Location: Emerging Pests and Pathogens ResearchTitle: Towards biological control of swallow-worts: the good, the bad and the ugly Author
Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2011
Publication Date: 1/1/2013
Citation: Sforza, R., Dolgovskaya, R., Reznik, S., Volkovitch, M., Garnier, Y., Auge, M., Bon, M., Milbrath, L.R. 2013. Towards biological control of swallow-worts: the good, the bad and the ugly. International Symposium on Biological Control of Weeds. USDA Forest Service. FHTET-2012-07:200. Interpretive Summary:
Technical Abstract: Native from Eurasia, the ugly swallow-worts (Vincetoxicum rossicum and V. nigrum - Apocynaceae) invaded forested landscapes and prevent native plant regeneration in eastern North America. We first aimed to understand where do the invasive populations of both species come from, then we evaluated the impact of potential biocontrol agents (BCA). Phytophagous BCA’s were selected since 2009: Chrysochus asclepiadeus (Col., Chrysomelidae), and Abrostola asclepiadis and A. clarissa (Lep., Noctuidae). Adults of the beetle feed on leaves while larvae are root feeders, and Abrostola spp. larvae are foliage feeders. Genetically, none of the native V. nigrum populations analyzed to date possess exactly the major multilocus genotype detected in the invasive North American populations, on contrary to V. rossicum for which source populations of the invasion are found to be in Ukraine. We have performed choice and no-choice specificity tests with French and Russian populations of C. asclepiadeus. We evaluated adult herbivory in no-choice tests on the 3 Vincetoxicum spp. as controls, and 7 Asclepias spp., and C. asclepiadeus fed on controls but also on Asclepias tuberosa, a monarch butterfly host plant. Choice tests revealed no herbivory outside the genus Vincetoxicum. Larval herbivory in choice tests was noticed on all controls, plus As. tuberosa, and As. syriaca. Similar results were obtained for both populations of C. asclepiadeus. No-choice tests with larvae of Abrostola asclepiadis from France revealed that they died in 5d on all the Asclepias spp., but developed to pupa in 23d on V. hirundinaria, in 20,6d on V. rossicum, and only reached the 3rd instar in 17,8d on V. nigrum. Similar results were obtained with Abrostola clarissa of Russian origin. To conclude, although C. asclepiadeus has a severe impact on swallow-worts, herbivory on several Asclepias spp. lead to consider it as a bad BCA. However, data with Abrostola spp. are very promising, and aimed to consider the two Abrostola species as good potential BCA against all genotypes of swallow-worts.