Abstract:
An insecticidal, acaricidal or nematocidal composition which comprises an organophosphorus compound represented by formula (I): ##STR1## wherein R 1 , R 2  and R 3  each represents C 1  to C 4  alkyl; A represents H, C 1  to C 4  alkyl, C 1  to C 4  alkylthio or N(R 4 )R 5  ; Z represents C(CN)R 4  or N-R 7  and an inert carrier show excellent effect for controlling harmful insects, mites and nematodes, do not give off a bad or irritating odor and exhibit very low toxicity to warm-blooded animals. R 4 , R 5 , R 6 , and R 7  are defined in the specification.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an organophosphorus compounds represented by formula (I): ##STR2## wherein R 1 , R 2  and R 3  each represents C 1  to C 4  alkyl; A represents H, C 1  to C 4  alkyl, C 1  to C 4  alkylthio or N(R 4 )R 5  (wherein R 4  and R 5  each represents H or C 1  to C 4  alkyl); Z represents C(CN)R 6  (wherein R 6  represents CN, C 1  to C 3  alkylsulfonyl, C 1  to C 3  alkylcarbonyl substituted with halogen, C 1  to C 3  alkylcarbonyl, C 1  to C 3  alkylcarbonyl substituted with halogen, C 1  to C 4  alkoxycarbonyl, C 1  to C 4  alkoxycarbonyl substituted with halogen, C 1  to C 4  alkylthiocarbonyl, C 1  to C 3  monoalkylaminocarbonyl or C 1  to C 3  dialkylaminocarbonyl) or N-R 7  (wherein R 7  represents CN, NO 2 , C 1  to C 3  alkylsulfonyl, C 1  to C 3  alkylsulfonyl substituted with halogen, C 1  to C 3  alkylcarbonyl or C 1  to C 3  alkylcarbonyl substituted with halogen). 
     The present invention also relates to a method for preparing the compound of formula (I), and insecticides, acaricides and nematocides which comprises the compound as an active ingredient. 
     2. Prior Art Statement 
     Recently, organophosphorus compounds having a guanidine group have been investigated and developed. For instance, Japanese Unexamined Patent Publication No. Sho 53-84922 disclose that these compounds can be used as insecticides, acaricides and nematocides. However, the insecticidal, acaricidal and nematocidal effects of these compounds are insufficient and are not necessarily satisfactory. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a novel organophosphorus compounds represented by the foregoing general formula (I). 
     Another object of the present invention is to provide a method for preparing a novel organophosphorus compound represented by the foregoing general formula (I). 
     A further object of the present invention is to provide an agricultural chemical having insecticidal, acaricidal and nematocidal effects higher than those attained by conventional agricultural chemicals and exhibiting very low toxicity to warm-blooded animals. 
     The inventors of this invention have synthesized a variety of organophosphorus compounds and have investigated the insecticidal, acaricidal and nematocidal activities of the organophosphorus compounds. As a result, the inventors have found out that excellent control of harmful insect pests can be achieved by an organophosphorus compound (hereinafter referred to as &#34;the compound of the present invention&#34;) represented by formula (I): ##STR3## wherein R 1 , R 2  and R 3  each presents C 1  to C 4  alkyl; A represents H, C 1  to C 4  alkyl, C 1  to C 4  alkylthio or N(R 4 )R 5  (wherein R 4  and R 5  each presents H or C 1  to C 4  alkyl); Z represents C(CN)R 6  (wherein R 4  represents CN, C 1  to C 3  alkylsulfonyl, C 1  to C 3  alkylsulfonyl substituted with halogen, C 1  to C 3  alkylcarbonyl, C 1  to C 3  alkylcarbonyl substituted with halogen, C 1  to C 4  alkoxycarbonyl, C 1  to C 4  alkoxycarbonyl substituted with halogen, C 1  to C 4  alkylthiocarbonyl, C 1  to C 3  monoalkylaminocarbonyl or C 1  to C 3  dialkylaminocarbonyl) or N-R 7  (wherein R 7  represents CN, NO 2 , C 1  to C 3  alkylsulfonyl, C 1  to C 3  alkylsulfonyl substituted with halogen, C 1  to C 3  alkylcarbonyl or C 1  to C 3  alkylcarbonyl substituted with halogen). 
