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The social wasp nests were quantified in three different plant physiognoniies (forested Caatinga, shrubby Caatinga, and agricultural systems) to analyze the effect of environmental seasonality and plant physiognomy on the richness, nest abundance, and species composition of social wasps in the region of tropical dry forest of Brazil. The forested Caatinga physiognomy had the greatest richness of species (S = 16), followed by shrubby Caatinga (S = 13) and by agricultural system (S = 12). The first axis of detrended correspondence analysis (DCA) explained 67.8% of the variability and shows a gradient of the fauna from agricultural system and shrubby Caatinga to forested Caatinga. In the first axis, wet season scores were much higher than those for the dry season in forested Caatinga. The second axis explained 18.7% of the variability and shows a separation of samples collected during the wet or the dry periods in shrubby Caatinga. This separation was less evident in the agricultural system. Variations in nest abundance were more intense in arbustive caatinga (45% decrease in number of active nests in the dry period), moderate in forested Caatinga (24% decrease in number of active nests in the dry period), and low in agricultural systems (8% decrease in the dry period). [ABSTRACT FROM AUTHOR]

Centris spp are oil-collecting solitary bees that are valuable pollinators of crops such as Brazil nut, cashew, and acerola. We investigated the genetic variability of populations of C. aenea in the northeastern region of Brazil. Total DNA was extracted from 59 individuals from 6 locations in the States of Pernambuco and Bahia and a 600-650-bp fragment of the mitochondrial COI/COII region amplified by PCR, followed by digestion with the restriction enzymes DraI and SspI. PCR-RFLP analysis revealed eight different haplotypes among the populations. Haplotype A1, revealed by DraI, was the most frequent (50%), and haplotypes A3 and A4 were exclusive to Feira de Santana, Bahia and Morro do Chapéu, Bahia, respectively. Among the haplotypes revealed by SspI, B2 was the most frequent (37%) and B3 was exclusive to Feira de Santana. This information revealing high haplotype diversity will be useful for developing management strategies for Centris, especially because of increasing interest in the rearing and/ or relocation of these bees for crop pollination.

Centris aenea Lepeletier is a solitary bee that has raised interest in management to pollinate crops, such as acerola, Malpighia emarginata. This study investigated the level of morphometric variability among populations of C. aenea from Northeastern Brazil. Traditional and geometric morphometric analyses were used. Head length, leg length, wing length, and wing shape were measured in samples (5-10 females) from eight localities. We did not find statistically significant differences among the populations (P > 0.01). The partial wing warps were similar in the populations and indicated that the bees were not morphometrically different. Our results suggest that C. aenea shows low population morphometric variability and highlight the need for further investigations on population variation in this species, preferably including populations sampled at the extremes of their geographic distribution. Significant insight into the population variation of C. aenea will probably require the use of molecular markers to allow a comparative approach between morphometric variability and genetic variability.