Effect of endophyte incidence in perennial ryegrass on distribution, host-choice, and performance of the hairy chinch bug (Hemiptera: Lygaeidae)

Finding toxic, fungal endophyte-infected, grass cultivars that are not avoided by phytophagous insects could be an advantageous strategy when mixing Kentucky bluegrass, Poa pratensis L., and endophyte-infected grasses to control turfgrass pests. Field observations revealed that nymphs of the hairy chinch bug, Blissus leucopterus hirstus Montandon, are found mainly in thatch rather than on plants, regardless of time of day. We therefore developed laboratory bioassays incorporating thatch as a component of the hairy chinch bug habitat as a 1st step toward searching for advantageous grass-endophyte associations for chinch bug management in northeastern America. In nonchoice tests, a high incidence of endophyte (Neotyphodium) infection in tillers of the perennial ryegrass 'Prelude II', Lolium perenne L., induced high mortality of 3rd instars, whereas Prelude II with lower incidence of infected tillers or the Kentucky bluegrass 'Merit' were significantly more suitable. Incidence of infected plants affected nymph habitat selection, because all individuals in the presence of Prelude II with elevated percentage of infected tillers were found in thatch, whereas a significantly higher proportion of plants was colonized by nymphs confined with Prelude II with a lower incidence of endophyte infection or with Merit. In choice tests, Merit was strongly preferred over Prelude II, regardless of endophyte status of the ryegrass. Moreover, nymph mortality was not affected by the presence of endophyte-infected Prelude II when Merit was also available. These results suggest that highly mobile 3rd-instar hairy chinch bugs have the capacity to avoid toxic endophyte-infected grass cultivars. Such behavior could limit the value of mixing endophyte-infected grasses with Kentucky bluegrass for lawn protection, unless toxic cultivars that are not avoided by the hairy chinch bug can be found.