control insect pests. Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is the dominant natural enemy of Aphis gossypii Glover (Homoptera: Aphididae), an important cotton pest, and has good efficiency in inhibiting aphid populations. The direct effects of environmental residues of sublethal fipronil doses on adult B. communis have not previously been reported. This study therefore aimed to evaluate the side effects and transcriptomic impacts of sublethal fipronil doses on B. communis. The results showed that exposure to the LC10 dose of fipronil significantly reduced the survival rate and parasitism rate of the F0 generation, but did not affect these indicators in the F1 generation. The LC25 dose did not affect the survival or parasitic rates of the F0 generation, but did significantly reduce the survival rate of F1 generation parasitoids. These results indicated that sublethal doses of fipronil affected B. communis population growth. Transcriptome analysis showed that differentially expressed genes (DEGs) in B. communis at 1 h after treatment were primarily enriched in pathways associated with fatty acid elongation, biosynthesis of fatty acids, and fatty acid metabolism. DEGs at 3 days after treatment were mainly enriched in ribosomal functions, glycolysis/gluconeogenesis, and tyrosine metabolism. Six DEGs (PY, ELOVL, VLCOAR, MRJP1, ELOVL AAEL008004-like, and RPL13) were selected for validation with real-time fluorescent quantitative PCR. This is the first report of sublethal, trans-generational, and transcriptomic side effects of fipronil on the dominant parasitoid of A. gossypii. The results of this study show that adaptation of parasitoids to high concentrations of pesticides may be at the expense of their offspring. These findings broaden our overall understanding of the intergenerational adjustments used by insects to respond to pesticide stress and call for risk assessments of the long-term impacts and intergenerational effects of other pesticides.

Moderate nitrogen application facilitates Bt cotton growth and suppresses population expansion of aphids (Aphis gossypii) by altering plant physiological characteristics.

Introduction: Excessive application of nitrogen fertilizer in cotton field causes soil and water pollution as well as significant increase of aphid population. Reasonable fertilization is an important approach to improve agricultural production efficiency and reduce agriculture-derived pollutions. This study was aimed to explore the effects of nitrogen fertilizer on the Bt cotton physiological characteristics and the growth and development of A. gossypii, a sap-sucking cotton pest. Methods: Five different levels of Ca(NO3)2 (0.0 g/kg, 0.3 g/kg, 0.9 g/kg, 2.7 g/kg and 8.1 g/kg) were applied into vermiculite as nitrogen fertilizer in order to explore the effects of nitrogen fertilizer on the growth and development of Bt cotton and aphids. Results: The results showed that the medium level of nitrogen fertilizer (0.9 g/kg) effectively facilitated the growth of Bt cotton plant and suppressed the population expansion of aphids, whereas high and extremely high nitrogen application (2.7 and 8.1 g/kg) significantly increased the population size of aphids. Both high and low nitrogen application benefited aphid growth in multiple aspects such as prolonging nymph period and adult lifespan, enhancing fecundity, and improving adult survival rate by elevating soluble sugar content in host Bt cotton plants. Cotton leaf Bt toxin content in medium nitrogen group (0.9 g/kg) was significantly higher than that in high (2.7 and 8.1 g/kg) and low (0.3 g/kg) nitrogen groups, but Bt toxin content in aphids was very low in all the nitrogen treatment groups, suggesting that medium level (0.9 g/kg) might be the optimal nitrogen fertilizer treatment level for promoting cotton seedling growth and inhibiting aphids. Discussion: Overall, this study provides insight into trophic interaction among nitrogen fertilizer levels, Bt cotton, and cotton aphid, and reveals the multiple effects of nitrogen fertilizer levels on growth and development of cotton and aphids. Our findings will contribute to the optimization of the integrated management of Bt cotton and cotton aphids under nitrogen fertilization.

Variation of Helicoverpa armigera symbionts across developmental stages and geographic locations.

