IMPACT OF FLUORIDE TOXICITY

SILKWORM GROWTH AND NUTRITION—IMPACT OF FLUORIDE TOXICITY
Mulberry as a foliage crop is grown extensively in the states of Andhra Pradesh, Karnataka, and Tamil Nadu, India, for feeding silkworms. The mulberry gardens in these regions occasionally get contaminated with many kinds of pollutants, and problems have cropped up in sericulture due to intoxication of silkworms feeding on contaminated mulberry leaves. Among various environmental polluting factors, fluoride exerts a very profound influence on the growth of the silkworms, especially where the fluoride concentrations range between 2 and 25 ppm in ground waters in drought-prone areas of India. Fluoride is generally regarded as
highly toxic to all organisms. Fluoride ingestion by silkworms has been found to result in a significant loss of silkworm body weight and a decrease in faecal output, which apparently is due to decreased consumption of food. The changes in the nutritional parameters appear to be dose and time dependent in both sublethal
(5.5 mg F/kg bw) and sub-sublethal (2.75 mg F/kg bw) dosages of fluoride consumed by silkworms. However, the changes in the sub-sublethal level of fluoride ingested by silkworms on the 4th  day were less compared to sublethal dose-treated silkworms, indicating that the silkworms on prolonged exposure can
recover from the toxic effect of fluoride at a lower dose.
Author: Rao Arava Vijaya Bhaskara.
Correspondence: Pondicherry University, Kalapet, Pondicherry 605014, India.