Tritrophic Effects of a Fungal Endophyte: Parasitoid Host Preference

Faculty Mentor(s)

Dr. Thomas Bultman, Hope College

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This research was supported by the Christine Tempas Summer Research Fund.


My research involved a tritrophic interaction between the grass tall fescue, aphids, and their natural enemies, parasitoids. Specifically, my research targeted the host preference of the parasitoid based on the diet of their aphid hosts. Aphids were fed on tall fescue that either contained or was free of a toxic alkaloid producing fungal endophyte. Parasitoids that had never parasitized before and parasitoids given previous experience were exposed to both aphid treatment groups, and the frequency of parasitism in each group combination was recorded. Data show that non-experienced, or naïve parasitoids significantly prefer aphids fed on an endophyte-free diet (E- aphids). Also, data show a trend for parasitoids preferring E- aphids regardless of previous experience. It is important to establish a preference pattern in this interaction because upon its solidification, further research can be performed regarding the specific chemical cues taking place in the acceptance or rejection of a host (i.e., tactile, or aromatic cues). This interaction is relevant to agriculture, as parasitoids serve as biological pest control and endophytes present in the forage grass, tall fescue, could have detrimental effects on the third trophic level.

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