     Thus, the present invention has completed on the basis of the foregoing finding. 
     These organophosphorus compounds do not give off any bad or irritating odor and have low toxicity to warm-blooded animals. Therefore, they can widely be used and thus have very high usefulness. 
     The organophosphorus compounds represented by the foregoing formula (I) also include stereoisomers such as optical isomers and geometric isomers. In addition, in formula (I), when A is amino or monoalkylamino, the organophosphorus compounds may exist in the form of a tautomer represented by the formula (I&#39;): ##STR4## (wherein R 1 , R 2 , R 3 , Z and A are the same as those defined above). These compounds (tautomeric isomers) are likewise included in the scope of the compound of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The compounds of the present invention can be prepared in accordance with, for instance, the following method. ##STR5## (wherein R 1 , R 2 , R 3 , Z and A are the same as those defined above and Hal means a halogen atom). 
     The foregoing reactions are in general carried out at a temperature ranging from -100° to +60° C. and preferably from -80° to +30° C. Moreover, these reactions are performed in the presence of a deacidifying agent, examples of which include organic lithium compounds such as n-butyl lithium, t-butyl lithium and phenyl lithium; inorganic bases such as sodium hydride, potassium hydride, metallic sodium, sodium hydroxide and potassium hydroxide; alkoxides such as sodium methoxide, sodium ethoxide and potassium t-butoxide; and organic bases such as triethylamine and pyridine. 
     In addition, these reactions are desirably carried out in the presence of a solvent. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; cyclic or non-cyclic aliphatic hydrocarbons such as hexane and cyclohexane; ethers such as diethyl ether, methyl ethyl ether, dioxane and tetrahydrofuran; nitriles such as acetonitrile, propionitrile and acrylonitrile; and aprotic polar solvents such as dimethylformamide, dimethylsulfoxide, sulfolane and hexamethyl-phosphoric acid triamide. 
     Typical examples of the compounds of the present invention are listed in the following Table 1. Each compound hereinafter is described by the corresponding number of the compound. 
     
                                           TABLE 1__________________________________________________________________________ ##STR6##                            (I)Comp.                            PhysicalNo. R.sup.1  R.sup.2       R.sup.3           A     Z          Property__________________________________________________________________________1   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           H     C(CN).sub.2                            oily                            substance2   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           H     C(CN).sub.2                            oily                            substance3   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           CH.sub.3                 C(CN).sub.2                            oily                            substance4   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           SCH.sub.3                 C(CN).sub.2                            oily                            substance5   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 C(CN).sub.2                            white                            crystal                            m.p. 67.0˜                            69.0° C.6   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 C(CN).sub.2                            oily                            substance7   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           H     C(CN)COOC.sub.2 H.sub.5                            oily                            substance8   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           SCH.sub.3                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance9   C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NH.sub.2                 C(CN)COOC.sub.2 H.sub.5                            white                            crystal                            77.0˜                            80.0° C.10  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance11  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 C(CN)COOC.sub.2 H.sub.5                            white                            crystal                            81.0˜                            82.0° C.12  C.sub.2 H.sub.5  n-C.sub.3 H.sub.7       CH.sub.3           N(CH.sub.3).sub.2                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance13  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 C(CN)COO-iso-                            oily                 C.sub.3 H.sub.7                            substance14  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           NHC.sub.2 H.sub.5                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance15  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           N(CH.sub.3).sub.2                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance16  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(C.sub.2 H.sub.5).sub.2                 C(CN)COOC.sub.2 H.sub.5                            white                            crystal                            73.5˜                            76.0° C.17  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           N(C.sub.2 H.sub.5).sub.2                 C(CN)COOC.sub.2 H.sub.5                            oily                            substance18  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 C(CN)CON(CH.sub.3).sub.2                            oily                            substance19  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 C(CN)SO.sub.2 CH.sub.3                            oily                            substance20  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 NSO.sub.2 CH.sub.3                            oily                            substance21  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 NSO.sub.2 CH.sub.3                            oily                            substance22  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 NNO.sub.2  oily                            substance23  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 NNO.sub.2  oily                            substance24  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 NCOCF.sub.3                            oily                            substance25  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           NHCH.sub.3                 NCOCF.sub.3                            oily                            substance26  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(CH.sub.3).sub.2                 NCN        oily                            substance27  C.sub.2 H.sub.5  n-C.sub.3 H.sub.7       CH.sub.3           NHCH.sub.3                 NCN        oily                            substance28  C.sub.2 H.sub.5  n-C.sub.3 H.sub.7       CH.sub.3           N(CH.sub.3).sub.2                 NCN        oily                            substance29  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           N(CH.sub.3).sub.2                 NCN        oily                            substance30  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       CH.sub.3           N(C.sub.2 H.sub.5).sub.2                 NCN        oily                            substance31  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       C.sub.2 H.sub.5           N(C.sub.2 H.sub.5).sub.2                 NCN        oily                            substance32  C.sub.2 H.sub.5  sec-C.sub.4 H.sub.9       n-C.sub.3 H.sub.7           NH-n-C.sub.3 H.sub.7                 C(CN).sub.2                            creamy                            substance__________________________________________________________________________ 
    
     IR Spectra of the compounds of Table 1 are listed in the following Table 2. 
