Effects of Neonicotinoids and Temperature on Crop Pollination

Informations

Funding country

Norway

Acronym

-

URL

-

Start date

1/1/2017

End date

12/31/2023

Budget

1,268,499 EUR

Fundings

Abstract

In NEOPOLL we investigate sub-lethal effects of Current Use Pesticides (CUPs) (i.e. the neonicotinoid clothianidin) on important pollinators, namely bumblebees. There is a limited number of studies quantifying the effects of neonicotinoids, in field realistic settings. Studies have shown that both climatic conditions and pesticides negatively affect bumblebees, but the additive effect of these drivers have previously never been studied. We are currently finalizing a laboratory experiment where we monitor individual learning, search behaviour and flower handling under different pesticide exposure levels. These experiments are conducted under two different climate conditions, 12°C and 28°C, to see whether the negative effects of the pesticide changes with temperature. We are currently analysing the data from this experiment. In relation to this experiment Malin Røyset Aarønes has analysed clothianidin accumulation in the exposed bumblebees and showed that there is accumulation both in the head and bodies of bumblebee workers. She found no effect on brood production and mortality, but the proven accumulation suggest that sub-lethal effects are possible, and that prolonged exposure might have adverse effects. In collaboration with NIVA we have developed laboratory procedures for analysing clothianidin exposure from nectar and pesticide accumulation in bumblebee honey, larvae and workers. These results are presented in master thesis of Aarønes that has now been published in the scientific journal Environmental Toxicology and Chemistry. We have also conducted a semi-field experiment focusing on foraging behaviour. Bumblebees were chronically exposed to two different pesticide doses and later allowed to forage outdoors in natural vegetation. By use of a custom-made video recording system we have measured individual foraging bouts lengths. In this experiment we also found no effect on brood production and mortality, showing that the exposure levels represented sub-lethal doses. We did find that foraging bout length increased with exposure level and that the effect of temperature on foraging bout length varied among concentrations. Control bumblebees (not exposed) were not sensitive to temperature, while bumblebees exposed to low concentrations spent longer time foraging under low temperatures. For the bumblebees subject to high concentrations the effect was even stronger. These results were part of the master thesis of Pawel Kolano and is also published in a special issue in the Journal of Pollination Ecology. Our experiments in Reading were conducted during the summer of 2021. Here bumblebee colonies were exposed to different doses of clothianidin and flupyradifurone under contrasting temperature conditions (at different times over summer). Colony development has been analysed and published in the master thesis of Nora Kildebo. We found that the effect of flupyradifurone on colony development (number of workers at the end of the experiment) was lower for flupyradifurone than for clothianidin, but that the effect of flupyradifurone was temperature dependent. Colonies exposed to low doses of flupyradifurone had lower growth at high temperatures, but higher growth at low temperatures, when compared to control colonies (unexposed). For colonies exposed to high levels of flupyradifurone the pattern was reversed; higher growth at higher temperatures and lower growth at lower temperatures. Colonies exposed to high levels of clothianidin had lower growth than control colonies, irrespective of the temperature conditions.