Impacto de inimigos naturais e de fatores meteorologicos sobre uma populacao de Brevicoryne brassicae (L.) (Hemiptera: Aphididae) em couve

The dynamics of a population of the cabbage aphid, Brevicoryne brassicae (L.), was studied to estimate the impact of natural enemies and meteorological factors using simple correlation and stepwise regression. Apterous B. brassicae were sampled by visual search, and natural enemies by suction net and pitfall traps. The aphids began to infest kale in July, reaching peak population in September. The factors Diaeretiella rapae (Mc'Intosh), ground spiders, rainfall and relative humidity showed significant correlation with B. brassicae population, in the period that embraced the whole population survey, which suggests that these factors had an important function in the mortality of the aphid. During the period of highest increase and decline of the population of B. brassicae, ground spiders constituted the most significant mortality factor related with the variation of the population density of the aphid.