Effect of plant volatiles in Cydia molesta responses to pheromones (quantity and qualitatively)

Abstract

Our work will focus on the effect of plant volatiles in Cydia molesta responses to pheromone. Volatiles emitted from host plants often synergism or enhance insect responses to suboptimal (under) sex pheromone doses quantity and qualitatively (pheromone and %E). The first goal of our work consisted in established, in the field under natural circumstances, a pheromone dose-response curve to determine a suboptimal pheromone dose. To concretize this, an Orchard block of Peach and Nectarine trees was used to test male capture to delta traps, containing a range of dosages. The tested treatments were: Hexane, 1μg, 10 μg, 100 μg, 1mg and 10 mg. We decide to use 1 mg as optimal and 100 μg as suboptimal for our experiment. Previous data (laboratory) show that comparing the dose response in the field and in the laboratory the curves do not overlap. In the field a higher concentration is required to elicit responses. According this mentioned conditions, we wondered if plant volatiles also synergize “off-blends” in under or over dose. Different proportions of (E)-8-dodecenyl acetate (E8-12:Ac) were tested in laboratory to verify which one was the optimal quantity in the complete pheromone blend ratio (2, 4, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 ng). Results showed that 10 ng was the optimal quantity in ratio to our laboratory population. We compare USA and Italian population of Cydia molesta and with this, we found that the curve response to %E E8-12:Ac of our Italian population is very different from the USA population. This can be explained by the fact that populations may be genetically different. With this knowledge, biological control can became more efficient.