Field bindweed (Convolvulus arvensis) is a perennial vine of Eurasian origin. It tends to form dense tangled mats and out-compete native forbs and grasses. Furthermore, field bindweed can harbor plant diseases and is toxic to horses. The weed was introduced to North America and Australia and is now considered one of the most noxious weeds of agricultural fields throughout temperate regions of the world.
This plant is difficult to control with conventional methods due to its extensive root system and seed longevity. In the 1970's, the United States Department of Agriculture (USDA) initiated a programme to control of field bindweed using biological control. Two biological control agents have been released to date: the gall mite Aceria malherbae and the bindweed moth Tyta luctuosa. The gall mite became established but impact under field conditions varies, whereas establishment of the bindweed moth could not be confirmed. The weed continues to be a problem, thus, additional biological control agents are needed.
At least two insect species show promise as potential biological control agents: the stem-mining agromyzid fly Melanagromyza albocilia and the root-feeding flea beetle Longitarsus pellucidus. Heavy infestations of a flea beetle, most likely L. pellucidus, were spotted near CABI's Swiss centre in the second half of July 2009. The flea beetles will be sent to a taxonomist for identification. Adults are being kept in cylinders and on potted plants to study their biology and to obtain eggs for larval transfer tests. Three single-choice oviposition and larval development tests using the target weed C. arvensis and the native North American C. equitans were set up in early August.
A field trip to south-western Slovakia is planned for early September to collect last instar larvae and puparia of M. albocilia. This trip is facilitated by our Slovakian partners Ludovit Cagan and Peter Toth. In addition, an updated test plant list is currently being developed with emphasis on native North American species closely related to the target weed. To date, we obtained seeds of 14 native North American Convolvulaceae in the genera Convolvulus, Calystegia, Ipomoea, Evolvulus, and Jaquemontia.
During 2009/2010, an updated test plant list will be circulated among interested parties in North America for comment. Plant material already obtained will be grown at CABI's Swiss centre to start host-specificity tests with L. pellucidus and M. albocilia in 2010. We are planning to conduct parallel no-choice and multiple-choice oviposition and larval development tests to evaluate their suitability as potential biological control agents for field bindweed.