Occurrence and population fluctuation of Brachycaudus schwartzi on peach tree, in the city of Jacuí, MG

Abstract

This work intended to study both occurrence and population fluctuation of the aphid Brachycaudus (Appelia) schwartzi, (Börner, 1931) (Homoptera: Aphididae), on peach tree in the city of Jacuí, MG, under the influence of climate factors and phenology of the plant, as well as to verify the ratio of forms over the period sampled. Three apical twigs about 25 cm long were sampled fortnightly per plant in 10 plants. Throughout the sampling period, the presence of B. schwartzi was found, but the highest peaks were registered from August, 1994 to December, 1994. The maximum peak occurred in September, 1994, where its population proved to be positively correlated with temperature and negatively with relative humidity and the plants were in the vegetative phase. The population of nymphs of first and second instars was greater in relation to the others, standing for 62.68% of the total of individuals sampled. The phenology of the peach tree was a factor of great importance in the population fluctuation of B. schwartzi.