Biological Control of Lily Leaf Beetle
Background Lily leaf beetle (Lilioceris lilii) is a serious pest of many herbaceous ornamental plants. While lily leaf beetles feed on a number of plant hosts, including Lilium spp., Fritillaria spp., Polygonatum spp. (Solomon's seal,) Solanum dulcamara (bittersweet nightshade,) S. tuberosum (potato,) Smilax spp., and Nicotiana spp., they can only reproduce and develop on Lilium species, which include Turk's cap lilies, tiger lilies, Easter lilies, Asiatic and Oriental lilies, and species of Fritillaria.
Figure 1. Adult Lily Leaf Beetle Figure 2. Lily Leaf Beetle Damage
Lilioceris lilii is native to Eurasia. It was first discovered in Montreal in the 1940s. The first New England occurrence was in Boston in 1992, and lily leaf beetles were first confirmed in Connecticut in 1999. Lily leaf beetle is now found throughout New England, New York, Pennsylvania, Quebec, Ontario and through central Canada to the western coast of North America.
Connecticut Presence Lily leaf beetle has been confirmed in all eight Connecticut counties. Property owners continue to report this exotic insect pest each year. Connecticut’s natural areas contain a number of species of native lilies. Many businesses in the green industry grow and sell ornamental lilies. Nurseries and garden centers have reported problems with lily leaf beetles damaging wholesale and retail host plants.
Control Methods There have been no natural enemies of lily leaf beetle recorded in North America. Current management approaches for lily leaf beetle include both chemical and mechanical or physical methods. Adults, larvae, and eggs can be hand-picked from plants and destroyed. Several insecticides are labeled for lily leaf beetle control, but some of these are toxic to bees and other non-target insects. With increasing trends of organic crop production and potential bans of insecticides in the future, biological control will provide a sustainable and viable alternative. A successful biological control program may reduce the costs and environmental impacts of insecticide use and will provide a new tool to enhance management options for control of lily leaf beetle.
Figure 3. Lily Leaf Beetle Damage to Buds Figure 4. Lily Leaf Beetle Damage to Lilies in a Landscape
Figure 5. Adult Female Laying Eggs Figure 6. Larvae and Larval Damage
Biological Control Three species of parasitoid wasps have been approved for release to help control lily leaf beetles and their damage. The parasitoid wasps lay their eggs in lily leaf beetle larvae, thereby disrupting the lily leaf beetle life cycle. Release and monitoring of two distinct biological control agents (the parasitoid wasps Tetrastichus setifer and Diaparsis jucunda) for biological control of lily leaf beetle began in Connecticut in 2012. These beneficial insects have previously been released in four other New England states (MA, ME, NH, and RI.)
Figure 7. Diaparsis jucunda Parasitoid Wasps Figure 8. Release of D. jucunda Parasitoid Wasps
Links to Additional Information on Lily Leaf Beetle:
Connecticut Agricultural Experiment Station Fact Sheet http://www.ct.gov/caes/lib/caes/documents/publications/fact_sheets/entomology/lily_leaf_beetle.pdf
Lily Leaf Beetle Online Tracker http://lilybeetletracker.weebly.com/
University of Maine Bulletin http://umaine.edu/publications/2450e/
University of Massachusetts Fact Sheet http://extension.umass.edu/landscape/fact-sheets/lily-leaf-beetle
University of Rhode Island Lily Leaf Beetle Photo Identification Guide http://web.uri.edu/biocontrol/lily-leaf-beetle-photo-identification-guide/
To view a larger, interactive map and see other aspects of the project, please visit the UConn Master Gardener website: http://mastergardener.uconn.edu/lily-leaf-beetle-research/
Prepared by: Gail K Reynolds and Donna Ellis, 2015
Photos by: Gail K Reynolds and Donna Ellis
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