Importance of conserving alternative pollinators: assessing the pollination efficiency of the squash bee, Peponapis limitaris in Cucurbita moschata (Cucurbitaceae)

Although the honey bee, Apis mellifera, has been considered the best pollinator for crops needing insect pollination, the current pandemic of varroatosis among honeybees highlights the need to find additional or alternative species as managed crop pollinators. Moreover, there is evidence that A. mellifera may not always be the most efficient pollinator. Introduction of A. mellifera into crops may be unnecessary, and even detrimental to non-Apis bee populations, which should be considered as an alternative for crop production improvement. Evaluating the pollination efficiency of non-Apis bees is one of the first steps in planning successful strategies for their conservation. In this study, we evaluated the pollination efficiency of Peponapis limitaris and A. mellifera in plots of Cucurbita moschata: pollen removal and deposition; pollinator visit frequency; and the pollinator visit-nectar production relationship. The results show P. limitaris to be the most efficient pollinator as: (1) both males and females remove and deposit almost four times as much pollen as A. mellifera; (2) they make significantly more floral visits than A. mellifera; and (3) their visit frequency shows a strong relationship to C. moschata nectar production during anthesis. Recommendations arising from this study are: (1) the introduction of A. mellifera be avoided in C. moschata crops; and (2) basic research be done on the biology of P. limitaris that contribute to its conservation and greater exploitation.