Abstract
The Neotropical bee Centris (Hemisiella) dichrootricha is a solitary bee that nests in pre-existing cavities that occur in the rain forest. This study describes the nesting biology of C. dichrootricha and its preference for nesting in Cerrado and gallery forest habitats. The study was conducted from January 2012 and December 2013, in Mirador State Park in the municipality of Formosa da Serra Negra, Maranhão State, Brazil. For this, wooden trap-nests of 6, 8, 10, 12, 14 and 16 mm in diameter were used; a total of 300 trap-nests were placed in the gallery forest and Cerrado areas, respectively. Traps were monitored monthly and all completed nests were collected and replaced with empty ones. The nests were then taken to the laboratory to analyze bee development and emergence, nests characteristics and parasites presence. The species used 29 of the trap-nests, which had diameters of 8, 10, 12 and 14 mm. A total of 87 C. dichrootricha specimens emerged. The nests were parasitized by two bee species, Mesocheira bicolor (Apinae) and Coelioxys sp. (Megachilinae), and one fly species, Antrax sp. (Diptera). The highest nesting incidence of 72.4 % was observed in the gallery forest, whereas only 27.6 % in the Cerrado; this difference in habitat use was significant (χ² = 5.56; p < 0.05; DF = 1). For the nests that were built in the gallery forest, 80.9% of the soil originated from the Cerrado. The females were significantly larger than the males (F1, 76 = 595.19; p < 0.001). There were 11 pollen types that belonged to six families. Pollen of the family Malpighiaceae was most frequently used, with four species represented (Byrsonima crassifolia, B. rotunda, B. spicata and Heteropterys sp.). C. dichrootricha showed a preference for nesting in cavities of various diameters in gallery forest sites. The present study provides a novel description of the nesting habits and biology of C. dichrootricha in habitats of Central/Southern Maranhão. C. dichrootricha primarily used resources from the Cerrado, including soil to build their nests, pollen and floral oils; we concluded that gallery forest and Cerrado areas are intrinsically related to the maintenance of local populations of this species.
Highlights
There are three subgenera of Centridini that nest in pre-existing cavities: Hemisiella, Heterocentris and Xanthemisia (Coville et al, 1983)
Studies on the biology of solitary bees in the Cerrado areas in Northeastern Brazil are incipient, and they include the occurrence of C. vittata nesting in natural trunk cavities of Astronium sp. (Anacardiaceae) (Ramos, Rêgo, & Albuquerque, 2007a; Ramos et al, 2010) and the biology of C. tarsata nesting in artificial cavities (Mendes & Rêgo, 2007)
The species’ seasonal nesting activity began at the onset of the rainy season, and most nest building ended in November. This seasonal pattern was maintained in the second year of the study for both the gallery forest and the Cerrado, but the number of nests built was lower in the second year than in the previous year (Fig. 1)
Summary
There are three subgenera of Centridini that nest in pre-existing cavities: Hemisiella, Heterocentris and Xanthemisia (Coville et al, 1983) These bees can be divided into two groups based on their use of building material for nests (Vinson, Frankie, & Williams, 1996), and this feature is one of the taxonomic criteria used to verify the phylogenetic affinity of bees (Michener, 2007). The group that includes Heterocentris and Xanthemisia uses wood chips for the construction of cells, and the Hemisiella subgenus builds their nests with sand (Vinson et al, 1996) Floral oil is another resource used to build nests, and it functions as a coating material for internal and external surfaces of the cells of the nests (Neff & Simpson, 1981). The aim of this study was to provide data on the biology and nest architecture of C. dichrootricha, including its seasonality, sex ratio, parasitism rate, and food source origin, and to assess its preference for nesting in Cerrado and gallery forests
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