A scientific note on the differential handling behaviour of two large carpenter bees on an inverted keel flower

ESTRAVIS-BARCALA, M. CECILIA; RAMELLO, PABLO J.; ALMADA, VALENTÍN; TORRETTA, JUAN P.; LUCIA, MARIANO

APIDOLOGIE

EDP SCIENCES S A

Lugar: Paris; Año: 2024 vol. 55

0044-8435

Given that Xylocopa (Neoxylocopa) augusti and X. (N.) frontalis are two sympatric and polylectic species of large carpenter bees, which present similar body size, reproductive phenologies, and share similar use of nesting and floral resources; they provide a good opportunity to examine their foraging behaviour on E. crista-galli flowers, a South American native tree used as nesting substrate by both bee species, and whose pollen is frequently found in the larval provisions of the former. We hypothesized that carpenter bees would mostly visit open flowers and actively collect nectar and pollen due to the availability of both rewards at this anthetic phase. Since there are many open flowers simultaneously in each raceme, we did not expect many visits to pre-anthetic flowers, which might pose a physical barrier to pollinators, since during this stage most of the standard remains folded, covering the other petals and fertile cycles. However, we did record differential handling behaviour between these two Xylocopa species. We observed a peculiar behaviour of X. frontalis bees, which consistently approached closed flowers, forcing their opening by inserting their proboscis in the base of the standard and moving towards the distal portion of standard to reach the anthers and collect pollen. In contrast, X. augusti bees concentrated their foraging effort in open flowers, and mostly ignored pre-anthesal flowers during their foraging bouts. Our findings suggest that, in the studied community, X. augusti and X. frontalis are able to differentially exploit the rewards offered by E. crista-galli flowers as a possible coexistence strategy.