Acute and chronic effects of carbaryl on survival, growth, and metamorphosis in the bullfrog (Rana tigrina)

Abstract

The effects of carbaryl (1-naphthalenyl methylcarbamate), an extensively used insecticide in agricultural operations, have been studied on survival, growth, and metamorphosis of the bullfrog tadpole Rana tigrina. The 96 hr LC₅₀ value for tadpoles (0.02 g) was 6.2 mg/L. The tadpoles were reared from hatching to metamorphosis in sublethal concentrations of carbaryl. Rates of feeding, defecation, and excretion increased with increasing concentration of carbaryl but the conversion rate decreased leading to the production of small froglets. The tadpoles exposed to the sublethal concentrations suffered no mortality until the appearance of the forelimb; however, during metamorphosis mortality was significant, even at 2 mg/L.