Dispersal Potential Of Ergot Spores By Insects Foraging In The Perennial Ryegrass Fields In The Columbia Basin Of Oregon And Washington

Research suggests that insects, specifically flies (dipterans) and moths (lepidopterans) effectively facilitate the dispersal of asexual spores (conidia) of ergot fungi (Claviceps spp.) in various agroecosystems through their foraging behavior. However, limited information exists about the insect-mediated dispersal potential of Claviceps spp. in cool-season grass growing regions of the U.S. Pacific Northwest. A two-year survey was conducted to characterize the insect communities present in perennial ryegrass (Lolium perenne L.) fields, determine the association of insect abundance with ergot disease in the lower Columbia Basin of Oregon and Washington, and quantify the incidence of contamination with Claviceps conidia using molecular techniques. Insects were sampled using universal black light traps, yellow sticky cards, and sweep nets. Thysanoptera was the most abundant insect order, followed by Diptera in both years. Dipterans, including muscid (Fannia canicularis L.) and anthomyiid flies (Delia radium L. and Botanophila discreta Meigen), were present in the grass seed fields surveyed. Pyralid and noctuid moths broadly represented Lepidoptera. A high-fidelity polymerase chain reaction detected the presence of Claviceps spores in 39% and 36% of dipteran insects collected in 2014 and 2015, respectively. Similarly, 44% and 17% of lepidopteran insects tested positive for the presence of Claviceps spores in 2014 and 2015, respectively. A significant positive correlation was observed between insect abundance and ergot incidence in perennial ryegrass seed fields surveyed.