Effects of Three Strawberry Entomopathogenic Fungi on the Prefeeding Behavior of the Aphid Myzus persicae

Entomopathogenic fungi are essential participants in ecosystems that help regulate arthropod communities. Many of them have a symbiotic-endophytic relationship with plants, endowing them with insecticidal or insect-repellent traits, which could be exploited for insect control in agriculture. Among insects, aphids are one of the most harmful taxa; they damage plants directly by sucking plant sap or indirectly by transmitting economically important viruses. Plant infestation by aphids depends on prefeeding activities related to host identification, particularly leaf walking and short probing. Although several aspects of aphid prefeeding activities have been studied in different hosts, this behavior has not been examined on plants colonized by entomopathogenic fungi. Here, we studied the effects of three strawberry endophytic entomopathogenic fungi, namely, Beauveria bassiana, Isaria fumosorosea and Metarhizium anisopliae var. robertsii, on the prefeeding activity of the aphid Myzus persicae by monitoring aphids feeding on leaves of fungus colonized and uncolonized plants. Our analysis revealed that the endophytes significantly affected aphid prefeeding behavior, which was typified by a reduction of the expected mean number of short probes, an avoidance to make a second probe, and a high propensity for abandoning the leaf. We discuss possible mechanisms of fungal interference with aphid activity.