Toxicity and persistence of permethrin‐impregnated clothing against the Australian paralysis tick, Ixodes holocyclus (Acari: Ixodidae)

Abstract

Permethrin is a pyrethroid insecticide that has been widely used for the impregnation of fabrics to prevent the bites from arthropods such as mosquitoes and ticks. There are two types of permethrin impregnation: Do‐It‐Yourself (DIY) packs and pre‐impregnated fabrics. Both forms have been on sale for many years in Australia, however to date, no data are available regarding their efficacy against Ixodes holocyclus. The aims of this study were to test and compare the contact toxicity of a DIY product versus two pre‐impregnated fabrics (shirt and trousers) against I. holocyclus, and to test the efficacy of the fabrics after repeated laundering. All treated and untreated fabrics were tested before laundering (0 washes) and after 10, 30 and 50 washes. Five ticks were placed onto each test fabric for 2 min, with four replicates for a total of 20 ticks per test. Both knockdown and mortality of I. holocyclus ticks were recorded at 60 min and 24 h, respectively. Logistic regression analysis was used to assess the relationship between knockdown and mortality in ticks exposed to each fabric product, before and after laundering. All of the unwashed treated fabrics were effective in causing 100% knockdown. With 10 washes, the percentage of knockdown with the pre‐impregnated shirt and trousers was 95% and 90%, respectively. The DIY product was less effective with only 15% knockdown. The levels of knockdown with the pre‐impregnated shirt and trousers further decreased with 30 washes to 70% and 20%, respectively, and then further declined to 45% and 20% with 50 washes. For the DIY product, knockdown was only 10% and 5% with 30 and 50 washes, respectively. There was minimal mortality recorded at 24 h even with the unwashed fabrics. This study indicated that the pre‐impregnated product was more effective in repelling I. holocyclus ticks than the DIY impregnation pack and the efficacy of this product degrades notably after 10 washes.

Adult Mosquito and Butterfly Exposure to Permethrin and Relative Risk Following ULV Sprays from a Truck-Mounted Sprayer

“…That differential sensitivity between the target insects and nontarget vertebrate organisms makes permethrin a desirable insect pest control tool. In fact, permethrin has been incorporated within articles of clothing and other materials to reduce interaction with disease vectors like mosquitoes and ticks (Banks et al 2015 ; Prose et al 2018 ; Panthawong et al 2020 ). However, conservation of nontarget invertebrates such as imperiled butterflies is problematic when they cohabitate with targeted insects like mosquitoes.…”