Impact of Organic Crops on the Diversity of Insects: A Review of Recent Research

Abstract

The conversion of forests to conventional agroecosystems is one of the causes of biodiversity loss. In contrast, organic farming practices that promote caring for the environment are seen as an alternative that promotes increased biodiversity. Although insects have one of the largest impacts on crops, to date there have been no published studies that specifically synthetize information on the impacts of organic farming practices on insects. The results of 35 studies that compare the diversity of insects on organic and conventional crops were analyzed by combining a classic review with meta-analysis tools. The purpose was to determine whether organic crops promote better conservation of insects. Species richness and abundance were significantly higher in organic crops, though the reviewed studies indicated a high heterogeneity for species richness and abundance. Likewise, organic farming was associated with higher trophic guild diversity. Insects were 34% more abundant on organic crops. Comparing studies at different landscape scales (plot, farm, landscape matrix), organic crops have a positive effect, with the greatest effect at the plot level. This review also indicates the great need for studies of this nature in the Neotropics and the importance of developing research on the complexity of ecological networks to understand the dynamics of interactions in these agroecosystems in addition to their taxonomic and functional richness.