Influence of agricultural land transformation and pest management practices on the arthropod diversity of a biodiversity hotspot, the Cape Floristic Region, South Africa

The Cape Floristic Region (South Africa), is a global biodiversity hotspot that has undergone considerable landscape change in recent years. The impact of habitat transformation on arthropod taxa and the effect of pesticides on non-target arthropods in this area were studied. Arthropod diversity in a remnant patch of natural vegetation (fynbos) was compared with that in two apple orchards, one under intensive chemical pest management (sprayed), and the other under fungicide treatments only (unsprayed). Pitfall traps and vacuum sampling collected 221, 152 and 106 insect species in the fynbos, unsprayed and sprayed orchards, respectively. Far more species of Hemiptera, Hymenoptera, and Orthoptera were found in fynbos than in either orchard. Cydnids, rove and ground beetle families were as species rich in the sprayed as in the unsprayed orchards whereas Diplopoda and Isopoda were more abundant in the unsprayed than the sprayed orchard. The introduced Argentine ant, Linepithema humile (Mayr), was the most abundant species in both orchards. The study clearly indicated that habitat transformation and the use of pesticides had a negative impact on arthropod diversity in the Cape Floristic Region.