Plants trap pollen to feed predatory arthropods as an indirect resistance against herbivory.

Plants commonly employ indirect resistance to reduce herbivory by provisioning predatory arthropod populations with additional resources. Numerous predatory arthropods consume pollen that is entrapped on dense, wooly trichomes of plants. Over two seasons, we supplemented pollen on the wooly leaves of turkey mullein, Croton setiger, in natural populations to determine if pollen entrapped on leaves supplements predatory arthropods and reduces herbivore populations and damage to the plant. Pollen supplementation increased the abundance of predatory spiders in both years and omnivorous Orius bugs in 1 yr but had no effect on predatory hemipterans. Pollen supplementation reduced the abundance of herbivorous fleahoppers. Pollen supplementation decreased the amount of leaf damage experienced by plants over the season, suggesting that pollen entrapment may act as an indirect resistance. While C. setiger plants have little control over the amount of pollen on their surfaces, pollen adds to the diet of predatory arthropods that reduce herbivory, thus attraction of predators may be an adaptive benefit of leaf structures such as wooly trichomes that entrap pollen.

Mirid (Hemiptera: Heteroptera) specialists of sticky plants: adaptations, interactions, and ecological implications.

Sticky plants-those having glandular trichomes (hairs) that produce adhesive, viscous exudates-can impede the movement of, and entrap, generalist insects. Disparate arthropod groups have adapted to these widespread and taxonomically diverse plants, yet their interactions with glandular hosts rarely are incorporated into broad ecological theory. Ecologists and entomologists might be unaware of even well-documented examples of insects that are sticky-plant specialists. The hemipteran family Miridae (more specifically, the omnivorous Dicyphini: Dicyphina) is the best-known group of arthropods that specializes on sticky plants. In the first synthesis of relationships with glandular plants for any insect family, we review mirid interactions with sticky hosts, including their adaptations (behavioral, morphological, and physiological) and mutualisms with carnivorous plants, and the ecological and agricultural implications of mirid-sticky plant systems. We propose that mirid research applies generally to tritrophic interactions on trichome-defended plants, enhances an understanding of insect-plant interactions, and provides information useful in managing crop pests.