A General Signal Pathway to Regulate Multiple Detoxification Genes Drives the Evolution of <i>Helicoverpa armigera</i> Adaptation to Xenobiotics

The study of insect adaptation to the defensive metabolites of host plants and various kinds of insecticides in order to acquire resistance is a hot topic in the pest-control field, but the mechanism is still unclear. In our study, we found that a general signal pathway exists in H. armigera which can regulate multiple P450s, GSTs and UGTs genes to help insects decrease their susceptibility to xenobiotics. Knockdown of HaNrf2 and HaAhR expression could significantly increase the toxicity of xenobiotics to H. armigera, and simultaneously decrease the gene expression of P450s, GSTs and UGTs which are related to the xenobiotic metabolism and synthesis of insect hormone pathways. Then, we used EMSA and dual luciferase assay to verify that a crosstalk exists between AhR and Nrf2 to regulate multiple P450s, GSTs and UGTs genes to mediate H. armigera susceptibility to plant allelochemicals and insecticides. The detoxification genes’ expression network which can be regulated by Nrf2 and AhR is still unknown, and there were also no reports about the crosstalk between AhR and Nrf2 that exist in insects and can regulate multiple detoxification genes’ expression. Our results provide a new general signaling pathway to reveal the adaptive mechanism of insects to xenobiotics and provides further insight into designing effective pest-management strategies to avoid the overuse of insecticides

<i>Corynebacterium</i> sp. 2-TD Mediated Toxicity of 2-Tridecanone to <i>Helicoverpa armigera</i>

Cotton bollworm (Helicoverpa armigera) is a Lepidopteran noctuid pest with a global distribution. It has a wide range of host plants and can harm cotton, tomato, tobacco, and corn, as well as other crops. H. armigera larvae damage the flower buds, flowers, and fruits of tomato and cause serious losses to tomato production. Tomato uses the allelochemical 2-tridecanone to defend against this damage. So far, there have been no reports on whether the adaptation of H. armigera to 2-tridecanone is related to its symbiotic microorganisms. Our study found that Corynebacterium sp. 2-TD, symbiotic bacteria in H. armigera, mediates the toxicity of the 2-tridecanone to H. armigera. Corynebacterium sp. 2-TD, which was identified by 16S rDNA gene sequence analysis, was screened out using a basal salt medium containing a unique carbon source of 2-tridecanone. Then, Corynebacterium sp. 2-TD was confirmed to be distributed in the gut of H. armigera by quantitative PCR (qPCR) and fluorescence in situ hybridization (FISH). The survival rate of H. armigera increased by 38.3% under 2-tridecanone stress after inoculation with Corynebacterium sp. 2-TD. The degradation effect of Corynebacterium sp. 2-TD on 2-tridecanone was verified by ultra-high-performance liquid chromatography (UPLC). Our study is the first to report the isolation of gut bacteria that degrade 2-tridecanone from the important agricultural pest H. armigera and to confirm bacterial involvement in host adaptation to 2-tridecanone, which provides new insights into the adaptive mechanism of agricultural pests to host plants

Additional file 5 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 5: Fig. S4. The abundance of Sphingomonas in the gut of the IMI-S and IMI-R strains and SXYC, SDBZ, XJSW and HBHS field populations. The bars with lowercase letters (a, b, c) are significantly different according to one-way ANOVA, followed by Tukey's multiple comparison test (P< 0.05)

Additional file 8 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 8: Table S2. Collecting information of Aphis gossypii field populations

Additional file 6 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 6: Fig. S5. The stand curve of IMI (A), urea IMI (B) and 5-OH IMI (C)

Additional file 1 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 1: Table S1. Total reads and good coverage in different samples

Additional file 7 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 7: Fig. S6. The changes in OD600 value of Sphingomonas in the control group (A) and IMI group (B) during the 3-day cultivation. The bars with different lowercase letters (a, b, c) are significantly different (one-way ANOVA followed by Tukey's multiple comparison, P< 0.05)

Additional file 4 of The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

Additional file 4: Fig. S3. Detection of Sphingomonas in nine field populations in 2019. Bars represent the mean ± SE (P < 0.05, Tukey’s test)