Pathogenicity gene variations within the order Entomophthorales

Fungi within the order Entomophthorales (subphylum Entomophthoromycotina) are obligate biotrophic pathogens of arthropods with a remarkable narrow host range. Infection takes place through the cuticle when conidia hit a susceptible host, facilitated by enzymatic and mechanical mechanisms. In the hemolymph, they proliferate as hyphal bodies or cell wall-less protoplasts for easy nutrient uptake and host immune response avoidance. Entomophthoralean fungi often manipulate their host to seek an elevated position shortly before host death in order to optimize disease transmission. After host death, conidia are produced and discharged when humidity gets high—usually during night. In an earlier secretome study of field-collected grain aphids (Sitobion avenae) infected with entomophthoralean fungi, a number of pathogenesis-related, secreted enzymes were discovered (Fungal Genetics and Biology 2011, vol. 48, 343–352). Among these were cuticle degrading serine proteases and chitinases, involved in fungal penetration of the aphid cuticle, and a number of lipases most likely involved in nutrient acquisition. In the current study, we are investigating the distribution and variation of selected pathogenicity genes within genera Entomophthora and Pandora, using fungal genomic DNA originating from field-collected, infected insect host species of dipteran (flies, mosquitoes) or hemipteran (aphid) origin.