A laboratory study on colonisation of aphids by some filamentous fungi

Interactions between the fungi Fusarium proliferatum, and Trichoderma harzianum, and the aphid Schizaphis graminum, a cereal pest, were studied by means of light and scanning electron microscopy. Fungi were applied in form of formulations. The fungus F. proliferatum adhered to the entire body of winged and wingless aphid morphs, though the wings were the preferred point of attachment. The hyphae penetrated the natural openings such as the spiracles reaching the tracheoles, from where they invaded the hemocoel and proliferated in the internal tissue. The formulation of T. harzianum interacted differently with winged and wingless aphid morphs. In particular, the formulation did not adhere to the wingless body, instead it tended to adhere to the wings in the winged morph, where T. harzianum subsequently developed with hyphae colonising the rest of the body. Even though penetration was not detected, treatment with the formulation was lethal for the winged morphs.