. . . . "rticularly important.As an optionally substituted pyridyl, R.sup.5 represents a mono- or disubstituted pyridyl group of the general formula (K) ##STR9## where R.sup.14 denotes halogen with the exception of I, (C.sub.1 -C.sub.4)alkyl, (C.sub.1 -C.sub.4)alkoxy or(C.sub.1 -C.sub.4)haloalkyl and Hal denotes halogen, in particular fluorine or H.As an optionally substituted thienyl or furyl, R.sup.5 rep" .