Neonicotinoids and Optimal Foraging Theory

Determination of how neonicotinoid ingestion affects the foraging behaviour of flower-visiting animals, and using Optimal Foraging Theory to assess the nature and extent of consequent changes to foraging efficiency, provide a novel approach for understanding how neonic ingestion affects the cognitive abilities of these animals, and their ultimate reproductive success. Neonicotinoids (neonics for short) are used worldwide as insecticides to protect agricultural crops, but may be ingested by non-target flower-visiting animals, such as bees, with negative impacts on their cognitive abilities and consequent adverse effects on their foraging behaviour, reproduction and pollination services. Optimal Foraging Theory may help to understand such effects as it hypothesises that nectar-feeding animals, including bees, will adopt foraging behaviour that maximises net rate of energy intake. Simple models of foraging movements exist but require further development to be useful in this regard. Observed movement patterns could then be compared with predicted patterns, derived from such models, and compared between neonicotinoid-affected and control individuals, with the expectation that control individuals will forage optimally, while neonicotinoid-affected individuals will not exhibit such behaviour and will exhibit reduced foraging success. However, there has been little attempt to develop and test predictions for cognitive foragers, like bees, that are moving between flowers or flower clusters, potentially limiting our ability to manage neonic-use to control agricultural pests. Addressing this gap should lead to enhanced knowledge and understanding of the impacts of neonics on non-target animals, along with other possible flow-on environmental impacts, including possible reductions in pollinator abundance and hence the harvest yields of crops requiring pollination, and could lead to refinements in policy and procedure for future use of neonics to control agricultural pests. The same issues apply to other insecticides and to interactions amongst insecticides.