Abstract
Ginkgo biloba is a typical relic plant that rarely suffers from pest hazards. This study analyzed the pattern of G. biloba pest hazards in Beijing; tested the antifeedant activity of G. biloba extracts, including ginkgo flavonoids, ginkgolide, and bilobalide, against Hyphantria cunea larvae; determined the activities of glutathione transferase (GSTs), acetylcholinesterase (AChE), carboxylesterase (CarE) and mixed-functional oxidase (MFO), in larvae after feeding on these G. biloba secondary metabolites; and screened for effective botanical antifeedants in the field. In this study, no indicators of insect infestation were found for any of the examined leaves of G. biloba; all tested secondary metabolites showed significant antifeedant activity and affected the activity of the four larval detoxifying enzymes. Ginkgolide had the highest antifeedant activity and the most significant effect on the detoxifying enzymes (P<0.05). Spraying leaves with G. biloba extracts or ginkgolide both significantly repelled H. cunea larvae in the field (P<0.05), although the former is more economical and practical. This study investigated the antifeedant activity of G. biloba secondary metabolites against H. cunea larvae, and the results provide new insights into the mechanism of G. biloba pest resistance. This study also developed new applications of G. biloba secondary metabolites for effective pest control.
Highlights
During the long-term co-evolution with insects, plants gained the ability to produce a plethora of secondary metabolites through accidental genetic mutation and genetic recombination
We tested the antifeedant activity of G. biloba extracts and isolated secondary metabolites, including ginkgo flavonoids, ginkgolide, and bilobalide, against H. cunea larvae
The results showed that all four preparations conferred significant antifeedant activity in leaf-disc assays and in artificial diets, and the activities of larval
Summary
During the long-term co-evolution with insects, plants gained the ability to produce a plethora of secondary metabolites through accidental genetic mutation and genetic recombination. Secondary metabolites are irrelevant for normal plant growth, but have key roles for chemical defense against insects by killing, repelling, inhibiting the feeding, or hindering the growth of insects [1]. These secondary metabolites have important effects on insects’ selection of host plants [2]. During co-evolution, plants developed a chemical defense system of secondary metabolites to prevent insect feeding, and insects adaptively developed detoxifying enzymes to defeat this plant chemical defense system [3].
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