The alarm pheromones are known for many species of aphids, and methods of using the synthetic pheromone to improve control of aphids by contact insecticides and biological agents have been devised. Highly active analogs have been prepared and plant-derived synergists identified. Laboratory studies on compounds obtained by chemical modification of the alarm pheromone and antifeedants derived from non-host plants have led to successful field trials against aphid-borne virus diseases in crops. Strategies for biotechnological production of aphid semiochemicals are described. The sex pheromones for a number of aphids have recently been identified. Further studies on the production, perception, and interspecific attraction of the pheromone components are described and possible uses for the sex pheromone are discussed.

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In autumn 1991, aphid parasitoids of the genus Praon (Hymenoptera; Braconidae) were caught in water traps with lures containing synthetic aphid sex pheromone components at three sites in England and one in Germany. At two of the English sites and at the German site, the traps were placed in winter cereal fields whilst the third English site was in woodland. Three species were caught, P. volucre, P. dorsale and P. abjectum. Those caught in cereal fields were almost entirely P. volucre, whilst P. dorsale dominated at the woodland site. Of the known aphid sex pheromone components, the most effective lure was the (+)‐(4aS,7S,7aR)‐nepetalactone. Nepetalactone traps placed at the woodland site in spring and summer caught few Praon females, and attraction may be confined to the autumn, when sexual female aphids are present in the field. Male parasitoids did not respond to the aphid pheromones at any time, although they were caught in suction traps operated at the woodland site during the autumn. At the cereal sites height had a significant influence on the efficiency of the pheromone traps, those placed just above the crop canopy being most effective. There was no evidence that any other genus of parasitoid responded to aphid sex pheromones at these sites.

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Summary. The sex pheromone of the grain aphid, Sitobion avenae (Fab.), is identified as (4aS,7S,7aR)-nepetalactone, for which specific olfactory cells are located in the secondary rhinaria of the male antenna. The related (1R,4aS,7S,7aR)-nepetalactol was not produced by females in significant amounts (ca 10,000-fold less than the nepetalactone), although cells in the male antenna were found that responded specifically to this compound. Behavioural activity in the linear track olfactometer showed attraction of males to the nepetalactone, but not to the nepetalactol.