Michael Samish

Ticks are highly important ectoparasites which transmit variable pathogens to both domestic animals and man. Tick control is based mainly on chemical acaricides which are harmful to the environment. Various studies demonstrated the susceptibility of different tick species to entomopathogenic fungi (EPF), particularly Metarhizium anisopliae, and suggested their use as biological control agents. In the recent years our team has investigated the potential use of EPF against ticks. This included elucidation of the factors determining EPF pathogenicity and the susceptibility of the target tick. At the early stages of the infection process we observed that adhesion of fungi conidia to different tick species with variable susceptibility to the fungi lacked any specificity. However, the initial pathogenic process (germination, appressorium differentiation) of the fungi conidia to epicuticular extracts from ticks was highly dependent on both the susceptibility level of various tick species and on the fungal strain virulence. We utilized M. anisopliae expressing GFP to follow the pathogenic process in-vivo. Different pattern of development was observed among susceptible and resistant ticks. Moreover, differences in response to EPF infection was recorded among various tick species which are resistant to the fungi. The implications of the information obtained in our studies on the selection of EPF strains for control of ticks will be discussed.