Geeta Saxena

A Comparative Study on the Toxicity of a Synthetic Pesticide, Dichlorvos and a Neem based Pesticide, Neem-On to Labeo rohita (Hamilton)

Fish and other organisms are affected by pesticides which pollute the natural water through agricultural runoff. Fishes are common bioindicators of water pollution. In the present study bioassay of synthetic pesticide, Dichlorvos and a plant origin natural pesticide, Neem-On was separately done on Labeo rohita. Data obtained from the toxicity tests were evaluated using the Probit Analysis Statistical Method. The 96h LC 50 of Dichlorvos and Neem-On was found to be 16.71ppm, 42.66ppm respectively. The fish exhibited erratic swimming, copious mucus secretion, loss of equilibrium and hitting to the walls of test tank prior to mortality. In this study, Neem-On was less toxic to fish as compared to Dichlorvos. Plant based pesticides are biodegradable and are target specific than the highly persistent broad spectrum synthetic chemicals. Therefore, use of plant based pesticides is less disastrous and more ecofriendly.

Acute Toxicity and Behavioural Responses of Labeo rohita (Hamilton) to a Biopesticide "NEEM-ON"

The objective of this study was to determine the toxicity of the neem biopesticide azadirachtin (NEEM-ON, Brand name) on the freshwater fish ‘Labeo rohita’. Fishes were exposed to various concentrations of botanical insecticide azadirachtin for 96 h and the percent mortality was recorded. The 96h LC50 value determined by Finney’s Probit Analysis Method was found to be 42.66 ppm. Behavioural patterns were observed critically during the whole experiment. The test fish exhibited erratic swimming, increased surfacing, decreased rate of opercular movement, reduced agility and inability to maintain normal posture and balance with increasing exposure time.

Acute Toxicity and Behavioral Responses of Labeo Rohita (Hamilton) to an Organophosphate (Dichlorvos)

Dichlorvos, a broad spectrum Organophosphate insecticide is a potential toxic pollutant, adversely affecting the fauna of aquatic ecosystem. The objective of the present work was to evaluate the acute toxicity and behavioral responses of Dichlorvos on Labeo rohita under static conditions. The median lethal concentration of the insecticide was found to be 16.71ppm and one tenth of LC50 (1.67ppm) was studied for sub acute studies. Data obtained from the Dichlorvos acute toxicity tests were evaluated using Finney’s Probit Analysis statistical method. Behavioral patterns were studied in lethal (1, 2, 3 & 4 d) and sublethal concentration (1, 5, 10 & 15 d). The test fish showed erratic swimming, increased surfacing, copious mucus secretion, loss of equilibrium and hitting to the walls of test tank before finally sinking to the bottom just before death. Fish under sublethal concentration were found under stress, but that was not fatal.