Reducing Expression of Salivary Protein Genes by Flonicamid Partially Contributed to Its Feeding Inhibition of the Brown Planthopper on Rice

Abstract

Flonicamid inhibits the feeding of piercing−sucking pests as a selective systemic insecticide. The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most serious pests on rice. During feeding, it uses its stylet to collect sap by penetrating the phloem, and at the same time, it delivers saliva into the rice plant. Insect salivary proteins play important roles in feeding and interacting with plants. Whether flonicamid affects the expression of salivary protein genes and then inhibits the feeding of BPH is not clear. Here, from 20 functionally characterized salivary proteins, we screened five salivary proteins (NlShp, NlAnnix5, Nl16, Nl32, and NlSP7) whose gene expressions were significantly inhibited by flonicamid. We performed experimental analysis on two of them (Nl16 and Nl32). RNA interference of Nl32 significantly reduced the survival rate of BPH. Electrical penetration graph (EPG) experiments showed that both flonicamid treatment and knockdown of Nl16 and Nl32 genes significantly reduced the feeding activity of N. lugens in the phloem and also reduced the honeydew excretion and fecundity. These results suggested that the inhibition of flonicamid on the feeding behavior in N. lugens might be partially attributed to its effect on the expression of salivary protein genes. This study provides a new insight into the mechanism of action of flonicamid on insect pests.

Plasticity of the Gene Transcriptional Level and Microbiota in the Gut Contributes to the Adaptability of the Fall Armyworm to Rice Plants

“…The qPCR analysis was conducted using a ChamQ Universal SYBR qPCR Master Mix (Vazyme, Nanjing, China) on a QuantStudio 6 Flex real-time PCR system (Applied Biosystems, Foster City, California) with specific primers (Table S1). The thermal cycling conditions were the same as our previous study S.…”

Roles of herbivorous insects salivary proteins

“…Treatment with flonicamid and knockdown of Nl16 and Nl32 genes (salivary protein genes) significantly reduced the feeding activity of N. lugens in the phloem and also decreased honeydew excretion and fecundity. These results suggest that the inhibition of flonicamid on the feeding behavior in N. lugens might be partially attributed to its effect on the expression of salivary protein genes [ 104 ].…”