Evaluation of Native Bees as Pollinators of Cucurbit Crops Under Floating Row Covers

Abstract

Production of cucurbit crops presents growers with numerous challenges. Several severe pests and diseases can be managed through the use of rotation, trap cropping, mechanical barriers, such as row covers, and chemical applications. However, considerations must also be made for pollinating insects, as adequate pollination affects the quantity and quality of fruit. Insecticides may negatively affect pollinators; a concern enhanced in recent years due to losses in managed Apis melifera L. colonies. Row covers can be used in place of chemical control before pollination, but when removed, pests have access to fields along with the pollinators. If pollination services of native bees could be harnessed for use under continuous row covers, both concerns could be balanced for growers. The potential of two bee species which specialize on cucurbit flowers, Peponapis pruinosa Say and Xenoglossa strenua Cresson, were assessed under continuous row covers, employed over acorn squash. Experimental treatments included plots with either naturally or artificially introduced bees under row covers and control plots with row covers either permanently removed at crop flowering, or employed continuously with no added pollinating insects. Pests in plots with permanently removed row covers were managed using standard practices used in certified organic production. Marketable yields from plots inoculated with bees were indistinguishable from those produced under standard practices, indicating this system would provide adequate yields to growers without time and monetary inputs of insecticide applications. Additionally, application of this technique was investigated for muskmelon production and discussed along with considerations for farm management.

Integrated pest and pollinator management – expanding the concept

“…In addition to cultural control techniques, other approaches, such as physical control of insect pests (eg exclusion netting and row covers), have received greater attention in recent years, many of which can require integration with pollinators when the crop is pollinator dependent (Minter and Bessin 2014;Leach et al 2016).…”

Delivering Integrated Pest and Pollinator Management (IPPM)

“…In particular, the expanding use of protective structures and materials in crop production worldwide, including as a means of physical pest control, signals this area as a priority for development of IPPM strategies. Existing IPPM-type solutions already in practice include the application and removal of netting [69] and floating row covers [70] at critical phenological time points, such that pest suppression benefits can be achieved without compromising pollinator-mediated yield. Bee colonies may alternatively be placed directly into such enclosures for pollination.…”

Nocturnal Bees as Crop Pollinators

“…Nocturnal bees visit a wide spectrum of wild and crop plants and they can efficiently pollinate some of them, such as Cambessedesia wurdackii (Melastomataceae) [62], Campomanesia phaea (Myrtaceae) [18], Paullinia cupana (Sapindaceae) [36,37], Machaerium opacum (Fabaceae) [56], Passiflora pohlii (Passifloraceae) [64], Trembleya laniflora (Melastomataceae) [33], and Cucurbita species (Cucurbitaceae) [65,66]. Several other species are visited by nocturnal bees, but there is still little information about their pollination efficiency.…”

“…In North America, squash bees of the genera Peponapis and Xenoglossa display crepuscular flight activity that begins before sunrise. Xenoglossa is only active during twilight, whereas Peponapis also forages throughout the day [65,66,80,81]. Both species are oligolectic on species of Cucurbita (Cucurbitaceae) and effective pollinators of cultivated pumpkins (Cucurbita foetidissima, C. maxima, C. pepo).…”