Studies on the Insecticidal Action of Nereistoxin, 4-N, N-dimethylamino- 1, 2-dithiolane I. Insecticidal Properties1

By Michihiko SAKAI

Laboratory of Insecticide, the Research Laboratories, Takeda Chemical Industries Ltd., Ichijoji, Kyoto

Some chemical, pharmacological and tox- of nereistoxin will be worthwhile to de- icological studies on a toxic substance velop new insecticides. in a marine annelid, Lumbriconereis hetero- The present paper publishes the results poda MARENZ, have been conducted, since of toxicological experiments with nereistox- it is well-known that the dead body of in on various species of insects and mites. annelid is toxic to flies, ants etc. This Those expereiments were so planned as substance was first isolated by NITTA (1934), to obtain more detailed informations of and named •gNereistoxin•h. Its chemical the insecticidal properties of nereistoxin. structure was determined as 4-N, N-di- methylamino-1, 2-dithiolane (I) by OKAICHI MATERIALS AND METHODS and HASHIMOTO (1962a), and its synthesis Synthetic nereistoxin hydrogen oxalate was accomplished by HAGIWARA et al. (1962). was used throughout the experiments. This material, prepared by the procedure (I) of HAGIWARAet al. (1962), was supplied by the Synthetic Department, the Research NITTA (1941) concluded from the results Laboratories, Takeda Chem. Ind. Ltd., Osa- of his pharmacological experiments, that ka. nereistoxin is a neuroactive substance Diluted solutions of test compounds were which affects the activities of motor prepared with acetone or water. Since nerves, but not those of sensory nerves nereistoxin hydrogen oxalate was not easi- in mammals. The toxicity to several insect ly soluble in acetone directly, the stock species was investigated by OKAICHI and solution prepared with acetone-water mix- HASHIMOTO (1962b). They found that, in ture (1:1) was diluted with acetone and spite of somewhat lower toxicity compared used as a acetone solution. To make a with DDT, parathion, etc., treated insects water solution of water-insoluble com- were knocked down rapidly, and some of pounds such as parathion, DDT, etc., a ten the knocked down insects revived in a per cent emulsifiable concentrate was pre- certain period. pared dissolving the compounds in the The interesting facts are that nereistoxin mixture of Tween-20 and acetone (1:4) is regarded to be neuroactive, and that it as a stock solution. belongs to a new compound possesing in- Experiments were so conducted as to secticidal action, which is distinguishable compare the effect of nereistoxin with from the insecticides of today. According- those of some commercial insecticides on ly, as OKAICHI and HASHIMOTO(1962b) sug- houseflies (Musca domestica L., Lab-em-7- gested, the chemical and insect toxicologi- em strain), German cockroaches (Blattella cal studies of the analogous compounds germanica L.), rice stem borers (Chilo sup- 1A part of this report was presented at the Annual Meeting of Japanese Society of Applied Entomology and Zoology (April 1964, Tokyo) (Received for publication, August 17, 1964) 324 December 1964 SAKAI: Insecticidal action of nereistoxin 325

pressalis WALKER), azuki bean weevils (Cal- Acetone solutions were topically applied losobruchus chinensis L.), tobacco cut worms on the back of thoraces of flies, using a (Prodenia litura FABRICIUS), common cab- micrometer-driven syringe. For the test by bage worms (Pieris rapae L.), diamond- injection, insecticidal solutions were pre-

back moths (Plutella maculipennis CURTIS), pared by dissolving the insecticides into striped flea beetles (Phyllotreta vittata FAB- 0.9 per cent sodium chloride solution. Flies

RICIUS), soy bean aphids (Aphis glycines were injected into their thoraces with a MATSUMURA), mulberry mealy bugs (Pseudo- fine stainless steel injection needle attach- coccus comstocki KUWANA) and spider mites ed to a micrometer-driven syringe. The

