Pesticides and land cover heterogeneity affect functional group and taxonomic diversity of arthropods in rice agroecosystems

Biodiversity can be characterised across several dimensions, which are crucial for the evaluation of ecosystem services. Functional diversity, a key aspect of biodiversity, provides a more realistic characterisation of the functioning of ecological communities than only studying their taxonomic diversity. The relevance of functional ecology studies has steadily increased in agroecosystems. However, the combined effects of pesticides and land cover heterogeneity on the taxonomic and functional diversity of arthropod communities have been studied less frequently. We sampled arthropods during the dry season in 19 rice fields located in two different regions of Northern Vietnam. We assorted the arthropods into functional groups corresponding to different feeding habits and calculated the taxonomic and functional group diversifies. Finally, we analysed the impacts of pesticide applications and land cover heterogeneity on both diversity measures. Taxonomic and functional group diversity measures were highly correlated. In turn, both diversity measures responded similarly to land cover heterogeneity and pesticides. Land cover heterogeneity had positive effects on taxonomic and functional group diversity, mainly at the early stage of rice crops. Conversely, the impact of pesticide application on both diversity measures was strongly negative. Our results suggest that rice agroecosystems can be more sustainable by increasing landscape heterogeneity and a reduced pesticide use. Such schemes may help to maintain higher levels of biodiversity that ensure ecosystem functioning, which will be therefore likely beneficial to provide ecosystem services in agroecosystems.