Aphids Limit Fecundity of a Weedy Annual (Raphanus Sativus)

Few previous studies document effects of herbivores on the reproduction of wild plants in situ. We examined the impact of aphids on seed production in wild radish ( Raphanus sativus L.), an annual herb. Aphid infestation increased during the three‐month flowering period. Flower and fruit production declined during the season, in part due to aphids. Inflorescences of late‐blooming plants more than doubled their fruit production when aphids were removed. Thus, aphids curtailed the blooming period of wild radish, perhaps conferring a selective advantage on early‐flowering plants. A few individuals were not susceptible to aphid colonization.