     
                       TABLE 2______________________________________Comp.No.    IR data______________________________________1      IR(neat) 2968, 2218(C═N), 1596(C═C), 1335,           1257(P═O), 996 cm.sup.-12      IR(neat) 2968, 2218(C═N), 1590(C═C), 1254(P═O),           1005 cm.sup.-13      IR(neat) 2968, 2216(C═N), 1540(C═C), 1256(P═O),           1160, 1014, 957 cm.sup.-14      IR(neat) 2968, 2218(C═N), 1506(C═C), 1275(P═O),           1011, 963 cm.sup.-15      IR(KBr)  3250(NH), 3160(NH), 2974, 2188(C═N),           1614(C═C), 1245(P═O), 1017, 963 cm.sup.-16      IR(neat) 2962, 2200(C═N), 1575(C═C), 1254(P═O),           1014 cm.sup.-17      IR(neat) 2968, 2218(C═N), 1728(C═O), 1596(C═C),           1272(P═O), 1097, 1092, 996 cm.sup.-18      IR(neat) 2968, 2212(C═N), 1713(C═O), 1515(C═C),           1254(P═O), 1020 cm.sup.-19      IR(KBr)  3292(NH), 3250(NH), 3178(NH), 29621,           2200(C═N), 1650(C═O), 1599(C═C),           1566(C═C), 1287, 1230, 1017 cm.sup.-110     IR(neat) 2968, 2194(C═N), 1692(C═O), 1572(C═C),           1266(P═O), 1092, 1023 cm.sup.-111     IR(KBr)  3238(NH), 2968, 2206(C═N), 1677(C═O),           1599(C═C), 1287, 1245, 1047 cm.sup.-112     IR(neat) 2968, 2194(C═N), 1692(C═O), 1572(C═C),           1473, 1446, 1413, 1269(P═O), 1020 cm.sup.-113     IR(neat) 2974, 2194(C═N), 1692(C═O), 1572(C═C),           1473, 1413, 1266(P═O), 1011 cm.sup.-114     IR(neat) 3232(NH), 2974, 2206(C═N), 1665(C═O),           1608(C═C), 1281, 1119, 1026 cm.sup.-115     IR(neat) 2974, 2194(C═N), 1692(C═O), 1569(C═C),           1428, 1266(P═O), 1011 cm.sup.-116     IR(KBr)  2968, 2206(C═N), 1674(C═O), 1602(C═C),           1287, 1245, 1023 cm.sup.-117     IR(neat) 2974, 2206(C═N), 1665(C═O), 1611(C═C),           1278(P═O), 1032, 942 cm.sup.-118     IR(neat) 3250(NH), 2968, 2188(C═N), 1626(C═O),           1458(C═C), 1398, 1245(P═O), 1029 cm.sup.-119     IR(neat) 2968, 2188(C═N), 1599(C═C), 1488, 1338,           1245(P═O), 963 cm.sup.-120     IR(neat) 2968, 1575(C═N), 1482, 1287(P═O), 1131,           1011, 963 cm.sup.-121     IR(neat) 3304(NH), 1602(C═N), 1272(P═O), 1116,           1017, 963 cm.sup.-122     IR(neat) 2968, 1587(C═N), 1497, 1386, 1251(P═O),           1011 cm.sup.-123     IR(neat) 3268(NH), 2968, 1602(C═N), 1311,           1251(P═O), 1020 cm.sup.-124     IR(neat) 2968, 1665(C═O), 1590(C═N), 1473,           1263(P═O)cm.sup.-125     IR(neat) 3244(NH), 2974, 1659(C═O), 1596(C═N),           1320, 1194, 1140, 1011 cm.sup.-126     IR(neat) 2968, 2182(C═N), 1581(C═C), 1245(P═O),           1134, 1017, 960 cm.sup.-127     IR(neat) 3250(NH), 2182(C═N), 1602(C═N), 1335,           1194, 1248, 1038 cm.sup.