Troponin C is required for copulation and ovulation in Nilaparvata lugens

Troponin C (TnC) is a calcium-binding subunit of the troponin complex that regulates muscle contraction in animals. However, the physiological roles of TnC, especially in insect development and reproduction, remain largely unknown. We identified seven TnC genes encoding four EF-hand motif protein in the rice pest, the brown planthopper Nilaparvata lugens. This species has emerged as an ideal model insect to study gene functions because of the availability of its complete genome sequence and of the susceptibility to RNA interference (RNAi). RT-qPCR combined with in situ hybridization showed that TnCⅠ was highly expressed in the bursa copulatrix of ovaries. RNAi-mediated knockdown of TnCⅠ in 2nd-to 5th-instar nymphs generated significantly lethal deficits, and also led to copulation and ovulation failure in adult females, although males displayed appropriate mating behavior. These new findings provide insights into understanding the physiological functions of TnCⅠ in the survival of, and female reproductive success, in N. lugens. Thus, this gene could be used as a target to explore methods for pest control of this important species.