Plant domestication can have negative consequences for defensive traits against herbivores, potentially reducing the levels of chemical defenses in plants and consequently their resistance against herbivores. We characterized and quantified the defensive flavonols from multiple cultivated ecotypes with wild ancestors of murtilla, Ugni molinae Turcz, an endemic plant from Chile, at different times of the year, and examined their effects on a native insect herbivore, Chilesia rudis Butler (Lepidoptera: Arctiidae). We hypothesized that domestication results in a decrease in flavonol levels in U. molinae plants, and that this negatively affected C. rudis performance and preference. Ethanolic extracts were made from leaves, stems, and fruit of murtilla plants for flavonol analysis. Flavonols identified were kaempferol, quercetin, rutin, and quercetin 3-D- β -glucoside, the last two being the most abundant. More interestingly, we showed differences in flavonol composition between wild and cultivated U. molinae that persisted for most of the year. Relative amounts of all four flavonols were higher in wild U. molinae leaves; however, no differences were found in the stem and fruit between wild and cultivated plants. In choice and no-choice assays, C. rudis larvae gained more mass on, and consumed more leaf material of, wild as compared with cultivated U. molinae plants. Moreover, when applied to leaves, larvae ate more leaf material with increasing concentrations of each flavonol compound. Our study demonstrates that domestication in U. molinae reduced the amount of flavonols in leaves as well as the performance and preference of C. rudis , indicating that these compounds stimulate feeding of C. rudis .
The pea weevil (Bruchus pisorum L.) (Coleóptera: Bruchidae) is one of the most damaging pests of pea (Pisum sativum L.) We investigated the role of pea volatiles on the electrophysiological and behavioral response of B. pisorum using electroantennography (EAG) and olfactometry bioassays. Plant volatiles emitted at different phenological stages were collected in situ by headspace on Porapak Q traps and analyzed through gas chromatography coupled to mass spectrometry (GC-MS). Most abundant volatiles identified in all phenological stages were terpenes and green leaf volatiles. All tested volatile extracts elicited significant EAG responses in both male and female B. pisorum, with females exhibiting a greater response (1.35 mV) than males (1.02 mV) to pea-pod volatiles. Volatiles from each phenological stage stimulated an attractant behavioral response of both males and females B. pisorum in olfactometer bioassay. A larger attraction of B. pisorum females was observed to volatiles from pods over other phenological stages (P < 0.001). These results suggest the relative importance of volatiles cues from plant mediating host location by B. pisorum. This work showed that plant volatiles elicited electrophysiological and behavioral responses and that B. pisorum female can discern between phenological stages of P. sativum based on those chemical cues