-128     IR(neat) 2968, 2182(C═N), 1599(C═N), 1491, 1410,           1281, 1251, 1020, 963 cm.sup.-129     IR(neat) 2968, 2182(C═N), 1596(C═N), 1491, 1443,           1410, 1272, 1248, 1212, 1020 cm.sup.-130     IR(neat) 2974, 2188(C═N), 1578(C═N), 1461, 1248,           1020, 954 cm.sup.-131     IR(neat) 2974, 2182(C═N), 1578(C═N), 1449, 1248,           1020, 975 cm.sup.-132     IR(neat) 3256(NH), 2968, 2206(C═N), 1569(C═C),           1251, 1026 cm.sup.-1______________________________________ 
    
     The compounds of the present invention exhibit excellent activity as active ingredients of insecticides, acaricides and nematocides. The compounds of the present invention are effective for controlling, for instance, agricultural and horticultural pests such as Coleoptera (for instance, Scarabaeidae, Chrysomelidae, Henosepilachna Vigintioctopunctata Mamestra brassicae, Pieris rapae, Plutera xylostella, Noctuidae, Adoxophyes orana and Chilo suppressalis), Hemiptera (for instance, Delphacidae, Deltocephalidae, Aleyrodidae, Aphididae and Scales) and Thysanoptera (for instance, Scirtothrips dorsalis and Thrips pulmi); Sanitary pests such as Mosquitoes, Flies, Blattidae, Fleas and Lice; Grain pests; cloth and house pests; Plant parasitic nematodes such as root-knot nematodes and root-lesion nematodes; and Plant parasitic metes such as Tetranychus urticae, Tetranychus kanzawai and Panonychus citri. They are also effective for controlling soil insect pests. The term &#34;soil insect pest&#34; used herein means, for instance, Gastropode such as slugs and snails; Isopoda such as Armadiliidium vulgare and Sow bugs. In addition, they are likewise effective for controlling insect pest such as Dicofol, organophosphorus compound-resistance plant parasitic mites, organophosphorus compound-resistant Aphididae and Musca domestica. 
     When the compounds of the present invention are used as active ingredients of insecticidal, acaricidal, nematocidal compositions and composition for killing or controlling soil pest insect, they may be used as such, but may in general be formed into a variety of formulations together with adjuvants such as emulsifiable concentrates, dusts, wettable powders, liquid formulations, aerosols and pastes like conventional formulations of agricultural chemicals. The formulations in general comprise 0.5 to 90 parts by weight of the active ingredient and 10 to 99.5 parts by weight of an adjuvant. When these formulations are practically used, they can be applied as such or after diluting them with a diluent such as water to a desired concentration. 
