Ant-infecting Ophiocordyceps genomes reveal a high diversity of potential behavioral manipulation genes and a possible major role for enterotoxins

Much can be gained from revealing the mechanisms fungal entomopathogens employ. Especially intriguing are fungal parasites that manipulate insect behavior because they presumably secrete a wealth of bioactive compounds. To gain more insight into their strategies, we compared the genomes of five ant-manipulating Ophiocordyceps species. These species were collected across three continents, from five different ant species in which they induce different manipulated behaviors. A considerable number of (small) secreted and pathogenicity-related proteins were conserved only in these ant-manipulating Ophiocordyceps species, and not in other ascomycetes. However, few of those proteins were conserved in all ant-manipulating species, suggesting that several different methods of behavior modification have evolved. This is further supported by a relatively fast evolution of previously reported candidate manipulation genes associated with biting behavior. Moreover, secondary metabolite clusters, activated during biting behavior, appeared conserved within a species complex, however not beyond. The independent co-evolution between these manipulating parasites and their respective hosts might thus have led to rather diverse strategies to alter behavior. Our data indicate that specialized secreted enterotoxins may play a major role as one of these strategies.