Silencing of triazophos-induced Hexokinase-1-like reduces fecundity in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae).

Hexokinase is a rate-limiting enzyme that plays pivotal roles in glucose homeostasis and energy metabolism via glucose (Glc) phosphorylation and Glc signaling mediation. Previous investigations have revealed the modulatory role of Hexokinase (Hex) genes involved in proper glucose regulation during insect diapause and embryo development, whereas whether it functions in insect fecundity remains largely unknown. We aimed to explore the relationship between Triazophos (TZP)-induced Hex-1 and fecundity of female Nilaparvata lugens. In this study, Hex-1 expression were characterized at different developmental stages and in various tissues of N. lugens, with the highest expression registered in brain tissues and 5th instar nymph. The present findings indicated that TZP + dsHex-1 silencing significantly reduced protein synthesis, including the fat body and ovarian protein content of female adults. Meanwhile, the glycometabolism with respect to the soluble sugar, trehalose and glucose content in female adults were strikingly influenced as a result of Hex-1 knockdown. The relative transcript level of Hex-1, vitellogenin (NlVg) and vitellogenin receptor (NlVgR) considerably decreased in TZP + dsHex-1 treated females compared to TZP and TZP + dsGFP-treated groups. More importantly, TZP + dsHex-1 silencing led to reduced number of eggs laid and vitellogenin (Vg) accumulation as well as retarded ovary development compared with TZP-treated and TZP + dsGFP-treated groups. Taken together, it is proposed that Hex-1 implicates in N. lugens fecundity by exerting profound effects on glycometabolism, protein sythesis and NlVg expression.