Interaction between ticks (Acari : Ixodidae) and pathogenic mematodes (Nematoda): Susceptibility of tick species at various developmental stages

The virulence of entomopathogenic nematodes (Steinernematidae and Helerorha bditidae) to tick species under laboratory conditions is reported. The susc eptibility of larval, nymphal, and adult stages of the ticks Hyalomma excav atum (Koch), Rhipicephalus bursa (Canestrini & Fanz), and R. sanguineus (La tereille) to 2 strains of Steinernema carpocapsae and 3 strains of Heterorh abditis bacteriophora were compared in laboratory assays. Preimaginal stage s of ticks were found to be more resistant to the nematodes than were adult ticks which exhibited 80-100% mortality in a dish containing 5,000 infecti ve juveniles of H. bacteriophora IS-3 or IS-5 strains isolated in Israel. T hese 2 strains were found to be much more virulent to unfed adult ticks tha n were the other isolates. No marked difference was found between engorged ticks and unfed adults of R, sanguineus or H. excavatum in terms of mortali ty, whereas engorged males and unfed females of R. bursa were significantly more susceptible than unfed males or engorged females.