The cotton aphid, <i>Aphis gossypii </i>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 2.5-fold when compared to control and importantly, foliar applications of VU041 and VU730 significantly (P&lt;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 48 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&lt;0.05) reduction of aphids able to reach E1 (phloem salivation) and E2 (phloem ingestion) waveforms when compared to the untreated control. Furthermore, VU730 mixed into water solubilizer and treated on a single lower leaf significantly (<i>P</i> &lt; 0.05) reduced G phase (xylem ingestion) waveforms on upper (untreated) cotton leaves.  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.

Optimization of inward rectifier potassium channel inhibitors to prevent hemipteran feeding

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