Feeding the Egyptian toad Bufo regularis for 14 weeks with flour infested for 1 year with Tribolium castaneum, at a dose level of 200 mg/50 g body weight, induced neoplasms in 22 out of 100 toads. These neoplasms comprise 22 primary hepatocellular carcinomas and 6 tumours in the kidney due to metastases from the primary hepatocellular carcinoma. It is speculated that the carcinogenicity of the flour used in this work is due to quinone derivatives secreted by the defensive glands of T. castaneum.

Biscuits made of flour infested with Tribolium castaneum induced the formation of hepatocellular carcinomas (22%) when force-fed to toads (Bufo regularis) at a dose level of 200mg/50g 3 times a week. Maximal time of exposure and observation was 16 weeks. Some metastatic deposits from the primary liver tumours were found in the kidneys. Thus, the carcinogenic potency of the biscuits was almost the same as that of the flour previously reported by the authors indicating that the temperature of the oven in which the biscuits were baked did not alter the carcinogenicity of the infested flour.

The results obtained are summarized as follows: (1) the active compounds of aphid's odour stimulated the syrphid females to deposit significantly higher percentages of eggs. These chemical compounds could be isolated by the solvent n-pentane. (2) Gas chromatography mass spectral analysis of n-pentane fractions of aphid's odour revealed the presence of several active peaks of hydrocarbon compounds. The active peaks ranged from docosane (Cz2) to octacosane (Cz8). Also, GC-mass spectral analysis of n-pentane fractions of the aphid-extract supernatant showed the same chain of hydrocarbon compounds which is present in the aphid odour.(3) Bioassay of the different cosane compounds showed that the different concentrations of tricosane, tetracosane, pentacosane and hexacosane have a kairomonal effect on the syrphid females and the second concentration of C23CII, C24CI1, C25CII and c 2 6 c I I stimulated the syrphid females to deposit a significantly higher percentage of eggs. While hexacosane (C2J was the most abundant hydrocarbon compound in aphid kairomone, tricosane (C2J was the most active hydrocarbon compound. (4) Bioassay of the different mixtures of cosane compounds showed that HCMI, HCM,, HCM,, HCM4, HCM5 and HCM, have a kairomonal effect on the syrphid females. The highest percentage of eggs was laid under the effect of the fourth mixture (HCM4) which contains tricosane (C,,), tetracosane (C24), pentacosane (C25), hexacosane (c26) and octacosane (C2*). (5) The chain of non-volatile hydrocarbon compounds of aphid-kairomone is secreted along with the cornicle secretion which contains volatile compounds. This kairomone stimulate the oviposition of syrphid females when it is received mechanically by the antennae. (6) The present study showed the importance of the different mixtures of cosane compounds as aphidkairomone. The use of aphid-kairomone could be promising in aphid biological control instead of the heavy use of insecticides.

Biological and chemical characterization of a kairomone excreted by the bean aphids, Aphis fabae Scop. (Horn., Aphididae), and its effect on the predator Mebsyrphus corollae Fabr. II-Behavioural response of the predator M. corollae to the aphid kairomoneAbstract: The present study shows the importance of aphid-kairomone as an additional stimulus which arrests and increases the occurrence of the predator M . corollae with the treated plants. This increase in occurrence could assist in the control of the aphid-pest when applied in the target area. The results are summarized as follows.(1) The first concentration of aphid-extract (AECJ stimulated the oviposition of syrphid females much more than the second concentration of hexacosane (C2&J and the addition of hexacosane to the aphid-extract did not increase its activity.(2) The experienced syrphid females deposited more eggs with C2&, AEC, and with a mixture of both than did the inexperienced females. (3) The aphid-extract (AEC,) and hexacosane (C2&,) affected the searching behaviour of syrphid females by significantly increasing the path length and the number of turns exhibited. (4) The syrphid females were significantly arrested by plants treated with either C&,, or AECI. (5) The results confirm that the predator syrphid females have used hexacosane and aphid-extract as a source of kairomone.