     The term &#34;adjuvant&#34; herein means carriers, emulsifying agents, suspending agents, dispersing agents, spreaders, penetrants, wetting agents, thickeners and stabilizers. These adjuvants may, if necessary, be added in an appropriate amount. The carriers can roughly be classified into solid carriers and liquid carriers. Examples of the solid carriers include vegetable and animal powder such as starches, active carbon, soybean flour, wheat flour, wood powder, fish meal and powdered milk; and mineral powders such as talc, kaolin, bentonite, calcium carbonate, zeolite, diatomaceous earth, white carbon, clay, alumina and powdered sulfur. On the other hand, examples of the liquid carriers are water; alcohols such as methyl alcohol and ethylene glycol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as kerosine; aromatic hydrocarbons such as xylene, trimethylbenzene, tetramethylbenzene, cyclohexane and solvent naphtha; halogenated hydrocarbons such as chloroform and chlorobenzene; amides such as dimethylformamide; esters such as ethyl acetate and glycerin esters of fatty acids; nitriles such as acetonitrile; and sulfur atom-containing compounds such as dimethylsulfoxide. If necessary, the compounds of the present invention may be admixed with or used simultaneously with other agricultural chemicals such as insecticides, acaricides, nematocides, bacteriocides, antiviral agents, attractants, herbicides and plant growth regulators. In admixtures, greater effectiveness may sometimes be attained. 
     Examples of insecticides, acaricides or nematocides include organophosphorus acid ester compounds such as DDVP, Diasinon, Malathion, Fenitrothion, Prothiofos, Dioxabenzofos and Acephate; carbamate compounds such as Carbaryl, Propoxur, Oxamyl, Carbofuran and Methomyl; organochlorine compounds such as Dicofol and Tetradifon; organometal compounds such as Cyhexatin and Fenbutatin oxide; pyrethroid compounds such as Fenvalerate, Permethrin, Deltamethrin and Bifenthrin; urea compounds such as Diflubenzuron, Teflubenzuron and Chlorfluazuron; heterocyclic compounds such as Buprofezin and Hexythiazox; and other compounds such as dinitro compounds, organosulfur compounds, amidine compounds and triazine compounds. In addition to the foregoing compounds, the compound of the present invention can also be admixed with or used simultaneously with microbial pesticides such as BT agents and insect pathogen virus pesticides. 
     Examples of the bactericides are organophosphorus compounds such as Iprobenfos, Edifenphos and Phosethyl-aluminum; organocopper compounds such as oxyquinoline copper, copper terephthalate; organochlorine compounds such as Fthalide and Chlorothalonil; dithiocarbamate compounds such as Maneb, Zineb and Propineb; dicarboximide compounds such as Iprodione, Vinclozolin and Procymidone; azole compounds such as Triadimefon, Bitertanol, Etaconazole, Propiconazole and Penconazole; benzimidazole compounds such as Thiophanate-methyl and Benomyl; carbinol compounds such as Fenarisol and Flutriafol; benzanilide compounds such as Mepronil and Flutolanil; phenylamide compounds such as Metalaxyl and Oxadixyl, and other compounds such as piperazine compounds, quinoxaline compounds, morpholine compounds, anthraquinone compounds, sulfonic acid compounds crotonic acid compounds, urea compounds and antibiotics. 
     As has been discussed above, the insecticides, acaricides and nematocides which comprise, as active ingredient, the compounds of the present invention are effective for controlling a variety of deleterious insects, harmful mites, destructive nematodes and harmful soil insect pests. These agricultural chemicals or formulations are applies at a concentration ranging from 1 to 20,000 ppm, desirably 20 to 2,000 ppm expressed in terms of the amount of the active ingredient. The concentration of these active ingredients can be appropriately adjusted depending on various factors such as shapes of the formulations, methods, purposes, time and places of application as well as the condition of infestation of insect pest. For instance, when aquatic insect pests are to be controlled, the insect pest can be controlled by spraying a solution of the compound having a concentration falling within the range defined above and, therefore, the concentration of the active ingredient required for controlling the aquatic insect pest is lower than that defined above. The amount of the agricultural chemicals or formulations to be applied per unit area (per 10 a) ranges from about 0.1 to 5,000 g and preferably 10 to 1,000 g expressed in terms of the amount of the active ingredient, but in a particular case, they may be applied in an amount outside the range defined above. 
     The application of a variety of formulations or dilute solutions thereof which comprise the compounds of the present invention can be performed according to any manner of application usually adopted, for instance, spraying (such as spraying, dusting, misting, atomizing, granule application and application on water surface); soil applications (such as mixing and drench); surface applications (such as coating, dressing and painting); and poison bait. It is also possible to control the development and growth of harmful insect pests, in particular deleterious insects through the action of excreta obtained by admixing the foregoing active ingredient to feed and giving the feed to domestic animals. Further, they can also be applied in accordance with ultra low volume application. In this method, the chemicals or formulations can comprise 100% active ingredient. 
