Effect of wheat plant volatiles on aphids and associated predator behavior: selection of efficient infochemicals for field study

Semiochemicals are involved in tritrophic interactions and affect the behaviors of both herbivores
and beneficial insects. Many volatile molecules from the wheat plant [Triticum aestivum L. (Gramineae)] have previously been
identified. To understand their effects on aphids and related auxiliaries. [Methods] The impact of four of these volatiles;
methyl-salycilate, cis-3-hexenyl acetate, hexenol, and 1-hexanol, was tested on the wheat aphid [Sitobion avenae (Fabricus)
(Homoptera: Aphididae)] and two major predators of this pest encountered in field crops, the hoverfly (Episyrphus balteatus
(DeGeer) (Diptera: Syrphidae)] and the multicoloured Asian ladybird [Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)].
Different doses of these chemicals were tested by performing four arm-olfactometer and wind-tunnel assays. [Results] The
results show that methyl-salycilate seemed to be attractive only toward H. axyridis but 3-hexenyl acetate and hexenol were
attractive to both S. avenae and H. axyridis. However, these positive responses decreased with increased dose of the tested
compounds. 3-hexenyl acetate also induced positive response in E. balteatus but 1-hexanol was more attractive to aphids than to
their natural enemies. [Conclusion] In conclusion, these results highlight the potential benefit of combining methyl-salycilate,
3-hexenyl acetate and hexenol in push and pull traps aimed to control S. avenae. Contrary to the three aforementioned compounds,
1-hexanol did not seem to have much potential as a semiochemical for the biological control of aphids.
Key words wheat, volatiles, infochemicals, aphid, predator, behaviour