Negative Effects of the Neonicotinoid Clothianidin on Foraging Behavior and Antennal Sensitivity in Two Common Pollinator Species, Osmia bicornis and Bombus terrestris

Insect species richness and abundance has declined rapidly over the last few decades. Various stressors, such as the conversion of natural habitats, climate change, land-use intensification, agrochemicals and pathogens, are thought to be major factors in this decline. We treated female bees of two common pollinator species in Europe, Osmia bicornis and Bombus terrestris, with a field-realistic dose of the neonicotinoid clothianidin. We tested its effects on the foraging behavior of O. bicornis under semi-natural conditions and on the antennal sensitivity of both bee species to common floral volatiles by using electroantennography. Clothianidin negatively affected the foraging behavior in O. bicornis by decreasing the number of flowers visited per foraging flight and by increasing the time per flower visit and the searching time between two flowers. It also decreased the antennal sensitivity to 2-phenylethanol in the two bee species. Thus, clothianidin is clearly a threat for bees via its effects on their foraging behavior and antennal sensitivity and is hence probably detrimental for pollination and the reproductive success of bees.

Application of Geo-spatial Technology in Characterization of African Honeybee (Apis mellifera) Apiaries into Ecosystem Zones for Productivity and Pollination Service

Seven major ecological zones of Nigeria with modern functional apiaries were mapped and sampled in the rainy season between April 2016 and October 2018 for estimating the bee foraging flight range and floral species diversity; collating satellite imagery data for geospatial zone mapping using GPS (Garmin Etrex 20) to capture the coordinates of apiaries locations and their attributes, climatic and topographic data and generating ecological zones: the wetland vegetation, savanna grassland, savanna woodland (disturbed), shrubby forest, lowland dense forest, and Highland rain forest. Honeybee flight ranges between 1 and 5 kilometer radius from where bees at the apiaries can forage for pollen and nectar. Igbeti/Malete/Buari bees forages at similar ecosystems within this range while those at Saki and Abuja apiaries have potentials to forage at different ecological zones ranging from woodland savanna to lowland and high forests. Abuja (woodland savanna and shrubby forest zones) apiaries produces average of 32 liters of honey per hive and Kwara (savanna grassland and wood land Savanna) produces average of 24 liters of honey per hive. There is also structural variation in the floral species diversity and richness as richness marginally differed at the locations. Highest index was observed in Orozo (H=2.62; Margalef = 3.05) and Agbungburu (H=2.54; Margalef = 3.06). Low index was attained at Buari (H= 2.10; Margalef= 2.32) and Igbeti (H= 2.11; Margalef= 2.62). Apiary managers and farmers acquiring relevant knowledge on apiculture and prevailing A. mellifera apiaries would assist management activities; contribute to better production and pollination for food security.

Honeybee lifespan: the critical role of pre-foraging stage

Assessing the various anthropogenic pressures imposed on honeybees requires characterizing the patterns and drivers of natural mortality. Using automated lifelong individual monitoring devices, we monitored worker bees in different geographical, seasonal and colony contexts creating a broad range of hive conditions. We measured their life-history traits and notably assessed whether lifespan is influenced by pre-foraging flight experience. Our results show that the age at the first flight and onset of foraging are critical factors that determine, to a large extent, lifespan. Most importantly, our results indicate that a large proportion (40%) of the bees die during pre-foraging stage, and for those surviving, the elapsed time and flight experience between the first flight and the onset of foraging is of paramount importance to maximize the number of days spent foraging. Once in the foraging stage, individuals experience a constant mortality risk of 9% and 36% per hour of foraging and per foraging day, respectively. In conclusion, the pre-foraging stage during which bees perform orientation flights is a critical driver of bee lifespan. We believe these data on the natural mortality risks in honeybee workers will help assess the impact of anthropogenic pressures on bees.