Distinct changes in life-history strategies of Folsomia candida Willem (Collembola: Isotomidae) due to multi- and transgenerational treatment with an insecticide

Multi- and transgenerational effects of the insecticide Trebon 30 EC (active ingredient etofenprox) on life-history traits of the collembolan Folsomia candida was examined in a four-generation long laboratory study. The experimental set-up of both treatments was similar, except that in the multigenerational treatment all four generations were treated by the insecticide, and in the transgenerational treatment only the parent generation was treated, but the consecutive three generations not. If the generation was treated with insecticide, six sublethal concentrations of the Trebon 30 EC were applied to see dose-response effects.
We concluded that the influence of both treatment methods is strong but appreciably distinct. In the multigenerational treatment, when all four generations were exposed to sublethal concentration of the insecticide, the population either become resistant, or it could compensate for the insecticide effect in the long term. According to our results, extinction could only arise if the Trebon 30 EC used repeatedly, and in five times higher concentration than the recommended field concentration. Moreover, a notable and apparent transgenerational effect was found as well. Whereas in the F1 and F2 generations a small number of life-history traits were changed, in F3 generation most of the measured parameters showed significant insecticide effect. This finding clearly indicates the long-term transgenerational effects, which are essential from ecological as well as environmental risk assessment point of view.