Neste estudo foram avaliados componentes do valor adaptativo de Zaprionus indianus Gupta, 1970, uma espécie recentemente introduzida no Brasil e, atualmente, em processo de colonização de praticamente todas as regiões brasileiras. Foram avaliadas a longevidade, a produtividade, a velocidade de desenvolvimento e a viabilidade de indivíduos amostrados de uma população de Mirassol (estado de São Paulo, Brasil). A longevidade foi maior do que aquelas registradas em populações indianas, enquanto que a produtividade foi similar ou maior do que a observada em outros Drosophilidae. O tempo de desenvolvimento, um dos principais componentes relacionados à habilidade competitiva, foi muito similar aos valores registrados para Drosophila sturtevanti Duda, 1927, espécie que ocorre em alta freqüência na mesma área que Z. indianus. Esses dados podem contribuir para o entendimento do sucesso de colonização desta espécie recém-introduzida na América do Sul.

This study aimed to evaluate fitness components of Zaprionus indianus Gupta, 1970, a species recently introduced in Brazil and currently in process of colonization. Longevity, productivity, developmental speed and viability of flies sampled from a population from Mirassol (state of São Paulo, Brazil) were evaluated. Longevity was higher than that of some Indian populations and productivity was similar or higher than in other Drosophilidae. Time of development, one of the main fitness components for competition, was very similar to the values scored in Drosophila sturtevanti Duda, 1927, a species that occurs in high frequencies in the same area as Z. indianus. These data might contribute further for understanding the colonization success of this newcomer species in South America.

The occurrence of hybrid dysgenesis was investigated in Drosophila sturtevanti Duda, 1927 using diagnostic crosses similar to those used for induction of dysgenics traits in D. melanogaster. Reciprocal test crosses were made, at 27° C, between an old laboratory strain of D. sturtevanti (COL, from Colombia), assumed to be an M'-like strain, and eight freshly collected strains from several natural populations. The gonadal dysgenesis indices were under 10% in most of crosses, except in hybrids of COL with I27, a strain from Minas Gerais (Brazil), in which the index values were moderate in both directions of crosses (25.71 and 12.87). The smallest productivity was also observed in hybrids of females COL mated to I27 males. No causal relationship between the observed gonadal dysgenesis and mobilization of P element or another transposable element could be effectively established.