Lethal effects of Imergard WP, a perlite-based dust, on Amblyomma americanum (Ixodida: Ixodidae) larvae and nymphs

Authors: Showler, Allan; Harlien, Jessica

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: As resistance in economically and medically important hard ticks to conventional synthetic toxin-based pesticides has become increasingly widespread, research efforts to identify alternative control tactics have intensified. Laboratory bioassays on the lone star tick, as a model for other tick species, were conducted to assess the efficiency of Imergard WP perlite-based dust versus CimeXa, a silica gel-based insecticidal product that is highly effective against tick larvae and nymphs. Each of the two inert desiccant dusts immobilized lone star tick larvae and nymphs within 4-6 h, and killed all of the ticks by 24 h after being briefly immersed in dry dusts, and after they crawled 7.3 cm across a filter paper disc treated with the dusts. Contact by crawling on a dried aqueous film of the dusts, however, did not immobilize and kill the ticks by 24 h. Similar to silica gel-based desiccant dust, dry perlite-based Imergard WP dust might protect cattle from problematic ticks, including cattle fever ticks, that vector the causal agents of debilitating disease agents. Perlite can potentially be stored indefinitely, it can retain its lethal properties for as long as adequate amounts remain on a surface, and it might be acceptable for limited application in environmentally sensitive habitats.

Technical Abstract: As resistance in economically and medically important ixodids (hard ticks, Ixodida: Ixodidae) to conventional synthetic toxin-based acaricides has become increasingly widespread, research efforts to identify alternative control tactics have intensified. Laboratory bioassays on the lone star tick, Amblyomma americanum (L.), as a model for other ixodid species, were conducted to assess the efficiency of Imergard WP perlite-based dust versus CimeXa, a silica gel-based insecticidal product that is highly effective against ixodid larvae and nymphs. Each of the two inert desiccant dusts immobilized A. americanum larvae and nymphs within 4-6 h, and killed 100% of the ixodids by 24 h after contact by brief immersion in dry dusts, and after they crawled 7.3 cm across a filter paper disc treated with the dusts. Contact by crawling on a dried aqueous film of the dusts, however, did not immobilize and kill the ixodids by 24 h. Similar to silica gel-based desiccant dust, dry perlite-based Imergard WP dust might prophylactically protect cattle from one-host ixodids, including cattle fever ticks, Rhipicephalus (Boophilus) spp,, that vector the causal agents of the debilitating and lethal disease, babesiosis, as well as other medically and agriculturally problematic ixodids. Perlite can potentially be stored indefinitely, it can retain its lethal properties for as long as adequate amounts remain on a substrate, and it might be acceptable for limited application in environmentally sensitive habitats.