Comparative Study of Toxicological Methods and Field Resistance to Insecticides in Diamondback moth(Lepidoptera: Plutellidae)

배추좀나방(Plutella xylostella L.)의 독성시험방법 비교와 지역별 약제저항성에 관한 연구

These studies were conducted to evaluate the five comparative test methods for detecting chemical resistance and to investigate resistant level of field populations of diamondback moth (Plutella xylostella L.). Leaf disc method was practically rocomrnendable because of its rapidity and low CV(l1.4%). Topical application method was a precise replicabiliLy(CV=8.00/0) but it was time consuming and difficult in mampulation. The other 3 methods showed higher CV ranging from 14.9% to 21.4%. Based on $LC_{50}$ values by topical application method, field populations of diamondback moth collected from 4 different regions, Kwangju, Kimhae, Jeju, and Inje to prothiofos showed from 3.3 to 61.1 times higher resistance than the susceptible strain, whereas to cypermethrin, Lhey were from 7.5 to 141.7 times higher than the susceptible. To cartap hydrochloride, they showed from 10.5- to 33.3-fold resistant levels as high as the susceptible. Finally, based on $LC_{50}$ values to Bacillus thuringiensis by leaf disc technique, the resistant levels of the field populations were from 1.9 Lo 8.1 times as compared to the susceptible.

배추좀나방의 독성시험방법 비교와 지역별 계통의 약제저항성 수준을 조사한 결과, 약제저항성 수준결정을 위한 다섯가지 독성시험 방법비교에서 leaf disc법의 CV가 11.4%로 정밀도가 높았으며 간편하고 처리가 용이한 방법이었다. Topical application법의 CV는 8.0%로 가장 정밀하고 반복성이 높았으나 시간을 요하고 시험조작이 불편한 점이 결점이었으며, insect-direct dipping법(CV=14.9%), leaf disc+insect spray법(CV=17.4%) 및 pot spray법(CV=21.4%)은 비교적 변이계수가 큰 편이었다. 배추좀나방의 지역별 계통에 대하여 topical application법에 의한 약제저항성수준은 $LC_{50}$,치로 감수성계통과 비교한 결과 공주, 김해, 제주 및 인제계통에 대하여 prothifos는 각각 61.1, 5.6, 5.4, 및 3.3배이고, cartap은 33.3, 12.8, 12.3 및 10.5배이며, cypermethrin은 141.7, 37.2, 32.5, 및 7.5배이며, Bacillus thringiensis에 대해 leaf disc법으로 조사한 저항성 수준은 광주, 김해, 제주 및 인제계통에 대하여 8.1, 2.7, 2.3 및 1.9배의 저항성으로 지역이나 약제에 따라 다른 수준의 살충제저항성을 나타냈다.