Research Accomplishment Reports 2007

Biology and Management of Insects Attacking Turf and Woody Landscape Plants

D.A. Potter
Department of Entomology

 

Project Description

This project focuses on insects impacting trees, shrubs, and turf grasses cultivated in lawns, landscapes, golf courses, sport fields, horse farms, and production nurseries. Its goals are to clarify the biology of major pests such as white grubs, grass-feeding caterpillars, Japanese beetles, wood borers, and scale insects, as well as their natural enemies, and to develop effective approaches to managing these pests with reduced chemical inputs. Some studies address immediate problems of Kentucky's homeowners and horticultural industry; others are to enhance understanding of insect-plant relationships to provide groundwork for future, novel approaches to pest management. Perennial ryegrass containing a hybrid (N. lolii x epichloe typhina) endophyte was shown to be highly resistant to the black cutworm, a pest that is tolerant of other endophytic turfgrasses. Incorporating the hybrid endophyte into turf-type cultivars would provide excellent resistance to caterpillar pests. Experiments with grasses having gene-knockout endophytes showed retention of insect resistance even when ergovaline and/or clavine alkaloids are eliminated, suggesting that ergot alkaloids associated with livestock maladies could be eliminated from pasture grasses without inducing pest insect outbreaks. A recently-discovered baculovirus was evaluated and provided good suppression of black cutworms on golf-type turf of soil- and sand-based putting greens and fairways, virus was mass-produced in vivo, and a study is underway to evaluate it for season-long suppression of cutworms on whole tees of two Kentucky golf courses. White grubs and associated pathogens were sampled on 30 Kentucky golf courses, the first survey of turf-infesting grubs and natural enemies in the southeastern USA. Masked chafers and Japanese beetles accounted for 74 and 24% of infestations, respectively. New strains of milky disease, nematodes, and other pathogens were found that may have potential as biological insecticides. A new method for suppressing problems with earthworm castings on closely-mowed turfgrass with a natural plant extract was evaluated. The sex pheromone of the maple shoot borer (Proteoteras aesculana), a serious nursery pest, was identified and the flight period was determined. Young trees received from west coast suppliers are infested in early spring, soon after transplant, and the window for preventive control was shown to be much broader than previously thought. Experiments showed that calico scale, a serious tree pest on horse farms and in landscapes, can be managed with low-risk insecticides using a bark-penetrating surfactant. This eliminates hazard from spray drift. Studies evaluating insect resistance of improved tall fescues were initiated to clarify how modifying endophytic and textural characteristics for livestock performance will affect pasture sustainability.

Impact

Maples account for 30% of the nursery crops grown in Kentucky and individual production nurseries may have 30,000 maples in the field at one time having wholesale value of about $5 million. Left unmanaged, maple shoot borer typically kills the terminal leader of 30-40% of the trees requiring costly retraining and loss in tree value. Our work clarified the overwintering stage, seasonal life cycle, and management of this pest. A protocol was developed whereby nursery producers can obtain 99% control with a single timed application. Our work also greatly extended the window for management providing growers flexibility during the busy spring planting season. Livestock maladies (e.g., fescue toxicosis) associated with consuming ergot alkaloids in endophytic pasture grasses cost Kentucky's equine and livestock industries hundreds of millions of dollars per year. Our research indicates that ergovaline can be removed from pasture grasses without substantially reducing resistance to insect pests, good news for sustainable pastures. White grubs and cutworms are the most destructive pests of turfgrasses in Kentucky and throughout most of the USA. Pressures to reduce pesticide usage on lawns, recreational areas, sport fields, and golf courses are increasing, especially where children may be exposed. This project is helping turfgrass managers to identify high-risk sites for grubs helping to reduce treatment costs and chemical inputs. It is prospecting for natural enemies having potential as bio-insecticides for grubs, and includes the first evaluation of a naturally-occurring insect virus to suppress turfgrass pests without chemicals. Calico scale, an invasive sucking pest, is killing thousands of shade trees on Kentucky horse farms and in landscapes. Often such trees are growing in locations where they cannot be sprayed because of hazards of drift. This project clarified the life cycle of the scale for the first time and showed it can be managed via low-risk systemic insecticides injected into the tree trunk or applied to the bark. This approach is being adopted by tree care professionals throughout Kentucky. A novel approach using trunk bands to physically exclude honeydew-seeking ants, which protect the scales from natural enemies, is being evaluated for biological control of scale outbreaks. This tactic will be tested at Commonwealth Stadium where a different soft scale species is killing many of the oaks in parking areas.

