Condição da colônia e alterações bionômicas em Geotrigona inusitata (Apidae, Meliponinae)

ABSTRACT. Abundance, spatial distribution of Meliponina bees' nests (Hymenoptera, Apidae, Apini) and plant species used as nesting sites in savanna areas of Maranhão, Brazil. This study aimed at identifying the stingless bees species (Hymenoptera: Apidae, Apini, Meliponina) those were found in three study sites of cerrado, northeastern Brazil. The study also aimed identifying the plant species those were used as nesting sites by the stingless bees and verifying their characteristics. We intended to verify abundance and spatial distribution of the nests and patterns of the plants used as nesting sites. Seventy-three nests of 15 species were found. The most abundant species were Partamona chapadicola Pedro & Camargo, 2003 (34,25%) and Oxytrigona sp. 2 (20,55%). Eleven tree species were used as nesting sites. The most common host tree species was Qualea parviflora (Vochysiaceae) where 38,36% of the nests (n=28) nestled, followed by Salvertia convallariodora (Vochysiaceae) (n=17, 23,29%). The 95% confidence interval of DHB was between 36,21 cm and 41,68 cm. This interval is related with older trees that should have more hollows to be used as nesting sites. This process might be occurring with S. convallariodora and Q. parviflora. The patterns of spatial distribution for study sites 1 and 2 were random and the pattern for study site 3 was uniform. Random pattern would be a sign for absence of competition. On the other hand uniform pattern would indicate competition. KEYWORDS.Meliponina, fragmentation, Cerrado, nesting sites, spatial distribution. RESUMO.O trabalho objetivou identificar as espécies de abelhas sem ferrão (Hymenoptera, Apidae, Apini, Meliponina) presentes em três áreas de cerrado no Maranhão, nordeste do Brasil, por meio do levantamento de seus ninhos. Também foi objetivo do trabalho identificar e caracterizar os substratos vegetais utilizados como locais de nidificação. Pretendeu-se averiguar a abundância e a distribuição espacial de ninhos, bem como padrões de uso dos substratos para nidificação. Foram encontrados 73 ninhos pertencentes a 15 espécies. As espécies mais abundantes foram Partamona chapadicola Pedro & Camargo, 2003 (34,25%) e Oxytrigona sp. 2 (20,55%). Identificaramse 11 espécies vegetais utilizadas para construção dos ninhos. O substrato de nidificação mais freqüente foi Qualea parviflora (Vochysiaceae), na qual encontrou-se 38,36% do total de ninhos (n=28), seguido por Salvertia convallariodora (Vochysiaceae) (n=17; 23,29%). O intervalo de confiança de 95% para o DAP situou-se entre 36,21 cm a 41,68 cm. Este intervalo representaria árvores mais velhas que teriam mais cavidades disponíveis para nidificação, o que poderia ser o caso de S. convallariodora e Q. parviflora. O padrão de dispersão dos substratos com ninhos mostrou-se aleatório nas áreas 1 e 2 e uniforme na área 3. Padrões de distribuição aleatórios seriam um indício da ausência de competição e padrões uniformes indicariam competição. PALAVRAS-CHAVE.Meliponina, fragmentação, cerrado, substratos de nidificação, distribuição es...

The proportions of males produced by queens or workers of Scaptotrigona depilis, and the sex-ratio in the brood, were estimated. Thirteen young combs were collected; from one half of each comb the cells were opened and the number of eggs per cell was recorded. Later, upon maturation, from the other halves of the combs the individual inside each cell was classified according to sex. If from a cell containing initially two eggs a male would emerge (supposedly the son of a worker) the proportion of such cells in the comb would represent the maximum overall workers' male production. Consequently, the difference with the number of males found in the second half of the comb would indicate the minimum contribution by the queen. In these 13 combs, on average, 7.3% of the cells contained 2 eggs, whilst in 30.9% of the cells a male developed. Males were found in 10 combs, in 2-79% of the cells. In 6 of the 13 combs 2-47% of the cells contained 2 eggs. In these 6 combs more than 40% of the cells had a male inside. In 5 of them, the frequency of males was significantly higher than the frequency of cells containing 2 eggs. Queens, therefore, produced the majority of the males. There was no correlation between worker and queen numerical investments in male production, indicating different response mechanisms of workers, compared to queens, to conditions favouring male production. There was also no correlation between the mean egg size of the queen and the percentage males in the combs.