Biology, rearing, and preliminary evaluation of host range of two potential biological control agents for mile-a-minute weed, Polygonum perfoliatum L.

Basic biology and rearing methods were determined for Timandra griseala Peterson (Lepidoptera: Geometridae) and Homorosoma chinensis Wagner (Coleoptera: Curculionidae), two potential biological control agents of mile-a-minute weed (Potygonum perfoliatum L., Polygonaceae). Both species also were tested for their ability to feed and develop oil crop plants in the family Polygonaceae. T griseata defoliated potted mile-a-minute weed, developing from egg to adult ill approximate to26d. However, T. griseata also fed and developed oil common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tartaricum Gaertn), and accepted these species and mile-a-minute weed equally in choice tests. Thus, the host range of T. griseata appears to be too broad for it to be considered for release in the United States. Homorosoma chinensis had a relatively high reproductive rate and short generation time on potted mile-a-minute weed. Internal feeding by H. chinensis larvae caused mortality of entire stems. Adult weevils fed oil foliage of common buckwheat and rhubarb (Rheum rhabarbarum L.) when given no choice during an 8-wk test period, but laid no eggs on these hosts. In the same test, an average of over 130 eggs per female was laid oil mile-a-minute weed. Newly emerged H. chinensis adults strongly preferred mile-a-minute weed to buckwheat and rhubarb in a choice test, and neonate larvae placed oil buckwheat and rhubarb all died within 24 h. Thus, H. chineasis may be host specific to mile-a-minute weed, but further testing must be conducted on other potential host plants before release in the United States call be recommended.