Continuous mercury treatment and develoment of grasshoppers
1988
Schmidt, G.H. (Hannover Univ. (Germany, F.R.). Lehrgebiet Zoologie und Entomologie. Fachbereich Biologie) | Fieldbrand, B.
Continuous HgCl2 treatment of the environment was investigated under neutral pH of the soil in which the eggs were layed. Acrolytus patruelis (H.-S.) was used as test animal. The insects were fed with wheat germs in hydroculture and rolled oats, both treated with a sublethal dosis of HgCl2. The eggs were layed in glass pots filled with sand which was mixed with various amounts of HgCl2. Two generations were bred. Elution profiles of mercury from the sandy soil demonstrated that only about 50 per cent can be eluted by 5 liter distilled water. At pH 1.5 the amount is increased up to 93 per cent. Under neutral conditions only half of the Hg amount is liberated and can have a toxic effect. The untreated wheat germs had a mean Hg content of 112 ng per gm dry weight originated from the seeds, in the treated ones it increased to about 300 ng per gm. The untreated rolled oats contained a mean content of mercury of 41 ng per gm dry weight and the treated ones about 150 ng per gm. Females fed on treated food produced more eggs than those of the control after 10 days. The time inbetween egg pod deposition was reduced to the half (3.2 days) with a mean number of 13 eggs resp. 9.8 eggs per pod in the control. In the F1 generation, the intervals of oviposition were further reduced to 1.9 days. Females which developed in 1.21 mg HgCl2 per kg sandy soil deposited 14 eggs per pod, the same did those of F2 generation. Hatching of the larvae depended on the Hg amount of the soil in which the egg pods were deposited
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