Abstract
Summary:Laboratory bioassays were conducted to assess the toxicity of ipronil to seven-day-old worker honey bees, using topical and oral applications duplicating likely ield exposure. In addition, residual effects of ipronil were assessed after potted cotton plants were sprayed with full and half recommended ield rates, exposed to ield conditions, then bees were exposed to different age residues. The acute dermal LD50 was 1.9 ng / bee, and acute oral LC50 was 0.4 ng / bee. The residual toxicity of ipronil on cotton leaves remained high for an extended period of 25 d and 20 d for full and half recommended rates of ipronil, respectively. These studies show that ipronil is highly toxic to honey bees via direct spray contact, ingestion, and contact with residues. The application of ipronil in lowering cotton is, therefore, unlikely to be compatible with use of managed honey bees.