Acute Toxicity Assessment of Azadirachtin‐Based Pesticides Using Murine Hybridoma and Oyster Cells

Abstract

In vitro acute toxicities of azadirachtin‐containing pesticides (Neemix™ and Bioneem™), formulated with neem tree extracts, and pure azadirachtin (AZA), the believed active ingredient, were studied using hybridoma and oyster cells and were compared to results obtained using the standard in vivo Daphnia pulex toxicity assay. Neem‐based pesticides showed relatively high toxicity to both hybridoma and oyster cells at concentrations of 1 μg AZA/mL and higher. The IC₅₀ values for hybridoma cells were 2.15 μg AZA/mL for Neemix™ and 1.67 μg AZA/mL for Bioneem™. Oyster cells had IC₅₀ values of 2.18 μg AZA/mL for Neemix™ and 9.46 μg AZA/mL for Bioneem™. Purified AZA, however, did not appear to be as toxic as the formulations. D. pulex was also more sensitive to neem‐based pesticide exposure than that of pure AZA. The applications and limits of these two in vitro models for testing the acute toxicity of AZA‐based pesticides are discussed in comparison with the in vivo D. pulex test.

Keywords:

• Neem pesticides
• Azadirachtin
• Hybridoma
• Oyster cells
• Daphnia pulex

Acknowledgments

We are grateful for the assistance of Dr. Jerome LaPeyre in the Department of Veterinary Science, Louisiana State University and Dr. John Supan in the Office of Sea Grant Development, Louisiana State University. Financial support was provided by the U.S. Geological Survey through the Louisiana Water Resources Research Institute (LWRRI).