Pepper domestication enhances parasitoid recruitment to herbivore-damaged plants

Abstract

Plant breeding has improved traits such as fruit flavor and yield but may have compromised direct and indirect defenses to herbivores compared to their wild ancestors. This has been termed the plant domestication-reduced defense hypothesis. We present evidence that domestication of Capsicum annuum (the chili pepper) from its wild progenitor, Capsicum annuum var. glabriusculum, has not affected resistance to the insect herbivore, Manduca sexta (the tobacco hornworm). Caterpillars performed equally well on the domesticated and wild pepper. Subsequent behavioral choice assays with one of the main natural enemies of M. sexta, the parasitoid wasp Cotesia congregata, showed that parasitoids preferentially chose herbivore-damaged domesticated pepper plants over their wild relative. To investigate this tri-trophic interaction further, we then assessed the efficiency of C. congregata to parasitize M. sexta on numerous wild pepper accessions and domesticated pepper cultivars in a large foraging enclosure. We found that herbivores feeding on domesticated plants were parasitized at more than twice the rate of those on wild genotypes. These results imply that pepper domestication has not changed resistance to herbivorous insects (i.e., leaf palatability as a direct defense), but rather has improved volatile attraction to recruit natural enemies.