Development And Evaluation Of Testing Methods For Ant Repellents

Abstract:
Repellents are biocides and a proof of efficacy is required for active substance inclusion as well as for product authorization. Here, we describe two test systems for efficacy evaluation of ant repellents with the substances DEET 50 %, Margosa extracts 100 %, baking powder: sodium hydrogen carbonate and sea sand. Monomorium pharaonis was tested in both systems. They are designed as choice tests and allow testing of solid and liquid substances. In the first test system, a forced-choice test, groups of 50 - 70 ant workers were set into an escape situation with a choice to escape either over a treated or an untreated surface. The second test system was a simulated use-test: Whole colonies, including workers, brood and queens were set into a test arena and allowed to forage. Between the nest and the food/water source, a barrier was placed which could only be passed over two small bridges, of which one was treated with the test substance and one untreated. In both test systems, ants crossing the surfaces were counted. The results of the study show that DEET repelled in both systems 100 % of the ants. Margosa repelled in the forced-choice test 96 % and 100% of the foragers were repelled in the simulated use-test. Baking powder had no repellent effect. 42 % of all workers in the forced-choice test and in the simulated use-test 51 % of the foragers crossed the substance. A comparison of the data revealed that the repellent effect of each substance was similar in both test systems.