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 whe n mixing Kentucky bluegrass, Poa pratensis L., and endophyte-infected grasses to control turfgrass pests. Field observations revealed that n ymphs of the hairy chinch bug, Blissus lucopterus hirstus Montandon, a re 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 Ist step toward s earching for advantageous grass-endophyte associations for chinch bug management in northeastern America. In nonchoice tests, a high inciden ce of endophyte (Neotyphodium) infection in tillers of the perennial r yegrass '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. In cidence of infected plants affected nymph habitat selection, because a ll individuals in the presence of Prelude II with elevated percentage of infected tillers were found in thatch, whereas a significantly high er proportion of plants was colonized by nymphs confined with Prelude II with a lower incidence of endophyte infection or with Merit. In cho ice tests, Merit was strongly preferred over Prelude Ii, regardless of endophyte status of the ryegrass. Moreover, nymph mortality was not a ffected by the presence of endophyte-infected Prelude II when Merit wa s 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 endophy te-infected grasses with Kentucky bluegrass for lawn protection, unles s toxic cultivars that are not avoided by the hairy chinch bug can be found.