Expression of three neuropeptide genes (SfEH, SfETH, and SfCCAP) in response to insecticide stress on the white-backed planthopper Sogatella furcifera (Hemiptera: Delphacidae)

Insect neuropeptides are involved in many important developmental processes. Here, we cloned three neuropeptide genes (SfEH, SfETH, and SfCCAP) from Sogatella furcifera (Horváth) and analyzed the relative expression levels of these genes through Real-time Quantitative polymerase chain reaction (RT-qPCR) during different developmental stages and in different wing types of S. furcifera following exposure to sublethal concentrations (LC10 and LC25) of methylaminoavermectin benzoate. The results revealed that the three neuropeptide genes (SfEH, SfETH, and SfCCAP) of S. furcifera contained open reading frame sequences of 222, 636, and 408 bp, encoding 73, 211, and 135 amino acids, respectively. Moreover, the expression of SfEH and SfETH reached its peak on day 3 of the 5th instar nymph stage, while the SfCCAP expressed pinnacle on 40 min after eclosion. Furthermore, the relative expression levels of the three genes were in the following order: SfEH, short-winged female > long-winged female > long-winged male; SfETH, long-winged female > short-winged female > long-winged male; and SfCCAP, short-winged female > long-winged male > short-winged female. Upon calculating the relative expression of the three peptide genes after 24 and 48 h of treatment with sublethal concentrations of methylaminoavermectin benzoate, it was found that the relative mRNA expression levels of SfEH and SfETH declined upon LC10 treatment but increased upon LC25 treatment. Meanwhile, the relative mRNA expression level of SfCCAP declined upon both LC10 and LC25 treatments. This result will help us understand the effects of pesticides on insect growth and development at the molecular level.