Evaluation of virulence of isolates of certain species of entomopathogenic anamorphic ascomycetes (Fungi, Ascomycota) in relation to adult individuals of the tick <i>Ixodes Persulcatus</i>

Abstract

In nature, entomopathogenic fungi (EPF) play an important role in the control of population density in many arthropods. The lethal effects of EPF on ixodid ticks (Ixodidae) have been, however, reported mainly in southern warm-loving species, which are mostly not found in Europe. The aim of this study was to evaluate in laboratory the virulence of nine selected psychrotolerant EPF isolates of Beauveria bassiana s. l. (6), Akanthomyces cf. muscarius (2) and Metarhizium anisopliae s. l. (1) at a moderate average daily temperature of +14°C in relation to overwintering adult taiga ticks (Ixodes persulcatus), collected at the end of May in the Kondopoga region of the Republic of Karelia. Under this temperature, the use of suspensions for infection with a concentration of infectious spores (conidia) of 3×107 per 1 ml, all isolates showed a lethal effect on ticks. Among these isolates, the most virulent and rapidly acting one was B. bassiana s. l. CCi-Ar (SI)14 from the Arkhangelsk Province, Bolshoy Solovetsky Island (N 65°, E 35°), that killed 70% of specimens after 9 days, and 95% after 11 days. At the same time, it was found that male ticks have a slightly higher death rate from fungal infections. However, the potential suitability of some EPF isolates for biological control of I. persulcatus populations at low temperatures, shown in this study, requires confirmation in further tests in real conditions of recreational areas actively visited by humans, where infection with dangerous pathogens (tick-borne encephalitis, Lyme borreliosis) transmitted by tick bites often occurs.