Electroantennography Responses of African Meliponine Bee Species (Hymenoptera: meliponini) to Hetero-Specific Trail Pheromones: Glandular Sequestration of Terpenyl Esters .

Abstract

Preliminary studies of electroantennographic responses of African meliponine bees to trail pheromones were performed using four meliponine species; Hypotrigona gribodoi, Meliponula ferruginea (black), Meliponula ferruginea (reddish brown) and Melipona bocandei. Experiments with Meliponula ferruginea (black) and (reddish brown) revealing antennae responses to pentane extracts containing the nasonov gland and tarsal glands respectively. Because the glandular origin of pheromone marks deposited by African meliponine bees species has not yet been investigated, we first confirmed if these species carry out scent marking and recruitment behavior at floral sources. Secondly we tested if either nasonov or tarsal gland secretions elicited trail-following behavior in newly recruited bees by means of chemical and electrophysiological analyses as well as with bio-assays testing both natural extracts and synthetic pheromone compounds from both glands. A significantly higher proportion of foragers from the four species were attracted and recruited additional foragers to floral resources baited with natural extracts from their own tarsal and nasonov glands. The dominant compound from postpharyngeal gland extracts detected by the chemo-receptors on the foragers antennae from these four species belongs to the chemical class of terpenoid esters, with (E)-{beta} Farnesene constituting a dominant part of this trail pheromone in all four species. This terpenoid could potentially be a singular olfactory cue with dual functionality for resource partitioning and competition avoidance between con-specific and hetero-specific foragers on floral resources, which commonly occurs when foragers from different colonies are scouting for food sources in overlapping foraging areas.