In the current scenario of a general decline of the honeybee worldwide, studies on the potential of alternative bee species in pollinating cultivated plants are important. Although melon, Cucumis melo, is a crop with great commercial importance, there is very little information on its pollinating fauna in Europe, and none from the southern Mediterranean area. In a locality in central Spain, using both pan‐traps and net collections, we found that melon flowers are visited by 31 species of bees spanning four families, though only four were both dominant and constant. These four species belonged to the family Halictidae (sweat bees) and mostly (three species) to the genus Lasioglossum. Five other species could be defined as accessory: honeybee, Apis mellifera, and four other halictids. Individuals of the dominant species were smaller, on average, than those from all the other species. Observations on the frequency of pollen and nectar foraging and on flower visit duration further suggested L. malachurum as the potential key pollinator. Females of this species started to forage on melon early in the flowering season and exhibited two activity peaks in summer, thus covering the whole season. Although in other sites across continents melon seems to be more heavily pollinated by honeybees, this seems to be not the case in the Mediterranean, where sweat bees seem to be the major pollinators of this crop.
Pollinators of most of the plants cultivated in in the Mediterranean regions of Europe are still unknown. We provide new data and we review previously available information on bees (Apoidea Latreille, 1802) associated with three economically important crops in Spain: melon, watermelon and almond. We found that overall 138 bee species spanning four families visit the studied crop species. The bee assemblages of melon includes 8-35 species, with moderate to high importance of small Lasioglossum Curtis, 1833 (Halictidae Thomson, 1869) and honeybee (Apis mellifera Linnaeus, 1758: Apidae Latreille, 1802). Watermelon flowers are visited by 14-20 species of bees, with low to moderate abundance of honeybees and predominance of small Lasioglossum. Bees collected on almond trees spanned 12-37 species, being the honeybee and medium-size to large Andrena Fabricius, 1775 (Andrenidae Latreille, 1802) and Osmia Panzer, 1806 (Megachilidae Latreille, 1802) predominant. The new samples expanded the geographical distributions of nearly one-fourth of the collected species. Diversity estimators slightly varied even within fields of the same crop, and a cluster analysis suggests both a certain overlap between melon and watermelon and a role of geographical distance on similarity among bee assemblages. Below ground-nesting and solitary species were more frequent than above ground-nesting and eusocial species, but for melon and watermelon the highest abundances were recorded for eusocial
1 The browntail moth Euproctis chrysorrhoea is a highly polyphagous univoltine forest pest. Although its young larvae usually overwinter in diapause from early autumn to the beginning of spring, winter larval feeding has been reported when this species feeds on the evergreen woody shrub strawberry tree Arbutus unedo. 2 The present study investigated life-history traits of four populations of E. chrysorrhoea feeding on A. unedo, including phenology of the different life stages, larval feeding activity and diapause incidence. By modelling the relationship between larval size and host plant leaf persistence, elevation and mean annual temperature, we also studied larval development in ten populations of this species sampled from a range of geographical locations in Spain, from both A. unedo and deciduous hosts. 3 The results obtained revealed that on A. unedo, E. chrysorrhoea phenology has shifted: from October to March, A. unedo larvae doubled their size, whereas, on deciduous Ulmus minor and Quercus faginea, larval size did not change. General linear models demonstrated that such differences were not related to environmental variables. We also found that on A. unedo larval feeding was arrested for 2 months, with this period representing a true diapause. 4 The results obtained in the present study suggest that E. chrysorrhoea populations are phenologically adapted to their local host plants, and that the presence of foliage is a key element in the phenological shift reported on A. unedo. These results may have implications with respect to the formation of E. chrysorrhoea host races.
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