Zaprionus indianus is a drosophilid native to the Afrotropical region that has colonized South America and exhibits a wide geographical distribution. In contrast, Z. sepsoides is restricted to certain African regions. The two species differ in the size of their testes, which are larger in Z. indianus than in Z. sepsoides. To better understand the biology and the degree of differentiation of these species, the current study evaluated spermatogenesis in males of different ages by conventional staining techniques and ultrastructural analysis. Spermatogenesis and the ultrastructure of spermatozoa were similar in the two species, and the diploid number was confirmed to be 2n = 12. A greater number of spermatozoa were observed in young Z. indianus (1-3 days old) compared to Z. sepsoides males, which showed a higher frequency of cells at the early stages of spermatogenesis. The head of the sperm was strongly marked by silver staining, lacto-acetic orcein and the Feulgen reaction; the P.A.S. reaction revealed glycogen granules in the testes of both species. Both species presented similar arrangement of microtubules (9+9+2), two mitochondrial derivatives of different size and 64 spermatozoa per bundle. Such similarity within the genus Zaprionus with other species of Drosophila, indicates that these structures are conserved in the family Drosophilidae. The differences observed the number and frequency of sperm cells in the early stages of spermatogenesis, between the young males of Z. indianus and Z. sepsoides, are features that may interfere with reproductive success and be related to the invasive potential of Z. indianus.

Uma discussão ainda em pauta refere-se ao uso de armadilhas abertas ou fechadas na padronização das coletas de drosofilideos para alguns estudos específicos. Neste trabalho são apresentados dados comparativos das coletas de drosofilídeos utilizando armadilhas abertas e fechadas em um período de 12 meses, em um fragmento de floresta semidecidual, localizada no Estado de São Paulo, Brasil. A eficiência das armadilhas foi avaliada usando os seguintes descritores da comunidade: abundância populacional, riqueza e diversidade de espécies. As armadilhas fechadas foram mais eficientes em relação à abundância populacional e à riqueza de espécies. Os resultados indicam que as armadilhas fechadas constituem o tipo mais adequado para padronização de coleta de drosofilídeos, em estudos de biodiversidade e sazonalidade.

The use of open or closed traps in order to standardize the drosophilid collection is still a matter of discussion among researchers. In this paper, comparative data of drosophilid collections, using open and closed traps are presented. The collections were made monthly, during one year, in one fragment of a semidecidual forest located in the São Paulo State, Brazil. The efficiency of the traps was evaluated by the use of community descriptors: population abundance and richness and diversity of species. Closed traps were more efficient than the open ones in relation to the population abundance and the species richness, indicating their adequacy for standardization of drosophilid collection in studies of biodiversity and seasonality.

A composição e a sazonalidade de populações de Drosophila foram analisadas de setembro de 1998 a outubro de 1999 em coletas mensais realizadas em duas matas do noroeste do Estado de São Paulo, Brasil, considerando-se as variáveis climáticas temperatura e pluviosidade. As curvas do componente de dominância apresentaram-se inclinadas, refletindo uma baixa diversidade e uma alta dominância de poucas espécies. Drosophila sturtevanti Duda, 1927 foi a mais abundante e frequente das 25 espécies registradas. Em contraposição a dados da literatura, a abundância e a freqüência de D. paranaensis Barros, 1950 foram maiores do que as de D. mercatorum Patterson & Wheeler, 1942. Foi observada uma correlação positiva entre a abundância e a pluviosidade para D. nebulosa Sturtevant, 1916. Esses achados são indicativos de mudanças na estrutura das populações de Drosophila devido a novas estratégias adaptativas surgidas em resposta às modificações ambientais.

The composition and the seasonality of the natural populations of Drosophila species in relation to the climatic variables temperature and rainfall were analyzed from September 1998 through October 1999 by monthly collections, in two woodlands in the Northwest of the State of São Paulo, Brazil. The diversity dominance component curves were inclined, reflecting low diversity and high dominance of few species. Among the 25 species recorded, Drosophila sturtevanti Duda, 1927 was the most frequent and abundant. On the opposite to data in literature, D. paranaensis Barros, 1950 abundance and frequency were greater than those from D. mercatorum Patterson & Wheeler, 1942. A positive correlation between abundance and rainfall was observed for D. nebulosa Sturtevant, 1916. These data are indicative of changes in the populations structure due to new adaptive strategies arised in response to environmental modifications.