The host range and impact of Bikasha collaris (Coleoptera: Chrysomelidae), a promising candidate agent for biological control of Chinese tallow, Triadica sebifera (Euphorbiaceae) in the United States

Native to China, the Chinese tallow, Triadica sebifera (Euphorbiaceae) is an aggressive woody invader in the southeastern United States. The flea beetle, Bikasha collaris (Coleoptera: Chrysomelidae), is a common herbivore attacking this plant in China. To evaluate its potential as a biological control agent the host specificity and impact were studied in China. The potential host range of B. collaris was evaluated on 68 plant species in 20 families through no-choice and choice tests. Adults only survived and fed on plants from the genus Triadica while larvae only developed successfully on T. sebifera in no-choice tests. Under choice conditions, adults showed a distinct preference for T. sebifera over other Triadica species. The impact of the above- and belowground herbivory on the growth of T. sebifera was evaluated in a common garden.B. collaris could reduce stem height, total biomass, number of leaves and stem diameter at a density of 10 individuals per plant. Above- and belowground herbivory had similar effects on plant growth parameters. The results of this study suggested that B. collaris is a potential biological control agent of T. sebifera though further tests on native North American species are needed.

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► The host range of Bikasha collaris is narrow. Adults only survived and fed on plants from the genus Triadica while larvae only developed successfully on Triadica sebifera.
► The impact of B. collaris on stem height, total biomass, number of leaves and stem diameter of T. sebifera was enhanced by increased density. Above- and belowground herbivory had similar effects on plant growth.
► B. collaris is a first subterranean potential biological control agent against T. sebifera.