(Tetranychus kanzawai KISHIDA). House- treated flies were kept in a wire-mesh flies, cockroaches, bean weevils, tobacco cage and fed with a mixture of milk and cut worms, cabbage worms and diamond- sugar. Thirty flies were treated for each back moths were reared in a room at of the dosages. the temperature of 25•}1•Ž. Soy bean Tests with German cockroaches by topi- aphids and mites were also laboratory cal application and injection were done in colonies reared in a greenhouse on seed- the same way as performed with houseflies lings of soy bean and kidney bean, re- except the treated cockroaches were fed spectively. Although the other insects with water. Oral administration of insec- were captured out-of-doors, they were kept ticidal solution was done as follows: after under the temperature of 25•}1•Ž for the insects were anaesthetized with carbon several days prior to the conduction of dioxide, they were fixed with adhesive the tests. tape ventral side up on a glass plate, For testing with houseflies, three to five then quantified droplets of insecticidal day's old male adults were used by four solution from a micrometer-driven syringe different testing methods. One was a bait were applied to the mouth parts of the test; i.e. ten flies were introduced into a cockroaches. In this manner, the insects a wire-mesh cage (9cm in diameter and swallowed the solution comparatively rap- 15cm deep) in which a cotton pad soaked idly. The treated cockroaches were trans- in the insecticidal solution was placed. ferred into glass pots and fed with water. The insecticidal solution was prepared by In these tests, ten males were used for a dissolving nereistoxin in 5 per cent sugar single dosage. solution. Three cages were prepared for Rice stem borer larvae employed in the a single concentration. topical application test were in the dor- In the second test, one ml. of acetone mant stage. They were collected from solution of insecticide was pipetted onto heavily infested rice plants in the suburb a bottom of a Petri dish (9cm in diameter). of Kusatsu City, Shiga Prefecture, in After evaporation of the solvent under November, 1963, and used for tests in gentle air stream, the dishes were covered January, 1964. They were kept in a re- with sheets of drawing paper on which ten frigerator up to 7 days before the tests flies (anaesthetized with carbon dioxide) were conducted, then transferred into 25•} were covered with a top side of dishes. 1•Ž. The larvae were treated topically on At the time of complete revival of flies the back of abdomen with a droplet of from anaesthesia, the paper sheets were acetone solution of test substance. Twenty drawn off; thus the flies were immedi- larvae were treated with each of the ately introduced into the dishes. To ob- dosages. tain the information on the revival symp- The possibility of killing rice stem borers toms, knocked down flies were transferred in the stems of rice plant was examined into uncontaminated Petri dishes. by spraying artificially infested rice plants The tests by topical application and in- (Kin-maze, one month after transplanting) jection were conducted with houseflies. with insecticidal solutions. Four days 326 Japanese Journal of Applied Entomology and Zoology Vol 8, No.4 after the egg-masses placed on the leaves used for the others. hatched out, i.e. the larvae bored into Adult soy bean aphids were transferred the stems, the plants were set on a turn onto soy bean seedlings three days before table, and sprayed with 30ml of insecti- the spray of insecticides. The plants cidal solution per pot with a paint