Abstract Karyotypes in the worldwide subfamily Oecanthinae show variations in diploid number, chromosome morphology, and sex-chromosome system. This study described the chromosome set and phylogenetic relationships of four Neotropical species, Oecanthus lineolatus, O. valensis, O. pallidus, and O. pictus. We used classical cytogenetics and Bayesian Inference for phylogenetic reconstruction, using the mitochondrial genes COI, 12S rRNA, and 16S rRNA; and analyzed the phylogenetic patterns of changes in chromosome numbers, using ChromEvol. We observed differences in chromosome number among species and two different sex-chromosome systems. Oecanthus pictus showed 2n = 21, X0♂/22, XX♀; O. lineolatus, 2n = 20, XY♂/XX♀; and O. valensis and O. pallidus, 2n = 18, XY♂/XX♀. The karyotype of Oecanthus was asymmetric, one group with large chromosomes and variation in heterochromatin distribution, and another with small acrocentric chromosomes. The phylogenetic tree recovered two main groups: one with the Palearctic species and another with species from different bioregions, but with low posterior probability. The Neotropical species grouped separately, O. valensis and O. pictus with Nearctic and Ethiopian species, and O. pallidus and O. lineolatus in another, well-supported clade. Together, the phylogenic and chromosome data suggest descending dysploidy events during the evolution of the group.

Abstract Diptera is a megadiverse order, reaching its peak of diversity in Neotropics, although our knowledge of dipteran fauna from this region is grossly lacking. This applies even to the most studied families, such as Drosophilidae. Despite its prominence, most aspects of the biology of these insects are still poorly understood, especially those linked to natural communities. Field studies on drosophilids are highly biased towards fruit-breeding species. Flower-breeding drosophilids, however, are worldwide distributed, especially in tropical regions, although being mostly neglected. The present paper shows the results of a biodiversity inventory of flower-breeding drosophilids carried out in several localities in Brazil, based on samples of 125 plant species, from 47 families. Drosophilids were found in flowers of 56 plant species, from 18 families. The fauna discovered turned out to be mostly unknown, comprising 28 species, with 12 of them (> 40%) still undescribed. Not taking into account opportunistic species, two-thirds of the flower-exclusive diversity was undescribed. The Drosophila bromeliae species group was the most representative taxon, with eight species (six undescribed), including four polyphagous and four Solanum-specialized species. This specialization on Solanum is reported for the first time for Drosophilidae. Other taxa of restricted flower-breeding drosophilids were the Drosophila lutzii species group and two species of the genus Zygothrica Wiedemann. Some specimens of the genera Cladochaeta Coquillett, Rhinoleucophenga Hendel and Scaptomyza Hardy were found, but their relations to flowers are unclear. Additionally, ten species of broad niche were found using flowers opportunistically. Localities and host plants were recorded for all species collected.

ABSTRACT In several arthropod groups, male genitalia is the most important feature for species identification, especially in cryptic species. Cryptic species are very common in the Drosophila genus, and the Neotropical Drosophila willistoni species group is a good example. This group currently includes 24 species divided into three subgroups: alagitans, bocainensis and willistoni. There are six sibling species in the willistoni subgroup – D. willistoni, D. insularis, D. tropicalis, D. equinoxialis, D. pavlovskiana and D. paulistorum, which is a species complex composed of six semispecies – Amazonian, Andean-Brazilian, Centroamerican, Interior, Orinocan and Transitional. The objective of this study was to characterize male genitalia of the willistoni subgroup, including the D. paulistorum species complex, using scanning electron microscopy and light microscopy. We also tried to contribute to the identification of these cryptic species and to add some comments about evolutionary history, based on male genitalia characters. Despite being cryptic species, some differences were found among the siblings, including the Drosophila paulistorum semispecies.

