Orco mutagenesis causes deficiencies in olfactory sensitivity and fertility in the migratory brown planthopper, Nilaparvata lugens

BACKGROUNDThe 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. RESULTSWe 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. CONCLUSIONOur 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. (c) 2022 Society of Chemical Industry.

Automated summary

The migratory brown planthopper (BPH), Nilaparvata lugens, exhibits strong olfactory responses to major rice volatile compounds, and the Orco gene plays a crucial role in BPHs. By utilizing gene editing technology, researchers generated a NlOrco-knockout mutant of BPHs, which showed no response to rice volatile compounds and lost their preference for host plants. These findings have significant implications for BPH control applications and the identification of potential target genes or chemical compounds.