     EXAMPLES 
     The method for preparing the compounds of the present invention will hereinafter be explained in more detail with reference to the following Preparation Examples. 
     Preparation Example 1: O-ethyl-S-sec-butyl-N-methyl, N-(2,2-dicyano-1-methylthiovinyl)phosphonoamidothiolate (Compound No.4) 
     0.5 g of 60% sodium hydride was rinsed with n-hexane and 20 ml of tetrahydrofuran was added thereto. Thereafter, the resulting solution was cooled down to 5° C. and 1.5 g of [(methylthio)(methylamino)methylene]propanedinitrile was gradually added to the solution maintained at 5° C. The resulting mixture was stirred for one hour. After 2.8 g of 93.4% toluene solution of O-ethyl-sec-butyl-phosphonochloridethiolate was diluted with 5 ml of tetrahydrofuran, the resulting solution was gradually dropwise added to the mixture maintained at 0° to 5° C. After the completion of the dropwise addition, the temperature of the solution was slowly brought back to room temperature and the solution was further stirred for an additional 12 hours to complete the reaction. After the completion of the reaction, about two-thirds of the reaction solution was distilled off under reduced pressure and the residue was poured into ice water. Then, the residue was extracted with dichloromethan. The dichloromethan phase was washed with sodium bicarbonate solution and with water and then dried over anhydrous magnesium sulfate. The dichloromethane was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: ethylacetate/benzene=1:9) to obtain 2.8 of Compound No.4 in the form of an oily substance. 
     Preparation Example 2: O-ethyl-S-sec-butyl-N-methyl, N-(2,2-dicyano-1-dimethylaminovinyl)phosphonoamidothiolate (Compound No.6) 
     0.5 g of 60% sodium hydride was rinsed with n-hexane and 20 ml of tetrahydrofuran was added thereto. Thereafter, the resulting solution was cooled down to 5° C. and 1.3 g of [(dimethylamino)(methylamino)methylene]propanedinitrile was gradually added to the solution maintained at 5° C. The resulting mixture was stirred for one hour. After 2.6 g of 93.4% toluene solution of O-ethyl-sec-butyl-phosphonochloridethiolate was diluted with 5 ml of tetrahydrofuran, the resulting solution was gradually dropwise added to the mixture maintained at 0° to 5° C. After the completion of the dropwise addition, the temperature of the solution was slowly brought back to room temperature and the solution was further stirred for an additional 12 hours to complete the reaction. After the completion of the reaction, about two-thirds of the reaction solution was distilled off under reduced pressure and the residue was poured into ice water. Then, the residue was extracted with dichloromethane. The dichloromethane phase was washed with sodium bicarbonate solution and with water and then dried over anhydrous magnesium sulfate. The dichloromethane was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: ethyl acetate) to obtain 2.4 g of Compound No.6 in the form of an oily substance. 
     Preparation Example 3: O-ethyl-S-sec-butyl-N-methyl, N-(2-cyano-2-ethoxycarbonyl-1-dimethylaminovinyl) phosphonoamidothiolate (Compound No.11) 
     0.25 of 60% sodium hydride was rinsed with n-hexane and 20 ml of tetrahydrofuran was added thereto. Thereafter, the resulting solution was cooled down to 5° C. and 1.0 g of ethyl[(dimethylamino)(methylamino)methylene]-cyanoacetate was gradually added to the solution maintained at 5° C. The resulting mixture was stirred for 30 minutes. After 1.4 g of 93.5% toluene solution of O-ethyl-S-sec-butyl-phosphonochloridethiolate was diluted with 2.5 ml of tetrahydrofuran, the resulting solution was gradually dropwise added to the mixture maintained at 0° to 5° C. After the completion of the dropwise addition, the temperature of the solution was slowly brought back to room temperature and the solution was further stirred for an additional 12 hours to complete the reaction. After the completion of the reaction, about two-thirds of the reaction solution was distilled off under reduced pressure and the residue was poured into ice water. Then, the residue was extracted with dichloromethane. The dichloromethane phase was washed with sodium bicarbonate solution and with water and then dried over anhydrous magnesium sulfate. The dichloromethane was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: dichloromethane:methanol=100:1) to obtain 1.3 g of Compound No.11 in the form of an oily substance. 
