Insetos praga e inimigos naturais no milho (Zea Mays L.) E NA Urochloa ruziziensis (Ger & Evr) cultivados em sistemas diversificados

Abstract

Intercropping crop systems between maize (Zea mays L.) and Urochloa ruziziensis (Ger. & Evr.) are commonly adopted in Brazil due to the adoption of Crop Livestock Integration (CLI) which provide plenty of hosts for insects it use plants of Poaceae family as host. The the aim of this study were (1) test how the diversity of plants affects the biological control exercised by predators of Rhopalosiphum maidis (Fit.) and the correlations existing in the different cultivation systems; (2) species of phytophagous stink bugs use intercropping as a nutritional resource for occurrence in CLI plants; (3) to identify the impact of each system on the abundance and population dynamics of R. maidis. The crop systems (treatments) studied were, (1) fallow, (2) maize hybrid SYN 7205 TG, (3) maize hybrid SYN 7205 TLTG Viptera, event MIR162 + Bt11, (4) U. ruziziensis implanted in the single system (monoculture ) (5) maize hybrid SYN 7205 TG + (6) U. ruziziensis and (7) maize hybrid SYN 7205 TLTG Viptera + (8) U. ruziziensis inplanted in intercopped system (simultaneous planting). The studies were carried out in the field during three seasons (two experiments in summer and one in fall). We identified that (1) in the three agricultural years, Orius spp., was the most important predator followed by Coccinelidae and Dermaptera; (2) it was not possible to find significant differences for the diversity of phytophagous stink bugs in the treatments and the Jaccard index revealed that the subgroups formed by maize treatments do not group with U. ruziziensis; (3) the maize cultivated single affected the abundance of R. maidis positively and there is a low reproductive performance of the corn leaf aphid in U. ruziziensis as well as in the treatment under fallow. We conclude that the intercropping between maize and U. ruziziensis is not favorable to phytophagous stink bugs or R. maidis and the degree of correlation between R. maidis and natural enemies (IN) varied, as the importance of the organisms that exercised biological control.