Diversity of invertebrates in Arabuko-Sokoke Forest and adjacent farmland, Gede-Kilifi County, Kenya

Abstract

The primary food of insectivorous bats is invertebrates. This study investigated invertebrate abundance in ASF and adjacent farmland, in order to understand its availability to foraging insectivorous bats found in both study sites. Invertebrate were sampled with solar powered lights, which attracted air-borne invertebrates to a suspended white cloth sheet, for four hours each night in 12 different stations each in ASF and farmland. In total 6,557 individuals of invertebrates were captured: 52% in the farmland and 48% in ASF. The order Hymenoptera (ants, bees, wasps and sawflies) was the most abundant (38.1%), followed by Coleoptera (beetles (28.1%). The Shannon-Weiner index of diversity was higher in ASF (1.72 ± 0.1) than in the farmland (1.41 ± 0.1). The mean number of invertebrates captured each night in the farmland was (260.5 ± 52.9, N=12), and in ASF (200.3 ± 36.4, N=12), but there was no significant difference between the medians of captured invertebrates in both study sites (Mann-Whitney U-Test, U=61: P>0.544). In conclusion, the farmland and forest had similar invertebrate abundance. This study, highlight the importance of agricultural landscapes, which have been ignored in many biodiversity surveys, in providing invertebrate prey items to insectivorous bats especially in the study area.