Metal-supplemented diets alter carbohydrate levels in tissue and hemolymph of gypsy moth larvae (Lymantria dispar, Lymantriidae, Lepidoptera)
- Univ. of Vienna (Austria)
Larvae of Lymantria dispar were exposed to two concentrations each of Cd, Pb, Cu, and Zn from hatching to day 3 of the fourth instar. The metals were applied via artificial diet (wheat germ diet); two control groups were reared on either an uncontaminated artificial diet (C) or on a natural diet (oak leaves, EF). High-pressure liquid chromatography (HPLC) was employed to analyze the hemolymph carbohydrates, whereas body glycogen and glucose were determined enzymatically. The results were analyzed with respect to diet-specific differences (oak leaves versus wheat germ diet) and metal exposure compared with the uncontaminated artificial diet. Hemolymph trehalose levels were higher in oak leaf-reared individuals than in those fed on the wheat germ diet (p < 0.01), whereas the opposite applied to the body glycogen and free glucose levels (p < 0.01). The average trehalose value of the control (C) (4.3 mg/ml) was reduced by metal contamination, dependent on both the metal itself and the concentration (Cd, Cu, Zn; 1.4--3.3 mg/ml). Sorbitol was not detected in the hemolymph of EF specimens, whereas it occurred in all artificial diet-fed groups. Metal- and dose-dependent differences in the hemolymph sorbitol levels were observed in the treatment groups, but not in the controls. Glycogen content increased in the low concentration of Cd, Pb, and Cu, whereas a decrease was observed for the low Cd and both Zn concentrations. Tissue free glucose was enhanced only in three of the metal groups. Generally, fresh and dry weights of larvae were reduced in all groups except the high Cu-contaminated one. The results may indicate that mass outbreaks of an important forest pest insect like L. dispar may be facilitated in metal-contaminated areas because parasitization success of antagonistic species may decline due to deterioration of nourishment within the metal-stressed host.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 268019
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 15, Issue 7; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dispersion of Metals from Abandoned Mines and their Effect on Biota in the Methow River, Okanogan County, Washington: Final Report 2002-2003.
Effects of cadmium in herbage on the apparent absorption of elements by sheep in comparison with inorganic cadmium added to their diet