O Pampa brasileiro (extremo sul do país) está, atualmente, vastamente modificado devido ao aumento das atividades agrícolas. Em muitos lugares, apenas pequenos fragmentos de campo permanecem em uma paisagem agrícola. Drosophilidae (Diptera) tem sido amplamente utilizadas como bioindicadores para monitorar os efeitos das mudanças antropogênicas em ambientes naturais. Porém, a fauna de Drosophilidae no Bioma Pampa de ambientes naturais ou perturbados, ainda permanece amplamente desconhecida. O presente estudo é uma das primeiras tentativas de preencher esta lacuna, apresentando resultados de coletas mensais no município de São Luiz Gonzaga (28º24'28"S, 54º57'39"W), no Pampa brasileiro. Um inventário de espécies foi conduzido em dois ambientes contrastantes, uma zona urbana e um remanescente de floresta (zona rural). Em ambos os locais, armadilhas com banana fermentada foram usadas para capturar drosofilideos adultos. A identificação foi feita através da morfologia externa e da terminália dos machos. No total, 13,379 drosofilideos foram analisados (zona rural: N = 8,812 and Sobs = 25; zona urbana: N = 4,567 and Sobs = 16). No presente estudo, 16 (60%) das 26 espécies coletadas foram encontradas exclusivamente ou preferencialmente no fragmento de mata. O período de maior riqueza foi entre os meses de junho a novembro (inverno-primavera), e o período de menor riqueza foi de dezembro a maio (verão-outono). Uma análise de cluster pelo Coeficiente de Jaccard mostrou que a composição da assembléia muda ligeiramente quando o período do ano com temperaturas mais elevadas (janeiro-maio) é comparado com o período de temperaturas menos elevadas (junho-outubro). A abundância das espécies foi também altamente afetada pela sazonalidade, como revelou o Índice de Morisita, onde as amostras foram agrupadas em períodos consecutivos dentro de uma mesma estação, mostrando a preferência sazonal de algumas espécies. O componente tempo foi determinante na diversidade da assembléia, superando o efeito espacial. A forte redução na diversidade na área urbana quando comparada com o pequeno fragmento de floresta, torna evidente a importância do ambiente natural para a preservação da diversidade no bioma Pampa, atualmente com sua paisagem altamente alterada.

The Brazilian Pampa (the southernmost end of the country) is currently a highly modified environment because of increasing agricultural activities. In many places, only small parts of grasslands remain inside an agricultural landscape. Drosophilidae (Diptera) have been widely used as a potential bioindicators to monitor the effects of anthropogenic changes in natural environments. However, the fauna of Drosophilidae in the Pampa Biome from natural and disturbed environments, still remains largely unknown. The present study represents one of the first attempts to fill this gap, showing results from monthly collections in the municipality of São Luiz Gonzaga (28º24'28"S, 54º57'39"W), in the Brazilian Pampa. A species inventory was carried out in two contrasting environments, an urban zone and a forest remnant (rural zone). In both areas banana-baited traps were used to capture adult drosophilids. The identification was made using external morphology and male terminalia. In total, 13,379 drosophilids were analyzed (rural zone: N = 8,812 and Sobs = 25; urban zone: N = 4,567 and Sobs = 16). In the present study, 16 (60%) out of 26 species were found exclusively or preferentially in the forest. The period of highest richness was between the months of June to November (roughly winter and spring), and the period of lowest richness was from December to May (roughly summer and autumn). An analysis of cluster by the Coefficient of Jaccard showed that species composition slightly changes when the period of the year with higher temperatures (from January to May) is compared with the period with lower temperatures (from June to October). The species abundances were also highly affected by seasonality, as revealed by the Morisita Index, since the samples clustered into similar groups in consecutive periods and in the same season, showing the seasonal preference of some species. The time component was a determinant in the diversity of the assemblage, surpassing the spatial effect. The strong reduction in diversity in the urban area when compared to a small forest patch is evidence of the importance of the natural environments in maintaining the diversity in the Pampa biome, currently a highly disturbed landscape.

Selenium is an important dietary micronutrient and an essential component of selenoproteins and the active sites of some enzymes, although at high concentrations it is toxic. We investigated diphenyl diselenide ((C6H5)2Se2 ) for its effects on the developmental stages of Drosophila melanogaster and found that in the larval and pupae stages the toxic threshold for this compound when added to the banana-agar medium on which the larva were fed was 350 µmol. In adult flies, fed on the same media, there were no observable toxic effects below 500 µmol but there were toxic effects above 600 µmol, indicating that adult flies were more resistant to selenium intoxication. In larvae, a when diphenyl diselenide was present above the toxic threshold there was increased activation of the hsp83 heat shock protein gene. Selenium promotes oxidation of sulfhydryl groups and affects the folding of proteins and this could explain the over-expression of hsp83 because the product of this gene is involved in protein folding and defense responses, including the response to heat shock.

