Derivatives of N-phenylpyrazoles

A method for the control or arthropod, plant nematode or helminth pests at a locus which comprises treatment of the locus with a pesticidally effective amount of a compound of the formula:

• wherein:
• R.sup.2 represents a halogen atom, the cyano or nitro group or a group R'SO.sub.2, R'SO or R'S in which R' represents a straight- or branched-chain alkyl group having from 1 to 6 carbon atoms which is unsubstituted or substituted by one or more halogen atoms, a cycloalkyl group having from 3 to 5 carbon atoms, a straight- or branched-chain alkenyl group having from 2 to 6 carbon atoms, or R.sup.2 represents the thiocyanato group, the sulphamoyl group which is unsubstituted or substituted by one or two straight- or branched-chain alkyl groups which may be the same or different and which have from 1 to 6 carbon atoms, the carbamoyl group which may be unsubstituted or substituted by one or two straight- or branched-chain alkyl groups which may be the same or different and which have from 1 to 6 carbon atoms, a straight- or branched-chain alkoxycarbonyl group having from 2 to 7 carbon atoms, a straight- or branched-chain alkanoyl group having from 2 to 7 carbon atoms, or a straight- or branched-chain alkyl group having from 1 to 6 carbon atoms which is unsubstituted or substituted by one or more halogen atoms;
• R.sup.3 represents the hydrogen atom, or the amino group --NR"R"' wherein R" and R"", which may be the same or different, each represent a hydrogen atom or a straight- or branched-chain alkyl group (having from 1 to 6 carbon atoms, and which is unsubstituted or substituted by straight- or branched-chain alkoxycarbonyl of 2 to 5 carbon atoms), cycloalkyl group having from 3 to 6 carbon atoms, formyl group, straight- or branched-chain alkanoyl group (which has from 2 to 7 carbon atoms or together form a 5- or 6-membered cyclic imide with the nitrogen atom to which they are attached and themselves are unsubstituted or substituted by one or more halogen atoms) or cycloalkylcarbonyl group (which has from 4 to 7 carbon atoms) or straight- or branched-chain alkoxycarbonyl group (which has from 2 to 7 carbon atoms and themselves are unsubstituted or substituted by one or more halogen atoms), or R.sup.3 represents a straight- or branched-chain alkylsulphenylamino group having from 1 to 4 carbon atoms, a straight- or branched-chain alkoxymethyleneamino group having from 2 to 5 carbon atoms which is unsubstituted or substituted on methylene by a straight- or branched-chain alkyl group having from 1 to 4 carbon atoms, or represents a halogen atom, a straight- or branched-chain alkyl group having from 1 to 4 carbon atoms, the carboxy group, or a straight- or branched-chain alkylthio, alkylsulphinyl or alkylsulphonyl group having from 1 to 6 carbon atoms which is unsubstituted or substituted by one or more halogen atoms, or represents a straight- or branched-chain trialkylsilylmethyl group having from 1 to 6 carbon atoms in each alkyl group which may be the same or different, a trialkylsilyl group having from 1 to 6 carbon atoms in each alkyl group which may be the same or different or the cyano or nitro group;
• R.sup.4 -R.sup.8 each represent a hydrogen atom, a halogen atom, a straight- or branched-chain alkyl or alkoxy group having from 1 to 4 carbon atoms which is unsubstituted or substituted by one or more halogen atoms, a straight- or branched-chain alkylthio or alkylsulphinyl group having from 1 to 4 carbon atoms which is substituted by one or more halogen atoms, the nitro or cyano group or a straight- or branched-chain alkylsulphonyl group having from 1 to 4 carbon atoms which is unsubstituted or substituted by one or more halogen atoms, provided that at least one of R.sub.4 -R.sub.8 must be other than a hydrogen atom;
• and
• R.sup.1 represents a halogen atom, or a cyano or nitro group;
• or when R.sup.3 represents a carboxy group, a slat thereof with a pesticidally acceptable base;
• provided that R.sup.1, R.sup.2 and R.sup.3 do not simultaneously represent three groups of the same genus selected from the genera (i) nitro, (ii) cyano, (iii) halogen, and (iv) unsubstituted alkyl.