Efficacy of fipronil aerially applied in oil adjuvants and drift retardants against boll weevils, Anthonomus Grandis Boheman (Coleoptera:Curculionidae)
Results of aerial application tests in the field and insecticide transfer tests in the laboratory showed that cottonseed oil was the most effective oil adjuvant to use with fipronil for controlling boll weevils under field conditions and for transferring fipronil from cotton leaf surfaces to boll weevils. The mineral oil and mineral oil + drift retardant more effectively transferred fipronil from cotton leaves to boll weevils than fipronil in water. Fipronil mixed with mineral oil was not as effective as fipronil mixed with cottonseed oil. Results of low volume aerial application of fipronil in aqueous mixtures with drift retardants showed that drift retardants slightly increased deposition of fipronil on cotton leaf surfaces compared to the standard application with water. Boll weevil mortalities from drift retardant-fipronil mixtures were slightly greater than an aqueous mixture of fipronil immediately after application. At 2 or 3 days after application, only drift retardant HM9733-A produced greater boll weevil mortality than that of fipronil in water.