Chlorpyrifos-Induced Toxicity in Duttaphrynus melanostictus (Schneider 1799) Larvae

Abstract

This study investigates the effects of continuous exposure to a widely used organophosphate pesticide, chlorpyrifos, on survival, growth, development, and activity of larvae of the Asian common toad, Duttaphrynus melanostictus Schneider 1799. Larvae were continuously exposed to six different concentrations (1-1,500 μg l(-1)) of commercial-grade chlorpyrifos for 14 days and monitored for 1 additional week. Chlorpyrifos at ≥1,000 μg l(-1) caused significantly high and dose-dependent mortality, and the weekly LC50(7 day-21 day) values ranged from 3,003 to 462 μg l(-1). Larvae surviving exposure to ≥500 μg l(-1) chlorpyrifos showed significant growth impairment, delays in metamorphosis, and decreased swimming activity. Tail abnormalities were the most common morphologic deformity at concentrations of 1,000 and 1,500 μg l(-1) chlorpyrifos. The findings of the present study highlight the need to recognize the potential risk that agrochemicals pose to amphibians inhabiting agricultural landscapes in Sri Lanka and other Asian countries.

Survival and cholinesterase activity of Asian common toad (Duttaphrynus melanostictus) tadpoles following short term exposure to a carbosulfan-based pesticide

“…It is likely that pesticide exposed tadpoles are at a disadvantage under natural conditions and may face threats and indirect mortality as a consequence of delayed development. Delayed development and metamorphosis due to exposure to other pesticides have also been reported earlier for D. melanostiscus (Jayawardena et al 2011;Wijesinghe et al 2011) and other amphibian species (Svartz et al 2012;Saka et al 2013). Among other factors, increased energetic costs involved in abnormal behaviour could have led to prolong developmental period of these tadpoles.…”

“…Tail bending due to the curvature in the spinal cord (scoliosis) especially could affect swimming patterns in the tadpoles (Alvarez et al 1995). Similar malformations have been reported earlier in D. melanostiscus tadpoles after exposure to some organophosphate insecticides and herbicides (Jayawardena et al 2011;Wijesinghe et al 2011). These deformed and abnormally behaved tadpoles could be highly vulnerable in the wild to increased predation due to reduced ability to evade predators (Relyea 2005;Yadav et al 2013).…”

Cadmium-Induced Toxicity on Larvae of the Common Asian Toad Duttaphrynus Melanostictus (Schneider 1799): Evidence from Empirical Trials

“…The developmental stage of the surviving tadpoles was also recorded at the end of the trial. The swimming activity of tadpoles was assessed every other day according to a method described in Sumanadasa et al (2008) and Wijesinghe et al (2011). Each tank was placed over a white paper on which a cross had been drawn, and the number of times that tadpoles crossed the lines was counted for 5 min between 0800 and 1200 hours.…”

“…In Sri Lanka, cadmium (Cd) has become one of the most commonly observed pollutants of freshwater ecosystems with recorded concentrations in water being in the range of 0.002-0.2 mg L -1 (e.g. Manage and Wijesinghe 2009;Ranasinghe 2009;Weeraratna and Ariyananda 2009;Bandara et al 2011). Apart from natural sources, anthropogenic activities such as the production of nickel-cadmium batteries, electroplating, phosphate mining and the use of phosphorus-fertilizers result in the addition of Cd into water bodies.…”

Acute Toxicity of an Organophosphate Insecticide Chlorpyrifos to an Anuran, Rana cyanophlyctis

“…Totally, 48 h LC 50 value were studied for chlorpyrifos in five d posthatch tadpoles of B. melanostictus and reported it as 1.47 ppm [29]. "Chlorpyrifos caused significantly high and dose-dependant mortality and the weekly LC 50 (7 d-21 d) values ranged from 3003 µg/L to 462 µg/L" [30]. The acute LC 50 value for chlorpyrifos Rhinella fernandezae tadpoles has been found [31] as 0.151 mg/L (in unpolluted area) and 0.293 mg/L (in area with high degree of anthropogenic disturbance).…”