Toxic and deterrent effects of phytohemagglutinin on the grain aphid Sitobion avenae

The toxicity and deterrent effects of phytoheamagglutinin (Phaseolus vulgaris agglutinin, PHA) to the grain aphid (Sitobion avenae F.) was investigated in the laboratory by use of liquid diets or gels containing various PHA concentrations. The addition of PHA to the liquid diet increased the aphid pre-reproductive period, mortality, and generation time and decreased aphid fecundity and intrinsic rate of natural increase. Aphids fed on sucrose-agarose gels with higher concentrations of PHA exhibited no phloem-feeding behavior. The number of gel penetrations was reduced and duration of the pathway phase was increased as PHA concentration increased. These results indicate that PHA is detrimental to S. avenae and that the effect of PHA is at least partially explained by suppression of feeding behaviour. PHA could be useful for managing S. avenae.