Comparison of Nesting Materials for the Orchard Pollinator Osmia cornuta (Hymenoptera: Megachilidae)
A population of the orchard pollinator Osmia cornuta (Latreille 1805) was released in an almond orchard in NE' Spain to test the attractiveness of 4 different man-made nesting materials. Wood blocks are found most attractive, followed by grooved boards, reed sections, and milk-carton nesting units. Bamboo reeds are much more attractive than Phragmites or Arundo reeds. No significant differences in the number of cells built per nest or in mortality rates are found between nesting materials. On the other hand, the sex ratio (MM / FF) of progeny differs between nesting materials, and tends to be higher in the least attractive ones. The highest cell production and female cell production is obtained in wood blocks, and therefore, these are considered the most suitable nesting materials for pollination operations with O. cornuta.