Scanning Electron Microscopy (SEM) analysis and biological control of Ixodes ricinus using entomopathogenic fungi

Some fungal species were isolated from scab or scab-like symptoms on leaves of various plant hosts in Iran. Some of them isolated from apple and pear leaves were investigated in the present study. The isolates were identified based on the morphological and cultural characteristics. On the other hand, for molecular identification and phylogenetic analyses were carried out based on the sequence of ITS-rDNA region (including 5.8S rDNA). As a result, six species, namely Acremonium fusidioides, Acrostalagmus luteoalbus, Clonostachys rosea, Sarocladium kiliense, Sarocladium strictum and Endoconidioma populi were identified. Among them, Acremonium fusidioides is a new taxon for the mycobiota of Iran. In the present study, pathogenicity of four native strains of entomopathogenic fungus; Metarhizium anisopliae, was studied against adult stage of Ixodes ricinus. For this purpose a total number of 180 adult ticks were examined in triplicate. Thirty ticks for each strain and negative and positive controls were immersed in 2.4 × 107 fungal conidia/ml in vitro. Samples were incubated in separate Petri dishes at 26 °C and 70% relative humidity. Positive control groups were treated with Cypermethrin and negative controls were immersed in the same volume of sterilized distilled water. Mortality rate and fungal grow on ticks for each strain were reported in comparison with control groups. M. anisopliae IRAN 437 C showed the highest virulence in mortality and mycelium grow on ticks. Cypermethrin killed the ticks with higher potency than that of entomopathogenic fungi. Scanning electron microscopy showed the growth of M. anisopliae on the surface of tick bodies and penetration of fungal hyphae through tick cuticle. Taken together, results obtained from this study show potential of Iranian Entomopathogenic fungi as a biocontrol agents of I. ricinus. This is the first report demonstrates the mechanism of action of entomopathogenic fungi of the genus Metarhizium on ticks at electron microscopy level.