Aphicidal and antifeedant activity of Synandrospadix vermitoxicus extracts against Myzus persicae on potato plants

Abstract

Potato crops are usually kept virus-free through intensive aphid vector control schemes that require multiple treatments with insecticides. The generalist aphid Myzus persicae developed different mechanisms of resistance to insecticides, and there is a need for sources of novel insecticides. Synandrospadix vermitoxicus (Griseb.) Engl., an Araceae family native to the northwestern region of Argentina, Paraguay, and Bolivia has been locally described as having insecticidal properties against insect larvae and could be a potential source of new natural insecticides against aphids. We tested the antifeedant and aphicidal effects of two extracts from the tubers of S. vermitoxicus, ethanolic and hexanic, on M. persicae. First, we treated potato leaves with the extracts to assess their antifeedant effect by measuring host preference changes in M. persicae. Then, we evaluated its aphicidal effect by offering the extracts to aphids through artificial diets and the aphid probing behaviour by electrical penetration graph. We also analysed the extracts for the main classes of secondary metabolites. We found that both extracts have antifeedant effects, with the hexanic being the strongest and accordingly, aphid probing behaviour was affected on leaves treated with hexanic extract. While the ethanolic extract affected the survival of aphids fed on artificial diets, the hexanic extract did not. The analysis of S. vermitoxicus extracts shows an array of flavonoids and triterpenoids compounds. Therefore, our results show that the tubers of this plant could be a source for a novel product with potential use on the control of M. persicae on potato crops.