A new study shows distinct effects of neonicotinoid pesticide exposure in different bumble bee body parts, explaining why pesticides have diverse harmful effects and highlighting the need for more sensitive safety testing.
Researchers at Queen Mary University of London have discovered that the neonicotinoid pesticide clothianidin disrupts different parts of bumble bee bodies in strikingly different ways. The researchers' new study shows that the impacts of pesticides are far from uniform, affecting the brain, legs, and kidney-like tissues in different manners that undermine each tissue's essential functions.
Distinct impacts on different tissues
By exposing bumble bees to a field-realistic dose of clothianidin, the scientists found dramatic differences in gene activity across body tissues – 82% of gene activity changes were tissue-specific.
"Each tissue we examined was severely affected by the pesticide," explains Professor Yannick Wurm. "Seeing impacts of pesticide exposure across the body helps to explain the multi-faceted problems that exposed bees have, from impaired movement to reduced learning ability and compromised immunity."
Neonicotinoid pesticides such as clothianidin are widely used to protect crops from pests. Yet, past research has shown that even low doses can threaten the survival of beneficial insects. In this study, the researchers applied high-resolution molecular diagnostics – commonly used in biomedicine but rarely for environmental questions – to pinpoint the specific molecular pathways disrupted by pesticide exposure. For instance, while brain genes involved in ion transport were affected, the hind femur (crucial for movement) showed changes in muscle-specific genes, and the detoxification gene activities of Malpighian tubules (a functional equivalent of kidneys) decreased.
"The findings suggest that traditional pesticide risk assessments, which often overlook tissue-specific damage, do not fully capture the sub-lethal impacts on pollinators," says Dr Federico López-Osorio, a co-author of the study.
Severe tissue-specific consequences prompt call to action
The researchers emphasise that these changes, akin to patterns seen in ageing and cancer, indicate a profound threat to bee health—affecting every tissue in damaging ways.
"We apply pesticides without fully understanding their effects on beneficial insect pollinators," said lead author Dr Alicja Witwicka. "Our findings show that every tissue is compromised in ways that undermine its vital role, which is why the effects are so devastating and widespread. This research is a call to action to rethink how we assess, regulate and apply pesticides, not only to protect pollinators but the ecosystems that depend on them."
This study highlights an urgent need to reevaluate pesticide safety practices to prevent further harm to natural pollinators—species essential for producing the many fruits and nuts we eat and for maintaining biodiversity. It comes at a time when citizens and governments worldwide are increasingly concerned about biodiversity loss, setting ambitious targets for reversing declines and restoring ecosystem health.
