CONICET | Buscador de Institutos y Recursos Humanos

Glyphosate (GLY) is a broad spectrum 26 herbicide used for weed 27 control. Presently, sub-lethal impact of GLY on non-target organisms such as 28 insect pollinators has not been evaluated yet. Apis mellifera is the main 29 pollinator in agricultural environments and a well-known model for 30 behavioural research. Moreover, honeybees are accurate biosensors of 31 environmental pollutants and their appetitive behavioural response is a 32 suitable tool to test sub-lethal effects of agrochemicals. We studied the effects 33 of field-realistic doses of GLY on honeybees exposed chronically or acutely 34 to it. We focused on sucrose sensitivity, elemental and non-elemental 35 associative olfactory conditioning of the proboscis extension response (PER) 36 and on foraging related behaviour. We found a reduced sensitivity to sucrose 37 and learning performance for the groups chronically exposed to GLY 38 concentrations within the range of recommended doses. When olfactory PER 39 conditioning was performed with sucrose reward with the same GLY 40 concentrations (acute exposure), elemental learning and short-term memory 41 retention decreased significantly compared to controls. Non-elemental 42 associative learning was also impaired by an acute exposure to GLY traces. 43 Altogether, these results imply that GLY at concentrations found in agro44 ecosystems due to standard spraying can reduce sensitivity to nectar reward 45 and impair associative learning in honeybees. However, no effect on foraging 46 related behaviour was found. Therefore, we speculate that successful forager 47 bees could become a source of constant inflow of nectar with GLY traces that 48 could then be distributed among nest mates, stored in the hive and have long49 term negative consequences on colony performance. 50