Behaviour of honey bees and bumble bees beneath three different greenhouse claddings

Abstract

Several new cladding materials for greenhouses are tested and some already introduced in greenhouse horticulture, aiming at maximizing the transmission of photosynthetic radiation and reducing the loss of heat. As a part of the evaluation this research focuses on the suitability of different claddings for use in combination with pollinators. Pollinators, honeybees and bumblebees, are applied in a number of greenhouse vegetable and floricultural crops. In a commercial nursery and in small experimental greenhouses with glass, polymethylmethacrylate and polycarbonate claddings, honey bees and bumble bees were introduced. Their orientation behaviour was studied shortly after introduction. The spectral photon distribution inside the greenhouses was determined. In the glass greenhouse the sun was visible as a circular strong light source, in the double layered polymer (polymethylmethacrylate and polycarbonate) greenhouses the sun looked like an arc along the whole length of the roof. All claddings showed good transmission of light for photosynthesis (400-700 nm wavelength). Ultraviolet was hardly transmitted by polycarbonate, partly by glass and fully by polymethacrylate. After introduction honey bees and bumble bees showed normal orientation behaviour beneath glass and polymethylmethacrylate, but not beneath polycarbonate. Beneath polycarbonate the bees did not return to their hives, neither beneath double layered (zigzag) nor single plane covers. The results indicate that polycarbonate should not be used for crops which need pollination