Insecticidal effect of imidacloprid to sucking, chewing insect pests, and predacious spiders

흡즙성 및 저작성 해충과 거미류에 대한 imidacloprid의 살충효과

Insecticidal activities of imidacloprid to sucking type insect pests, brown planthopper (BPH, Nilaparvata lugens) and peen peach aphid (GPA Myzus persicae), to chewing type insect pests, tobacco cut worm (TCW; Spodoptera litura) and beet armyworm (BAW, Spodoptera exigua) and to spiders, Pirata subpiraticus, Pachygnata clercki and Ummeliata insecticeps, as natural enemies were investigated by several bioassay methods. $LD_{50}$ of the chemical by topical treatment to BPH was 0.015 ${\mu}g/g$(48 hrs), while $LC_{50}s$ by leaf dipping and root zone treatment were 18.1 and 21.5 ppm, respectively. There was no difference in insecticidal activities between leaf dipping and root zone treatment. Imidacloprid also showed ovicidal effect of root zone treatment and its $LC_{50}$ was 6.8ppm $LD_{50}$ (48 hrs after treatment) of imidacloprid to GPA was $0.4{\mu}g/g$ in case of topical application and $LC_{50}s$ by leaf dipping and root zone treatment were 1.9 ppm and 13.7 ppm respectively. Leaf dipping was more effective than root zone treatment in GPA At topical application $LD_{50}$ (48 hrs after treatment) of imidacloprid to chewing type insect pests, TCW and BAW, were greater than 1,492 and $312{\mu}g/g$ and $LC_{50}s$ by leaf dipping method were 4,803 and Heater than 5,000ppm respectively. This means that imidacloprid has much less effect on chewing type insect pests, TCW and BAW. $LD_{50}$(48 hrs after treatment) of imidacloprid to wandering spiders, Pirata subpiraticus, Pachygnata clercki at topical application were greater dan $2941{\mu}g/g$ and greater than $2,976{\mu}g/g$ respectively and that to webbing spider, Ummeliata insecticeps, was 357 ${\mu}g/g$. Imidacloprid showed very low toxicity to the spiders and its selective toxicity ratios between spiders and BPH were greater than 19,600, greater than 19,800 and 23,800, respectively.

흡즙성 해충과 저작성 해충 및 천적에 대한 imidacloprid의 살충력을 처리방법별로 조사하였다. 흡즙성 해충인 벼멸구에 대하여 imidacloprid의 미량국소처리에 의한 $LD_{50}$은 $0.015{\mu}g/g$ (48시간)이었으며, 유묘침지와 근부처리시의 $LD_{50}$은 각각 21.5 와 18.1 ppm을 보였으며, 처리간의 살충력 차이는 보이지 않았다. Imidacloprid 액제를 근부처리를 하였을 경우 20 ppm에서도 살란효과가 99%을 보였으며, 반수살란농도는 6.8 ppm이었다. 복숭아혹진딧물에 대한 imidacloprid의 $LD_{50}$은 $0.4{\mu}g/g$(48시간)이었으며, 엽침지처리와 근부처리 48시간 후 $LC_{50}$은 각각 1.9과, 13.7ppm으로 엽침지처리에 의한 살충효과가 높았다. 저작성 해충인 담배거세미나방과 파밤나방에 대한 imidacloprid의 $LD_{50}$은 1492.5이상과 $3125{\mu}g/g$으로 살충력이 낮았으며, 엽침지처리에 의한 $LC_{50}$은 각각 4803.3과 5000 ppm 이상을 보여 imidacloprid는 흡즙성 해충보다 저작성 해충에 대해 살충력이 낮았다. 배회성거미인 황산적거미(Pirata subpiraticus)와 턱거미(Pachygnata clercki)에 대한 $LD_{50}$이 각각 294.1과 $2976.3{\mu}g/g$ 이상으로 독성이 매우 낮았으며, 조망성거미인 등줄가슴애접시거미(Ummeliata insecticeps)에 대한 $LD_{50}$은 357.1 ${\mu}g/g$로 역시 독성이 낮았다. Imidacloprid의 거미류와 벼멸구간 선택독성은 각각 196,000 이상과 199,000이상 및 23,800이상으로서 독성이 벼멸구에는 높은 반면 거미류에는 낮았다.