Understanding non-lethal effects of pesticides on honey bees

Scientists are developing a new way of studying bees in the laboratory to determine whether pesticides are having a negative effect on their health and behaviour.

Understanding the effects of pesticides on honey bee health is imperative in making informed choices about the risks associated with use of pesticides in crop production. Previously, tests have focused on whether the pesticide kills developing bees, but scientists are developing new lab-based methods for understanding the non-lethal effects of pesticides on bees.

Dr Ashley Mortensen, who has recently joined Plant & Food Research’s Pollination & Apiculture Team, has been studying bee behaviour as part of her PhD studies at the University of Florida. Tests for pesticide responses involve rearing honey bees in a lab environment prior to exposure to the pesticide. Dr Mortensen’s research analysed changes in behaviour that occur as a result of rearing bees in an artificial environment so that these can be factored into standardised tests and not confused with other changes that may occur as a response to pesticide exposure.

Her research has been published in the journal Behavioural Ecology and Sociobiology.

“One obvious way that stressors, such as pesticides, pests or disease, prevent bees from pollinating plants is by killing the bees either during immature development or by reducing the lifespan of the adults,” says Dr Mortensen. “However, even if the bees don’t die, changes in their behaviour after exposure to one or more stressor during development could reduce bees’ efficiency at hive tasks such as rearing brood, tending to the queen, or foraging for nectar or pollen.”

“This work is expected to further our understanding of how pesticides or other developmental stressors, like pathogens, temperature change and more, could alter the behaviour of adult bees.”

Dr Mortensen’s research will inform the development of new standardised tests for use by regulatory agencies around the world to determine what pesticides are safe for use in the environment and how or when they can be used in crop production.

New Zealand has more than 7,800 registered beekeepers with close to 800,000 hives producing nearly 15,000 tonnes of honey each year (Fresh Facts 2017). Commercial hives are used in the pollination of many of New Zealand’s high value fruit crops, including kiwifruit, apples and berryfruit.

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