     Preparation Example 4: O-ethyl-S-sec-butyl-N-methyl, N-(N&#39;,N&#39;-dimethyl-N&#34;-cyanoguanidino)phosphonoamidothiolate (Compound No.26) 
     0.5 g of 60% sodium hydride was rinsed with n-hexane and 20 ml of tetrahydrofuran was added thereto. Thereafter, the resulting solution was cooled down to 5° C. and 1.3 g of N-methyl-N&#39;, N&#39;-dimethylamino-N&#34;-cyanoguandine was gradually added to the solution maintained at 5° C. The resulting mixture was stirred for one hour. After 2.8 g of 93.5% toluene solution of O-ethyl-sec-butyl-phosphonochloridethiolate was diluted with 5 ml of tetrahydrofuran, the resulting solution was gradually dropwise added to the mixture maintained at 0° to 5° C. After the completion of the dropwise addition, the temperature of the solution was slowly brought back to room temperature and the solution was further stirred for 12 hours to complete the reaction. After the completion of the reaction, about two-thirds of the reaction solution was distilled off under reduced pressure and the residue was poured into ice water. Then, the residue was extracted with dichloromethane. The dichloromethane phase was washed with sodium bicarbonate solution and with water and then dried over anhydrous magnesium sulfate. The dichloromethane was distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: ethyl acetate) to obtain 2.5 g of Compound No.26 in the form of an oily substance. 
     Specific examples of formulations will be described below, but the adjuvants such as carriers and surfactants are by no means limited to those used in the following examples. In the following specific formulations, the term &#34;part&#34; means &#34;part by weight&#34; unless otherwise specified. 
     Formulation Example 1 (Wettable Powder) 
     20 parts of Compound No. 5, 56 parts of acid clay, 15 parts of white carbon, 4 parts of calcium lignin sulfonate and 5 parts of polyoxyethylene alkylphenyl ether was uniformly mixed and pulverized to give a wettable powder. 
     Formulation Example 2 (Emulsifiable Concentrate) 
     To 20 parts of Compound No. 5, 75 parts of xylene was added. And then, 5 parts of New Calgen ST-20 (available from Takemoto Oil &amp; Fat Co., Ltd.) was added to the resulting solution as an emulsifying agent and then the mixture was mixed and dissolved to give an emulsifiable concentrate. 
     Formulation Example 3 (Granule) 
     5 parts of Compound No. 6, 3 parts of calcium lignin sulfonate, one part of sodium dodecylbenzenesulfonate, 30 parts of bentonite and 61 parts of clay were sufficiently pulverized and mixed. The mixture was then sufficiently kneaded while adding water, followed by granulation and drying to give a granule. 
     The insecticidal, scaricidal and nematocidal effects of the compounds of the present invention will hereunder be explained with reference to the following Test Examples. 
     Test Example 1 
     The emulsifiable concentrate obtained by Formulation Example 2 was diluted with water to 500 ppm and the resulting diluted emulsions were sprayed on leaves of chinese cabbage. After air-drying, the leaves were introduced into a plastic container having a size of 21 cm (height)×13 cm (width)×3 cm (depth), then 10 third instar larvae of common cutworm were put on the leaves. The container was then placed in a thermostated room maintained at 26° C. After 2 days, the number of surviving larvae was recorded to obtain the mortality (%) (repeated twice). The results thus obtained are summarized in the following Table 3. 
     
                       TABLE 3______________________________________        Concn. of ActiveCompound No. Ingredient (ppm)                     Mortality (%)______________________________________2            500          1003            500          904            500          1005            500          1006            500          1007            500          1008            500          1009            500          10011           500          10016           500          10019           500          10020           500          10026           500          10028           500          10029           500          10030           500          10032           500          90Comparative  500          20Compound AUntreated    --           0______________________________________ 
    
     The Comparative Compound A as set forth in Table 3 is a compound represented by the following structural formula and disclosed in Japanese Unexamined Patent Publication No. Sho 53-84922. ##STR7## Test Example 2 
     The emulsifiable concentrate obtained by Formulation Example 2 was diluted with water to 500 ppm and the seedling of rice plant were immersed therein for 10 seconds. After air-drying, the seedlings whose roots were wrapped round with absorbent cotton were introduced into a test tube, then 10 second instar larvae of green rice leafhopper were put into the test tube, the opening thereof was closed with gauze. The tube was placed in a thermostated room maintained at 26° C. After 2 days, the number of surviving larvae was recorded to obtain the mortality (%) (repeated twice). The results thus obtained are summarized in the following table 4. 