sprayer were sprayed with insecticides dissolved from the distance of 80cm. Five days in water containing the wetting agent after spraying, the survival rates were (0.02 per cent). determined cutting open the stems. The In the test with the spider mites, the insecticidal solution for spray was pre- toxicity to adult females and ovicidal ac- pared by dissolving the test substances in tion were investigated. To test the toxicity water containing 0.02 per cent of a wet- to the adults, twenty females were trans- ting agent (Dine, manufactured by Takeda ferred to bean leaves which were placed Chem. Ind.). on wetted filterpaper in open Petri dishes. Male azuki bean weevils were introduced The mites were sprayed with a vertical into a Petri dish which was treated on its sprayer, and the mortalities were deter- bottom surface with a deposit from ace- mined after 2 days. To observe ovicidal tone solution containing insecticide. Thir- action, kidney bean leaves on which eggs ty weevils were introduced per dish. In (1•`2 days old) of the mites were ovipo- another series of test with the weevils, sited were used. The leaves were sprayed the insecticidal solution was prepared by with the test solutions, then the hatching dissolving insecticides in water containing rates of twenty eggs were determined 0.02 per cent of the wetting agent. Imme- seven days after the spray. In these tests, diately afterward the insects were wrap- three Petri dishes were sprayed with a ped in gauze and dipped into the test solu- single insecticidal solution. tion for ten seconds; then they were trans- Mulberry mealy bugs were exposed to ferred onto a sheet of filter-paper to re- the deposits of test substances in Petri move excess solution. The treated insects dishes. The deposits were produced as in were kept in a Petri idsh, and the mor- the same way as performed in the test of talities were determined. houseflies or azuki bean weevils. Ten in- In the tests with tobacco cut worms sects were employed for a single Petri dish. (second instar larvae), cabbage worms All experiments, except the spray test (third instar larvae), diamond-back moths of rice stem borers and the aphids, were (immature larvae), striped flea beetles conducted in a room at the temperature (adults) and daikon leaf beetles (immature of 25•}1•Ž. larvae), they were fed with pieces of leaf RESULTS AND DISCUSSION of their host plants, which were treated with insecticides. Circular pieces of leaf Houseflies In the bait-test, the mortalities (2cm in diameter) punched out with a of flies increased as the time after the cork borer were dipped for ten seconds exposure elapsed (Table 1). The dead into the insecticidal solutions prepared flies after 22 hours exposure could not with water containing 0.02 per cent of revive in the following days. the wetting agent. After that the pieces Knockdown effect of nereistoxin was of leaf were dried under gentle air-stream, almost equal in strength to malathion, then transferred into a Petri dish together when flies were in contact with the de- with the test insects. Ten insects and posits of insecticides (Table 2). In this four pieces of leaf were placed in a dish, case, however, knocked down insects by and two dishes were prepared for a single nereistoxin revived after they were trans- treatment. Cabbage leaves were used for ferred into uncontaminated dishes. Even tobacco cut worms and common cabbage if flies were knocked down by 200ƒÊg/dish worms; and Chinese cabbage leaves were of nereistoxin, thirty per cent of knocked December 1964 SAKAI: Insecticidal action of nereistoxin 327

