POPULATION DYNAMICS OF APHIDS IN MAIZE CULTIVARS IN OFF-SEASON CROP AND INFLUENCE ON ITS PARASITOIDS

This work aimed to study populational dynamics of aphids on off-seasonmaize genotypes over the culture cycling and the influence of these genotypes onparasitoids of aphids. Fifty-three simple and/or triple hybrids were evaluated in additionto the AL Bandeirante variety, in Cruzália county, São Paulo State, during autumn-wintercrop of 2006. The evaluation was carried out at 39, 53, 67 and 75 days after the sowing,using 5 plants per sample in the two central lines. A cardboard was placed on the basalpart of the whorl with an opening of 3 x 3 cm, totalizing 45 cm2 per sample, counting, inthe inside of the whorl, the number of apterous adults, alate adults, nymphs and parasitized (mummy). The aphids identified were Rhopalosiphum maidis and Rhopalosiphum padiand the parasite was only Lysiphlebus sp. The most important period of aphids occurrencein off-season maize was after 53 days from emergency, before tassel opening. Populationof aphids and parasitoids differed among cultivars, where AS 1567 and 30F87 stood outwith the most quantity of nymphs and parasitism, respectively.