Submitted to: Resistance Pest Management Newsletter
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2005
Publication Date: 12/1/2005
Citation: Gore, J. 2005. Development of a bioassay to detect changes to susceptibility of cotton aphid aphis gossypii glover, to commercial neonicotenoid insecticides. Resistance Pest Management Newsletter. Volume 14 no. 2 Interpretive Summary: A bioassay was developed to quantitatively measure changes in cotton aphid susceptibility to commercially available neonicotenoid insecticides. Plants grown in the greenhouse were sprayed with commercial formulations of Intruder, Trimax and Centric. A range of rates were used for each insecticide to generate a dose mortality curve and estimate LC50 values. Terminal leaves were removed from each plant and placed in Petri dishes with a 2% agar solution. Cotton aphids collected from non-treated cotton were transferred to the treated leaves and mortality was rated at 24 hours. Results of this experiment demonstrated the utility of using live plants to monitor cotton aphid susceptibility to the neonicotenoid class of insecticides.
Technical Abstract: A bioassay was developed to detect changes in cotton aphid, Aphis gossypii Glover, susceptibility to commercially available neonicotenoid insecticides. Formulated Intruder (acetamiprid, Dupont), Trimax (imidacloprid, Bayer Crop Science), and Centric (thiamethoxam, Syngenta Crop Protection) were applied to cotton plants grown in a greenhouse. A series of rates of each insecticide were applied to plants in a spray chamber. After 24 hours, the uppermost terminal leaf was removed from each plant and placed in a Petri dish lined with a 2% agar solution. Five cotton aphid nymphs were placed on each leaf and mortality was rated at 24 hours. LC50 values averaged 0.0008, 0.0013, and 0.0020 kg ai/ha for acetamiprid, imidacloprid, and thiamethoxam, respectively. This experiment demonstrates the utility of utilizing live plant tissues to measure cotton aphid susceptibility to the neonicotenoid insecticides.