Table 1. Mortalities of houseflies at various times in bait test of nereistoxin hydrogen oxalate.

Table 2. Knockdown effect of the deposit of nereistoxin hydrogen oxalate and malathion on houseflies and the revival of knocked down insects.

*transferred into an uncontaminated dish . ** at 100 minutes.

Fig. 1. Dosage-knockdown rate curves obtained with adult houseflies at various times after injection of nereistoxin hydrogen oxalate.

Nereistoxin 1: 2hr. (•›), 2: 3hr. (•œ), 3: 4hr. (•¢), 4: 6hr. (•£), 5: 24hr. (• ), Ethyl-parathion P: 24hr. (•~). down flies were alive on the next day. The revival symptoms were observed In contrast, only 8ƒÊg/dish of malathion also in the injection test with houseflies. killed total flies with an exposure period Figure 1 shows the dosage-knockdown rate of 100 minutes. curves obtained at various times after 328 Japanese Journal of Applied Entomology and Zoology Vol 8, No.4

Table 3. Knockdown and killing effects of nereistoxin hydrogen oxalate on adult German cockroaches in various administration.

the injection. The KD-50's (ƒÊg/g) at 2, 3, knocked down considerably rapidly even 4, 6 and 21 hours after the treatment were with the topically applied nereistoxin, in 2.2, 2.6, 3.7, 4.6 and 5.6, respectively. contrast to the result of topical application The value for injected ethyl-parathion was test with houseflies. On the other hand, 1.8ƒÊg/g (21 hours). Although it was clear the dosage of 20ƒÊg/g killed 40 per cent of that some of the knocked down flies re- the insects, when nereistoxin was admin- vived in a certain period, immobilized istered orally. This result indicates nere- flies after 21 hours could not revive, i.e. istoxin was more toxic to German cock- they were completely dead. In this respect, roaches in oral administration than in injected nereistoxin was not so much toxic topical application or in injection. as parathion, but its killing effect was Rice stem borers In Figure 2, the dosage- considerably strong. knockdown rate curves at various time On the contrary, topically applied nere- after topical application of nereistoxin to istoxin hydrogen oxalate was not effective rice stem borer larvae are shown. The to houseflies. The dosage of 500ƒÊg/g slope of curve was low after 3.3 hours, caused merely the mortality of 15 per cent while it was somewhat steeper after 6 after 24 hours. OKAICHI and HASHIMOTO hours (the slopes were 1.7, 3.5, 5.0, 3.8, (1962b) reported the LD-50 of free base 4.0, 4.0 and 3.9 after 3.3, 4.3, 6, 24, 48, of nereistoxin to houseflies was 40ƒÊg/g. 72, and 120 hours, respectively). When the This difference in toxicity between the number of motionless larvae was counted free base and the hydrogen oxalate would on each of additional 5 days, no changes

possibly be due to the difference in lipoid were found compared with 120 hours' data. solubilities of the two forms. The LD-50's (ƒÊg/g) at various times were German cockroaches German cockroaches calculated as follows; 2.1, 1.3, 1.5, 1.7, were fairly tolerant against the killing 2.1, 2.3 and 4.3 after 3.3, 4.3, 6, 24, 48, effect of nereistoxin (Table 3). Namely, 72, and 120 hours respectively. The LD- all cockroaches revived on the next day 50 of ethyl-parathion was 2.6ƒÊg/g, and after treatment by topical application and the slope was 4.0. Thus, rice stem borer injection. Nevertheless, the insects were larvae were knocked down rapidly, then December 1964 SAKAI: Insecticidal action of nereistoxin 329

Fig. 2. Dosage-knockdown rate curves obtained with the larvae of rice stem borer at various times after topical application of nereistoxin hydrogen oxalate.

Nereistoxin 1: 3.3hr. (•›), 2: 4.3hr. (•œ), 3: 6hr. (•¢), 4: 24hr. (•£), 5: 48 hr. (• ), 6: 72hr. (•¡), 7: 120hr. (•¤), Ethyl-parathion, P: 48hr. (•~).

Table 4. Effect of sprayed nereistoxin hydrogen oxalate and ethyl-parathion on the rice stem borer larvae in the stems of rice plant.

