Common pesticides quietly stress stingless bees without killing them
Miotelo L, Araújo JF, Malaspina O, Nocelli RCF
Pollinators
The stingless bees pollinating tomatoes, peppers, and native flowering plants in tropical and subtropical gardens are absorbing pesticide residue that scrambles their nervous system and stress response, even when the dose is too low to kill them outright.
Scientists exposed stingless bees to tiny, sublethal doses of two widely used insecticides and measured enzymes in their heads and bellies that control nerve signaling and toxin cleanup. Both chemicals threw those enzyme systems off balance, with thiamethoxam causing bigger and longer-lasting disruptions than fipronil. Even though the bees survived, their internal chemistry was clearly struggling, which hints at hidden harm that a simple survival count would miss.
Key Findings
Thiamethoxam (LC50/2 = 0.027 ng/uL, LC50/5 = 0.010 ng/uL) caused more pronounced changes in AChE, CaE-3, and GST enzyme activity than fipronil (LC50/2 = 0.0055 ng/uL, LC50/5 = 0.0022 ng/uL).
Enzyme disruptions were tracked over six time points (1 to 96 hours), with significant Treatment x Time interactions showing effects intensified at longer exposure durations.
AChE changes signal disrupted nerve signaling (cholinergic regulation), while CaE-3 and GST changes point to activated detoxification and oxidative stress pathways in Melipona scutellaris.
chevron_right Technical Summary
Two common pesticides, thiamethoxam and fipronil, disrupt nerve and detox enzymes in stingless bees even at low doses that don't kill them outright, with thiamethoxam causing more damage over time. This suggests routine pesticide exposure could quietly weaken bee health long before any bees are found dead.
Abstract Preview
Original paper
Enzymatic biomarkers reveal sublethal effects of thiamethoxam and fipronil on the stingless bee Melipona scutellaris.
Bees are key pollinators in natural and agricultural ecosystems, yet they are increasingly affected by the intensive use of pesticides. Although not primary targets of these compounds, bees may be ...
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