Abstract: Infection of entomopathogenic nematodes Steinernema carpocapsae BJ（Sc BJ），S. feltiae Otio（Sf Otio），S. ceratophorum D43（Sc D43） and S. glaseri NC32（Sg NC32） (Steinernematidae)，and Heterorhabditis bacteriophora E-6-7 （Hb E-6-7） (Heterorhabditidae) to female Haemaphysalis longicornis Neumann was conducted. The nematodes dosage used was 4 000 Ijs/dish. The results showed that the five entomopathogenic nematodes had lethal effects on female H.longicornis.Hb E-6-7 and Sc BJ were the most virulence species to variousdevelopmental stages of female ticks: the cumulative mortality and the LT₅₀ of unfed female ticks from nematodes infection were 82.5%，9.0 d and 75.0%，8.8 d, respectively; feeding female 90.0%，8.0 d and 82.5%，8.0 d; engorged female 93.3%，7.3 d and 86.7%，7.3 d. Sc D43 infection also caused high mortality (80.0%) to engorged female ticks, but the LT₅₀ was relatively long （11.7 d）. Lethal effects of Sf Otio and Sg NC32 to this tick were low. Engorged female ticks were more sensitive than unfed and feeding female ticks.

Key words: Entomopathogenic nematodes, steinernematid, heterorhabditid, Haemaphysalis longicornis, virulence