Deltamethrin Impairs Honeybees (Apis mellifera) Dancing Communication.

As a commonly used pyrethroid insecticide, deltamethrin is very toxic to honeybees, which seriously threatens the managed and feral honeybee population. Because deltamethrin is a nerve agent, it may interfere with the nervous system of honeybees, such as dance behavior and memory-related characteristics. We found that the waggle dances were less precise in honeybees that consumed syrup containing deltamethrin (pesticide group) than those that consumed normal sucrose syrup (control group). Compared with the control group, honeybees of the pesticide group significantly increased number of circuits per 15 s, the divergence angle, return phases in waggle dances, as well as the crop content of the dance followers. Furthermore, six learning and memory-related genes were significantly interfered with the gene expression levels. Our data suggest that the sublethal dose of deltamethrin impaired the honeybees' learning and memory and resulted in cognitive disorder. The novel results assist in establishing guidelines for the risk assessment of pesticide to honeybee safety and prevention of nontarget biological agriculture pesticide poisoning.

Thermoregulation in mixed-species colonies of honeybees (Apis cerana and Apis mellifera).

Apis cerana and Apis mellifera normally display different strategies in cooling hive temperature, raising the question whether they would coordinate their efforts in to achieve stable thermoregulation in mixed colonies. The results show that the normal temperatures in the brood area in mixed colonies are more similar to those of pure A. cerana colonies than pure A. mellifera colonies. Under heat stress, A. cerana workers are more sensitive, and initiate fanning earlier than A. mellifera workers. In mixed colonies, the former become the main force for thermoregulation. When worker bees of both species were fanning together at the entrance, their own species-specific postures were adopted, but due to a significantly smaller number of A. mellifera workers engaged in fanning, the cooling efficiency of mixed colonies were closest to that of pure A. cerana colonies.