Cavity Length Affects the Occupation of Trap-Nests by Centris analis and Tetrapedia diversipes (Hymenoptera: Apidae)

The ideal cavity dimensions for neotropical cavity-nesting bees with the potential to be managed as pollinators have not been getting proper attention. We investigated whether the occupancy of trap-nests by Centris analis Fabricius and Tetrapedia diversipes Klug, and other nesting aspects, are affected by different trap-nest length. The used trap-nests were cardboard tubes 5, 10, 15 and 20 cm in length, and Ø 8 mm. Occupation rates of 10-cm trap-nests by C. analis was higher than that of the 5-cm ones (χ2=11.17, gl=1, p<0.001). On the other hand, there was not difference between the occupation rates of 10 and 15-cm long trap-nests (χ2=0.51, gl=1, p=0.48), and between the ones measuring 15 and 20 cm long (χ2=1.36, gl=1, p=0.24). T. diversipes occupied a smaller number of 5-cm trap-nests than the 10-cm ones (χ2=1.52, gl=1, p=0.22), as well as that the 15-cm ones were more occupied than the 10-cm trap-nests (χ2=4.23, gl=1, p=0.04); moreover, there was not difference between the occupation of 15 and 20-cm trap-nests (χ2=0.28, gl=1, p=0.59). Both species showed higher rates of dead immatures in nests set in the shortest trap-nests, whereas these mortality rates were lower in the longest ones. By taking into consideration that there was not significant difference in many of the assessed parameters in comparison to values recorded for 15 and 20-cm long trap-nests, it seems likely to recommend the adoption of 10-cm long trap-nests for C. analis reproduction in agricultural sites that depend on the pollination service provided by this bees species.

Bionomic Aspects of the Solitary Bee Tetrapedia diversipes Klug, 1810 (Hymenoptera: Apidae: Tetrapediini)

The study aimed to describe bionomic aspects of Tetrapedia diversipes Klug, 1810 in order to allow the conservation or breeding of these bees. The nesting biology was studied using trap nests made with cardboard-paper tubes and plastic straws during the period between December 2014 and September 2015, in the Bee Unit of the Federal University of Ceará, Brazil. A total of 135 nests were obtained with 593 brood cells, from which emerged 448 adults and individuals of two parasitic species. The proportion of females (n = 297) was higher than that of males (n = 151) resulting in a sex ratio of 1.97:1. The total mortality in the nests was 24.45% and the majority of deaths recorded occurred at the pupal stage (33.1%). During their reproductive life, females of this bee species were able to construct up to 16 brood cells. The trap-nests removal and transfer to the laboratory shortly after finished by the bees reduced the attack of natural enemies.