[19] Evaluation acaricidal efficacy of botanical extract from Eupatorium adenophorum against the hard tick Haemaphysalis longicornis (Acari: Ixodidae)

The aim of this study was to evaluate the acaricidal activity of a botanical extract fromEupatorium adenophorumagainst the hard tickHaemaphysalis longicornis. This could result in developing effective extracts ofE. adenophorumas a source of natural, low-toxicity plant-based acaricidal drugs. Adult engorged females ofH. longicorniswere collected from naturally infected goats. The engorged females were reared in the laboratory and their offspring (larvae and nymphs) were used as test ectoparasites. The toxic effects of botanical extracts fromE. adenophorumagainst larvae and nymphs ofH. longicorniswere evaluated. The results showed that the extracts with 1.5 and 1.0g/ml (w/v) concentrations were toxic forH. longicornis, comparable to a toxic effect of 2% chlorpyrifos (positive control). The median lethal time (LT50) for larval and nymphal ticks with 1.5g/ml (w/v) concentration of extract were 0.790 (LT99=1.065) and 1.018 (LT99=10.608) hours, respectively, whereas the LT50 of 1.0g/ml (w/v) concentration were 1.445 (LT99=6.047) and 1.313 (LT99=29.932) hours for larval and nymphal ticks, respectively. At a concentration of 1.5g/ml (w/v), an acaricidal effect of 100% was achieved for both larval and nymphal ticks, while a concentration of 1.0g/ml (w/v) resulted in 100% (for larvae) and 93% (for nymphs) within a 6h period. In additional, we found that the relatively low concentration (0.5g/ml) also obtained a good acaricidal effect during the short experimental period, with 2.22 and 2.651h LT50 for larval and nymphal ticks, respectively. These results indicate thatE. adenophorumcontains potent acaricidal ingredients against the hard tickH. longicornis.

Copyright © 2013 Elsevier Inc. All rights reserved.