Bee size increases pollen deposition in Cucurbita maxima (Cucurbitaceae) crops

Abstract

The study of the performance of animal pollinators has expanded in recent decades mainly due tothe concern on crop productivity. Among insects, bees are the main pollinators of most Angiosperm species.The aim of this paper was to study the effect of bee body size on the pollination of Cucurbita maxima Duch.(Cucurbitaceae) var. zapallito crops. We quantified stigmatic pollen deposition by single visits of bee specieswith different body sizes. Bee species were classified into four categories accordingly to their intertegular distance:Very small (≤ 1.7 mm), Small (1.71 mm < 2.7 mm), Medium (2.71 mm < 3.7 mm) and Large (> 3.71 mm).Fifteen bee species belonging to the Apidae and Halictidae families were observed depositing pollen on thestigmas of C. maxima. The number of pollen grains deposited and the probability of pollen deposition per visitincreased significantly with body size. Large bees Xylocopa augusti and Bombus pauloensis were the mostefficient species at depositing pollen on stigmas followed by medium-sized bees Eucera fervens and Apis mellifera.The results show that several wild bee species play an important role in the pollination of C. maximacrops. This research provides baseline data for the design of pollination studies to develop strategies to optimizepollination of this crop.