Suitability of nesting substrates for the cavity nesting bee Osmia rufa
Zdzislaw Wilkaniec and Karol Giejdasz
Materials and construction methods were investigated to improve artificial nests suitable for Osmio rufo that were simple to use and durable for several seasons. In 1999 we tested common reed (Phragmites) stalks, plastic drinking straws, plastic thermoshrink electro-insulating tubing, packing paper and grooved wooden laminates (which were assembled to form blocks with cylindrical chambers inside); these nesting tubes were all 6 mm in diameter and 22 cm long. In 2000 we tested reed, wood, cork and wooden tubes lined with plastic sheet used for inkjet printers; all tubes were 7 mm in diameter and 18 cm long. We measured the percentage of each type of material actively provisioned by female O. rufo, the number of the brood cells and cocoons in the tubes, and the number of adults that emerged. All nest tubes made of reed and those made of printer sheeting inserted into openings in wooden blocks were occupied by 0. rufo. The greatest mean number of brood cells was found in nests made of wood (8.3 in 1999 and 12.2 in 2000). The number of cocoons also was highest in wooden nests (5.8 in 1999 and 9.4 in 2000). Reed stalks (4.3 cocoons per nest in 1999 and 5.2 in 2000) and cork (4.7) had the second greatest numbers of cocoons per nest. The number of cocoons was low in paper and in all types of plastic tubes. The production of adult bees per occupied nest was greatest in wooden nests (5.3 in 1999 and 8.8 in 2000). Overall the average production of bees per nest tube offered was greatest in either wood or reed stems. Managing O. rufo was easiest in the disassembled nests made of wood. The design of these nests permitted easy removal of the cocoons and nest reuse for several breeding seasons.