Herbivory-induced effects on pollination services to undamaged neighboring flowering species

Abstract

Reproduction in flowering plants depends to a large degree on interactions with competitors, mutualists, and antagonists, but may also depend on the context within which interaction partners exist. Herbivory can reduce plant attractiveness to pollinators, but since many flowering plant species are visited by the same pollinators, the effects of herbivory on pollinator behavior may have consequences for undamaged neighboring plant species. We assessed how herbivory to a dominant plant species affects pollination services to neighboring flowering species in a community in which we simulated herbivory to milkweeds (Asclepias syriaca) by removing foliar tissue and applying jasmonic acid exogenously. We measured the quality of pollination services to undamaged neighboring plants by assessing the proportion of heterospecific pollen deposited on stigmas of four undamaged neighboring plant species, and measured seed production in one of these species. Our results indicate that simulated herbivory to a dominant plant species may have community-wide effects on pollination services. Simulated herbivory to milkweed increased the proportion of heterospecific pollen deposited on two neighboring plant species (Vicia cracca and Clinopodium vulgare), reduced it for one species (Lysimachia quadrifolia) and resulted in no change for another (Galium palustre). Additionally, simulated herbivory to milkweed resulted in a non-significant trend for lower seed production per fruit in V. cracca. These results support the hypothesis that herbivory on one flowering plant species can impact pollinator services for other flowering species at the patch level. These effects highlight the interconnectedness and interdependence of flowering plant species in plant-pollinator communities.