Microsphecia brosiformis (Credit: CABI)

Melanagromyza albocilia larva mining a stem of field bindweed (Credit: CABI)

Madeleine Hiscock and Quentin Donzé setting up an open-field test (Credit: CABI)

Microsphecia brosiformis feeding on a root of field bindweed (Credit: CABI)

Melanagromyza albocilia (Credit: CABI)

Field bindweed (Convolvulus arvensis) in wheat (Credit: CABI)

Field bindweed (Convolvulus arvensis) flowers (Credit: CABI)

Field bindweed (Convolvulus arvensis) in maize (Credit: CABI)

Open field test with Melanagromyza albocilia in southern Germany (Credit: CABI)

Arthur Knecht setting up an open field test with M. albocilia in southern Germany (Credit: CABI)

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Project Overview

So, what’s the problem

Field bindweed (Convolvulus arvensis) is a perennial vine of Eurasian origin. The plant was introduced to other continents including North America and is now considered one of the most noxious weeds of agricultural fields throughout temperate regions. Forming dense tangled mats of vegetation, it outcompetes native forbs and grasses, and can severely reduce crop yields. It can harbour plant diseases and contains alkaloids that may be toxic to some grazing animals, in particular to horses. Its extensive root system and long-lived seeds make it difficult to control by conventional means. Biological control offers an alternative approach: one reason for the plant’s impact may be the absence of natural enemies that attack it in its area of origin.

The weediness of field bindweed is largely attributable to its extensive root system and North American insects attacking the leaves are having little impact. So the United States Department of Agriculture (USDA) initiated a programme to manage field bindweed using biological control in the 1970s. Two biological control agents were introduced from Europe: the gall mite Aceria malherbae and the bindweed moth Tyta luctuosa. The impact of the gall mite varies, while local establishment of the bindweed moth has only been reported from the western USA and reports from Oregon suggest low impact. The weed continues to be a problem and additional biological control agents are being sought.

What is this project doing?

The project was revived in 2009 in an initiative set-up by the late Dr Richard Hansen (USDA-APHIS-CPHST). Dr John Gaskin (USDA-ARS-NPARL, Sydney, Montana) took over the role of consortium chair for the USA in 2018. CABI’s centre in Switzerland is investigating additional potential agents. So far, we have studied five insect species that showed potential for biological control, and are planning work on two more species.

A guiding principle for biological control is that any released agent should not impact plants other than the target weed. Risk of potential non-target damage is assessed by testing whether a candidate agent feeds or develops on other plant species that it might encounter if introduced. Assessing the impact an agent might have on the target weed is also important so the most-damaging ones can be prioritized.