Pathogens of bark beetles (Curculionidae: Scolytinae) and other beetles in Bulgaria

The presence and diversity of beetle pathogens associated with different tree species in Bulgaria was investigated. In total, 818 specimens belonging to 22 beetle species were examined. Pathogens occurred in 9 host species. The infections were found in the gut (virus, nematodes, protozoans, microsporidia) and haemolymph (nematodes) of the infected insects. The following pathogen species: ItEPV, Beauveria bassiana, B. brongniartii, Isaria farinosa, Gregarina typographi, Gregarina spp., Chytridiopsis typographi, Chytridiopsis sp., and nematodes were revealed. Insects with mycoses were mummified and filled up with fungal structures, formed pseudosclerotium. Most pathogens were established in bark beetles (Scolytinae). For the first time, the fungus B. bassiana was reported in Tomicus piniperda, Orthotomicus longicollis, O. erosus, X. spinole, Taphrorychus villifrons and Phylobius sp. in Bulgaria. We also present the first records of gregarines in O. longicollis, Acanthocinus aedilis, Rhagium inquisitor, Pyrochroa coccinea, and of the microsporidium Chytridiopsis sp. in O. longicollis.

The effect of beetles on the dispersal stages of Bursaphelenchus mucronatus Mamiya & Enda (Nematoda: Aphelenchoididae) in wood chips of Pinus sylvestris L.

The effect of the presence of beetle adults (Monochamus galloprovincialis, Acanthocinus aedilis, Rhagium inquisitor and Hylobius abietis) in Scots pine wood chips on the occurrence of the third (Lᵢᵢᵢ) and the fourth (Lᵢᵥ) dispersal stage of the nematode Bursaphelenchus mucronatus was studied. Possible infestation of the beetles with Lᵢᵥ of the nematode while being in close contact with the pine chips was also explored. Adults of M. galloprovincialis and A. aedilis contributed to B. mucronatus Lᵢ formation in the chips. Callow adults of M. galloprovincialis were more efficient elicitors of moulting of Lᵢᵢᵢ into Lᵢᵥ than emerged beetles of the same species. Only M. galloprovincialis adults became infested with Lᵢᵥ callow beetles containing more nematodes than emerged beetles.

An Entomogenous Fungus on Acmaeops proteus (Kby.) (Coleoptera: Cerambycidae)

Records of diseases of Cerambycidae have appeared very infrequently in the literature. Crawshay (1907) described an unidentified disease of larvae of Tetropium gabrieli Weise. Garman (1921) and MacLeod (1954a) reported a fungus, Beauveria globulifera, a strain of Beauveria bassiana (Bals.) Vuill., from adults of Cyllene robiniae (Forst.) and a larva of Acanthocinus aedilis (L.) respectively. Duffy (1953) recorded the fungi lsaria sp. on adults of Phryneta spinator (Fab.), and Entomophthora grylli on larvae of Saperda carcharias (L.). A wilt disease, suspected of being caused by a virus, was reported by Beeson (1931) in larvae of Celosterna scabrator Fab.) reared in glass tubes.