Ecological parameters and effective distance of insecticidal lights

Key Words：Insecticidal light, capable insectkilling distance, median trapping distance, golden trapping distance

Abstract：       The effective distance for light-trapping Spodoptera litura Fabricius and Spodoptera exigua Hübner, and the relative trapping efficiency of lighttraps at two different heights, were studied using markreleaserecapture methods. The results indicate a lower recovery rate of marked insects at longer distances from light-traps and that the recovery rate for lights hung at 0.8 m was significantly greater than that of lights hung at 1.3 m. Lights hung at 0.8 m trapped significantly more S. litura and S. exigua than those at 1.3 m, but lights at both heights trapped both species equally effectively. Three ecological parameters, the Capable Insect\|killing Distance (CID), the Median Trapping Distance (MTD₅₀) and the Golden Trapping Distance (GTD_61.8), are proposed to quantify and standardize the effective distance of lighttraps. The fitted results show that the CID for S. litura Fabricius and S. exigua using 0.8m high lighttraps was 115.1 and 110.9m respectively; the MTD₅₀ was 71.8 m and 67.4 m respectively and the GTD _61.8 was 61.5 m and 57.1 m respectively. The effective trapping area was 4.2 and 3.9 hm² respectively. The CID for these species using 1.3 m high lighttraps was 108.1m and 107.8m respectively, the MTD₅₀ was 66.6m and 64.7 m respectively and the GTD_61.8 was 56.7 m and 54.5 m respectively. The effective trapping area for each species was 3.7 hm² and 3.6 hm² respectively.