Living fruits of Psychotria brachyceras Müll. Arg. (Rubiaceae) as the main larval host of Zygothrica orbitalis (Sturtevant, 1916) (Diptera, Drosophilidae)

ABSTRACT Zygothrica is a genus of Drosophilidae (Diptera) whose species utilize flowers and fungi for breeding sites, with records of fungi being used as courtship arena. Due to this habit, its representation in Drosophilidae surveys using banana-baited traps is generally low. However, Zygothrica orbitalis was well represented in a few samples with these traps. In this study, we report for the first time the breeding site of Z. orbitalis in living fruits of Psychotria brachyceras (Rubiaceae), noting that the use of living fruits is rare among Drosophilidae. The fructification of the plant occurs in the area of study from May to August, with previous collection records of the species in the Restinga (sandbank or strand) forest. Additionally, the emergence of some individuals of the invasive species Drosophila suzukii was observed, which highlights the necessity for continuous study of this plant to understand the dynamics between a native and an exotic species. Besides the ecological importance, our results are relevant for understanding the evolution of trophic resource use by the Zygothrica genus.

Diversity of Drosophilidae (Insecta, Diptera) in the Restinga forest of southern Brazil

Abstract Although members of Drosophilidae are frequently the topic of ecological studies in Brazil, few have explored Restinga or, until only recently, Pampa biome environments. This study proposes to describe the diversity and temporal variation of the Drosophilidae assemblage from a Restinga forest of Rio Grande do Sul, Brazil. We performed monthly collections from February 2013 to January 2014 using yeasted banana-baited traps. A total of 25,093 individuals of 46 species were sampled. Drosophila simulans and the D. willistoni subgroup were the dominant taxa; D. polymorpha, D. immigrans, D. paraguayensis and Zygothrica orbitalis were of intermediate abundance, and the other 40 species were rare. Based on sampling effort estimators, our collections were sufficient. Jaccard and Morisita indices evaluated using ANOSIM reveal little similarity in the composition of samples across months. Canonical correspondence analysis shows that the variables of maximum and minimum temperature are the main factors responsible for differentiation of the species composition of the assemblage throughout the year, whereby collections in the coldest periods (July, August and September) are those with a more differentiated composition. In these months, the dominance of D. simulans and the D. willistoni subgroup decreases while increased abundance of the D. tripunctata group (as D. paraguayensis) and Z. orbitalis occurs. In comparison to other studies carried out in environments in southernmost Brazil, we observed a similar pattern of fluctuation in abundance over the year, with a higher abundance of dominant species in warmer months and population sizes decreasing in colder months.

Spatiotemporal transcription of the P element and the 412 retrotransposon during embryogenesis of Drosophila melanogaster and D. willistoni

Transposable elements (TEs) are mobile nucleotide sequences which, through changing position in host genomes, partake in important evolutionary processes. The expression patterns of two TEs, P element transposon and 412 retrotransposon, were investigated during Drosophila melanogaster and D. willistoni embryogenesis, by means of embryo hybridization using riboprobes. Spatiotemporal transcription patterns for both TEs were similar to those of developmental genes. Although the two species shared the same P element transcription pattern, this was not so with 412 retrotransposon. These findings suggest that the regulatory sequences involved in the initial development of Drosophila spp are located in the transposable element sequences, and differences, such as in this case of the 412 retrotransposon, lead to losses or changes in their transcription patterns.