Dichlorvos toxicity in the white-footed mouse (Peromyscus leucopus)

Area of Science:

• Toxicology
• Veterinary Entomology
• Rodent Pest Control

Background:

• Organophosphate pesticides like dichlorvos (DDVP) are widely used for ectoparasite control in laboratory rodents.
• While generally safe for Mus musculus, preliminary observations suggest increased toxicity of DDVP in Peromyscus leucopus.

Purpose of the Study:

• To investigate the differential susceptibility of P. leucopus and M. musculus to the toxic effects of DDVP.
• To determine the safety and efficacy of DDVP for ectoparasite control in P. leucopus colonies.

Main Methods:

• Comparative exposure of P. leucopus and M. musculus to varying doses of pelleted DDVP.
• Monitoring mortality rates and measuring serum cholinesterase levels in exposed rodents.
• Histopathological examination of key organs (brain, liver, kidneys) to identify lesions.

Main Results:

• Mortality was observed in P. leucopus at DDVP doses of 1, 3, and 6 g/cage (3%, 20%, 53% respectively), while M. musculus showed no mortality.
• Significant reductions in serum cholinesterase were recorded in DDVP-exposed P. leucopus compared to controls.
• No DDVP-induced histopathological lesions were found in the brain, liver, or kidneys of either species.

Conclusions:

• Peromyscus leucopus exhibits significantly higher susceptibility to dichlorvos toxicity than Mus musculus.
• The observed toxicity in P. leucopus is linked to a pronounced decrease in serum cholinesterase activity.
• DDVP is not recommended for ectoparasite control in P. leucopus due to its toxicity profile.