Meisner, J., Department of Toxicology, Volcani Center, Agricultural Research Organization, Israel
Ascher, K.R.S., Department of Toxicology, Volcani Center, Agricultural Research Organization, Israel

DURING a research programme on phagostimulants1-3 for the larva of the Egyptian cotton leafworm, Spodoptera littoralis Boisd., it was found that their incorporation into poison baits did not sufficiently improve the latter's attractivity. Further stimuli, for example optical ones, seemed to be needed. We therefore determined the influence of edible colours, similar to those used in studying boll weevil attraction4, on the feeding rate of S. littoralis. A range of commercial food colours of the 'Edicol Supra' and 'Edilake' ranges (Imperial Chemical Industries, England), now produced under the label of 'Certicols' and 'Certolakes', respectively (Williams (Hounslow) Ltd), were tested. The 'Edilake (Certolake)' colours are aluminium lakes containing a high proportion of alumina as extender of the corresponding 'Edicol Supra (Certicol)' dyes, which are sodium salts. 'Edilakes' are used mainly when water-soluble food colours would be unsuitable, for example in fatty or oily media, and contain generally from 15 to 25% of the corresponding 'Edicols'. © 1973 Nature Publishing Group.