Increasing the gyne production ability in Bombus terrestris (Hymenoptera: Apidae) colony using pyriproxyfen

Bumblebees are valuable assets in terms of pollination services in wild plants and greenhouses. The most well-studied species of bumblebees is Bombus terrestris which is commercially reared and sold on a large scale worldwide. Even though the artificial rearing of bumblebees started in the 1950s, there are still some problems in the mass-rearing process of them. One of the main problems is the low rate of gyne production in the late phase of the colony, to start the new colonies. So, the main objective of this study was to increase the number of produced gynes in the B. terrestris colonies by changing the caste of the larva from worker to queen. For this purpose, we used pyriproxyfen which is a juvenile hormone analogue compound. The first and early second-stage larvae were treated with 1,3 and 6 ppm of pyriproxyfen and the onset time of emergence, number, weight, mating succession, and diapause survival of new gynes were recorded. The results showed that the 3 ppm treatment had the highest number of the produced gynes, and also the shortest onset time of emergence. There was no difference in mating succession and diapause survival among the treatments. Based on the experiment results, we concluded that using a 3 ppm concentration of pyriproxyfen compound on young larvae of B. terrestris can induce the juvenile hormone effect and increase the number of produced gynes in the colony. We suggest that pyriproxyfen as a juvenile hormone analogue, regarding the concentration, type, and time of application on the young larvae, can be used to increase the number of produced gynes in the bees’ colony.