Diversity of arthropods in grain production systems under different soil managements

No tillage system and cover crops are receiving more attention due to their contribution to improve soil characteristics, reduce soil erosion and help pest control. Altogether they provide refuge and reserve of food for beneficial insects and spiders. Arthropods were sampled during three growing seasons in Santo Antônio de Goiás, GO Brazil (latitude 10o 5’ S, longitude 10o 5’ W, elevation 850 m above MSL), under conventional and no tillage soil management. The experimental design was a split plot, arranged in randomized complete blocks with four replications. The main plots consisted of cover crops crotalaria (Crotalarea juncea), sorghum (Sorghum bicolor) or no cover crop. Subplots were the grain crops corn (Zea mays), dry bean (Phaseolus vulgaris), and rice (Oryza sativa). Each main plot (120 m2) was divided in three subplots (40 m2). Arthropods were sampled weekly using one pitfall per plot. In the first year study, there was no difference among treatments. This may be explained by a disequilibrium resulted from the management system previously adopted. In the following years, there was an increase in species diversity and abundance, along with stability of the populations which may be resulted from better management practices. The majority of the main taxonomic groups captured was observed in the no tillage system. The microclimatic conditions proportioned by the straw contributed to increase survivorship and their population sizes. Only in the third year it was detected significant differences between cover crops. Preferences of arthropod groups for cover crops varied with species and type of cover plants.