Effects of Trichoderma virens on cotton aphids

We tested for effects of the fungus Trichoderma virens as an endophyte in cotton on the population growth of the cotton aphid, Aphis gossypii Glover. Four-week old plants were inoculated with T. virens via soil drench with 10 ml aqueous suspensions of 10⁷ spores/ml. We used water for the untreated control plants. Endophytic colonization was confirmed with greater than 50% of leaf samples from treated plants testing positive at 7, 14 and 21 days post-inoculation (dpi). After 7 dpi, we placed five juvenile aphids on treated and untreated control plants and recorded the number of aphids after one and two weeks of infestation. We utilized a generalized linear model and F test to compare aphid numbers on treated and untreated plants at weeks 1 and 2. Overall, we observed a tendency for lower aphid populations on fungal-treated plants after the first week but not after the second week. Our results highlight the potential for T. virens to affect aphid-plant interactions when present as an endophyte in cotton.