Douglas S. Richmond

Overseeding Endophytic Perennial Ryegrass into Stands of Kentucky Bluegrass to Manage Bluegrass Billbug (Coleoptera: Curculionidae)

Abstract Studies were conducted to determine the utility of overseedingendophyte enhanced varieties of perennial ryegrass, Loliumperenne L., into existing stands of Kentucky bluegrass, Poapratensis L., to manage bluegrass billbug, Sphenophorusparvulus Gyllenhal, larval populations and their damage. Twocommercial varieties of endophyte enhanced perennial ryegrass (RepellII and Triple Play) were overseeded at two different rates in thefield. S. parvulus larval populations, their damage, andturfgrass composition were monitored over the course of 3 yr.Significantly fewer larvae were found in plots overseeded with RepellII, whereas Triple Play had no significant effect on larval populationdensity. Endophyte infection was confirmed in ≈58% of all Repell IIshoots, whereas only ≈31% of Triple Play shoots were infected.Regression analysis, using a segmented model, demonstrated that larvalpopulations declined as the proportion of endophyte-infected perennialryegrass increased. However, no additional reductions in larvalpopulation density were achieved in stands containing >40%endophyte-infected perennial ryegrass. Visual damage varied withcultivar, seeding rate, and year, but generally decreased as theproportion of endophyte-infected perennial ryegrass increased. Althoughseeding rate had an initial effect on turfgrass composition, thesedifferences were not detected after the first year of the study.Results indicate overseeding existing stands of Kentucky bluegrass withendophytic varieties of perennial ryegrass can reduce S.parvulus larval populations and their damage. However, plantgenetic characteristics (i.e., different cultivars) may be overridingdeterminants of many aspects of plant performance includingestablishment, tolerance to insect feeding, and expression ofendophyte-mediated resistance.

Hairy chinch bug (Hemiptera: Lygaeidae) damage, population density, and movement in relation to the incidence of perennial ryegrass infected by Neotyphodium endophytes.

Abstract Studies examined hairy chinch bug, Blissus leucopterus hirtus Montandon, damage, population density, and movement in stands of perennial ryegrass, Lolium perenne L., containing various proportions of endophyte infected plants (E+). Our main objective was to determine the utility of mixtures containing E+ for management of chinch bugs. Chinch bug damage and population density decreased linearly as the proportion of E+ increased. This trend held true even when chinch bug populations were extremely high. Chinch bug nymphs emigrated more quickly from stands containing 100% E+ than they did from stands containing 50 or 0% E+, whereas adult chinch bug emigration was relatively unaffected by the proportion of E+. Our results indicate that turfgrass mixtures containing E+ can reduce chinch bug damage and population density.

Black cutworm (Lepidoptera: Noctuidae) larval emigration and biomass in mixtures of endophytic perennial ryegrass and Kentucky bluegrass.

Abstract Studies examined the possibility that mixtures of endophytic perennial ryegrass and Kentucky bluegrass provide resistance against larvae of the black cutworm, Agrotis ipsilon (Hufnagel). We hypothesized that resistance against A. ipsilon in such stands would stem from the influence of Kentucky bluegrass on A. ipsilon growth and behavior rather than the influence of endophytic perennial ryegrass. In replicated greenhouse experiments, black cutworm larvae initially emigrated more quickly from pots containing monocultures of endophytic perennial ryegrass than from Kentucky bluegrass monocultures or polycultures of Kentucky bluegrass and endophytic perennial ryegrass. However, biomass of emigrating larvae decreased linearly as the proportion of Kentucky bluegrass increased. Turfgrass mixtures containing endophytic perennial ryegrass and Kentucky bluegrass may provide resistance against A. ipsilon mainly through the physiological effects of Kentucky bluegrass on A. ipsilon growth and development, but possibly through the influence of endophytic perennial ryegrass on A. ipsilon movement and foraging behavior as well.