Exploiting assembly pheromone for the control of ixodid ticks

The effect of an Assembly Pheromone – Deltamethrin complex (AP – D complex) on the larvae of five ixodid tick species viz. Rhipicephalus sanguineus, R. microplus, R. haemaphysaloides, Hyalomma marginatum and Haemaphysalis bispinosa, as well as the adults of R. sanguineus and R. microplus, was assessed by in vitro bioassays. All the larval as well as adult stages of ticks exposed to the AP – D complex were lured and killed within 24 hours of exposure, except H. bispinosa. Exposure to the AP – D complex for an hour resulted in 70%, 95%, 90%, 90%, 95% mortality of the larval stages of Rhipicephalus sanguineus, R. microplus, R. haemaphysaloides, H. bispinosa and H. marginatum respectively. No mortality was observed when the larval stages of the five tick species were exposed to AP alone (positive control). Exposure of adults to the AP – D complex for an hour resulted 92% and 90% mortality of R. microplus and R. sanguineus, respectively. Negligible mortality was recorded in adult ticks exposed to deltamethrin alone (Negative control), while no mortality was recorded when exposed only to AP (Positive control). Hence, the AP – D complex is better in luring and killing ticks than AP or D alone, regardless of the life stage. Our results suggest that the development of a sustained release AP – D complex device may be an effective means of controlling ticks in India.

A novel approach to control brown dog tick, Rhipicephalus sanguineus using sustained release poly-ɛ-caprolactone-pheromone microspheres

Control of brown dog tick, Rhipicephalus sanguineus was attempted by utilizing sustained release preparations of synthetic analogues of assembly pheromones. The assembly pheromone, in defined ratio, was encapsulated using poly-ɛ-caprolactone by water-in-oil-in-water double emulsion solvent evaporation technique. In the in vitro bioassay, percent mortality with test microspheres was 95.6, 64 and 44 among the unfed larvae, unfed nymph and unfed adults respectively, 24 hours post-exposure. Field trials were carried out to evaluate the efficacy of microspheres in luring and killing environmental stages of R. sanguineus in dog houses/kennels. Engorged and unfed stages in the environment were found adhered and dead on the specially designed lure.