Comparison between biological and conventional management caterpillars in soybeans

This study compared the conventional management (chemical) and biological control for caterpillars in RR soybeans. The experiment was conducted in São Raimundo Mangabeiras, Maranhão, using soy M 9144 RR, sown on 30/12/2013. The experimental design was randomized blocks, with two treatments repeated 10 times in plots of 3 ha. The treatments were control of pests, especially defoliating caterpillars, by conventional chemical and biological control methods. In the conventional treatment, four sprayings with insecticides were conducted; in the biological tretment, five releases of Trichogramma pretiosum (100,000 adults ha^-1) and four sprayins of Beauveria bassiana (4.2 x1013 viable conidia ha^-1) were conducted. The caterpillars present in the crop were evaluated by the beat-cloth method at five points per plot. The most abundant pest was Chrysodeixis includens (Lepidoptera: Noctuidae), which occurred throughout the experimental period. On some dates, the conventionally managed plots showed higher numbers of Anticarsia gemmatalis (Lepidoptera: Erebidae) and C. includens, differing significantly from the biologically managed plots (t-test 5%). The mean yield was significantly higher (t test, 5%) in the biologically than in the  conventionally managed plots.

Keywords: Lepidoptera, biological control, parasitoid eggs.