Protozoan parasites and pathogens of forest pest arthropods.
Study of protozoan parasites and pathogens of forest pest insects is a perspective concerning the biological control. The subject of our investigations in this respect were 2 arthropod species which are serious pests in the forests, nurseries, greenhouses, etc.: Lymantria dispar and Oxidus gracillis. Our research on the pathogens of L. dispar started since 1995 in cooperation with European and USA investigators. As a result of our study three protozoan parasites - Vairimorpha disparis, Nosema lymantriae and Endoreticulatus schubergi (Microsporidia) were observed on this pest. In 2000 experimental studies on the introduction of an entomopathogenic fungus Entomophaga maimaiga into L. dispar populations in Bulgaria have started. The results obtained showed that the fungus has been successfully introduced in Bulgaria and practical results are expected in the next years. O. gracilis is a new invasive species for Bulgarian fauna from Far East which lives so far in greenhouses, nurseries, etc. Its wider distribution in the country is expected at our climatic conditions. Three protozoan parasites were recorded in this millipede - Stenophora nematoides, Stenophora robusta and Fonsecaia polymorpha (Apicomplexa: Sporozoa). While S. nematoides and S. robusta showed a high prevalence, F. polymorpha was detected in a few individuals only.