Insect cuticular hydrocarbons (CHCs) play important roles in mate recognition and chemical communication. To explore the cues regulating courtship and mating behaviour in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), CHCs were extracted from mature virgin female and male oriental fruit flies using n‐hexane. Nine compounds – i.e., 4‐allyl‐2,6‐dimethoxyphenol (designated ‘compound 3’) and eight ester compounds – had significantly greater abundance in female samples than in males. Of these nine compounds, six (1, 2, 4, 5, 6, and 8) elicited electrophysiological responses from the antennae of male flies. Compound 3 did not elicit a detectable male antennal response, but in Y‐tube olfactometer bioassays, it exhibited robust attractiveness to conspecific males at close range. We speculate that compound 3 is a close‐range sex pheromone in B. dorsalis. A mating competition experiment revealed that compound 3 significantly increased the competitiveness of males, which implied that compound 3 might be used in control programs of B. dorsalis.

Short-range semiochemicals convey individual-specific information, which is important for final successful courtship and copulation. In this study, an electroantennography (EAG) instrument was used to determine the legs of male Bactrocera dorsalis that might participate in the perception of 4-allyl-2,6-dimethoxyphenol (4-DMP), a female-biased cuticular hydrocarbon (CHC) component. By performing comparative RNA-seq analysis, nine differentially expressed OBPs between 4-DMP-stimulated (M4‑DMP) and unstimulated (M) male flies were screened out. Among the four downregulated OBPs, BdorOBP2 exhibited the strongest binding to 4-DMP than BdorOBP4, BdorOBP19a, and BdorOBP56h. Functional analyses confirmed that the reduction in transcript abundance of BdorOBP2 led to a significant decrease in behavioral responses of male flies to 4-DMP. In silico simulation revealed dramatic changes in the key residues and conformation between the two complexes, implying that BdorOBP2 might activate different receptors after binding to 4-DMP or methyl eugenol (ME). The results of this study suggest that BdorOBP2 mediates behavioral responses to 4-DMP and could be a promising molecular target for strategies of pest control.

BACKGROUND: Diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most important crucifer pests. Commercial sex attractants have been developed to monitor and control P. xylostella. However, some studies have demonstrated a variety of pheromone responses of P. xylostella in different locations of the world. Soluble pheromone-binding proteins (PBPs), as a subfamily of odorant-binding proteins (OBPs), could selectively bind and transport pheromones across aqueous sensillar lymph to the surface of olfactory receptor neurons. It is worthy to study whether the mutation of PxylPBPs is one of the reasons for the different responses of sex attractors in different regions. RESULTS: In this study, P. xylostella males were collected from seven Chinese provinces, including Hainan, Guangdong, Yunnan, Fujian, Hunan, Zhejiang, and Hebei. PxylPBP1, PxylPBP2, and PxylPBP3 were cloned, and 3, 6, and 32 types of mutation pattern were identified, respectively. These mutation patterns were distributed in each province with different frequency. The results of fluorescence displacement binding assay and in silico simulation revealed that the three mutant PxylPBP3 were more sensitive to Z11-16:Ald than the reference protein (ACI28451). CONCLUSION: This result implied that mutation of PxylPBP3 may have contributed to regional differences in pheromone responses of P. xylostella.

BACKGROUND The tobacco‐rice rotation cropping (TRRC) is an ecologically friendly system that can both alleviate soil nicotine pollution and decrease the brown planthopper (BPH, Nilaparvata lugens Stål) fitness on rice. However, few studies on this green and effective rotational cropping system have been reported. In particular, the underlying mechanisms of TRRC on the significant reduction of field pest population at the molecular level is still unknown. RESULTS Field investigation showed that BPH population decreased significantly in TRRC than in rice‐rice successive cropping (RRSC) field. In addition, the short neuropeptide F (NlsNPF) and its receptor NlA7 of BPH had half‐times lower levels in the TRRC field. Behavioral bioassay indicated a 1.93‐fold increase in the number of salivary flanges of the dsNlsNPF group, while BPH fitness parameters, such as honeydew, weight gain, and mortality decreased significantly. Dopamine (DA) content in BPH decreased by ~11.1% under the influence of nicotine, and its presence increased the expression levels of NlsNPF and NlA7. Exogenous DA application eliminated the inhibitory effects of nicotine on BPH feeding and restored the fitness levels of its parameters. Independent application of either a mixture of dsNlsNPF with a nanocarrier or nicotine to the normal rice field revealed that the latter could produce better effects in combination with dsRNA. CONCLUSION These findings confirmed that DA regulated NlsNPF to inhibit the BPH feeding behavior in TRRC. The results not only provided novel findings on the mechanism of pest‐host interactions, but also presented new method for integrated pest management. © 2023 Society of Chemical Industry.