Both landscape and local scale factors matter for the parental investment strategies of the pollinatorOsmia caerulescens

Effects of hillside aspect, landscape features, and kleptoparasitism on the reproductive success of the solitary bee Osmia caerulescens

“…The results also show that the differences of the landscape regarding the zones (simple and complex) did not affect the abundance or body size of O. caerulescens . Several studies have shown that O. caerulescens is an abundant species which is well‐adapted to agricultural environments (Baños‐Picón et al ., 2013; Rosas‐Ramos et al ., 2017). Its generalist character, which makes it less sensitive to environmental disturbance and habitat loss (Klein et al ., 2002; Williams et al ., 2010; Taki et al ., 2013), probably allows it to adapt to both zones of the valley, not being influenced by the landscape changes that it exhibits.…”

“…Although foraging distance of O. caerulescens is not known, average distances of 75–125 m between the nest and the visited resources, with maximum distances up to seven times larger than mean distances, have been described for other bee species with similar body sizes (Gathmann & Tscharntke, 2002; Zurbuchen et al ., 2010; Hofmann et al ., 2020). In previous studies, O. caerulescens has been shown to be well‐adapted to altered anthropogenic habitats, capable of using a wide range of diameters to establish its nests and in which the investment in its offspring is affected by both landscape and local factors (Baños‐Picón et al ., 2013; Rosas‐Ramos et al ., 2017). In the study area, 19.93% of O. caerulescens nests were attacked by different natural enemies such as kleptoparasites Stelis phaeoptera (Kirby) and Chrysura dichroa (Dahlbom); parasitoids as Melittobia sp.…”

“…Different studies have suggested that an increase of the nest diameter results in an increase in the number of brood cells and the offspring body size(Rosas‐Ramos et al ., 2017; von Königslöw et al ., 2019), and upon analysing the effect of the nest diameter on these variables in O. caerulescens we also found this positive effect (number of brood cells, trap‐nest as random factor: F 1, 1058 = 118.05, P < 0.0001; individual dry weight, trap‐nest as random factor: F 1, 2701 = 389.5, P < 0.0001). In order to standardise this influence, we studied only those O. caerulescens nests established in 4.5 and 5 mm diameters, the preferred tube sizes for the species (Westrich, 1990).…”

“…Bees (both adults and larvae) are nutritionally dependent on floral resources (Michener, 2007), which have a direct effect on their population sizes (Roulston & Goodell, 2011). A greater abundance and richness of flowers increase the abundance and richness of bees as well as their investment in offspring (Kim, 1999; Holzschuh et al ., 2007; Rubene et al ., 2015; Rosas‐Ramos et al ., 2017; Westerfelt et al ., 2018), since in solitary bees, the body size of each offspring is determined by the amount of food stored by the female in the brood cell (Seidelmann, 2014). Nevertheless, the availability of floral resources has become increasingly scarce in agroecosystems (Potts et al ., 2010).…”

Nesting, Sex Ratio and Natural Enemies of the Giant Resin Bee in Relation to Native Species in Europe

“…Despite the great expansion of the M. sculpturalis, the species has also displayed a male-biased sex ratio [21]. This trait is usually associated with a poor reproductive potential [22], and it could be a response to disadvantageous conditions due to eroded genetic diversity, resources shortage, inadequate climatic conditions or parasite pressure [23][24][25][26][27]. Therefore, whether the unbalanced sex ratio is a low fitness response or a generalized trait is still to be unveiled.…”