The effects of vegetational succession on populations of weevils (curculionidae)

Abstract

A single group of phytophagous insects, Curculionidae , (weevils), were studied on four successional limestone grassland sites of differing ages. Specimens were taken from the sites using a D-vac suction apparatus to estimate populations. The sites were surveyed by a point quadrat method, recording numbers of plant species, height classes and floral structures. An older hawthorn scrub site was also studied for comparison. Successional age correlated with the numbers of species and abundance of weevils, and accounted for 96% and 88% of the variation respectively. Comparisons were made between measures of habitat diversity and weevil populations. Number of plant species and spatial diversity seemed to have some importance in determining the abundance of weevils. Numbers of plant species present, plant species diversity, spatial diversity, and architectural diversity all were factors which affected species numbers, but these factors are not necessarily independent and it was not possible to ascertain their inter-relationship. However, spatial diversity accounted for the greatest amount of the variation in numbers of weevil species (38%) and thus it was clear that other unmeasured factors were also important in determining the size of weevil populations. The palatability of the flora of the different sites was estimated using Gepaeaspp. and some conclusions were made.