     
                       TABLE 4______________________________________        Concn. of ActiveCompound No. Ingredient (ppm)                     Mortality (%)______________________________________1            500          1002            500          1003            500          1004            500          1005            500          1006            500          1007            500          1008            500          1009            500          10010           500          10011           500          10013           500          10014           500          10016           500          10018           500          10019           500          10020           500          10023           500          9024           500          10025           500          10026           500          10027           500          10028           500          9029           500          10030           500          10031           500          10032           500          90Comparative  500          60Compound AUntreated    --           0______________________________________ 
    
     The Comparative Compound A as set forth in Table 4 is the same as that defined above in connection with Table 3. 
     Test Example 3 
     A kidney bean leaf was cut into 3×5 cm 2 . The leaf was put on a filter paper wetted with water for preventing drying of the leaf and 20 female adults of kanzawa spider mite were released on the leaf. After 24 hours, 500 ppm of concentration of active ingredient prepared by diluting with water the emulsifiable concentrate obtained by Formulation Example 2 were sprayed on the leaf. After air-drying, the mites were held in a thermostated room maintained at 26° C. After 24 hours, the number of surviving adults were recorded to obtain the mortality (%) (repeated twice). The results thus obtained are summarized in the following Table 5. 
     
                       TABLE 5______________________________________        Concn. of ActiveCompound No. Ingredient (ppm)                     Mortality (%)______________________________________1            500          1002            500          1003            500          1004            500          1005            500          1006            500          1007            500          1008            500          1009            500          10010           500          10011           500          10012           500          10013           500          10014           500          10015           500          10016           500          10019           500          10020           500          10024           500          10025           500          10026           500          10028           500          10029           500          10031           500          100Comparative  500          100Compound AUntreated    --           0______________________________________ 
    
     The Comparative Compound A is the same as that defined above in connection with Table 3. 
     Test Example 4 
     To a 1/5,000 are pot, soil contaminated with root-knot nematodes was packed and the soil was admixed with the granules obtained by Formulation Example 3 in an amount of 250 g and 25 g/are expressed in terms of the amount of the active ingredient. 
     Two days after the treatment, seedlings of tomato at 3rd to 4th-leaf stage were transplanted in the soil. Twenty-five days after the transplantation, the degree of the invasion of root-knot nematodes (root-knot index) was determined (repeated twice). 
     The root-knot index was evaluated on the basis of the following evaluation criteria: 
     
         ______________________________________0        no invasion of root-knot nematodas1        slight invasion of root-knot nematodas2        medium invasion of root-knot nematodas3        severe invasion of root-knot nematodas4        very severe invasion of root-knot nematodas______________________________________ 
    
     The results thus obtained are summarized in the following Table 6. 
     
                       TABLE 6______________________________________Compound Amount of Active IngredientNo.      (g/are)            Root-Knot Index______________________________________1        250                02        250                03        250                04        250                05        250                06        250                07        250                08        250                09        250                010       250                011       250                012       259                013       250                a14       250                015       250                016       250                017       250                019       250                020       250                021       250                023       250                024       250                026       250                027       250                028       250                028       250                029       250                030       250                031       250                032       250                0Comparative    250                4CompoundUntreated    --                 4______________________________________ 
    
     The Comparative Compound A as set fourth in Table 6 is the same as the defined above in connected with Table 3. 
     EFFECT OF THE INVENTION 
     The compounds of the present invention represented by the foregoing general formula (I) exhibit effectiveness in controlling harmful insects, mites and nematodes and thus can be used as novel insecticides, acaricides and nematocides which do not give off a bad or irritating odor and have low toxicity to warm-blooded animals.