ENVIRONMENTALLY SAFE CONTROL OF TICKS: USE OF IXODES (ACARINA, IXODIDAE) TICK SEXUAL BEHAVIOR PECULIARITIES FOR PATHOGENIC FUNGAL EFFECT REINFORCEMENT

摘要

Indigenous strains of hyphomycetes fungi Beauveria bassiana (BBIR) isolated from the bodies of Ixodes ricinus (L.) in Moldova (2004) and Paecilomyces farinosus (PFIP) isolated from Ixodes persulcatus Schulze (St. Petersburg Region, Russia) were testedfor their activity against male and female I. ricinus collected by flagging during April-May from Curonian Spit, Kaliningrad Region (2007) and I. persulcatus from St. Petersburg Region (2006,2007). Ticks directly submerged for 3-5 sec into a suspensionof 5 x 10~7 fungi conidia per 1 ml of distilled water, and then kept individually in humidity gradient glass tubes for 30 days at 22 ± 1.5°C, demonstrated a low level of mortality (mean 15.9 ± 1.6%). For both of the tested tick species, the off-host copulation mode of female insemination is known. These peculiarities were used to reinforce the effect of fungi. One-day contact of treated males with nontreated females enhanced the fungal action on both sexes: the younger the females, the stronger was the effect (max. 61.9, mean 34 ± 9.2%). Mortality of their sex mates was much higher in the same series of experiments (62.2 ± 6.8%), because even unsuccessful attempts to copulate reinforced the entry of conidia inside the male body cavity. A total of846 ticks were tested. Sexual behavior peculiarities of Ixodes ticks, that is, off-host copulation and repeated attempts at contact with attached females on the vertebrate host, make the sprinkling of fungi as safe biopesticides early in the spring, whenmales and noninseminated females prevail, very promising. The use of indigenous fungi is an environmentally safe method of tick control.