Transboundary Emerging and Exotic Animal Disease/ Exotic Animal Disease Practice Exam

Which tick species would treatments be least effective against?

1. Ornithodoros erraticus

2. Rhipicephalus appendiculatus

3. Boophilus microplus

4. Amblyomma variegatum

The correct answer is: Ornithodoros erraticus

The effectiveness of treatments against different tick species can vary significantly, often due to resistance mechanisms or life cycle characteristics. Ornithodoros erraticus, the choice in question, is a soft tick that belongs to the family Argasidae. This tick has a unique feeding behavior, often feeding rapidly and emerging from hiding places, making it less susceptible to certain topical treatments that are effective on hard ticks. Additionally, soft ticks are generally more resilient and can survive in a broader range of environmental conditions, which may affect the efficacy of conventional acaricides. Comparatively, the other tick species listed, such as Rhipicephalus appendiculatus, Boophilus microplus, and Amblyomma variegatum, are hard ticks (family Ixodidae) that tend to be more vulnerable to standard treatments. Hard ticks have a more exposed feeding habit that generally allows for effective treatment penetration, and they often do not have the same level of resistance to acaricides as some soft tick species. This makes treatments more reliable against them compared to Ornithodoros erraticus, leading to the conclusion that treatments would be least effective against this particular species.