Companion planting attract-and-kill method for wireworm management in potatoes
Vernon, R.S., van Herk, W.G., Clodius, M., Tolman, J. (2016). Companion planting attract-and-kill method for wireworm management in potatoes. Journal of Pest Science, [online] 89(2), 375-389. http://dx.doi.org/10.1007/s10340-015-0707-6
Management of wireworms in potatoes is commonly through the use of insecticides applied at planting. With many insecticides for wireworm control now disappearing worldwide, there is an urgent need for lower risk, efficacious, and cost-effective alternative strategies for use in the twenty first century. To address this need, a novel intercrop attract-and-kill (A&K) method for controlling wireworm damage to tubers and reducing wireworms was evaluated in British Columbia (Agriotes obscurus), and Ontario (Melanotus spp.). Wheat seed treated with fipronil and/or thiamethoxam was planted in-furrow alongside untreated mother tubers. In BC trials, wheat seed treated with fipronil, or fipronil plus thiamethoxam, provided comparable blemish reductions to in-furrow granular applications of Thimet 15G, containing phorate. With these A&K treatments, mean reduction in wireworms relative to untreated controls ranged from 89 to 100 %, as compared to a 59.2 % reduction with Thimet. In the Ontario studies, mean blemish reductions of 81.2 % occurred with intercropped fipronil-treated wheat, and a 66.6 % reduction in damage with fipronil plus thiamethoxam in comparison to Thimet (83.4 % reduction). Reduction in potato yield due to competition with intercropped wheat was seldom observed. It is concluded that an A&K strategy with wheat treated with fipronil at 5 g active ingredient (AI)/100 kg seed would require only 3.4 g AI/ha, relative to 3250 g AI of phorate/ha to achieve comparable control. This A&K strategy offers a highly effective means of wireworm blemish and population control; has low environmental risk; and would be comparable to the cost of currently used prophylactic insecticide treatments such as phorate.