The microsporidium Tubulinosema loxostegi from the beet webworm Loxostege sticticalis (Lepidoptera: Crambidae) is able infect a broad range of insects from different orders

The microsporidium Tubulinosema loxostegi is a natural pathogen of the beet webworm, Loxostege sticticalis , capable of causing epizootics in populations of this agricultural pest. Recent findings of susceptibility of the Siberian silk moth and the Colorado potato beetle to this parasite indicate its ability to infect insect hosts from different families and orders, which requires further investigation. To determine the physiological host range and assess the ecological iinfection potential of T. loxostegi , we tested its ability to infect phylogenetically and ecologically diverse insect taxa, with an emphasis on Lepidoptera. Only two species out of 12 lepidopterans tested turned out to be refractory (not able to support the development of the microsporidium), namely Galleria mellonella (Pyralidae) and Manduca sexta (Sphingidae). The species found to be susceptible besides the type host (with high mortality or/and high proportion of specimens displaying developed infection) included Glyphodes pyloalis (Crambidae), Aglais urticae and Aglais io (Nymphalidae), Pieris brassicae (Pieridae), Dendrolimus sibiricus (Lasiocampidae), Bombyx mori (Bombycidae), Hyphantria cunea (Erebidae), Orgyia antiqua (Erebidae), and Mamestra brassicae (Noctuidae). Among non-lepidopteran hosts, susceptibility was displayed only by the orthopteran Locusta migratoria (Acrididae), and not by the hymenopteran Apis mellifera carnica (Apidae) and the heteropteran Podisus maculiventris (Pentatomidae). These results extend the known host range of T. loxostegi across multiple lepidopteran superfamilies and different insect orders, expanding our knowledge of insect susceptibility to this parasite and confirming the importance of determination of its infection potential and the associated risks to the ecosystems.