Avaliação experimental da invasão de drosophlla malerkotliana em guildas de espécies nativas da Amazônia

Abstract

The present work aimed to perform an experimental evaluation of the effect of exploration competition of Drosophila malerkotliana on Drosophila willistoni, a native species of the Amazon rainforest. In the first step the species were studied separately to gather information that will help for the final competition experiment. A strain of the invasive species collected in Manaus in 1995 and the native species was obtained from collections in Igarapé-Açú in 1997. One or two days after the ecIosion, the individuals belonging to each strain were placed in separate population boxes, with sterilized sand and petri dishes containing culture medium on the bottom. On the first day, 14 males and 42 females of each strain were placed in each box. Thereafter, the dead adults were observed daily, ending this observation with the death of the last individual of at least one of the strains. The reproduction of the two species was analyzed by counting the pupae. When the first pupae appeared in the culture medium, they were removed and counted daily until the end of the experiment (26 days). During the renewal of the plates the larvae present were used for the experiment that will be carried out on interference competition. A better performance was recorded for Drosophila malerkotliana in relation to Drosophila willistoni, both because of the higher reproduction rate and because of the lower mortality rate. It is possible that this better performance results from the availability of fresh resources, since the medium of each plate was renewed two to three times, and this species is favored by this type of situation. In the continuation of the experiment, the same strains will be evaluated under similar conditions but without renewal of the culture media.