Effects of Sublethal Concentration of Insecticides On the Pupal Duration, Emergence, Adult Longevity and Oviposition of Tobacco Cutworm, Spodoptera litura (Fab.) (Lepidoptera : Noctuidae)

This study was conducted to determine the effect of sublethal concentrations ($LC_{10}$ and $LC_{30}$) of insecticides on pupal duration, emergence, adult longevity and oviposition of tobacco cutworm, Spodoptera litura Fabricius, when 3rd instar larva of tobacco cutworm was treated with insecticides of chlorpyrifos, ethofenprox, chlorfenapyr-bifenthrin and hexaflumuron-chlorpyrifos . Pupal duration of female and male were 6.9 days and 8.0 days at untreatment, and were 7.2 to 7.6 days and 8.3 to 8.6 days at insecticide treatment, respectively. Thus pupal duration at the insecticide treatment was slightly longer than that at the untreatment, and that of the males was slightly longer than that of the females even though significant difference between sublethal concentrations and among insecticides was not observed. Percent mergence was 88％ at untreatment and ranged from 79％ to 95％, in particular which showed above 91％ treated with chlorfenapyr-bifenthrin and ethofenprox, at insecticide treatment. Adult longevity was 7.7 days and 7.9 days for female and male at untreatment respectively, and 7.1 to 8.4 days for female and 7.7 days to 9.0 days for male at treatment. There was a significant difference between insecticides and sublethal concentrations of insecticides except showed the longest adult longevity at hexaflumuron-chlolfyrifos treatment. Total number of eggs laid were less at treatment (778-948) than that (1,010) at untreatment regardless of sublethal concentrations of insecticides. Accordingly the pupal duration and oviposition of tobacco cutworm were affected at the insecticide treatment of sublethal concentration.

담배거세미나방의 유충에 처리된 살충제 아치사농도가 용기간, 우화율, 성충수명 및 산란에 미치는 영향

담배거세미나방의 유충에 처리된 살충제의 아치사농도($LC_{10}$ 및 $LC_{30}$)가 용발육, 성충수명 및 산란에 미치는 영향을 조사하였다. 용기간은 무처리의 암컷과 수컷에서 각각 6.9일과 8.0일, 살충제 처리에서 각각 7.2-7.6일과 8.3-8.6일로 무처리보다 살충제 처리에서 길었으나 살충제의 종류 및 아치사농도에 따른 유의한 차이는 없었다. 우화율은 무처리에서 88%, 살충제 처리에서 약 79-95%로 약제처리유무 및 아치사농도 처리에간 뚜렷한 경향이 없었으며, 특히 chlo.fenapyr-bifenthrin 및 ethofenprox처리에서 91.0% 이상의 높은 우화율을 나타내었다. 성충수명은 무처리의 암컷과 수컷에서 각각 7.7일과 7.9일, 살충제 처리에서 각각 7.1-8.4일과 7.7-9.0일로 hexaflumuron-chlorpyrifos의 $LC_{30}$처리에서 가장 길었던 것을 제외하면, 살충제 처리유무 및 농도에 따른 유의한 차이는 없었다. 총 산란수는 무처리에서 1,010개, 살충제 처리에서 778-948개로 살충제 처리유무에 따른 차이는 있었으나, 살충제의 종류 및 농도에 따른 유의한 차이는 없었다. 따라서 담배거세미나방의 용기간 및 산란은 유충에 처리된 살충제의 아치사농도처리에 의해 영향을 받았다.