Development of antifeedant insecticides targeting hemipteran potassium ion channels

Sunday, November 13, 2022

8:12 AM – 8:24 AM PT

Location: Vancouver Convention Centre, Meeting Room 110

Presenting Author(s)

FO

Flinn O’Hara

PhD Student
University of Florida
Gainesville, Florida

Co-Author(s)

JD

Jeffry A A. Davis

Professor
Louisiana State University Agricultural Center
Baton Rouge, Louisiana
ZL

Zhijun Liu

Louisiana State University
Baton Rouge, Louisiana
DS

Daniel Swale

Associate Professor
University of Florida
Gainesville, Florida

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a destructive agricultural pest, due to photosynthate removal and plant virus transmission. Therefore, we aimed to test the antifeedant properties of small-molecule inhibitors of inward rectifier potassium (Kir) channels expressed in the aphid salivary glands. Two Kir channel inhibitors, VU041 and VU730, reduced the secretory activity of the aphid salivary gland by 3.3-fold and importantly, foliar applications of VU041 and VU730 significantly (P < 0.05) increased the time to first probe, total probe duration, and nearly eliminated ingestion of phloem. Although promising, foliar applications of chemicals have significant pitfalls including non-target toxicity and increased costs of application. Thus, we tested the capability of a novel natural product based solubilizer to increase plant systemicity and bioavailability of VU041 and VU730, which are highly lipophilic modulators. To study systemic movement throughout the plant and across the leaf surface, the adaxial side of a single cotton plant leaf was treated with a Kir inhibitor solubilized into the water-soluble concentrate. Upper leaves were infested with aphids 60-72 hours after chemical treatment and changes to feeding behavior were quantified through electrical penetration graph (EPG) methodology. Trans-laminar and translocation of Kir modulators was confirmed as we observed a significant (P < 0.05) reduction of aphids able to reach E1 (phloem salivation) and E2 (phloem ingestion) waveforms when compared to the untreated control. These data further support hemipteran Kir channels as a target to prevent feeding and plant virus transmission through novel delivery mechanisms that enable plant systemicity.