Identification and functional analysis of the female determiner gene in the bean bug, Riptortus pedestris

BACKGROUNDHoming-based gene drives targeting sex-specific lethal genes have been used for genetic control. Additionally, understanding insect sex determination provides new targets for managing insect pests. While sex determination mechanisms in holometabolous insects have been thoroughly studied and employed in pest control, the study of the sex determination pathway in hemimetabolous insects is limited to only a few species. Riptortus pedestris (Fabricius; Hemiptera: Heteroptera), commonly known as the bean bug, is a significant pest for soybeans. Nonetheless, the mechanism of its sex determination and the target gene for genetic control are not well understood.RESULTSWe identified Rpfmd as the female determiner gene in the sex determination pathway of R. pedestris. Rpfmd encodes a female-specific serine/arginine-rich protein of 436 amino acids and one non-sex-specific short protein of 98 amino acids. Knockdown of Rpfmd in R. pedestris nymphs caused death of molting females with masculinized somatic morphology but did not affect male development. Knockdown of Rpfmd in newly emerged females inhibited ovary development, while maternal-mediated RNA interference (RNAi) knockdown of Rpfmd expression resulted in male-only offspring. Transcriptome sequencing revealed that Rpfmd regulates X chromosome dosage compensation and influences various biological processes in females but has no significant effect on males. Moreover, RNAi mediated knockdown of Rpfmd-C had no influence on the development of R. pedestris, suggesting that Rpfmd regulates sex determination through female-specific splicing isoforms. We also found that Rpfmd pre-mRNA alternative splicing regulation starts at the 24-h embryo stage, indicating the activation of sex differentiation.CONCLUSIONOur study confirms that Rpfmd, particularly its female-specific isoform (Rpfmd-F), is the female determiner gene that regulates sex differentiation in R. pedestris. Knockdown of Rpfmd results in female-specific lethality without affecting males, making it a promising target for genetic control of this soybean pest throughout its development stages. Additionally, our findings improve the understanding of the sex-determination mechanism in hemimetabolous insects. (c) 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Automated summary

The study identifies Rpfmd as the female determiner gene in the sex determination pathway of R. pedestris, which influences sex differentiation and ovary development. Knockdown of Rpfmd leads to female-specific lethality and male-only offspring, showing potential for genetic control. The findings also enhance understanding of sex determination mechanisms in hemimetabolous insects.