Effective light device for trapping stored products pyralid moths
Abstract: Although laboratory studies have demonstrated that UV-LED attracts Indian meal moth Plodia interpunctella and tobacco moth Ephestia elutella, they are seldom caught by commercial light traps equipped with a black light fluorescent tube (BL).Our study was conducted to investigate this inconsistency and to provide a basis for trap device improvement. The predominant wavelengths emitted by BL and UV-LED are almost equal, i. e., 360-370 nm, but the directivity of light emitted from the respective devices differs greatly: Light from BL disperses in all directions, whereas light from LED is highly directional. The irradiance of LED dissipates out of the light path along the axial center. First, we confirmed the effects of UV-LED as a trap lure. Results show that both species were caught at 10-2 W/m2 (15 cm distant from LED at the axial center) intensity, but the number of catches decreased above that irradiance level. Moth behaviors under light exposure were observed. When UV light at intensity of 10-1 W/m2 was irradiated to the active moths for 10 s under dark conditions, the locomotive or flight activities ceased within 15 s.These results suggest that UV light induces attraction and interferes with moth locomotion, depending on the irradiance. When the irradiance on the prospective flight paths to the sticky surface of a trap is kept at approximately 10-3 W/m2, these pyralid moths would be caught by a light trap.