Metarhizium anisopliae

Metarhizium anisopliae appears to be a single generalist species but actually comprises specialized strains adapted to different hosts and environments. Some strains excel against grasshoppers, others against beetles, others against mosquitoes. This strain-level specialization within species-level generalism provides the best of both worlds: the flexibility of broad host range with the efficiency of local adaptation.

The fungus has been engineered for enhanced effectiveness against specific targets. Modified M. anisopliae strains express spider toxins or scorpion venoms, dramatically increasing kill speed against mosquitoes. These transgenic strains are being developed to control malaria vectors in Africa, where conventional insecticides are losing effectiveness to resistance. The fungus provides a biological delivery vehicle for toxins that evolution produced in other organisms.

M. anisopliae also lives as an endophyte in plant roots, suggesting a more complex ecology than simple insect pathogenesis. The fungus may protect plants from root-feeding insects while benefiting from the root environment between pathogenic episodes. This dual lifestyle—plant associate and insect pathogen—indicates metabolic versatility that may underlie the fungus's broad host range. Understanding how Metarhizium navigates multiple ecological roles informs both basic biology and applied development.