Effect of proctolin on the egg-laying activity of Apis mellifera queens
C R E Miranda, M M G Bitondi and Z L P Simões.
The effect of the neuropeptide proctolin on egg-laying activity was investigated in Africanized honey bees (Apis mellifera). Proctolin was administered orally or injected (1 Iμg proctolin solution in 1 μI saline) into newly mated queens that had just initiated oviposition. Controls received only 1 μg saline. The eggs oviposited by each treated or control queen in a restricted comb area over a period of 6 hours were counted, and this was considered to be an oviposition episode. Oviposition episodes were repeated at 24-48-h intervals for 2 weeks using the same queens, and those resulting in 50 or more eggs were used for statistical comparisons. For the group of injected queens, the presence of more than one egg per comb cell was also recorded. The egg-laying activity was not significantly altered (P = 0.453; z = 0.75) after oral treatment with proctolin. However, when proctolin was administered by injection an increase in egg-laying activity (P = 0.014; z = 2.45) was observed. Moreover, proctolin-injected queens laid more than 1 egg per cell more frequently than controls (P = 0.004; z = 2.84). The significance of these findings for the understanding of the regulation of honey bee reproduction is discussed.