Publications

Baumler, R.B. and Potter, D.A. (2007). Knockdown, residual, and antifeedant activity of pyrethroids and home landscape bioinsecticides against Japanese beetles (Coleoptera: Scarabaeidae) on linden foliage. J. Econ. Entomol. 100: 451-458.

George, J., Redmond, C.T., Royalty, R.N., and Potter, D.A. (2007). Residual effects of imidacloprid on Japanese beetle (Coleoptera: Scarabaeidae) ovipositional behavior, egg hatch, and larval viability in turfgrass. J. Econ. Entomol. 100:431-439.

Romero, A., Potter, M.F., Potter, D.A. and Haynes, K.F. Haynes (2007). Insecticide resistance in the bedbug: a factor in the pest's sudden resurgence? J. Med. Entomol. 44:175-178.

Potter, D.A., Stokes, J.T., Redmond, C.T., Schardl, C.L., and Panaccione, D.G. (2008). Contribution of ergot alkaloids to suppression of a grass-feeding caterpillar assessed with gene-knockout endophytes in perennial ryegrass. -147.-Entomol. Exp. Appl. 126:138

Potter, D.A. (2008). Managing insect pests of sport fields: What does the future hold? Acta Horticulturae (in press).

George, J. and Potter, D.A. (2008). Potential of azadirachtin for managing black cutworms and Japanese beetle grubs in turfgrass. Acta Horticulturae (in press)

Potter, D.A. and Held, D.W. (2008). June Beetles (Phyllophaga spp.) In V. Resh and R. Carde (eds.), Encyclopedia of Insects, 2nd ed. Academic Press (in press)

Held, D.W. and Potter, D.A. (2008). Japanese beetle. In V. Resh and R. Carde (eds.), Encyclopedia of Insects, 2nd ed. Academic Press (in press)

Redmond, C.T. and Potter, D.A. (2007). Silicon fertilization does not enhance creeping bentgrass resistance to cutworms and white grubs. U.S. Golf Assoc. Turfgrass and Environmental Research Online 6(3):1-7.

Redmond, C.T. and Potter, D.A. (2007). Does silicon fertilization enhance creeping bentgrass resistance to insects? Golf Course Management Feb. 2007: 134-137.

Seagraves, B.M., Potter, D.A., Haynes, K., Hayden, D., Fulcher, A., Hartman, J., and McNiel, R. (2006). Biology and seasonal phenology of the maple shoot borer, Proteoteras aesculana (Lepidoptera: Tortricidae). In 2006 Nursery and Landscape Program Research Report, Univ. KY Agric. Expt. Sta. PR-537, pp. 17-18.

Potter, D.A., Seagraves, B.M., Redmond, C., Fulcher, A., Hayden, D. and McNiel, R. (2006). Managing flatheaded apple tree borer in nursery-grown maples. In 2006 Nursery and Landscape Program Research Report, Univ. KY Agric. Expt. Sta. PR-537, pp. 19-21.

Potter, D.A., Seagraves, B., Tittle, S., Redmond, C.T. and Haynes, K.F. (2007). Managing maple shoot borer: Implementation in Kentucky production nurseries. In 2007 Nursery and Landscape Program Research Report, Univ. KY Agric. Expt. Sta. PR-554, pp. 19-21.

Potter, D.A. and Redmond, C.T. (2007). Systemic control of calico scale with bark- or soil-applied dinotefuron (Safari). In 2007 Nursery and Landscape Program Research Report, Univ. KY Agric. Expt. Sta. PR-554, pp. 21-22.