The populations of the soybean caterpillar, Anticarsia gemmatalis, were evaluated by weekly assessions of the number of these caterpillars from January through March, during the soybean cropping cycles from 1982/83 to 89/90, aiming to determine the populational intensity of the insect and the efficacy of its natural control agents. The highest ocurrence of A. gemmatalis caterpillars was registered between January 30th and March 1st, when soybean plants were between growing stages R2 (full flowering) and R5 (pod grains beginning to fill). The total mortality of A. gemmatalis due to parasitoids and entomopathogens varied from 10% (83/84) to 89% (86/87). In the average and along the years there was 56% total mortality, from which 29% was due to the fungus Nomuraea rileyi (Farlow) Samson, 15% due to the parasitoid Microcharops bimaculata (Asmead), 6% due to the fungus Entomophthora sphaerosperma (Fresius), 4% due to the nuclear polyhedrosis virus Baculovirus anticarsia and 1% due to each of the parasitoids Patelloa similis (Townsed) and Euplectrus chapadae (Asmead). In four of the eight cropping seasons, there was no significant difference in grain yields for the areas with natural biological control and chemical control, thus showing the great importance of the natural biological control agents to control the caterpillars of A. gemmatalis This fact has to be carefully considered in an integrated soybean management programs aiming to rationalize or to reduce the use of agrochemicals in the crop.
Anticarsia gemmatalis; natural biological control; soybean
