Insects visitFusarium xyrophilumpseudoflowers on the hostXyris surinamensis(Xyridaceae) and carry fungal DNA on their bodies

Abstract

AbstractThe fungusFusarium xyrophilumproduces flower-like structures (i.e., pseudoflowers) that were recently discovered on yellow-eyed grasses (Xyrisspp.) in Guyana. It is unknown whether these pseudoflowers, which are composed entirely of fungal tissue, are true mimics that attract insects as a means of fungal dispersal. We evaluated the potential ofF. xyrophilumto affect insect visitation patterns to flowers and pseudoflowers by 1) documenting insect visitation toX. surinamensisin Guyana, 2) measuring the presence ofF. xyrophilumDNA on insects, and 3) evaluating fluorescence and volatile production on flowers and pseudoflowers. We report for the first time Vespidae, Formicidae, Salticidae, Acrididae, and Tetrigidae visitingXyris. Diverse insects, including Conocephalini spp. (meadow katydids; Tettigoniidae),Camponotusspp. (carpenter ants; Formicidae), and a Geometridae sp. (geometer moths) were found to visit flowers and pseudoflowers.Fusarium xyrophilumDNA was detected on 3/12 (25%) of captured insect bodies using conventional and quantitative PCR. Volatiles produced in the field by pseudoflowers and flowers were similar, except for the presence of a sesquiterpene, putatively identified here as α-gurjunene, which was detected both inF. xyrophilumpure cultures and field-collected pseudoflower samples, but not from flowers. The production of this sesquiterpene byF. xyrophilumand the fluorescence ofX. surinamensispeduncles represent potential signals involved in insect attraction for this system. These observations, along with the overlap in insect visitors of flowers and pseudoflowers and the detection ofF. xyrophilumDNA on insect bodies, are consistent with insect visitors being vectors ofXyrispollen andF. xyrophilumpropagules between host plants.