recovered slowly during 5 days. Although but we might possibly state that in the the killing effect of nereistoxin was rather second test nereistoxin and ethyl-parathion lower than that of parathion, it was sur- were approximately equitoxic. Probably, prisingly higher than that on houseflies the fluctuation between the replications in topical application test. would have been due to differences in Since the result of topical application climatic and cultivating conditions. Any- test suggested the possibility to kill the way, it is obvious from those results that rice stem borer larvae in the stem of rice nereistoxin is not practically effective to plant, a spray test was conducted. The control rice stem borers. results are shown in Table 4. In the first Azuki bean weevils When the weevils test of duplicated experiments, nereistoxin were in contact with the deposits of insec- showed less effectiveness than parathion, ticides in Petri dishes, LD-50's (ƒÊg/dish) 330 Japanese Journal of Applied Entomology and Zoology Vol 8, No.4 and slopes (in parentheses) of the dosage- insects, does not produce the killing effect, mortality curves were calculated as fol- but the continuous contact of nereistoxin lows: 7.9 (6.0), 0.74 (6.0), 0.90 (5.7), and with the insects is effective to kill insects. 70 (4.5) for nereistoxin, ethyl-parathion, Leaf chewing insects The larvae of to- lindane and Sevin, respectively. bacco cut worm, common cabbage worm, In the dipping test, the knocked down diamond-back moth and daikon leaf bee- weevils by nereistoxin revived in a certain tle, and the adults of striped flea beetle period. One hour after the treatment with were tested in the leaf feeding method. 0.1 per cent and 0.01 per cent of nereis- The results are summarized in Table 5. toxin solutions, the knockdown rates were Since immobilized insects did not revive 100 per cent and 94 per cent respectively, at least for three days, it is concluded but the rates decreased to 50 per cent and that nereistoxin had killing effect on 3.3 per cent respectively after 2 days. those leaf-chewing insects. The compound For allethrin, tested in the same con- was more toxic against diamond-back centrations, the rates were found to be moths, but somewhat less against tobacco 100 per cent at the both concentrations cut worms when compared with lindane. after 1 hour, and after 2 days they were Soy bean aphids and spider mites Nereis- 100 per cent and 23.3 per cent respectively. toxin was a little effective to decrease The number of motionless insects after 2 the aphid populations, but it was almost days did not change in the additional 24 ineffective against spider mites (Table 6). hours. For ethyl-parathion, lindane and No ovicidal action was observed in the Sevin, LC-50's in the dipping test were test with the eggs of spider mite, i.e. all calculated as 0.00017, 0.00020 and 0.0032 of the eggs had hatched out even in spray- per cent, respectively. ing with 0.1 per cent solution of nereis- Comparing the killing effect of nereis- toxin after 7 days. toxin in the dipping test to that in the Mulberry mealy bugs By 250 and 500ƒÊg/ contact test, this compound was extremly dish of nereistoxin, all of the bugs in the less toxic in the dipping test. Therefore, Petri dishes were immobilized after 2 days. it is presumed that the administration of In comparing, ethyl-parathion was not a certain limited dosage of nereistoxin, completely effective with the dosage of which is just sufficient to knock down the 250ƒÊg/dish (90 per cent in the mortality).

Table 5. Toxicity of nereistoxin hydrogen oxalate to various leaf-chewing insects.

*No deads in the controls . December 1964 SAKAI: Insecticidal action of nereistoxin 331

