Suitability of Various Species of Viburnum as Hosts for Pyrrhalta viburni, an Introduced Leaf Beetle

Viburnum leaf beetle [(Pyrrhalta viburni (Paykull)], a newly introduced pest of viburnums in the United States, feeds selectively on plants in the genus Viburnum. We measured in the laboratory the ability of larvae of viburnum leaf beetle to complete development and propensity of adults to feed on a number of species of Viburnum ranging in susceptibility from completely susceptible to quite resistant as determined by earlier field observations. As expected, larvae completed development on viburnums rated as ‘susceptible,’ but were largely unable to do so on those rated as ‘moderately’ or ‘highly’ resistant. The pattern of host acceptance by adults was less consistent, with some adults feeding considerably on species not found to be susceptible in the field. Several accessions were not fed on at all by adults, indicating the presence of deterrent or toxic factors. Our results suggest that the species previously identified as resistant in the field are unsuitable hosts for viburnum leaf beetle, and will not likely be devastated by the pest even if all susceptible hosts are eliminated from an area.