Desenvolvimento de colmeias de abelhas Melipona interrupta Latreille, 1811 (Hymenoptera: Meliponini) sob diferentes temperaturas em condições de laboratório

Abstract

Bees are important pollinators, especially of the Meliponini tribe, known as indigenous stingless bees, which has great importance for the pollination of native flora. They are able to regulate the internal temperature of the nest. This regulation is essential for the development and protection of immature and adults from the extreme outside emperatures, enabling the survival of the colony. On the generation of new individuals, the workers are tasked to build new cells and provision them with larval food, and the queen is responsible for laying eggs. Evidences of the influence of environmental factors in the production of queens and males throughout the year in different species of Melipona have been recorded. Climate change affect living beings, like bees, in different ways, each species has a different tolerance to environmental conditions. This study aimed to verify the influence of temperature on the development of hives of Melipona interrupta, with emphasis on the efficiency of the nests thermoregulation, amount of posture realized by the queen and the generation of males and females, queens and workers. To fulfill these objectives the 30 colonies from the Meliponary of GPA/INPA with equivalent development conditions were separated into five groups, with six hives each. The hives of the control group were kept at the Meliponary exposed to natural temperature. The four treatment groups were kept in laboratory under different temperature ranges (artificially induced) to generate a thermal gradient. Temperatures were monitored by thermo-hygrometers, the posture was daily photo documented and segregation of gender and caste observed in disks sampled through time. The optimum average temperature was estimate in 30 ºC for M. interrupta. Relative to the thermoregulation, it was found that as higher the temperatures at which the colonies are exposed (between 31 ºC and 38 ºC) the thermoregulatory effort of the bees increased. However, as the external temperature deviates from 30 ºC (for more or less), the efficiency of this thermoregulation is lower, showing little thermoregulatory capacity of the species. Likewise it was observed that increasing the external temperature (between 31 ºC and 38 ºC) causes proportionally decreased egg laying by the queen and increased mortality of immature. At temperatures below the optimum, between 24 ºC and 26 ºC, the bees build larger number of closed involucrum blades to regulate the temperature. Also there is a reduction in the number of daily posture. The high mortality of immature caused by higher temperatures than the optimum 30 ºC modify the number of the generated individuals in the colony, and therefore, the proportion of queens, workers and males born. Not being established whether if the temperature affects directly the segregation itself. The reduction in the number of births, caused by increasing of the temperature, affects negatively the generation of offspring, and also its workforce, jeopardizing the proper functioning and survival of the colony. The results of this study allow us to conclude that natural or anthropogenic changes that modify the temperature the colonies are exposed, may compromise their survival.