Urbanisation is an expansive process and a majority of insects live in human-modified areas. At the same time, a decrease in pollinator species richness and abundance has recently been observed in Europe, which in turn may have serious ecological and economic consequences. This study investigates the abundance, species richness and functional traits of wild bees in urban city parks in comparison to natural areas. The aim of this research was to assess the potential conservation values of urban green areas for bees. The present study demonstrates that a large and diversified city park may be a favourable habitat for bees, comparable to the natural fauna both in terms of the number and abundance of bee species. However, the study also showed that there were differences in the occurrence of species with different functional traits in the city parks investigated and in the natural landscape.

An efficient antioxidant system is of particular importance for insects whose high metabolic rates promote increased formation of reactive oxygen species (ROS). The amount of ROS can be additionally increased by environmental factors. This study investigates the ability of red mason bees (Osmia bicornis L.) to inactivate free radicals during insect development. Both male and female bees were studied, from the larval to the active imago stage. The activity of four antioxidant enzymes, superoxide dismutase, catalase, peroxidase and glutathione S-transferase, was measured; and glutathione content and total antioxidant status were determined. The highest values of the examined parameters were found in feeding stages-in larvae and in active imagines of both genders. Significant differences between genders were noted mainly in catalase activity, which was lower in overwintering imagines and active females than in males. Most differences were observed between females and males after emergence.

The influence of simulated climate change on body weight and depletion of fat body reserves was studied during diapause in the European solitary bee Osmia rufa L. (Hymenoptera: Megachilidae). Insects (females) were reared and collected from outdoor nests from September to March. One cohort of females was weighed and dissected immediately for analyses, whereas another cohort was subjected to simulated warmer temperature (15°C for 7 d) before analyses. A gradual decline in body mass and fat body content was recorded with declining temperatures from September to January in female bees from natural conditions. Temperature increased gradually from January to March with a further decline in body mass and fat body content. The fat body development index dropped from five in September-October (≈ 89% individuals) to four for the period from November to February (≈ 84% individuals) and further to three in March (95% individuals) before emergence. Simulated warmer winter temperature also resulted in a similar decline in body weight and fat body content; however, body weight and fat body content declined faster. The fat body development index dropped to three in December in the majority of individuals and continued at this level until March just before emergence. Taken together, our data indicate an earlier depletion of fat body reserves under simulated climate change conditions that may impact ovarian development and reproductive fitness in O. rufa.

SUMMARY Materials and construction methods were investigated to improve artificial nests suitable for Osmia rufa 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. rufa, 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 O. rufa. 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. rufa 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.