Amidoacetonitrile derivatives

1. A composition for the control of parasites, comprising a compound of formula I

or a salt thereof, wherein

X is Cl, Br, or CF 3 ;

Y is a single bond, O, S, S(O), or S(O) 2 ; and

W is O or S;

and one or more carrier or dispersant.

2. The composition according to claim 1 , further comprising an effective amount of a natural or chemically modified macrocyclic lactone of formula A

wherein X is —CH(OH)—; —C(O)—; or —C(═N—OH)—;

Y is —CH 2 —; ═CH—; —CH(OH)—; or —C(═N—OCH 3 )—;

R 1 is hydrogen or one of radicals

wherein R 4 is hydroxyl, —NH—CH 3 , or —NHOCH 3 ;

R 2 is hydrogen, —CH 3 , —C 2 H 5 , —CH(CH 3 )CH 3 , —CH(CH 3 )C 2 H 5 , —CH(CH 3 )═CH—CH(CH 3 ) 2 , or cyclohexyl; and

the depicted dashed bond between atoms 22 and 23 may be a single or a double bond;

where if the depicted dashed bond is a double bond, then Y is ═CH—, and

where if the depicted dashed bond is a single bond, then Y is —CH 2 —, —CH(OH)—, or —C(═N—O—CH 3 )—,

or a physiologically acceptable salt thereof.

3. The composition according to claim 2 , wherein the macrocyclic lactone is a compound of the formula A, wherein

X is —CH(OH)—;

Y is —CH 2 —;

R 1 is the radical

R 2 is —CH 3 or —C 2 H 5 ; and

the bond between atoms 22 and 23 represents a single bond.

4. The composition according to claim 2 , wherein the macrocyclic lactone is selected from the group consisting of avermectins, milbemycins, and derivatives thereof, in free form or in the form of a physiologically acceptable salt.

5. The composition according to claim 2 , wherein the macrocyclic lactone is selected from the group consisting of Ivermectin, Doramectin, Moxidectin, Selamectin, Emamectin, Eprinomectin, Milbemectin, Abamectin, Milbemycin oxime, Nemadectin, and a derivative thereof, in free form or in the form of a physiologically acceptable salt.