O presente estudo reúne dados de pesquisa de nove locais de coleta no estado de Santa Catarina, sul do Brasil. Foram obtidas amostras durante aproximadamente quatro anos em áreas florestais, litorâneas e urbanas. As moscas foram atraídas através de isca de banana fermentada e capturadas em armadilhas. Dentre as espécies do gênero Zygothrica Wiedemann 1830 coletadas, Zygothrica apopoeyi Burla 1956, Z. bilineata (Williston 1896), Z. dispar (Wiedemann 1830), Z. lanceolata Burla 1956, Z. nigropleura Grimaldi 1987, e Z./poeyi (Sturtevant 1921) foram registradas pela primeira vez no estado de Santa Catarina e, com exceção de Z. bilineata, também no sul do Brasil. Além destas espécies, também foram coletadas Zygothrica hypandriata Burla 1956, Z. orbitalis (Sturtevant 1916) (como Z. parilis), Z. prodispar Duda 1925 e Z. vittimaculosa Burla 1956. Com exceção de Z. bilineata e Z. hypandriata, estes registros representam os novos limites de distribuição geográfica sul para estas espécies. Todas as espécies coletadas foram representadas por poucos indivíduos, provavelmente como conseqüência do método de coleta, e a maioria delas foi capturada em invernos e primaveras. Cinco/espécies foram restritas ao local estudado mais preservado e a maioria dos indivíduos foi coletada em áreas de floresta. Entretanto, quatro espécies também foram capturadas em ambientes urbanos ou xéricos, indicando uma tolerância mais alta e uma versatilidade ecológica mais ampla do que previamente era pensado para este gênero, pelo menos para algumas de suas espécies.

The present paper brings together survey data from nine collection sites in Santa Catarina state, southern Brazil. Samples were obtained during about four years in forested, coastal and urban areas. Flies were attracted by fermented banana baits and captured in traps. Among the species of the genus Zygothrica Wiedemann 1830 collected, Zygothrica apopoeyi Burla 1956, Z. bilineata (Williston 1896), Z. dispar (Wiedemann 1830), Z./ lanceolata Burla 1956, Z. nigropleura Grimaldi 1987, and Z. poeyi (Sturtevant 1921) were recorded for the first time in Santa Catarina state and, except for Z. bilineata, also in southern Brazil. Apart from these species, we also collected Zygothrica hypandriata Burla 1956, Z. orbitalis (Sturtevant 1916) (as Z. parilis), Z. prodispar Duda 1925 and Z. vittimaculosa Burla 1956. Except for Z. bilineata and Z. hypandriata, these are the new southernmost records for the geographical distribution of these species. All the collected species were represented by few individuals, probably as a consequence of the collection method, and most of them was captured in winters and springs. Five species were restricted to the more preserved studied site, and most individuals were collected in forest sites. Nevertheless, four species were also captured in urban or xeric environments, indicating a higher tolerance and a wider ecological versatility in this genus as compared to what was previously thought, at least for some species.

Body color polymorphism of urban populations of cosmopolite fly Drosophila kikkawai Burla, 1954 was investigated in relation to its possible association with environmental temperature. Samples of D. kikkawai were collected in spring, summer, autumn and winter between 1987 to 1988, in zones with different levels of urbanization in the southern Brazilian city of Porto Alegre, Rio Grande do Sul. A clear association was observed between darker flies and both seasons with low temperatures and areas of low urbanization (where temperature is generally lower than in urbanized areas). Results of preliminary laboratory experiments involving six generations of flies grown in chambers at temperatures of 17º and 25ºC confirmed this tendency to a relationship between body color and temperature, with allele frequency of the main gene involved in body pigmentation changing over time.

Chromosomal polymorphism in natural populations of Drosophila willistoni from Uruguay and southern Brazil was investigated in order to understand the genetic characteristics and evolutionary potential of these almost geographically marginal populations. The level of chromosomal polymorphism in samples from Uruguay was higher than in those from the southernmost Brazilian state of Rio Grande do Sul. The increase in the polymorphism of these populations, in which the species almost reaches its southern limit, contradicts the low level of paracentric inversion polymorphism expected under the central-marginal chromosomal polymorphism cline previously reported. The high frequency of some inversions and the presence of unique inversions in samples from Uruguay indicate the uniqueness of these populations.