2017 年 2017 巻 64 号 p. 109-112
Abstract A new pest, Welsh onion root darkwinged fungus gnat (tentative name) (Bradysia sp.) injurious to Welsh onion in fall and winter, and carrot in spring in the northern part of Saitama Prefecture, its distribution on parasitized Welsh onion plants and susceptibility to insecticides were investigated. Welsh onion was primarily parasitized by larvae at the stem plate, but the number of larvae increased at the leaf sheath covered with soil increased by soil covering work. As a result of examining the susceptibility of the larvae to insecticides registered on Welsh onion in laboratory conditions, 8 insecticides had a corrected mortality rate of 70% or more out of 30 insecticides; Thiodicarb WP, Clothianidin WS, Cypermethrin E, Dinotefuran WS, Fulfenokthlon E, Lufenuron E. Methomyl WP, and Tephrtorin G.