Larval deltamethrin exposure causes severe cross-stage carryover toxicity and male reproductive failure in Osmia cornifrons.
Mokkapati JS, Boyle NK, Grozinger CM
Pollinators
If you grow fruit trees or keep a pollinator garden, the mason bees you're counting on to set your blossoms may arrive already broken by the pesticides on neighboring crops — not visibly, but reproductively, which means fewer bees next season without any obvious warning sign.
Researchers raised baby mason bees on pollen spiked with a common insecticide called deltamethrin, then watched what happened as they grew up. Even at very low doses, the males that survived had dramatically fewer and weaker sperm — and females were far more likely to die before emerging at all. When the same adult bees were exposed to the pesticide again, things got worse rather than better, showing the early damage primed them for harm rather than building any resistance.
Key Findings
Larval exposure to 10 ppm deltamethrin caused over 50% mortality before adulthood in Osmia cornifrons mason bees.
Even the lowest dose tested (0.001 ppm, far below typical field concentrations) caused significant reductions in male sperm abundance and viability that persisted into adulthood.
Female emergence declined at all exposure levels, skewing sex ratios increasingly male — a signal of population-level risk since females drive reproduction.
chevron_right Technical Summary
A pesticide sprayed on orchards leaves lasting damage in mason bees even when larvae are exposed to trace amounts — reducing sperm count, viability, and female survival, and making adult bees more vulnerable rather than tolerant when re-exposed.
Abstract Preview
Solitary bee larvae rely entirely on maternally provisioned pollen, making them especially vulnerable to dietary contamination. Yet, little is known about how pesticide exposure during development ...
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