Plant traits mediate effects of predators across pepper (Capsicum annuum) varieties
- Current address: Department of Plant Sciences, University of California-Davis, One Shields Avenue, Davis, CA 95616, U.S.A.
- The magnitude of plant intra-specific variation for indirect defence and the underlying plant traits influencing predators remain relatively unstudied, particularly in cultivated plants.
- We tested whether differences in flower number, pollen production, and leaf trichome density among 17 pepper (Capsicum annuum Linnaeus) varieties influenced the abundance and predation intensity by the omnivorous mite Amblyseius swirskii Athias-Henriot.
- A greenhouse experiment was conducted where pepper plants were infested with thrips (Frankliniella cephalica Crawford DL) and subsequently exposed to A. swirskii. We estimated thrips and mite density based on arthropod counts conducted over a 4-week period, and also performed flower and trichome counts, and estimated pollen production per anther.
- Significant differences were found among varieties for all three traits, as well as mite and thrips density. After accounting for all traits in a multiple regression model, we found that flower and trichome number had significant positive effects on mite density (by providing food and shelter, respectively). Increased mite density was in turn associated with a decrease in thrips density, presumably as a result of mite predation. Moreover, we found that flower number (but not trichome density) increased the strength of thrips suppression and that such an effect was mediated by mite density.
- These findings suggest that genetic variation for plant traits may indirectly influence herbivore suppression in peppers (although traits may vary in the strength or direction of their effects), and underscore the evolutionary potential and importance of selection not only for direct but also indirect resistance in crops.