CROP LIFE TABLE OF SOME SOYBEAN CULTIVARS AND SEASONAL DISTRIBUTION OF THE INSECT FAUNA ON THIS CROP

Field trials were carried out to evaluate the role of the different components that would lead to yield losses in soybeans (Glycine max (L.) Merrill) with emphasis on the incidence of insect pests and time at which the damage occurred, in relation to the crop cycle. The experiments were conducted at Vicosa, MG, Brazil, during the 1985-86 season. The evaluations were performed on the Primavera, Bossier, IAC-5, IAC-8, Doko and Sucupira cultivars, by the use of crop life tables. The insect fauna was composed mainly of phytophagous insects, and their occurrences was strictly associated with the existence of structures in the plant which could be used as food source by these pests. The main pest species were defoliators (Lepidoptera and Coleoptera) and plant sucking insects (Hemiptera). The crop life tables indicated that the highest percent reduction in plant numbers occurred between planting time and seedling emergence. The main factor affecting emergence was soil crusting during that period. In the vegetative phase, losses were attributed mainly to weeding, poor plant formation, and damages inflicted by insects, pigeons and other unknown factors.