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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #331096
Title: Toxicity of flonicamid to the cotton leafhopper, Amrasca biguttula (Ishida) is by disruption of ingestion, an EPG study

Author
item TARIQ, KALEEM - Huazhong Agricultural University
item NOOR, MAH - Huazhong Agricultural University
item Backus, Elaine
item ASAD, ALI - Huazhong Agricultural University
item ZHANG, HONGYU - Huazhong Agricultural University

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2016
Publication Date: 2/13/2017
Citation: Tariq, K., Noor, M., Backus, E.A., Asad, A., Zhang, H. 2017. Toxicity of flonicamid to the cotton leafhopper, Amrasca biguttula (Ishida) is by disruption of ingestion, an EPG study. Pest Management Science. 73:1661-1669.

Interpretive Summary: Flonicamid is a novel systemic insecticide with highly targeted action against piercing-sucking insect pests in numerous crops around the world. Its mode of action is imperfectly known, but thought to involve inhibition of feeding. In the present study, the mechanism of action of flonicamid on the feeding behavior of the cotton leafhopper, Amrasca biguttula, was investigated using electropenetrography (EPG). The cotton leafhopper is one of the most destructive pests of cotton in Asia. This species is thought to cause damage by injecting enzymatic saliva into various, presently unknown, cotton tissues and then sucking up (ingesting) the liquefied cell matter. EPG findings indicated flonicamid significantly increased the mean duration of non-feeding periods and strongly inhibited ingestion by treated insects. Cessation of ingestion was dose-dependent, and near complete suppression was observed when the flonicamid concentration was increased to 10,000 mg per L. Therefore, it is proposed that starvation caused by inhibition of active ingestion is the mechanism of toxicity for flonicamid. Knowledge of the mechanism of flonicamid activity against cotton leafhopper will aid in judging the appropriate use of this new insecticide for field management of leafhopper populations and preservation of cotton yields.

Technical Abstract: The cotton leafhopper, Amrasca biguttula (Ishida) (Hemiptera: Cicadellidae), is one of the most destructive pests of cotton in Asia. This species is thought to cause damage by injecting enzymatic saliva into various, presently unknown, cotton tissues and ingesting the resulting macerate. Flonicamid is a novel systemic insecticide that is being used to control the cotton leafhopper. In the present study, the mechanism of action of flonicamid on the feeding behavior of the cotton leafhopper was investigated using electropenetrography (EPG). EPG recordings of cotton leafhoppers feeding on cotton plants revealed six waveforms (i.e., NP, A1, A2, A3, A4, A5, and A6). Non-probing was represented by NP. By comparison with defined EPG waveforms of a related leafhopper species, waveforms A2 and A3 are thought to represent active ingestion with (A2) and without (A3) simultaneous watery salivation. The meanings of A4, A5, and A6 are presently unknown, but all were very minor waveforms in duration per insect. EPG findings indicated that flonicamid significantly increased the mean duration of non-probing periods and strongly inhibited ingestion by treated insects. Inhibition of ingestion was dose-dependent, and near complete suppression was observed when the flonicamid concentration was increased to 10,000 mg L-1. In addition, starved insects given access to water died at a significantly faster rate than insects treated with flonicamid; thus, untreated insects could ingest water but treated insects could not ingest from plants. The results showed that flonicamid disturbed the feeding behavior of A. biguttula by inhibiting active ingestion and increasing non-probing, which resulted in the slow death of the leafhoppers. Therefore, it is proposed that starvation caused by inhibition of active ingestion is the mechanism of toxicity for flonicamid. Knowledge of the mechanism of flonicamid activity against cotton leafhopper will aid in applicability and use of this new insecticide for field management of leafhopper populations.