Assessment of Acute Toxicity and Behavioral Disruptions in Indian Major Carp (Labeo Rohita) Under Pyrthrum Stress

Abstract

The extensive use of pesticides in agriculture has raised serious concerns regarding their inadvertent entry into aquatic ecosystems and subsequent toxicity to non-target organisms. Pyrethrum, a botanical insecticide derived from Tanacetum cinerariifolium, is often regarded as an eco-friendly alternative to synthetic pesticides; however, its toxic effects on aquatic fauna remain insufficiently explored. The present study evaluates the acute toxicity and associated behavioral alterations induced by pyrethrum in the Indian major carp Labeo rohita. Acute toxicity bioassays were conducted under laboratory conditions following APHA guidelines, and median lethal concentrations (LC₅₀) were determined for 24, 48, 72, and 96 hours of exposure. The LC₅₀ values exhibited a time-dependent decline, indicating increased toxicity with prolonged exposure, with the lowest LC₅₀ recorded at 96 hours (21.40 µg/L). Mortality increased with both concentration and exposure duration, reaching 100% at higher concentrations. In addition to lethality, pronounced behavioral and physiological disturbances were observed, including erratic swimming, surfacing and gulping, avoidance responses, excessive mucus secretion, reduced opercular movement, fin damage, and body discoloration. Dissolved oxygen levels declined significantly in exposure tanks, suggesting elevated metabolic stress and impaired respiration. These findings demonstrate that pyrethrum is highly toxic to Labeo rohita even at low concentrations and induces severe behavioral disruptions. The study underscores the ecological risks associated with botanical insecticides and highlights the need for cautious application and stringent regulation to protect aquatic ecosystems.