We investigated developmental characteristic of life cycle of the lawn cutworm, Spodoptera depravata (Lepidoptera: Noctuidae), which is one of the most economically damaging pests to grasses. For larval culture the turfgrass, Zoysia japonica (Poales: Poaceae), was provided at 25℃ and 60 ± 5% humidity. Developmental period of each stage was as follows: 4.11 ± 0.19 days for eggs, 25.17 ± 3.02 for larvae, 8.80 ± 0.28 for pupae and 7.57 ± 0.95 for adults. Larvae was grown to 7th instar, unlike pre-existing data, which indicated the final age as the 6th instar. Body length of larvae changed on average from 2.772 mm immediately after hatching to 2.3 cm at 7th instar and head capsule width changed on average from 0.423 mm at 1st instar to 2.82 mm at 7th instar. Pre-period of eggs deposition was 2 days, oviposition period was 4.6 days, average fecundity per female was about 419 eggs, and hatching rate was about 83%.

We investigated primary ecological characters, such as life cycle and morphology of the lawn cutworm, Spodoptera depravata (Lepidoptera: Noctuidae), which is one of the most economically damaging pests to grasses. For larval culture the turfgrass, Zoysia japonica, was provided as a feed source at 25℃ and 60±5% humidity. Development period of each stage was as follows: 4.11±0.19 days for eggs, 25.17±3.02 for larvae, 8.80±0.28 for pupae and 7.57±0.95 for adults. Larval stages continued to 7th instar and this result contrasts to pre-existing data, which indicate 6th instar in S. depravata. Developmental period of each instar of S. depravata ranged from the minimum of 2.1 days to the maximum of 4.81 days, with the 7th instar longest. Correlation analysis between body length and head capsule width of each instar showed a significant correlation between the two measures. Pupal colors were changed from the light brown and green right after pupation to dark brown as pupal cuticle hardens. Wing length of adults in both sexes was similar, but forewing of male had obvious outer line and eyespot with dark gray-brown background, whereas that of female had less obvious in these characters, with light gray-brown background. Pre-period of eggs deposition was 2 days, oviposition period was 4.6 days, average fecundity per female was about 419 eggs, and rate of hatching was about 83%.

우리나라산 곤충병원성 선충(Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSN1, S. glaseri Dongrae, S. longicaudum Nonsan, S. monticolum Jiri)을 이용한 잔디밤나방(Spodotera depravata)의 환경 친화적 방제 가능성을 알아보기 위하여 실내와 야외에서 실험을 수행하였다. 아울러 잔디의 예고가 곤충병원성 선충의 효과에 미치는 영향과 야외에서 곤충병원성 선충의 처리가 잔디밭에 분포하고 있는 개미와 집게벌레의 밀도 변화에 미치는 영향도 조사하였다. 잔디밤나방 3령충은 곤충병원성 선충에 대하여 처리 5일째 53.3%에서 66.7%의 보정사충율을 나타내었다. S. carpocapsae GSN1과 S. monticolum Jiri의 잔디밤나방 3령충에 대한 반수치사농도 (LC)는 6.9와 3.9마리였다. S. carpocapsae GSN1의 병원성은 잔디밤나방의 령기에 따라 차이가 있어 2령충에서 73.3%로 가장 높았으며, 3령충부터 감소하였다. 예고는 곤충병원성 선충의 병원성에 영향을 미쳤다. 들잔디의 예고가 14mm인 pot에서 4령충의 치사율은 S. carpocapsae GSN1 처리가 40.0%였고, S. monticolum Jiri처리는 33.3%였으며 fenitrothion은 83.3%의 치사율을 나타내었으나 45mm구에서는 모두 낮았다. 곰개미(Formica japonica) 분포지에서 선충처리구의 보정사충율은 fenitrothion 처리구에 비하여 낮았으나, 개미의 감소율은 fenitrothion구에서 56.7%로 높았고, S. carpocapsae GSN1 처리구와 S. monticolum Jiri 처리구에서는 각각 0%, 6.7%로 낮았다. 잔디의 예고는 S. carpocapsae GSN1과 fenitrothion의 효과에 영향을 미쳤다. S. carpocapsae GSN1은 3-4cm 예고구에서는 62.2%의 방제효과를 나타내였으나, 6-8cm와 12-14cm의 예고구에서는 전혀 효과가 없었다. 그러나 fenitrothion 처리구에서는 유의적 차이가 없었다. 못뽑기집게벌레(Forficula scudderi)의 밀도도 fenitrothion 처리구에서만 감소를 보였다. 즉, 3-4cm 예고구에서는 100%의 감소율을 보였고, 6-8cm 구에서는 41.7%, 12-14cm 구에서는 16.1%의 감소율을 나타내었다.