Distribution of Nasal Myiases Affecting Roe Deer in Spain and Associated Risk Factors

Area of Science:

• Veterinary Parasitology
• Wildlife Ecology
• Infectious Disease Epidemiology

Background:

• Nasal bot flies (Cephenemyia stimulator and Oestrus ovis) are significant parasites affecting cervids.
• Understanding their prevalence and distribution in roe deer populations is essential for wildlife health management.

Purpose of the Study:

• To assess the prevalence and intensity of Cephenemyia stimulator and Oestrus ovis in Spanish roe deer.
• To identify key factors influencing the spread and infestation levels of these nasal bot flies.
• To report the first instance of mixed myiasis by both species in roe deer.

Main Methods:

• Examination of 1600 roe deer heads from 2018 to 2025.
• Prevalence and larval intensity data collection for C. stimulator and O. ovis.
• Statistical analysis to identify risk factors for infestation.

Main Results:

• High prevalence of C. stimulator (39.9%) with substantial larval intensity (mean 44.1).
• Low prevalence of O. ovis (1.6%) with a low larval burden (mean 2.6).
• Roe deer abundance identified as a primary risk factor for C. stimulator; younger animals showed higher larval burden. Infestation rates were higher in northern Spain.

Conclusions:

• Cephenemyia stimulator poses a significant and increasing threat to roe deer in Spain.
• Management strategies should focus on controlling roe deer overpopulation, particularly in northern regions.
• Further research into effective control measures for nasal bot flies in wildlife is warranted.