Mouthparts and nectar feeding of the flower visiting cricket Glomeremus orchidophilus (Gryllacrididae).

Glomeremus orchidophilus (Gryllacrididae) is a flower visiting cricket on the tropical island La Réunion. This species is the only Orthoptera shown to be a pollinator of a plant. We studied its nectar feeding behavior and mouthpart morphology in detail. Since G. orchidophilus possesses biting-and-chewing mouthparts, our objective was to find behavioral and/or structural specializations for nectar-feeding. The comparative analysis of feeding behavior revealed that fluid is taken up without movements of the mouthparts in Glomeremus. A comparative morphological examination of two Glomeremus species, together with several representatives of other Gryllacrididae and other Ensifera taxa revealed subtle adaptations to fluid feeding in Glomeremus. All representatives of Gryllacrididae were found to possess a distinct patch of microtrichia at the tip of their galeae. However, in Glomeremus a channel is formed between the distal components of the maxillae and the mandibles on each side of the body. Micro-CT and SEM examination revealed a longitudinal groove that extends over the galea beginning at the patch of microtrichia in the studied Glomeremus species. We hypothesize that the microtrichia take up fluid by capillarity and the action of the cibarium and pharyngeal pumps transports fluid along the channels between the maxillae and mandibles into the preoral cavity. These mouthpart features allow nectar uptake from flowers that is unique in Orthoptera.