Pollination of Cucumber, Cucumis sativus L. (Cucurbitales: Cucurbitaceae), by the Stingless Bees Scaptotrigona aff. depilis Moure and Nannotrigona testaceicornis Lepeletier (Hymenoptera: Meliponini) in Greenhouses

When for a successful fruit development the fertilization of flowers is necessary, bees can be used as crop-pollinators in greenhouses. In the present study, we investigated the effectiveness of the stingless bees Scaptotrigona aff. depilis Moure and Nannotrigona testaceicornis Lepeletier as pollinators of cucumber plants (Cucumus sativus var. caipira) in greenhouses during the Brazilian winter season. The study was conducted in four greenhouses (GH), of which two greenhouses contained bee colonies to ascertain pollination of the cucumber plants (GH I, with S. aff. depilis, GH II, with N. testaceicornis), whereas the other two greenhouses (GH III, GH IV) had no bee colonies and served as control groups. Furthermore, we planted cucumbers in an open field plot (OA) where pollination by any/various visiting insects could occur. Each of the experimental areas measured 87.5 m(2). Without pollination (GH III, GH IV), the plants produced a low number of cucumbers, and the fruits were smaller and less heavy than in those experimental areas where pollination occurred. In the open field area, not protected against unfavorable climatic conditions, the plants produced fewer flowers than the plants in the greenhouses. The highest cucumber yield (with the highest amount of perfect fruits) was found in those greenhouses which housed the stingless bees as pollinators (GH I, GH II). Our results demonstrate that stingless bees can be successfully and efficiently used as pollinators of greenhouse cucumbers during the winter season.