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The entomopathogenic fungus Metarhizium anisopliaeis used as a biological pest control agent against various arthropod species, including ticks. However, the efficacy depends on tick species, tick stage and fungus strain. We studied the effect of M. anisopliaeon engorged larvae and nymphs of Ixodes ricinus, the most abundant tick species in Europe, under laboratory and semi-field conditions. A significant reduction of engorged larvae and nymphs could be shown under laboratory as well as under semi-field conditions. Only 3.5% of the larvae treated in the lab and only 18.5% kept under semi-field conditions were able to develop into nymphs compared to the recovered nymphs of the control groups, which were regarded as 100%. Only 7.1% of nymphs were recovered as adult ticks after fungal treatment under semi-field conditions compared to the control (100%). The efficacy of blastospores of M. anisopliaeagainst engorged larvae and nymphs of I. ricinusunder semi-field conditions was demonstrated in this study, showing their high potential as a biological control agent of ticks. Further studies will have to investigate the effect of this agent against other stages of I. ricinusas well as other tick species before its value as a biological control agent against ticks can be fully assessed.

Coxiella burnetii, the causative agent of Q fever, and Rickettsiaspp. are bacterial pathogens that can be transmitted by ticks of the genus Dermacentor(i.e., Dermacentor marginatusand D. reticulatus). In Germany, the occurrence of these ticks is currently limited to few areas. However, due to increasing temperatures, these vectors will likely extend their distribution in the future, and C. burnetiiand Rickettsiaspp. might spread with them. To assess the prospective risk of human infections by these agents, it is important to know their current distribution. We collected 666 adult Dermacentorspp. and 119 rodents, mainly Microtus arvalis, in 3 Q fever endemic areas in southern Germany. Ticks and rodent organ pools were screened by PCR for C. burnetiiand Rickettsiaspp. No evidence of C. burnetiiinfections could be found in ticks or rodents, suggesting that these animals do not play an essential role in the epidemiology of Q fever in Germany. Rickettsia raoultiiand R. slovacacould be detected in 30.3% and 0.75% of all examined ticks, respectively. In contrast, no rickettsia infections could be found in any rodent samples. Both rickettsia species can cause tick-borne lymphadenopathy (TIBOLA), a usually mild human disease. Because of the possible transmission of these rickettsiae to humans, TIBOLA should be considered in the differential diagnosis of tick-borne diseases. Our data show that a spread of these rickettsiae is possible in Germany and that more studies on the distribution of these agents are necessary.