A novel eDNA-based surveillance strategy targeting quiescent ticks in soil

Area of Science:

• Molecular biology
• Entomology
• Ecology

Background:

• Ticks are significant ectoparasites and vectors of pathogens, necessitating effective surveillance.
• Current surveillance methods focus on the host-seeking tick stage, overlooking their soil-dwelling quiescent phase.
• Geographic expansion and increased tick populations highlight the need for improved detection strategies.

Purpose of the Study:

• To develop a novel molecular approach for detecting, identifying, and quantifying tick DNA directly from soil samples.
• To expand existing tick surveillance strategies by targeting ticks in their quiescent soil-dwelling stage.
• To provide a standardized and cost-efficient method for identifying medically and veterinarily important tick species.

Main Methods:

• Optimization of a DNA extraction protocol for arthropods from soil samples.
• Development of multiplex Polymerase Chain Reaction (PCR) assays with novel species-specific primers targeting the 5.8S-ITS2-28S rRNA gene cluster.
• Testing of the assay's ability to detect and differentiate four key tick species (Amblyomma americanum, Ixodes scapularis, Rhipicephalus annulatus, R. sanguineus) in individual and pooled soil samples.

Main Results:

• Successful detection and identification of individual tick species from soil samples.
• Clear differentiation of all four target species in pooled soil samples.
• High sensitivity demonstrated, detecting as few as 5 tick eggs per 40 ml of soil, with no cross-reactivity between species-specific primers.

Conclusions:

• The developed molecular approach offers a robust, standardized, and cost-efficient method for tick detection in soil.
• This technique complements existing surveillance methods by targeting ticks in their quiescent stage.
• The approach facilitates enhanced tick surveillance and supports targeted control interventions for tick-borne diseases.