The seasonal dynamics of wireworm activity and damage of the different potato varieties in the northwest of Russia under condition of water deficiency

The dominant pests of potato tubers in the Northwestern Region of Russia among the wireworms are the larvae of the click beetle Agriotes lineatus (Coleoptera, Elateridae). Under arid conditions of 2019, the high level of potato tubers damage by wireworms has been recorded in July only. Over dry seasons a short-time contacts of wireworm larvae with food and water sources in the dry soil and their migrations to the deeper and more humid levels are most possible. Under such conditions, the larvae could not be observed during the attractive baits changing or the dig-upping of potato samples, despite the damaged tubers presence. Thus, in case of dry spring the evaluation of the wireworm population density before the potato planting using the standard method of “sample plots” could give the biased results. In this case, it is necessary to undertake the entire complex of preventive measures independently from the results of pest number evaluations over the spring season. It has been shown that the larvae of A. lineatus developed the food preferences for the tubers of different potato varieties during entire vegetative period starting from the potato planting. As a result of the numerous field evaluations over 2015-2019 the resistant varieties Alyi Parus, Liga, Nayada, Sirenevyi Tuman has been distinguished. Preliminary data of the 2019 have shown that the varieties Red Fantasy, Gala, Gusar, Manifest, Rubin and others are also resistant to wireworms.