Efficient bait for sampling the wireworm Melanotus okinawensis (Coleoptera: Elateridae) in a sugarcane field

Bait trap efficiencies were compared to construct a sampling method for wireworms, larvae of the click beetle Melanotus okinawensis (Coleoptera: Elateridae). Various combinations of bait material, bait preparation methods, and bait exposure periods were compared. Wireworms were more efficiently attracted by germinating rice seeds than other bait materials, such as sweet potato, potato, and carrot. Among the bait materials related to rice, germinating rice seeds attracted significantly more wireworms than other materials, such as unpolished rice, polished rice, rice seeds, and rice husks. Rice bran and germinating unpolished rice were lesser attractants than germinating rice seeds. Attractiveness increased only slightly with increasing periods of incubation of rice seeds. Attractiveness increased more slowly with the increase of rice seeds, indicating that 30g was sufficient for attraction. The number of captured wireworms increased with increasing periods of field exposure, but we judged that three days of exposure might be an appropriate choice because the difficulty of handling traps increased with increasing periods of exposure. Under semiarid soil conditions, bait attractiveness was greatly enhanced by daily irrigation. It was shown that germinating rice seeds with moistened sphagnum moss are as effective as germinating rice seeds with daily irrigation.