Biology session

Springtails have significant role in integrating processes of the soils, consequently studying side-effects of insecticids has a high priority. I was intrested in the effects of the insecticid, Trebon 10 F, on the Folsomia candida’s Willem (Collembola) mortality, reproduction, food choice and growth.

I found significant dose-dependent effect in juvenil production. Mortality was not dose-dependent.

I used the field concentration, tenth part and tenfold concentration of the Trebon in the reproduction, food choice and growth tests. I searched for multigenerational effects.

In the food choice test I offered baker’s yeast and ground leaf of maize. Baker’s yeast is a high quality food comparing to maize. Baker’s yeast was preferred by groups treated with the most concentrated solution and treated groups from the first generation. Other treated groups didn’t preferred any food. Some controls preferred maize leaf. A possible explanation of this result is that springtails stressed more with Trebon require better quality food. In third generation no food preference was detected. It supports the hypothesis that two generation are enough to disappear the Trebon effects.

In the reproduction test, no effect was detected on the number of eggs in any generation. Diagonal of the eggs decreased in parental generation, but increased in first generation, if the concentration of Trebon increased. Trebon had an effect on the ratio of egg’s shape in parental generation, but no effect was found in the first generation

In the growth test the growth curves had differences between the previously non-treated offspring. Increasing concentration had a marginally significant rising effect on body length, and the increasing concentration had a significant rising effect on body width. Increasing concentration marginally significantly decreased relative growth per day. Relative growth of the non-treated offspring significantly decreased.

These results raise the hypothesis (1) that parental generation decrease the investment to offspring in harsh enviroment, and (2) F. candida can give information about the enviroment to offspring in some ways. Consequently, offspring can adapt to it. Another hypothesis (3) raises up that in reproduction test offspring show the first symtoms of resistence.

Summed up, this study showed that Trebon has effect on reproduction, growth and food choice of F. candida, which can be multigenerational as well.