Natural habitat fragments obscured the distance effect on maintaining the diversity of insect pollinators and crop productivity in tropical agricultural landscapes

摘要

In tropical regions, habitat change and fragmentation partly occur due to urbanization. This change of land-use can affect many ecosystem services and their providers, such as pollination and pollinators. Within agricultural systems, monoculture systems and pesticide application are the most detrimental to pollinators and insect communities. In this study, we investigated the effect of distance from natural habitat on the diversity of insect pollinators and cucumber productivity. As the independent variable, distance from natural habitats was classified into two different groups i.e. agricultural area near to (less than 200m) and far from (more than 1km) the natural habitat. We found that the abundance of insect pollinators was significantly lower in agricultural areas near to natural habitats compared to those located far from natural habitats. Cucumber farms located near to natural habitats had 54% similar species composition of insect pollinators with cucumber farms located far from natural habitats. The productivity of cucumbers did not differ between cucumber farms near to and far from natural habitats. An expected result was the positive correlation between pollinator abundance (i.e. Xylocopa spp.) and the productivity of cucumber. Our findings suggest that the diversity of pollinators in tropical agricultural landscape is influenced more by a landscape composition of high natural habitat fragments than spatial distance between cropland and natural habitats.