Reproductive capacity evaluation of honeybees workers (Apis mellifera) in single-cohort model colony
Lucas Trevisoli Agostini, Lucas Trevisoli Agostini , Anete Pedro Lourenço , Zilá Luz Paulino Simões
Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brazil; Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brazil ; Departamento de Ciências Biológicas, Faculdade de Ciências Biológicas e da Saúde, Universidade Federal dos Vales do Jequitinhonha e Mucuri, BRazil ; Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brazil
The bees comprise the most important economic group of pollinators. Approximately 35% of the world’s food crop production are depending on pollinators. In Apis mellifera colony, the workers, the sterile female caste, execute many tasks during adult life. As young nurses, they take care of the larvae and of the colony. As they getting old they assume the forager condition. These workers have extremely reduced reproductive organs when compared to the queens, however, the ovaries of these workers are maintained functionally competent. In the absence of the queen, the workers in the colony may activate their ovaries and lay haploid eggs, originating males. The main purpose of this study is to evaluate the reproductive capacity of the workers maintained in single-cohort colonies. The expression of vitellogenin gene (Vg) that has been traditionally used as a parameter to assess the insect fertility will be evaluated as control. In A. mellifera, the huge reproductive capacity of the queen is linked to the high concentration of Vg in the haemolymph. Here, we used newly emerged bee workers and a fertile queen to construct a single-cohort colony. Forty days after the introduction of the bees, the queen was removed and around 500 newly emerged workers were introduced. The bees were paint-marked, which allowed us to control the age. We collect new emerged, 3, 7, 15, 25, 40, 50 days worker bees. All of them were assessed regarding the ovary activation and the level of activation. For total RNA extraction, we used the head of bees; the obtained total RNA was submitted to a reverse transcription (cDNA synthesis), followed by a quantitative PCR in order to obtain the level of expression of Vg. After 15 days 90% of the collected bees showed activated ovaries. From 25 days on, signals of ovary degeneration were observed, this process culminated with a complete degeneration at 50 days. These ovary activation and degeneration reflect the Vg expression during the period assessed.