Pest survey card on Diabrotica undecimpunctata undecimpunctata and D. undecimpunctata howardi

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for Diabrotica undecimpunctata undecimpunctata and Diabrotica undecimpunctata howardi surveys. These are required to design risk-based pest surveys, in line with current international standards. These subspecies are classified as Union quarantine pests not known to occur in the EU. Both subspecies are polyphagous and feed on relevant crops and weeds widely distributed across the EU, where climate is suitable for their establishment. Both subspecies are multivoltine and complete up to four generations in the United States. Adults of D. undecimpunctata howardi overwinter in facultative diapause, which is missing for D. undecimpunctata undecimpunctata. The adults of these subspecies are strong flyers and they annually recolonise areas in the northern range of their distribution, where overwintering is hampered by low temperatures. In international trade, though, both subspecies mostly move on host plants for planting with soil (larvae feed on roots), hindering detection by visual examination. Detection surveys in the EU should focus on Cucumis melo, C. sativus and Zea mays, which are the major hosts for both subspecies, and should extend to other cucurbits and Arachis hypogaea for D. undecimpunctata howardi, and to Phaseolus vulgaris for D. undecimpunctata undecimpunctata. Delimiting surveys should include all other wild and cultivated known hosts present in the survey area. Adults can be detected by visual examination of the plants, especially of feeding damage on leaves, on the silks of maize and the young fruit of cucurbits, but also with sticky traps. Detection of the immature stages should focus on visual examination of roots. The timing of the survey should coincide with the crop growing season. The adults can be identified using morphological and molecular techniques. ©