Male-specific lethal-3 gene is critical for survival and fecundity in rice brown planthopper, Nilaparvata lugens.

Male-specific lethal-3 (MSL3) is a component of the dosage compensation complex in Drosophila melanogaster, where its mutation leads to male-specific lethality. However, the function of MSL3 in hemipteran insects remains unclear. This study investigated the role of the MSL3 homolog in a major rice pest, the brown planthopper (Nilaparvata lugens). We cloned and characterized the gene NlMSL3 from N. lugens, which is 1467-bp long and encodes a protein of 488 amino acids. Phylogenetic analysis revealed that MSL3 is conserved across various insect orders, with high conservation in the chromo-barrel domain. Quantitative real-time polymerase chain reaction indicated differential expression levels of NlMSL3 between male and female insects during development, with the highest expression in the testes. RNA interference-mediated knockdown of NlMSL3 in N. lugens resulted in significant mortality in later instar nymphs and adults compared with the control group. In females, NlMSL3 knockdown impaired feeding behavior, leading to decreased body weight, notably reduced honeydew excretion, flat abdomens, decreased vitellogenin expression, and defective ovarian development. When dsNlMSL3-treated males were mated with control females, the number of eggs laid was similar to that laid by the females mated with control males; however, none of the eggs laid by the former hatched into nymphs. These results highlight the crucial role of NlMSL3 in the development and fecundity of N. lugens.