Search

BACKGROUND: The migratory brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae), is the most destructive pest affecting rice plants in Asia and feeds exclusively on rice. Studies have investigated the olfactory response of BPHs to the major rice volatile compounds in rice. The insect olfactory co‐receptor (Orco) is a crucial component of the olfactory system and is essential for odorant detection. Functional analysis of the Orco gene in BPHs would aid in the identification of their host preference. RESULTS: We identified the BPH Orco homologue (NlOrco) by Blast searching the BPH transcriptome with the Drosophila Orco gene sequence. Spatiotemporal analysis indicated that NlOrco is first expressed in the later egg stage, and is expressed mainly in the antennae in adult females. A NlOrco‐knockout line (NlOrco−/−) was generated through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9‐mediated mutagenesis. The NlOrco−/− mutants showed no response to rice volatile compounds and consequently no host‐plant preference. In addition, NlOrco−/− mutants exhibited extended nymphal duration and impaired fecundity compared with wild‐type BPHs. CONCLUSION: Our findings indicated that BPHs exhibit strong olfactory responses to major rice volatile compounds and suggest that NlOrco is required for the maximal fitness of BPHs. Our results may facilitate the identification of potential target genes or chemical compounds for BPH control applications. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The homeotic complex gene Abdominal‐B (Abd‐B) is involved in regulating the development of posterior abdomens and has been extensively studied in holometabolous insects. However, the function of Abd‐B in hemimetabolous insects is not fully understood. Here, we functionally characterize an Abd‐B homologue in the brown planthopper (BPH), Nilaparvata lugens. The full‐length cDNA of the N. lugens Abd‐B homologue (NlAbd‐B) is 2334 nt, with an open reading frame of 1113 bp. NlAbd‐B has the highest expression level at the egg stage relative to the nymphal and adult stages and is mainly expressed in the fourth to the ninth abdominal segment of embryos. RNA interference (RNAi)‐mediated knockdown of NlAbd‐B in nymphs disrupted the development of genitalia both in females and males and caused a genitalia‐to‐leg transformation. Parental RNAi of NlAbd‐B in both female and male adults caused an extra abdominal segment in offspring nymphs, while parental RNAi of the N. lugens abdominal‐A homologue in both female and males adults led to embryos with leg‐like appendages on the second to the eighth abdominal segment. These findings suggest that NlAbd‐B plays a pivotal role in genital development and posterior abdominal patterning and thus highlight the conservational role of Abd‐B in holometabolous and hemimetabolous insects. [ABSTRACT FROM AUTHOR]