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Developmental disruptions induced by insect growth regulator (Novaluron) in Bufo melanostictus tadpoles
Author(s) -
Pancharatna Katti,
Ghodageri Manjunath,
Deshpande Prasad A.,
Javalkar Rutesh
Publication year - 2010
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/jat.1514
Subject(s) - metamorphosis , novaluron , biology , tadpole (physics) , larva , amphibian , bufo , insect growth regulator , zoology , anatomy , endocrinology , toxicology , toad , ecology , physics , particle physics
Novaluron is an insect growth regulator (IGR) used against fruit‐borers and domestic pests. In this study, effects of different concentrations (0.5, 0.75, 1.0, 1.5 µg l −1 ) of novaluron on the tail regeneration, limb development and metamorphosis were examined in Bufo melanostictus . Thyroxine (1.0, 2.0, 3.5, 5.0 µg l −1 ), which promotes amphibian development/metamorphosis, and vitamin A (5, 20, 40, 60 IU l −1 ), which disrupts development and induce polymelia, were used for comparison. Bufo melanostictus tadpoles were raised in the laboratory from eggs collected around Dharwad in August 2007. The tail of tadpoles was amputated at limb‐bud stage under ether anesthesia. Ten tadpoles were exposed to each concentration of chemicals in triplicate for 5 days and then reared in conditioned water. Tadpoles were fed on boiled spinach. In controls (tadpoles exposed to ringer solution), the tail regenerated on the 5th day, hind‐limbs and fore‐limbs appeared on days 15 and 24, respectively; metamorphosis was complete on the 30th day. In 1 and 2 µg l −1 thyroxine exposed tadpoles, regeneration of tail, development of limbs and metamorphosis were preponed to the 4th, 7th, 11th and 23rd day respectively. Exposure to vitamin A resulted in the regeneration of laterally drooped tails, delay in limb development and arrest of metamorphosis in all the concentrations used. Novaluron at lower dose (0.5 µg l −1 ) was not effective, but at 0.75 µg and higher concentrations it elicited results comparable to those of vitamin A. The study indicates that novaluron interferes with amphibian development if found as contaminant in the water bodies where amphibians live and reproduce. Copyright © 2010 John Wiley & Sons, Ltd.