Turfgrass Species and Endophyte Effects on Survival, Development, and Feeding Preference of Black Cutworms (Lepidoptera: Noctuidae)

Abstract

Growth, developmental rate, and survival of black cutworms, Agrotis ipsilon (Hufnagel), were compared on cool-season turfgrasses used commonly on golf courses, including cultivars with or without Neotyphodium spp. (=Acremonium spp.) endophytes. We also studied feeding preferences of neonates and 5th instars, including possible effects of induction of preference, to clarify patterns of movement of larvae between creeping bentgrass, Agrostis palustris Hudson, putting greens and peripheral areas. Development of black cutworms on 3 diverse cultivars of Kentucky bluegrass, Poa pratensis L., was much poorer than on all other turfgrasses tested. Most larvae that fed on Kentucky bluegrass did not survive to pupation. In contrast, endophyte-free 'Assure' perennial ryegrass, Lolium perenne L., and 'SR8300' tall fescue, Festuca arundinacea Schreber, were generally as suitable for cutworms as creeping bentgrass, the standard grass used on putting greens. Larvae reared on endophyte-infected SR8300 tall fescue showed no adverse effects; those fed endophyte-infected Assure perennial ryegrass showed only small reductions in growth rate compared with larvae reared on the same cultivar without endophyte. In laboratory choice tests, 1-d-old larvae consistently preferred creeping bentgrass over Kentucky bluegrass or tall fescue, regardless of which grass they had fed upon during the preceding 24 h. There was evidence for induction of preference for perennial ryegrass over creeping bentgrass in 1 of 2 trials. Preferences of 5th instars were more variable, but creeping bentgrass was preferred consistently over Kentucky bluegrass. In paired field plots, 5th instars did not discriminate between creeping bentgrass and perennial ryegrass, but preferred both of those species over Kentucky bluegrass. These results indicate that black cutworm densities could build up in areas of tall fescue or perennial ryegrass surrounding golf course putting greens and tees, and that endophyte infection of those grasses will not necessarily provide resistance. Use of Kentucky bluegrass in higher-mowed, peripheral areas may reduce numbers of black cutworms developing in roughs and fairways and later crawling onto putting greens.