none Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Diseases and disorders; Diseases; Microbial diseases; Ecology; Population dynamics; Land and freshwater zones; Palaearctic region; USSR Aphidius ervi (Braconidae ); Alloxysta erythotrax (Cynipidae ); Hemipteran hosts; Acyrthosiphon pisum; Pathogenicity; Reaction of host to parasite; Pathogenicity in Acyrthosiphon pisum (Hemiptera); Ukraine Acyrthosiphon pisum (Aphidoidea); Fungal parasites; Hymenopteran parasites; Alloxysta erythotrax & Aphidius erwi; Reaction of host to parasite; Entomophthora (fungi) & Parasitica (Hymenoptera) pathogenicity; Fungal diseases; Entomophthora aphidis; Pathogenicity; Population changes; Pathogenic reaction to fungal & hymenopteran parasites; Ukraine; Fungal & hymenopteran parasite pathogenicity, ecological implications