Activities of esterase and acetylcholinesterase on the diamond backmoth, Plutella xylostella (Lepidoptera : Yponomeutidae) and beet armywarm, Spodoptera exigua (Lepidoptera : Noctuidae) and inhibitions of acetylcholinesterase with flupyrazofos

The activities of esterase and acetylcholinesterase(AChE) on the Diamond backmoth (DBM), Plutella xylostella (Lepidoptera: Yponomeutidae) and Beet armywarm (BAW), Spodoptera exigua (Lepidoptera: Noctuidae) and inhibitions of AChE with flupyrazofos were clarified from the results of a series of experiments. These findings are described in brief as follows. The AChE activities of DBM and BAW in heads were $1.5{\sim}11.1{\mu}$mol/g/min in $1st{\sim}4th$ instar larvae of DBM and $1.7{\sim}45.2{\mu}$mol/g/min in $1st{\sim}6th$ instar larvae of BAW, respectively. Those were $25{\sim}30$ times higher in above 4th instar larvae of BAW than that of the 1st instar larvae of DBM. The activities of aliesterase in heads were $1.7{\sim}4.7$ times higher in $2nd{\sim}4th$ instar larvae of DBM and $8{\sim}55$ times higher in $3rd{\sim}6th$ instar larvae of BAW than 1st instar larvae of DBM. In abdomens, those were $3{\sim}17$ times higher in $2nd{\sim}4th$ instar larvae of DBM and $12{\sim}30$ times higher in $3rd{\sim}6th$ instar larvae of BAW than 1st instar larvae of DBM. Median AChE inhibition concentration $(I_{50})$ of flupyrazofos to the 2nd instar larvae of DBM and BAW were 92 nM and $15{\mu}M$, respectively, and those to the 4th instar larvae of DBM and BAW were $1.8{\mu}M$ and 3.1 mM, respectively. Insensitivity ratio of flupyrazofos in the 2nd instar BAW larvae showed ca. 162 times higher than that in the 2nd instar larvae of DBM, and that of the 4th instar BAW larvae showed ca. 1,720 times higher insensitivity to flupyrazofos than that of the 4th instar DBM larvae. AChE activities in the 2nd instar larvae of DBM and BAW at 32 h after applicaton of flupyrazofos decreased from 67.6% to 32.4% of the activity of the untreated control. That of the 4th instar larvae of DBM increased for 0.5 h after application flupyrazofos up to 75% of the untreated control, and after that it decreased to 34.5% of the untreated control at 32 h. In contrast, in the 4th instar larvae of BAW AChE activities increased for 8 h gradually up to 102 % of the activity of the untreated control, and then the activity decreased to 97% of the untreated control at 16 h after treatment.

배추좀나방과 파밤나방의 효소활성 및 flupyrazofos 에 의한 AChE 활성 저해

매추좀나방과 파밤나방에 대한 flupyrazofos 의 작용기작을 구명하기위하여 한국화학연구소에서 분양을 받아 실내에서 19 세대 누대 사육한 배추좀나방과 포장에서 채집하여 실내에서 인공사료를 이용하여 25세대 누대사육한 파밤나방을 대상으로 효소활성도 및 flupyrazofos 에 의한 AChE 활성 저해정도를 조사한 결과는 다음과 같다. 배추좀나방과 파밤나방의 머리에 있는 AChE의 활성도는 배추좀나방 1령$\sim$4령에서 $1.5\sim11.1$ ng/larva/ruin 이었고, 파밤나방 1령$\sim$6령에서 $1.7\sim45.2$ ng/larva/min로 나타나 4령이상의 영기에서는 $25\sim30$배이상 높았다. 배추좀나방과 파밤나방에 대한 aliesterase 의 활성도는 배추좀나방 1령충에 비하여 배추좀나방 2령$\sim$4령에서는 머리와 복부에서 각각 $1.7\sim4.7$배와 $3\sim17$배 이하였으나, 파밤나방 3령$\sim$6령에서는 $8\sim55$배와 $12\sim30$배 이상이었다. Flupyrazofos 에 의한 AChE 반수저해농도 $(I_{50})$는 배추좀나방 2령과 4령에서 각각 92 nM과 $1.8{\mu}M$이었고 파밤나방 2령과 4령에서 각각 $15{\mu}M$과 3.1mM로 나타나 파밤나방은 배추좀나방 보다 약 $162\sim1,720$배 이상 높은 농도를 보였다.