Photographer:Mike Quinn Source:www.bugguide.net Copyright:CC BY-ND-NC 1.0
Adult Description: The coreopsis leaf beetle (Phaedon desotonis) is a member of the family Chrysomelidae consisting of the leaf beetles receiving their name sake from their herbivorous diet. There are eight known species from the genus Phaedon in the United States. All eight species share a characteristic convex oblong body, metallic elytra, and are 3-5 mm long. The coreopsis leaf beetle has a metallic green pronotum, a purple to brown metallic body, and small punctures that are barely noticeable relative to other Phaedon spp.
Host Plant: Coreopsis spp. and Bidens aristosa (Asteraceae)
The coreopsis leaf beetle is capable of causing severe damage to plants in the larval stage because of constant feeding on leaves. When larval densities are high, plants can be damaged to the point of being eaten down to the ground. In Florida, the protected official state wildflower has been a recorded host increasing the pest damage potential of the coreopsis leaf beetle.
Larval coreopsis leaf beetles can be seen in May feeding on host plants. Adults emerge in mid-June and feed for a few weeks before copulating and dropping eggs near the base of the host plant in a protected area. The eggs will remain dormant until the following spring when larvae emerge and begin a new generation.
The native history of the coreopsis leaf beetle is unknown, but most likely from the southeastern United States. It was mistaken for a similar beetle Phaedon viridis until 1983 when it was described by Balsbaugh. The coreopsis leaf beetle looks like native Texas Phaedon species, but was rarely collected in Texas until 2012. In that year, the pest seemingly exploded in central Texas indicating range expansion, likely due to host plant expansion. This pest has been documented in Central and North Texas.
Unknown
U.S. Habitat: The coreopsis leaf beetle is able to survive in a wide range of habitats with it's preferred host plants present.
U.S. Present: AL, AR, GA, FL, OK, TX
There are currently no management plans specific for the coreopsis leaf beetle, but common leaf-beetle pesticides carbaryl (Sevin), chlorpyrifos (Dursban) and acephate (Orthene) are effective. There are environmentally sound alternatives to conventional pesticides available, such as the bacterium Bacillus thuringiensis var. tenebrionis (M-Trak®). Its best to treat when there are lots of larvae because it prevents the larvae from turning in adults. Still treat even if there are numerous adults present and be sure to fully cover the foliage for best success. If you believe that invasive coreopsis beetles are established in your area, please contact local parks and wildlife officials. To report a suspected population to TISI please send an email with photos to Ashley Morgan-Olvera at arm001@shsu.edu. If you wish to have identification confirmation, please contact us and we will give you mailing instructions. All specimens will be deposited in the Sam Houston Natural History Collections.
References
Balsbaugh, E. U., Jr. 1983. A taxonomic revision of the genus Phaedon north of Mexico (Coleoptera: Chrysomelidae). North Dakota Insects Schafer-Post Series 15, 73 p.
Braman, S.K., Pendley, A., and W. Corley. 2002. Plant susceptibility to and seasonal occurrence of Phaedon desotonis Balsbaugh, a leaf beetle attacking Coreopsis. Journal of Environmental Horticulture 20: 220-223.
Thomas, M.C. 2004. Phaedon desotonis Balsbaugh (Coleoptera: Chrysomelidae), a Coreopsis (Asteaceae) pest new to Florida. Florida Division of Plant Industry, DACs-P-01670. 2 pp.
Wheeler, A. G., Jr., and E. R. Hoebeke. 2001. Phaedon desotonis Balsbaugh (Coleoptera: Chrysomelidae): New distribution records, first host-plant associations, and seasonality of a seldom-collected beetle of rock-outcrop communities. Proceedings of the Entomological Society of Washington 103: 826-831.
Internet Sources
http://www.freshfromflorida.com/pi/pest-alerts/phaedon-desotonis.html
https://citybugs.tamu.edu/2012/04/13/newish-enemy-of-coreopsis/
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