Avaliação de Cultivares de feijão nhemba {Vigna ünguièulata (L.) Walp) quanto à resistência ao gorgulho {Callosobruchus maculatus (Fab.)) (Coleoptera: Bruchidae).

Abstract

ABSTRACT The present work was carried out at the Instituto de Investigacao Agrária de Moçambique (IIAM), between the months of May and December 2005, and its general objective was to evaluate the performance of different cowpea varieties {Vigna unguiculata (Lineau. Walper)) , for resistance to the weevil Callosobruchus maculatus (Coleoptera: Bruchidae). Five (5) varieties were tested, of which two (2) are local, namely INIA-36 and IT82E-18, and three introduced IT82F-16, SUDAN and CP-2 from Nigeria. The ÍNIA-36 variety, considered by Chilenge (1990), as the most susceptible, was used to create the weevil used in the test, in five (5) liter flasks, in greenhouse number four (4) at IIAM, at temperatures and environmental relative humidity. Newly emerged adults from these jars were used to infest new jars containing 1.125 kg of each cowpea variety used in the study. The infestation of new flasks was carried out in another greenhouse, with mean ambient temperatures of 27±4 °C and relative humidity of 63%, with 10 pairs (10 females and 10 males previously selected) being placed per flask. After two (2) months the following variables were evaluated: number of eggs, percentage of infestation, weight loss, emerged adults and the effect of the granule insecticide (Carbon Dichloroethylene tetrachloride) on the weevil control. The analysis of the results showed that there were significant effects of the varieties and their interactions with the grain insecticide and the initial insect population regarding the variables number of eggs, emerged adults, consumed seed mass and germination percentage. The CP-2 variety showed the best performance of all the varieties under study and the lowest was observed in the IT82E-18 variety. The rest behaved as intermediaries. Granol insecticide had a significant effect on weevil control, as this product maintained lower levels of number of eggs and emerged adults, percentage of infestation, weight loss and did not affect percentage seed germination in all varieties.