Effects of the ant,Lasius NigerL., on the Feeding and Excretion of the Bean Aphid,Aphis FabaeScop

ABSTRACT Banks (1958) confirmed that colonies of Aphis fabae, attended by the ant Lasius niger, multiply more than ant-free colonies on bean plants, in the absence of the aphids’ insect enemies. He showed that, when the aphids were ant-attended, they changed their excretion behaviour and that the normal dispersal of adult apterae from young apical growth of bean plants was delayed. No significant differences were found between the reproduction rates of individual ant-attended and ant-free aphids living on leaves of the same age, but the reproduction rates were significantly affected by the age of the plant tissue on which the aphids fed. The increased multiplication of ant-attended colonies was attributed to the delay in dispersal of adult apterae from the young growth, where they reproduced more, to the old growth, where they reproduced less.