Relative Toxicity and Residue Stability of Insecticides for Argentine Ant Control, 1979

Abstract

Abstract Residues of 10 insecticides were prepared, tested fresh and after I mo and 6 mo of aging against field collected argentine ant workers in replicated tests. Insecticides included toxicants no longer registered, currently registered and experimental compounds. Tests were run in 9 cm Petri dishes each with a 9 cm filter paper attached to the bottom by a fine peripheral bead of paraffin. Side walls of the dishes were coated with teflon emulsion to prevent the ants from escaping and humidity was provided by a moistened 5 cm length of dental wick taped to the Petri dish lid. A 5 replicate series of each toxicant and concentration was prepared by pipetting 0.5 ml of 1% of 0.5% water diluted insecticide onto each filter paper and allowing them to air-dry for I da. The resulting residues were at the rate of ca 800 mg/m^ for 1% and ca 400 mg/m^ for 0.5% applications. Ants were collected from foraging trails Just prior to each test and were continuously exposed in groups of 10-20 workers/replicate until KD-90 minutes was reached. If mortality occurred in control dishes before KD-90s were reached on residues, mortality for each replicate was corrected with Abbott's formula.