Cotton bollworm (Helicoverpa armigera) poses a global problem, causing substantial economic and ecological losses. Endosymbionts in insects play crucial roles in multiple insect biological processes. However, the interactions between H. armigera and its symbionts have not been well characterized to date. We investigated the symbionts of H. armigera in the whole life cycle from different geographical locations. In the whole life cycle of H. armigera, Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria were the dominant bacteria at the phylum level, while Enterococcus, Enterobacter, Glutamicibacter, and Bacillus were the four dominant bacteria at the genus level. Furthermore, high similarity in symbiotic bacterial community was observed in different stages of H. armigera, which were dominated by Enterococcus and Enterobacter. In fields, the dominant bacteria were Proteobacteria and Bacteroidetes, whereas, in the laboratory, the dominant bacteria were Proteobacteria. At the genus level, the dominant bacteria in cotton bollworm eggs of wild populations were Enterobacter, Morganella, Lactococcus, Asaia, Apibacter, and Enterococcus, and the subdominant bacteria were Bartonella, Pseudomonas, and Orbus. Moreover, the symbionts varied with geographical locations, and the closer the geographical distance, the more similar the microbial composition. Taken together, our study identifies and compares the symbiont variation along with geographical gradients and host development dynamic and reveals the high flexibility of microbiome communities in H. armigera, which probably benefits for the successful survival in a complicated changing environment.

Sexually dimorphic morphology, feeding behavior and gene expression profiles in cotton aphid Aphis gossypii.

BACKGROUND: Sexual dimorphism exists in most insects; however, less is known about sexual dimorphism in aphids. In this study, we identified sexually dimorphic differences in morphology, feeding behavior and gene expression between sexual females and males of the cotton aphid through electron microscopy, electrical penetration graph techniques and RNA sequencing. RESULTS: All males were alate with a slender reddish-yellow body and abdominal yellow-black stripes, whereas all sexual females were apterous with a pudgy green body. Sensillum types on the antennae were identical between the two sexes, although males had more sensilla, possibly because the antennae are significantly longer in males compared with sexual females. In terms of feeding behavior, males spent more time probing mesophyll cells and the phloem sieve, and salivating into the phloem sieve. By contrast, sexual females spent more time ingesting xylem sap. In total, 510 and 724 genes were specifically expressed in sexual females and males, respectively, and were significantly enriched in signaling pathways related to reproduction for sexual females (e.g. ovarian steroidogenesis, oxytocin signaling pathway) and energy and flight for males (e.g. thermogenesis, insulin signaling pathway). Moreover, 8551 differentially expressed genes were identified between the two sexes, of which the 3720 upregulated genes in sexual females were mostly enriched in signaling pathways of metabolism and energy, such as thermogenesis and the citrate cycle. CONCLUSION: This study provides insight into sexual dimorphism in aphids and lays a foundation for revealing the molecular mechanism underlying differences between the two sexes in cotton aphid. © 2023 Society of Chemical Industry.

Insulin Receptor Substrate-1 (IRS1) Regulates Oogenesis and Vitellogenesis in Propylea japonica by Mediating the FOXO Transcription Factor Expression, Independent of JH and 20E Signaling Pathways.

The insulin receptor substrate (IRS), as the core cytoplasmic adapter protein in the insulin/insulin-like signaling (IIS) pathway, is an important mediator of cellular signaling. However, it is still unknown how IRS crosstalk with hormone signaling regulates insect growth, development, and reproduction. In this study, we demonstrated that knockdown of IRS1 significantly inhibited oogenesis, vitellogenesis, and the development of nurse cells and follicular epithelial cells. In addition, qRT-PCR results showed that FOXO transcription factors significantly responded to silencing of the IRS1 gene. However, IRS1 silencing had no significant effect on the expression of juvenile hormone/20-hydroxyecdysone (JH/20E)-signaling genes, JH synthesis, and degradation enzyme-related genes and the JH/20E titers. Our results suggested that the IIS pathway regulated ovarian development and Vg production through FOXO, independent of JH and 20E signaling pathways. This study revealed the reproductive regulation mechanism in Propylea japonica, which provides a theoretical basis for large-scale expansion of P. japonica as an environment-friendly biological control strategy.