Factors affecting the virulence of entomopathogenic nematodes to engorged female Boophilus annulatus ticks.
The laboratory trials rank the virulence of entomopathogenic nematode strains (3 heterorhabditids and 6 steinernematids) to engorged female Boophilus annulatus ticks according to 3 parameters of the infection process: the effect of exposure time on tick mortality, the quantity of nematodes that penetrate ticks, and the rate of tick mortality after the injection of 1, 2, or 3 nematodes. Exposure of the ticks to heterorhabditid strains for 6 hr resulted in >80% mortality, but only 20 or 65% mortality after exposure to most steinernematids. The quantity of nematodes recovered per tick exposed to nematodes for 6 days averaged from 16 to 141. For steinernematids, a negative correlation was obtained between tick mortality and the average quantity of nematodes recovered. Injecting 1 infective juvenile from 1 of 2 heterorhabditid strains into each tick resulted in close to 100% mortality. Increasing the quantity of nematodes injected into each tick had little or no additive effect on tick mortality.
Glazer
I
I
Department of Nematology, ARO, The Volcani Center, Bet-Dagan, Israel.
Alekseev
E
E
Samish
M
M
D000818:Animals; D001404:Babesiosis / Q000517:prevention & control; D002417:Cattle; D002418:Cattle Diseases; D005260:Female; D017168:Rhabditida / Q000472:pathogenicity*; D017172:Rhabditoidea / Q000472:pathogenicity*; D013984:Tick Infestations / Q000662:veterinary; D013987:Ticks / Q000469:parasitology*