Behavioural responses of first instar codling moth, Cydia pomonella (L.), to α-farnesene: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Horticultural Science with Honours at Lincoln University

Abstract

First instar codling moth larvae from laboratory-reared (lab) and field-collected (wild) colonies were observed in closed still air arenas containing apple skin or a range of α-farnesene concentrations. Larvae from the lab colony showed a strong attraction toward the apple skin in contrast to the less responsive wild larvae. Differences in conditions between the lab and wild colony experiments could account for this result. Experiments using a range of α-farnesene concentrations on treated filter papers showed that wild larvae orientated more strongly towards the treated papers compared with the lab larvae. The optimum α-farnesene concentration for successful larval searching, in both lab and wild colonies, was 10⁻⁶g. Concentrations above and below this level were less attractive. Wild larvae on average walked 90% faster than lab larvae. Similarly, head turning and lifting (klinotactic behaviour) occurred 30% and 60% respectively more often in the wild larvae. Klinotactic behaviour was independent of α-farnesene concentration. A novel model showed that head orientation and walking speed were important components of successful larval searching behaviour.