Evolution of repellent tolerances in representative arthropods

Area of Science:

• Entomology
• Parasitology
• Evolutionary Biology

Background:

• Insect repellents are crucial for preventing vector-borne diseases.
• Understanding species-specific responses to repellents is vital for effective control strategies.
• Previous research has not comprehensively mapped repellent tolerance across diverse arthropod taxa.

Purpose of the Study:

• To evaluate the efficacy of eight commercial insect repellents against key arthropod vectors.
• To analyze patterns of repellent tolerance across different species and their evolutionary relationships.
• To investigate the evolutionary trajectory of repellent tolerance in arthropods.

Main Methods:

• Testing eight commercial insect repellents against Ornithodoros parkeri, Dermacentor variabilis, Aedes aegypti, and Xenopsylla cheopis.
• Quantifying species' tolerance levels using a defined character state system (0=sensitive, 1=intermediate, 2=tolerant).
• Mapping tolerance states onto a cladogram representing accepted species classification to infer evolutionary patterns.

Main Results:

• Distinct patterns of tolerance to repellents were observed for each tested species.
• Repellent tolerance levels were mapped onto a phylogenetic tree, revealing evolutionary trends.
• Aedes aegypti exhibited the least evolved tolerance, while Xenopsylla cheopis showed the most evolved tolerance.
• Parallel evolutionary changes in repellent tolerance were identified between arachnid lineages and Xenopsylla cheopis.

Conclusions:

• Species-specific variations in repellent tolerance are significant.
• The evolution of repellent tolerance is not uniform and follows distinct phylogenetic pathways.
• Arthropod evolution demonstrates convergent or parallel development of tolerance mechanisms to insect repellents.