Acute toxicity evaluation of triazophos, deltamethrin and their combination on earthworm, Eudrilus eugeniae and its impact on AChE activity

ABSTRACT

The acute toxicity of three formula grade pesticides namely, triazophos (an organophosphate, OP), deltamethrin (a pyrethroid) and combined pesticide (triazophos + deltamethrin) was determined in earthworm, Eudrilus eugeniae. They were exposed to different concentrations of these pesticides for 48 h by paper contact toxicity method. The LC₅₀ values for triazophos, deltamethrin and of combination were determined as 0.076, 0.031 and 0.065 μg/cm², respectively. To study the sublethal effect of these pesticides, E. eugeniae were exposed to 5% and 10% of LC₅₀ of pesticides for 48 h. Morphological alterations such as coiling, clitellar swelling, mucus release and bleeding followed by body segmentation were observed in exposed earthworm. Acetylcholinesterase (AChE) activity assayed in different regions of body segment exhibited a significant (p < 0.05) decrease in its activity particularly in the pre-clitellar region as compared to other regions. The altered behavioural responses in pesticides exposed earthworms would have been due to decline in AChE activity of the nervous system.

KEYWORDS:

• AChE activity
• behavioural changes
• combined pesticide
• Deltamethrin
• Eudrilus eugeniae
• Triazophos

Acknowledgements

Authors express their gratitude to the Head of the Department of Zoology, for providing Central Instrumental facility developed with the financial assistance from DST-FIST and UGC-SAP Phase I & II for carrying out this work. Financial assistance to the authors (SS and RKT) from UGC is gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Ms. Shikha Singh is a Ph.D scholar doing research mainly focused on biochemical and molecular aspects of toxicological impact on fish and earthworm.

Mr. Rishikesh K. Tiwari is a Ph.D scholar doing research mainly focused on biochemical and molecular aspects of toxicological impact on fish and earthworm.

Dr. Ravi S. Pandey is Professor of Zoology at University of Allahabad (India). He has more than 35 years of teaching and 40 years of research experience. He published a good number of research papers in the journal international repute (peer reviewed journals). His present research field mainly focused on biochemical and molecular aspects of toxicological impact on fish and earthworm.