Table 6. Effect of nereistoxin hydrogen oxalate houseflies were killed by considerably low on soy bean aphids and spider mites dosages in the injection test. Although in spray tests. nereistoxin was not effective to control rice stem borers in the stems of rice plant, the results of spray test seem to suggest the possibility of discovery of new insecti- cidal compounds which will be derived from nereistoxin, and will be useful to control rice stem borers in the practical fields. As demonstrated in the test with azuki bean weevils, it may be expected nereis- Although the immobilized bugs by nereis- toxin in continuous contact with insects toxin seemed to revive 4 days after trans- supresses the revival of insects from ferring into uncontaminated dishes, there knockdown, thus results in killing effect . was difficulty due to their slow motion in The symptoms of nereistoxin poisoned distinguishing whether they were recover- insects were quite dissimilar to those of ing or dying. known insecticides. In houseflies and Ger- Other observations and general discussion man cockroaches, hypersensitivity, con- Summarizing the results described above, vulsion or agony, namely, those symptoms it would be possible to conclude that the which are generally found for organic insecticidal potency of nereistoxin hydro- phosphorus and chlorinated insecticides gen oxalate is higher against plant chew- were scarcely observed in the case of ing insects, such as rice stem borers, nereistoxin. The insects were knocked common cabbage worms, diamomd-back down quite rapidly with little abnormal moths, striped flea beetles. In these ex- movement, in another expression , just as periments, it is not unnatural to presume being anaesthetized. Sometimes, the ap- that those lepidopterous and coleopterous pendages of knocked down insects trem- insects (except rice stem borers which bled slightly. This trembling was also ob- were topically applied) took the greater served in the period before revival occurr- amount of nereistoxin into their body ed. orally. Although, unfortunately, the ex- From the observations of toxic symptoms , periments to confirm the contact toxicity it appeared that the mode of action of of nereistoxin against those insects are nereistoxin is quite different from those lacking, the oral toxicity of nereistoxin of other insecticides. This possibility is seemed to be higher than the contact tox- now under investigation. icity. This difference was apparent from SUMMARY the results of the test with German cock- roaches. Also in the test with houseflies, The insecticidal properties of synthetic nereistoxin was considerably more toxic nereistoxin (4-N, N-dimethylamino-1 , 2-di- when it was fed as a bait than when it thiolane) hydrogen oxalate on houseflies , was applied topically. On the other hand, German cockroaches, azuki bean weevils , rice stem borers were much sensitive to rice stem borers, soy bean aphids , spider topically applied nereistoxin, in spite of mites, mulberry mealy bugs and several the insensitivity of adult houseflies treated species of leaf-chewing insects were in- similarly. It cannot be helped to conclude vestigated. that this species specificity was presum- There were some differences in the tox- ably due to the difference in the cuticle icity even to a single species due to dif- permeability of nereistoxin hydrogen oxal- ferences between the methods of admini- ate between these two species, because stration. In general, it appeared that 332 Japanese Journal of Applied Entomology and Zoology Vol 8, No.4 the oral toxicity of nereistoxin was higher ACKNOWLEDGEMENT than the contact toxicity. Although some The author would like to express his of the knocked down insects revived from acknowledgement to Dr. C. HARUKAWA, knockdown effect of nereistoxin, it was Adviser of the Laboratories, Prof. T. apparent the killing effect was higher YAMASAKI, the University of Tokyo, Dr. S. against plant-chewing insects, such as rice TATSUOKA, Director of the Laboratories, stem borers, common cabbage worms, Mr. R. HATTA and Dr. T. KOBAYASHI in the diamond-back moths, etc. author's laboratory for their invaluable Aphids and mites were considerably advice and helpful guidance. Thanks are tolerant to nereistoxin. The killing effect due to Mr. M. NUMATA for his supply of of topically applied nereistoxin was higher nereistoxin. on rice stem borers than on houseflies The author is indebted to Miss J. NAKA- and German cockroaches. Accordingly, JIMA for her technical assistance, and to the difference of the permeability of nere- the members of author's laboratory for istoxin to the cuticle between rice stem their supply of test insects. borers and houseflies was presumed. The spray test conducted with the larvae of rice stem borer suggested the possibility REFERENCES of existence of new insecticidal compounds HAGIWARA, H., K. KONISHI, M. NUMATA and Y. which will be derived from nereistoxin OKA (1962) Abstracts of the 6th Symposium and effective to control the borers in prac- on the Chemistry of Natural Products (July, tical fields. 1962, Sapporo): 88•`93.

The toxic symptoms which were brought NITTA, S. (1934) Yakugaku Zasshi (J. Pharm . by nereistoxin were very much dissimilar Soc. Jap.) 54: 648•`652. to those by organic phosphorus and chlo- NITTA, S. (1941) Tokyo Igakukai Zasshi (Tokyo rinated insecticides. This indicates the J. Med. Sci.) 55: 285•`301. OKAICHI, T. and Y. HASHIMOTO (1962a) Agr. Biol difference of the mechanism of insecticidal . Chem. 26: 224•`227. action between nereistoxin and other in- OKAICHI, T. and Y. HASHIMOTO (1962b) Bull. Jap . secticides. Soc. Sci. Fish. 28: 930•`935.

