Methods and compositions for controlling ectoparasites

1. A method for inhibiting hatching of an ectoparasite egg comprising exposing the ectoparasite egg to a topical composition comprising at least one metal chelating agent wherein the at least one metal chelating agent is a compound of formula (Ia):

wherein X is a covalent bond, CH 2 —Z—CH 2 or —Z—

wherein R 1 and R 1′ are independently selected from hydrogen, or C 1-3 alkyl

wherein at least one of R 2 , R 2′ −, R 3 , R 3′ −, R 4 and R 4′ − is a methyl group and the remaining R 2 , R 2′ , R 3 , R 3′ , R 4 and R 4′ are independently selected from hydrogen or C 1-3 alkyl

Z is selected from a covalent bond, —NH—, —O—, —S—, —C(O)— and —C(S)—;

or a pharmaceutically, veterinary or agriculturally acceptable salt thereof.

2. A method according to claim 1 wherein Z is —NH—, —O— or S.

3. A method according to claim 1 wherein the compound of formula (Ia) is selected from:

6,6′-dimethyl-2,2′-dipyridyl,

5,5′-dimethyl-2,2′-dipyridyl,

4,4′-dimethyl-2,2′-dipyridyl,

or a pharmaceutically, veterinary or agriculturally acceptable salt thereof.

4. A method according to claim 1 , wherein the ectoparasite egg is laid by an ectoparasite of a species from an order selected from the group consisting of Lepidoptera, Hemiptera, Orthoptera, Psocoptera, Hymenoptera, Isoptera, Coleoptera, Dictyoptera, Thysanoptera, Homoptera, Diptera, Anaplura, Malophaga, Siphonaptera, Arachnida and Phthiraptera.

5. A method according to claim 4 , wherein the ectoparasite egg is laid by an ectoparasite of a species selected from the group consisting of Helicoverpa spp. Crocidolomia pavonana (Cabbage cluster caterpillar), Pieris rapae (Cabbage white butterfly), Phthorimaea operculella (Potatoe moth), Chrsyodexis spp. (Tobacco loopers), Plutella xylostella (Diamondback moth), Eiphyas postvittana (Walker)(light briown apple moth), Bovicola ovis (Sheep louse), Bovicola bovis, Haemotopinus eurysternus (short-nosed cattle louse), Linognathus vituli (long nosed cattle louse), Solenoptes scabiei suis, Sarcoptes scabiei bovis, Psoroptes ovis, Pthirus pubis, Pediculus humanus capitus, Pedicululs humanus humanus, Sarcoptes scabiei var, humani and Dermatophgoides spp.

6. A method of treating ectoparasite infestation in a host comprising topically applying to the host so that the ectoparasite egg on said host comes into topical contact with an effective amount of at least one metal chelating agent wherein the at least one metal chelating agent is a compound of formula (Ia):

wherein X is a covalent bond, CH 2 —Z—CH 2 or—Z—

wherein R 1 and R 1′ are independently selected from hydrogen, or C 1-3 alkyl

wherein at least one of R 2 , R 2′ −, R 3 , R 3′ −, R 4 and R 4′ − is a methyl group and the remaining R 2 , R 2 ′, R 3 , R 3 ′ , R 4 and R 4′ are independently selected from hydrogen or C 1-3 alkyl

Z is selected from a covalent bond, —NH—, —O—, —S—, —C(O)— and —C(S)—;

or a pharmaceutically, veterinary or agriculturally acceptable salt thereof.

7. A method according to claim 6 , wherein the host is a plant, an animal or a human.

8. A method of claim 6 wherein the ectoparasite infestation is caused by an ectoparasite of a species from an order selected from the group consisting of Lepidoptera, Hemiptera, Orthoptera, Psocoptera, Hymenoptera, Isoptera, Coleoptera, Dictyoptera, Thysanoptera, Homoptera, Diptera, Anaplura, Malophaga, Siphonaptera, Arachnida and Phthiraptera.

9. A method according to claim 6 , wherein the ectoparasite infestation is caused by an ectoparasite of a species from the group consisting Helicoverpa spp. Crocidolomia pavonana (Cabbage cluster caterpillar), Pieris rapae (Cabbage white butterfly), Phthorimaea operculella (Potatoe moth), Chrsyodexis spp. (Tobacco loopers), Plutella xylostella (Diamondback moth), Eiphyas postvittana (Walker)(light briown apple moth), Bovicola ovis (Sheep louse), Bovicola bovis, Haemotopinus eurysternus (short-nosed cattle louse), Linognathus vituli (long nosed cattle louse), Solenoptes scabiei suis, Sarcoptes scabiei bovis, Psoroptes ovis, Pthirus pubis, Pediculus humanus capitus, Pedicululs humanus humanus, Sarcoptes scabiei var, humani and Dermatophgoides spp.

10. A method according to claim 6 , wherein the ectoparasite infestation is a lice infestation.

11. A method according to claim 6 , wherein the metal chelating agent is applied simultaneously, separately or sequentially with a second ectoparasiticide.

12. A method according to claim 11 , wherein the second ectoparasiticide controls nymphs and/or adult ectoparasites.

13. A method according to claim 1 , wherein said composition is formulated for use in a direct topical application in a form selected from the group consisting of a dip, spray, aerosol, shampoo, mousse, emulsion, solution cream, dust, and lotion.

14. A method according to claim 6 , wherein said composition is formulated for use in a direct topical application in a form selected from the group consisting of a dip, spray, aerosol, shampoo, mousse, emulsion, solution cream, dust, and lotion.

15. A method according to claim 1 , wherein said ectoparasite egg is human head lice eggs and the composition is formulated for use in a topical application to human scalp and is in a form selected from the group consisting of a dip, spray, aerosol, shampoo, mousse, emulsion, solution cream, dust, and lotion.

16. A method according to claim 6 , wherein said ectoparasite egg is human head lice eggs and the composition is formulated for use in a topical application to human scalp and is in a form selected from the group consisting of a dip, spray, aerosol, shampoo, mousse, emulsion, solution cream, dust, and lotion.

17. A method according to any of claims 13 - 16 wherein said composition 5,5′-dimethyl-2,2′-dipyridyl.