Variation in the Impact of Insect Herbivory on Trifolium Pratense Through Early Plant Succession

Publisher Website
Google Scholar
Abstract
(1) Insect herbivores on Trifolium pratense growing in three communities of different successional age were reduced by the use of a foliar insecticide. The performance of these (insecticide-treated) plants was compared with control plants with natural levels of insect herbivory over a three-year period. (2) Under reduced levels of insect herbivory, plants grew taller and produced more leaves while individual leaf area was unchanged. (3) Herbivory resulted in a reduction in plant size (assessed by total leaf area) and an increase in size variability (measured by the coefficient of variation). (4) The number of seed heads per plant and individual seed weight were reduced by herbivory. There was no difference in seed viability, but in the field more plants became established from seeds produced by insecticide-untreated plants. (5) In two of the three communities, herbvivory significantly reduced the survivorship of plants. This was due to the death of small individuals which were more prevalent among control plants. It is concluded that insect herbivory reduces plant fitness and interacts with plant competition in determining changes in numbers of T. pratense plants.