摘 要

Nereistoxin (4-N, N-dimethylamino-1, 2-dithiolane)の 殺 虫 作 用 に 関 す る 研 究

第1報 殺 虫 効 果 に つ い て

坂 井 道 彦

武 田薬 品 工 業 株 式 会社 研 究 所

Nereistoxinの 殺 虫 効 果 を,イ エ バ エ 成 虫,チ ャバ ネ を用 い た 。 ゴ キ ブ リ成 虫,ア ズ キ ゾ ウ ム シ 成 虫,ニ カ メ イ ガ 幼 虫, 本 化 合 物 の 殺 虫 力 は 同 一種 の昆 虫 を供 試 して も ,薬 剤 ダ イ ズ ア ブ ラ ム シ,カ ン ザ ワ ハ ダ ニ,ク ワ コ ナ カ イ ガ 投 与 法 の違 い に よ り異 な った 。 す な わ ち,チ ャバ ネ ゴ キ ラ,ハ ス モ ン ヨ トウ 幼 虫,コ ナ ガ 幼 虫,モ ン シ ロ チ ョ ウ ブ リに経 口投 与 した と き,お よび イエ バ エ に 食 餌 と混合

幼 虫,キ ス ジ ノ ミ ム シ 成 虫 お よ び ダ イ コ ン サ ル ハ ム シ 幼 し て与 えた と きに は 殺 虫 力 は局 所 施 用 した 場合 よ り も高

虫 を 用 い て 試 験 した 。 か った し,ハ ス モ ン ヨ トウ,モ ン シ ロチ ョウ,コ ナ ガ, Nereistoxinは 合 成 し た 修 酸 塩(hydrogen oxalate) ダ イ コ ンサ ル ハ ム シ,お よび キス ジ ノ ミム シに 食 葉 に 処 December 1964 SAKAI: Insecticidal action of nereistoxin 333

理 し て与 えた と きの 殺 虫 力が 高 か った こ とか ら,本 化 合 あ り,概 して 吸 収 口 を有 す る昆 虫 に は 効 力 が 低 か った 。 物 は 経 口的 に 虫 体 に 侵 入 した と き に高 い殺 虫 力 を有 す る また,一 般 に経 口毒 性 が 高 い と見 られ るが,ニ カ メ イガ と推 察 され る。 幼 虫 に は接 触 毒 性 が 高 か った 。 しか しな が ら,ニ カ メ イ ガ幼 虫 にNereistoxinを 局 供 試 虫 に対 す る薬 剤 投 与 法 が 異 な る と,Nereistoxin 所 施 用 した と きは,仰 転 作 用 と と も に高 い 殺 虫作 用 が あ は 仰 転 作 用 の み を示 し,中 毒 虫 は回 復 して死 に到 らな い り,こ れ に 反 して イエ バ エ に同 様 の 施 用 を行 な っ て も ほ 場 合 が あ った 。 ア ズ キ ゾ ウ ム シ の 試 験 結 果 に見 る よ う とん ど作 用 は な か った 。 イエ バ エ に注 射 し た場 合 は強 い に,こ の 回 復 は 一 定 薬 量 が 虫体 に 処 理 され た と きに 起 殺 虫 力 が あ るの で,昆 虫 の 種 に よ っ て表 皮 透 過 性 に大 き り,薬 剤 に継 続 接 触 した と き は回 復 が 抑 制 され 死 に到 る な 差 が あ る と推 定 され る。 と思 われ る。 ク ワ コナ カイ ガ ラに対 して は,か な りの殺 虫 効 果 また Nereistoxinに よ る昆 虫 の 中 毒 症 状 は,痙 れ ん ・苦も は 仰 転 効 果が あ った が,ダ イ ズア ブ ラ ム シお よび カ ンザ ん な どの症 状 が きわ め て少 な く,一 般 の 殺 虫 剤 と異 な っ ワハ ダ ニ(成 虫 お よび卵)に は 殺 虫 力 は低 か った 。 た特 有 の殺 虫 作 用 機 構 を暗 示 す る もの と し て興 味 深 い 。 以 上 述 べ た よ うに,本 化 合 物 の 殺 虫 力 には 種 特 異 性 が