Performance of Aphis fabae and Brevicoryne brassicae on plants treated with growth regulators

It was shown that the fecundity of aphids may be altered on plants treated with plant growth stimulators and retardants. There was evidence that the reduced fecundity and smaller size of Aphis fabae on broad beans treated with ethylene bisnitrourethane was related to the reduced nutritional value of the plants to the aphids, levels of soluble nitrogen being reduced. The reduced fecundity of A. fabae on broad beans treated with gibberellic acid may be related to the apparent toxicity of the compound when fed directly to the aphid. CCC (chlormequat chloride) seemed toxic to both A. fabae and Brevicoryne brassicae, and the number of embryos per adult A. fabae reared on CCC‐treated beans was reduced, although this did not reduce fecundity. Apart from any direct action of CCC on the aphids, there is evidence that the substance may reduce the availability of nutrients from the phloem of treated plants to the insects by reducing translocation, and there is further evidence that amino acid content of the sap may be reduced.