Pheromones are essential for colony organization in honeybees. The pheromones 9-ODA ((E)-9-oxodec-2-enoic acid) and 9-HDA ((E)-9-hydroxydec-2-enoic acid), produced by the mandibular gland of the queen, have various functions within the colony, including inhibition of ovarian development of workers, attraction of swarms, and stabilization of the cluster group. An example of reaction of the colony to adverse conditions is absconding, which is defined as mass exit of all of the adult individuals, leaving even brood and food. In this study, the pheromones 9-ODA and 9-HDA were determined in virgin and normal mated, egg-laying European Carniolan and Africanized queens, as well as in mated queens that were in absconding colonies, using liquid chromatography with UV detection developed methodology. Absconding was induced by maintaining free-flying five-standard-Langstroth-frame colonies in a chamber artificially heated to 45 ºC. The obtained results showed that the amount of 9-ODA in Africanized queens (6.56 µg bee-1) is very low compared with European queens. However, large amounts of 9-HDA were found in the queens of absconding Africanized swarms (107.4 µg bee-1). According to our results, the quantities of 9-ODA and 9-HDA in Africanized honeybees in Brazil may be contributing to the high rates of absconding, promoting low effect of stabilizing agent, and high effect of attraction of dispersers cluster.

O comportamento de nidificação de Centris (Hemisiella) trigonoides Lepeletier, 1841, e o comportamento de seus cleptoparasitas foram estudados em Monte Santo, Bahia, Brasil. As abelhas construíram seus ninhos com uma mistura de solo e óleo, dentro de cavidades preexistentes na madeira de uma construção abandonada, assim como em gomos de bambu de 8 e 9 mm de diâmetro. Os ninhos completados tinham de uma a cinco células alongadas, arranjadas em uma série linear e orientadas horizontalmente. O tempo gasto para construir uma célula foi altamente variável, sendo em geral de 4,5 a 5,5 h. Após finalizar a construção da célula, as fêmeas fizeram uma ou duas viagens para coletar um líquido incolor, provavelmente óleo floral, usado para revestir as paredes internas da célula. Para aprovisionar uma célula foram realizadas de cinco a oito viagens de coleta para obtenção de pólen e néctar, e de quatro a seis viagens para coleta de óleo. Imediatamente após a oviposição, as fêmeas fecharam as células usando o solo que elas tinham coletado previamente. Três espécies cleptoparasitas pertencentes ao gênero Coelioxys Latreille, 1809 atacaram os ninhos. Entradas de cleptoparasitas dentro dos ninhos occorreram, na maioria dos casos, enquanto a fêmea hospedeira estava ausente do ninho. As fêmeas de C. (H.) trigonoides apresentaram comportamentos defensivos para evitar parasitismo, tais como expulsar os parasitas e guardar os ninhos. Machos de C. (H.) trigonoides usaram o local de nidificação como abrigo durante as horas mais quentes do dia, assim como para dormir. Eles deixavam as cavidades no dia seguinte entre 09:00 e 10:30 h. Isto sugere que machos e fêmeas têm padrões temporais de atividade distintos.

The nesting behavior of Centris (Hemisiella) trigonoides Lepeletier, 1841, and the behavior of their cleptoparasites were studied at Monte Santo, Bahia, Brazil. The females constructed their nests within preexisting holes in wood from an abandoned building as well as in bamboo canes of 8 and 9 mm in diameter, using a mixture of soil and oil. Completed nests had one to five elongated cells arranged in a linear series and oriented horizontally. The time spent to construct a cell was highly variable, but it was generally between 4.5 to 5.5 h. After finishing the construction of a cell, females made one or two trips to collect a colorless liquid, probably floral oil, used to line the inner cell walls. Five to eight pollen-nectar collecting trips and from four to six oil-collecting trips were made to provision one cell. Immediately after oviposition, the females closed the cells using soil that they had previously gathered. Three cleptoparasites species belonging to the genera Coelioxys Latreille, 1809 attacked the nests. Visits of cleptoparasites into the nests occurred mainly while the host female was absent from the nest. Centris (H.) trigonoides females showed defensive behaviors to avoid parasitism, such as chasing the parasites and guarding the nests. Centris (H.) trigonoides males used the nesting sites for shelter during the hottest hours of the day, as well as for sleeping. They would leave the cavities the following day between 09:00 and 10:30 a.m. That suggests that males and females have distinct temporal activity patterns.

Neste estudo foram investigadas a riqueza de espécies e a abundância sazonal de abelhas que nidificam em cavidades em áreas de Floresta estacional semi-decídua e Caatinga na Bahia. A amostragem foi realizada com dois tipos de ninhos-armadilha (= N.A.): gomos de bambu e tubos de cartolina preta (58 x 6 mm e 105 x 8 mm). Os N.A. foram inspecionados uma vez por mês. Foram coletados 146 ninhos de 11 espécies de abelhas na floresta e 121 ninhos de sete espécies na caatinga. Além disso, cinco espécies de abelhas cleptoparasitas foram criadas a partir destes ninhos. As freqüências de nidificação mais altas ocorreram na estação úmida em ambas as áreas. Parasitismo de ninhos foi importante apenas para Centris tarsata Smith, 1874, e foi mais alto na caatinga do que na área de floresta. A mortalidade de adultos pré-emergentes foi alta, especialmente em C. tarsata,Tetrapedia diversipes Klug, 1810 e Euglossa cordata (Linnaeus, 1758). Informações sobre o número de células por ninho, tamanho, forma e arranjo das células nos ninhos, assim como o número de adultos produzidos e o número de gerações por ano foram também apresentados. A riqueza de espécies, os padrões temporais de nidificação e o percentual de parasitismo foram comparados com outros habitats.

In this study were examined the species richness and seasonal abundance of cavity-nesting bees in areas of dry semi-deciduous forest and caatinga in the State of Bahia, Brazil. Sampling was done employing two types of trap-nests: bamboo canes and tubes made of black cardboard with dimensions of either 58 x 6 mm or 105 x 8 mm. The traps were inspected once a month. One hundred and forty-six nests of 11 bee species were collected in the forest, and 121 nests of seven species were collected in the caatinga. Five species of cleptoparasitic bees were also reared from these nests. The highest nesting frequencies occurred in the wet season in both areas. Nests parasitism was important only for Centris tarsata Smith, 1874, and was higher at the caatinga site than in the forest. The mortality of pre-emergent adults was high, especially in C. tarsata,Tetrapedia diversipes Klug, 1810 and Euglossa cordata (Linnaeus, 1758). Information on the number of cells per nest, the size, shape, and arrangement of brood cells in the nests, as well as the number of adults produced and the number of generations per year are also presented. Species richness, temporal patterns of nesting, and percentage of parasitism were compared with other habitats.