The Importance of Maize Management on Dung Beetle Communities in Atlantic Forest Fragments

Abstract

Dung beetle community structures changes due to the effects of destruction, fragmentation, isolation and decrease in tropical forest area, and therefore are considered ecological indicators. In order to assess the influence of type of maize cultivated and associated maize management on dung beetle communities in Atlantic Forest fragments surrounded by conventional and transgenic maize were evaluated 40 Atlantic Forest fragments of different sizes, 20 surrounded by GM maize and 20 surrounded by conventional maize, in February 2013 and 2014 in Southern Brazil. After applying a sampling protocol in each fragment (10 pitfall traps baited with human feces or carrion exposed for 48 h), a total of 3454 individuals from 44 species were captured: 1142 individuals from 38 species in GM maize surrounded fragments, and 2312 from 42 species in conventional maize surrounded fragments. Differences in dung beetle communities were found between GM and conventional maize communities. As expected for fragmented areas, the covariance analysis showed a greater species richness in larger fragments under both conditions; however species richness was greater in fragments surrounded by conventional maize. Dung beetle structure in the forest fragments was explained by environmental variables, fragment area, spatial distance and also type of maize (transgenic or conventional) associated with maize management techniques. In Southern Brazil's scenario, the use of GM maize combined with associated agricultural management may be accelerating the loss of diversity in Atlantic Forest areas, and consequently, important ecosystem services provided by dung beetles may be lost.

Fig 1. Map of the study region.

Location of the 40 forest fragments in the Campos Novos, Santa Catarina state, southern Brazil, near conventional or transgenic maize crops. The twenty fragments sampled in the first year (2013) are circled.

Fig 2. Dung beetle species richness in relation to fragment size (log area) in 40 Atlantic Forest fragments adjacent to transgenic and conventional maize in Campos Novos, Southern Brazil.

Fig 3. Distribution of dung beetle species richness in relation to spatial distance (PCNM) in 40 Atlantic Forest fragments adjacent to transgenic and conventional maize in Campos Novos, Southern Brazil.

Fig 4. Distribution of dung beetle abundance in relation to spatial distance (PCNM) in 40 Atlantic Forest fragments adjacent to transgenic and conventional maize in Campos Novos, Southern Brazil.