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.

The global loss of bee diversity and abundance is a central issue in conservation biology. There is increasing evidence that cities may play an important role in bee conservation, although urbanization may also have negative impacts. Here, we investigate individual body size variation and wing asymmetry (based on 11 traits) in the solitary bee Anthophora plumipes along a rural-urban gradient in Poland. The body size of captured individuals did not show any changes along the gradient. Directional asymmetry was present, since differences between sides in 10 out of 11 traits deviated significantly from zero, with the right-side wing traits being generally larger. In contrast to our expectations, the forewing was more asymmetric in rural than in suburban and urban areas. Similarly, the absolute asymmetry of 11 wing traits (i.e. pooling differences but ignoring direction) was also significantly greater in rural than in suburban and urban landscapes. Since asymmetry may be attributed to environmental pollution and food shortages, we conclude that the urban landscape provides bees with habitats of higher quality and thus should be considered as an important habitat for bee conservation.

Varroa destructor is the main pest of the honey bee Apis mellifera, causing colony losses. We investigated the effect of temperature on the autumn abundance of V. destructor in bee colonies over 1991–2020 in Central Europe. We tested the hypothesis that temperature can affect autumn mite populations with different time-lags modulating the bee abundance and brood availability. We showed that raised spring (March–May) and autumn (October) temperatures reinforce autumn V. destructor infestation in the bee colonies. The critical temperature signals embrace periods of bee activity, i.e., just after the first cleansing flights and just before the last observed bee flights, but no direct effects of phenological changes on V. destructor abundance were found. These effects were potentially associated with increased bee reproduction in the specific periods of the year and not with the extended period of activity or accelerated spring onset. We found significant effects of autumn bee abundance, autumn capped brood abundance, and the number of colonies merged on autumn mite infestation. We also observed differences in V. destructor abundance between bees derived from different subspecies. We indicated that climatic effects, through influence on the bee abundance and brood availability, are one of the main drivers regulating V. destructor abundance.

There is growing concern about declines in pollinator species, and more recently reservations have been expressed about mismatch in plant-pollinator synchrony as a consequence of phenological change caused by rising temperatures. Long-term changes in honeybee Apis mellifera phenology may have major consequences for agriculture, especially the pollinator market, as well as for honey production. To date, these aspects have received only modest attention. In the current study, we examine honeybee and beekeeping activity in southern Poland for the period 1965–2010, supplemented by hive yields from a beekeeper in southern UK in the same period. We show that despite negative reports on honeybee condition, and documented climate change, the studied apiary managed to show a marked increase in honey production over the 46 year study period, as did that from the UK. The proportion of the annual yield originating from the first harvest decreased during the study period and was associated with rising temperatures in summer. Honeybee spring phenology showed strong negative relationships with temperature but no overall change through time because temperatures of key early spring months had not increased significantly. In contrast, increasing yields and an increased number of harvests (and hence a later final harvest and longer season) were detected and were related to rising temperatures in late spring and in summer.

The aim of this investigations was to assess morphological changes in the midgut epithelium of bees nourished with pollen substitute or pollen substitute enriched with a probiotic preparation. One-day old worker bees were kept in cages placed in a temperature controlled environment. During the two-week feeding period workers were fed beebread (control), pure pollen substitute or pollen substitute fortified with three different doses of probiotic preparations: Biogen or Trilac (experimental groups). The assessment of histological changes of the bee midgut was carried out in bees feed for 8 and 14 days. Slight changes in the epithelium as well as strong merocrine-type secretion were recorded in bees nourished pollen substitute supplemented with probiotic preparations. Differences were observed, primarily, in quantities of the developed peritrophic membranes. Their quantities were particularly high after 14 days of feeding with the pollen substitute fortified with probiotic preparations. The development of numerous peritrophic membranes could have contributed to better utilization of nutrients contained in feed and better condition of bees.