Differential attraction of drosophilids to banana baits inoculated with Saccharomyces cerevisiae and Hanseniaspora uvarum within a Neotropical forest remnant

Background. Yeasts are a necessary requisite in the diet of most Drosophila species that, in turn, may vector their dispersal in natural environments. Differential attractiveness experiments and the isolation of yeasts consumed by Drosophila may be informative for characterizing this association. Hanseniaspora uvarum is among the most common yeast species isolated from Drosophila crops, with high attractiveness to drosophilids. Saccharomyces cerevisiae has been widely used to collect flies, and it allows broad sampling of almost all local Drosophila species. Pronounced differences in the field concerning Drosophila attractivity to baits seeded with these yeast species have been previously reported. However, few explicit generalizations have been set. Since late fifties, no field experiments of Drosophila attractivity were carried out in the Neotropical region, which is facing shifts in abiotic and biotic factors. Our objective is to characterize preference behavior that mediates the interaction in the wild among Neotropical Drosophila species and yeasts associated with them. We want to set a broad generalization about drosophilids attracted to these yeasts. Here we present the results of a differential attractiveness experiment we carried out in a natural Atlantic Rainforest fragment to assess the preferences of Drosophila species groups to baits inoculated with H. uvarum and S. cerevisiae. Methods. Both yeast species were cultured in GYMP broth and separately poured in autoclaved mashed banana that was left fermenting. In the field, we collected drosophilids over five arrays of three different baits: non-inoculated autoclaved banana and banana inoculated with each yeast. In the laboratory the drosophilids were sorted to five sets according to their external morphology and/or genitalia: tripunctata; guarani; willistoni; exotic; and the remaining flies pooled in others. Results and Conclusions. Uninoculated banana baits attracted virtually no flies. We found significant departures from random distribution over the other two baits (1:1 proportion) for all sets, except the pooled others. Flies of the sets willistoni and exotic preferred H. uvarum over S. cerevisiae, while the remaining sets were more attracted to S. cerevisiae. Previously, various authors reported similar patterns in attraction experiments with S. cerevisiae and H. uvarum. It is also noteworthy that both yeast species have been isolated from natural substrates and crops of Drosophila species. Taken together, these results suggest that the preferences among Drosophila species groups may be reflecting deep and stable relations with yeast species in natural environments. They can be summarized as: forest dwelling species from subgenus Drosophila (such as tripunctata and guarani groups) are attracted to banana baits seeded with S. cerevisiae; while exotic (as D. melanogaster) and subgenus Sophophora species are preferentially attracted to baits seeded with H. uvarum

Seasonal and Altitudinal Changes in Population Density of 20 Species of Drosophila in Chamundi Hill

A year long study was conducted to analyze the altitudinal and seasonal variation in a population of Drosophila (Diptera: Drosophilidae) on Chamundi hill of Mysore, Karnataka State, India. A total of 16,671 Drosophila flies belonging to 20 species of 4 subgenera were collected at altitudes of 680 m, 780 m, 880 m and 980 m. The subgenus Sophophora was predominant with 14 species and the subgenus Drosilopha was least represented with only a single species. Cluster analysis and constancy methods were used to analyze the species occurrence qualitatively. Altitudinal changes in the population density, and relative abundance of the different species at different seasons were also studied. The diversity of the Drosophila community was assessed by applying the Simpson and Berger-Parker indices. At 680 m the Simpson Index was low at 0.129 and the Berger- Parker index was high at 1.1 at 980 m. Linear regression showed that the Drosophila community was positively correlated with rainfall but not elevation, Furthermore the density of Drosophila changed significantly in different seasons (F = 11.20, df 2, 9; P<0.004). The distributional pattern of a species or related group of species was uneven in space and time. D. malerkotliana and D. nasuta were found at all altitudes and can be considered as dominant species

Drosophila suzukii (Diptera, Drosophilidae) no Distrito Federal: novas perspectivas a partir capturas realizadas em áreas cultivadas.

Na publicação: Marcelo Lopes-da-silva

Expandindo fronteiras: o estabelecimento de Drosophila suzukii (Diptera, Drosophilidae) no Brasil Central.

Na publicação: Marcelo Lopes-da-silva

Scenario of the spread of the invasive species Zaprionus indianus Gupta, 1970 (Diptera, Drosophilidae) in Brazil

Zaprionus indianus was first recorded in Brazil in 1999 and rapidly spread throughout the country. We have obtained data on esterase loci polymorphisms (Est2 and Est3), and analyzed them, using Landscape Shape Interpolation and the Monmonier Maximum Difference Algorithm to discover how regional invasion occurred. Hence, it was apparent that Z. indianus, after first arriving in São Paulo state, spread throughout the country, probably together with the transportation of commercial fruits by way of the two main Brazilian freeways, BR 153, to the south and the surrounding countryside, and the BR 116 along the coast and throughout the north-east

Variations on a theme: diversification of cuticular hydrocarbons in a clade of cactophilic Drosophila

<p>Abstract</p> <p>Background</p> <p>We characterized variation and chemical composition of epicuticular hydrocarbons (CHCs) in the seven species of the <it>Drosophila buzzatii </it>cluster with gas chromatography/mass spectrometry. Despite the critical role of CHCs in providing resistance to desiccation and involvement in communication, such as courtship behavior, mating, and aggregation, few studies have investigated how CHC profiles evolve within and between species in a phylogenetic context. We analyzed quantitative differences in CHC profiles in populations of the <it>D. buzzatii </it>species cluster in order to assess the concordance of CHC differentiation with species divergence.</p> <p>Results</p> <p>Thirty-six CHC components were scored in single fly extracts with carbon chain lengths ranging from C₂₉to C₃₉, including methyl-branched alkanes, <it>n</it>-alkenes, and alkadienes. Multivariate analysis of variance revealed that CHC amounts were significantly different among all species and canonical discriminant function (CDF) analysis resolved all species into distinct, non-overlapping groups. Significant intraspecific variation was found in different populations of <it>D. serido </it>suggesting that this taxon is comprised of at least two species. We summarized CHC variation using CDF analysis and mapped the first five CHC canonical variates (CVs) onto an independently derived <it>period </it>(<it>per</it>) gene + chromosome inversion + mtDNA COI gene for each sex. We found that the COI sequences were not phylogenetically informative due to introgression between some species, so only <it>per </it>+ inversion data were used. Positive phylogenetic signal was observed mainly for CV1 when parsimony methods and the test for serial independence (TFSI) were used. These results changed when no outgroup species were included in the analysis and phylogenetic signal was then observed for female CV3 and/or CV4 and male CV4 and CV5. Finally, removal of divergent populations of <it>D. serido </it>significantly increased the amount of phylogenetic signal as up to four out of five CVs then displayed positive phylogenetic signal.</p> <p>Conclusions</p> <p>CHCs were conserved among species while quantitative differences in CHC profiles between populations and species were statistically significant. Most CHCs were species-, population-, and sex-specific. Mapping CHCs onto an independently derived phylogeny revealed that a significant portion of CHC variation was explained by species' systematic affinities indicating phylogenetic conservatism in the evolution of these hydrocarbon arrays, presumptive waterproofing compounds and courtship signals as in many other drosophilid species.</p