Fungal Endophytes Can Negatively Affect Cotton Herbivores Above and Below Ground

We evaluated a Chaetomium globosum strain isolated as an endophyte from upland cotton (Gossypium hirsutum) plants for effects on both insect and nematode herbivores when present as an endophyte in cotton. Antagonistic effects of endophytic C. globosum were observed in greenhouse trials against a range of insect and nematode herbivores with different feeding modes including phloem-feeding cotton aphids (Aphis gossypii), leaf-chewing beet armyworms (Spodoptera exigua), and root-knot nematodes (Meloidogyne incognita). Endophytic C. globosum reduced infection and fecundity of root-knot nematodes attacking cotton roots belowground. It also reduced the fecundity of cotton aphids and beet armyworms feeding on cotton foliage aboveground. The Chaetomium fungi are known to produce a number of bioactive metabolites (i.e., chetomin, chetocin, cochliodinol, etc). However, the specific mechanisms by which endophytic C. globosum negatively affects herbivores of cotton remain to be determined.