Insecticidal efficacy of three insect growth regulators (IGRs) against larvaeof three European populations of Tribolium confusum (Col.: Tenebrionidae)

Abstract: The effectiveness of three Insect Growth Regulators (IGRs) was evaluated in thelaboratory to control 1-3 instar larvae of three European populations of Tribolium confusum(Col.: Tenebrionidae) originating from Greece (GR), Germany (GER) and France (FR). Thetested IGRs were diflubenzuron, fenoxycarb and pyriproxyfen and applied on hard wheat at threedose rates; 1, 5 and 10ppm. The effectiveness of the tested IGRs was evaluated after 14d ofexposure of larvae on the treated commodity at 25°C. The most effective of the tested IGRs wasdiflubenzuron since it controlled 82.7% of the treated larvae, on average, while the less effectivewas fenoxycarb. Significant differences between pyriproxyfen and diflubenzuron or pyriproxyfenand fenoxycarb were not always recorded. The strain from Germany appeared to be moresusceptible to the tested IGRs in comparison with the strains from France or Greece. However,between FR and GR strains significant differences in susceptibility to the tested IGRs were notalways recorded. Increase of dose rate significantly enhanced efficacy of all three IGRs. Thus,the most effective dose was 10ppm, since it provided control against more than 90% of thetreated larvae, in all of the tested cases.