Occurrence of pathogens in populations of Ips typographus, Ips sexdentatus (Coleoptera, Curculionidae, Scolytinae) and Hylobius spp. (Coleoptera, Curculionidae, Curculioninae) from Austria, Poland and France

Abstract

Occurrence of pathogens in four important forest pest insect species, Ips typographus, Ips sexdentatus, Hylobius abietis and Hylobius pinastri , from Austria, Poland and France was investigated in 2006–2008. Insects were collected from 46 sampling sites. In total 5,634 living adult beetles were dissected. Some dead adults and some very few dead larvae were inspected for fungal infection. Eight pathogen species ( Ips typographus entomopoxvirus, Gregarina typographi , Mattesia sp., Chytridiopsis typographi , Unikaryon montanum , Beauveria bassiana , Beauveria caledonica and Isaria farinosa ) were found in I. typographus from the three countries. Four pathogen species were found in I. sexdentatus from Austria and France ( Gregarina cf. typographi , Metschnikowia cf. typographi , B. bassiana and B. caledonica ). Five pathogen species were found in H. abietis from Austria and Poland ( Gregarina hylobii , Ophryocystis hylobii , Nosema hylobii , B. bassiana and B. brongniartii ) and two in H. pinastri from Poland ( G. hylobii and O. hylobii ) . Some of the pathogen species were found for the first time in one of the three countries or are reported for the first time in one of the investigated beetle species. Differences in occurrence and geographical distribution of these pathogens are discussed with regard to their respective apparent host spectrum and possible ecological requirements.