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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED PEST MANAGEMENT FOR MID-SOUTH AREA ROW CROPS

Location: Southern Insect Management Research Unit

Title: Electrical penetration graphic evidence of pymetrozine toxicity to the rice brown planthopperis by inibition of phloem feeding

Authors
item He, Yueping -
item Chen, Li -
item Chen, Jianming -
item Zhang, Juefeng -
item Chen, Liezhong -
item Shen, Jinliang -
item Zhu, Yu Cheng

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 2010
Publication Date: January 21, 2011
Citation: He, Y., Chen, L., Chen, J., Zhang, J., Chen, L., Shen, J., Zhu, Y. 2011. Electrical penetration graphic evidence of pymetrozine toxicity to the rice brown planthopperis by inibition of phloem feeding. Pest Management Science. 67(4):483-491.

Interpretive Summary: Pymetrozine is a valuable novel insecticide for control of sucking insects including many economically important pests, such as planthoppers, aphids, and whiteflies. Pymetrozine-treated insects die slowly with symptoms similar to starvation, suggesting the chemical might act as an antifeedant. However, the mode of action for this chemical is not well understood. The major objective of this study was to explore the effect of pymetrozine on the feeding behavior of a sucking insect to better understanding the action mechanisms of pymetrozine. The activity test showed that pymetrozine primarily functioned as a feeding inhibitor to cause starvation and death to target insects. Pymeytrozine-treated insects died at a significantly slower speed than insects treated with starvation. Electrical penetration graph data indicated that pymetrozine significantly inhibited phloem ingestion, although it had no effect on xylem ingestion. The inhibition was strongly dose-correlated. The phloem ingestion was totally suppressed when the pymetrozine concentration increased to 400 mg per littler. Starvation caused by inhibition of phloem ingestion might be a major toxicity mechanism of pymetrozine. This study suggested that pymetrozine disturbed feeding behavior in sucking insects mainly through inhibition of phloem ingestion rather than xylem “drinking”. The results might be helpful in interpretation of the toxicity mechanism of pymetrozine to sucking insects, and may provide valuable information for improving efficacy and field application of pymetrozine for better controlling sucking insects.

Technical Abstract: BACKGROUND: Pymetrozine is a valuable novel insecticide for control of sucking insects including the brown planthopper Nilaparvata lugens (Stål), one of the most serious pests on rice. This study was conducted to elucidate action mechanisms of pymetrozine on the feeding behavior of the planthopper. RESULTS: The activity test showed that pymetrozine primarily functioned as an antifeedant that caused starvation and death in N. lugens, rather than having neuro-toxicity. Pymeytrozine-treated insects died at a significantly slower speed than the insects treated with starvation. Electrical penetration graph (EPG) data indicated that pymetrozine significantly inhibited phloem ingestion. The inhibition was strongly dose-correlated, and phloem ingestion was totally suppressed when the pymetrozine concentration was increased to 400 mg L-1. Starvation caused by inhibition of phloem ingestion might be a major toxicity mechanism of pymetrozine. However, EPG data showed that pymetrozine had no effect on the xylem ingestion. It is likely that pymetrozine-treated N. lugens, even without phloem sap feeding, could live for a while on water and the limited nutrients from xylem ingestion before they died. CONCLUSION: Our study revealed that pymetrozine disturbed feeding behavior in N. lugens mainly through inhibition of phloem ingestion rather than xylem “drinking”. The toxicity resulted in a slow death similar to starvation. The manuscript was revised according to reviewers’ comments and suggestions.

Last Modified: 7/22/2014
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