Florivory: The ecology of flower feeding insects and their host plants.

摘要

Florivory is defined as feeding on plant reproductive structures from bud inception until seed coat formation. Therefore, florivorous insects consume sepals, petals, stamens, styles, carpels, and ovules, as well as nectar and pollen. Flower tissue is usually a high quality but ephemeral food resource. Pollinators and florivores respond directly to the floral display, but with opposing effects on plant fitness. This research addresses for the first time the general ecological relationships of florivores and their host plants. I have tabulated economically important florivores, and florivores from all orders of Insecta, Lepidoptera, and species of Heliothinae (Lepidoptera: Noctuidae).;The effects of plant part (bud, leaf, flower, fruit, seed, stem, and root) availability, longevity, nutritional content, allelochemistry, size, and toughness on insect life history traits were reviewed for herbivorous insects, and predictions were tested using data on the microlepidoptera of Britain. Distinct guilds of plant part feeders emerged, suggesting that plant part specialization may relate to diversification in these small moths.;In growth studies of four Lepidoptera, Euchloe hyantis (Pieridae), a chemical specialist/reproductive structure specialist, Pieris rapae (Pieridae), a chemical specialist/plant part generalist, Trichoplusia ni (Geometridae), a polyphagous plant part generalist, and Heliothis zea (Noctuidae), a polyphagous reproductive structure specialist, larvae grew equally well on Descurainia pinnata (Brassicaceae), an upright native species, and Sisymbrium altissimum (Brassicaceae), a more broadly branching introduced species, but showed higher growth and survival on reproductive structures, which were higher in water and total nitrogen.;I focused three years of field research on the adult and larval responses of E. hyantis, a univoltine flower specialist, to variation in host architecture, phenology, and species. Survival was higher on S. altissimum due to the rapid senescence of D. pinnata, and larvae decreased host reproduction. In floral display manipulation experiments, females approached and landed on hosts based on display height and size (number of inflorescences), and post-alighting cues favored oviposition on D. pinnata. Oviposition site selection criteria based on attributes of the floral display provided a mechanism for host range expansion in Euchloe hyantis.