Research on the Effect of Alpha-Tocopherol (vit. E) on the Growth and Reproduction of the Colorado Potato Beetle (Leptinotarsa Decemlineata Say)

Abstract

The influence of alpha-tocopherol on the Colorado potato beetle has been investigated. Integrated biochemical, biological and histological studies were made. The biochemical studies embraced the gas-chromatographic analyses concerning the qualitative and quantitative composition of tocopherols in the leaves of Solanum rostratum and Solanum tuberosum, as well as in imaginal tissues, in the larvae and in the eggs. In the biological experiments Colorado potato beetles were reared on normal potato leaves and also on leaves to which the increased doses of alpha-tocopherol were applied. As criteria, fertility, mortality, the duration of beetles’ activity and the consumption were considered. In the histological investigation the gonads of the larvae and adults were examined. The experimental results have shown that the most important differences occur in the reproduction of the insect. When increased doses of alpha-tocopherol were applied an increase in the quantity of eggs laid was recorded. Histological studies revealed that a higher quantity of sperm was present in the gonads of the males fed on increased doses of alpha-tocopherol and the gonads of the females were larger and the oocytes had thick follicular epithelium comprising large cells than in untreated adults. Generally it was established that alpha-tocopherol acted as a stimulant of fecundity in this particular insect.