Function of Vitellogenin receptor gene in reproductive regulation of Zeugodacus cucurbitae (Coquillett) under the high-temperature background

Abstract

Climate warming has increased the frequency of extreme heat events, and Zeugodacus cucurbitae , as an important tropical pest,extreme heat tends to change its reproductive strategies.To clarify the reproductive strategies of Z. cucurbitae under the background of high temperature, Z. cucurbitae were exposed to short-term high temperatures of 25°C,33°C,37°C,41°C,and 45°C for 1h in this paper, and effects of these temperatures on the reproduction of Z. cucurbitae in three consecutive generations (F1,F2,and F3 generations) were evaluated, followed by using siRNA to interfere with the expression of Vitellogenin receptor(VgR) gene and evaluated the silencing efficiency of RNAi.The results showed that(1) short-time high temperature was generally detrimental to the reproduction of Z. cucurbitae, but the F1 exposed at 45°C for 1h stimulated its oviposition and when the offspring (F2andF3) were continuously exposed to 45°C-1h short-term high temperature,F3 could not survive.(2) After short-time high-temperature treatment, the injection of siRNA resulted in significant inhibition of VgR gene expression at 24h and72h.The total oviposition quantity, oviposition days, and hatchability of eggs after the interference were significantly lower than the other groups, and the inhibition effect of total oviposition quantity was the most obvious, decreasing by 88.4% and 95.2% at 25°C and 45°C, respectively, compared with the control check (CK). The ovarian development and ovarian diameter were also significantly lower than the other groups. In conclusion, the VgR gene is essential for the regulation of reproduction in Z. cucurbitae.This study can provide a reference for the integrated control of Z. cucurbitae in the high-temperature seas