Peter J. Silk, Silk Biochemical Services
Edward G. Kettela and Graham Thurston, Natural Resources Canada, Canadian Forest Service-Atlantic Forestry Centre
Vince Nealis, Natural Resources Canada,Canadian Forest Service-Pacific Forestry Centre
SERG Project #2005/04
Year of Project: 2005
Report Received: 2006
Small quantities of the primary sex pheromone component, (E)-11,13-tetradecadienal (E11,13–14:Ald), were synthesized using a known synthetic strategy with refinements, using alkylation of 3-sulfolene (a "masked" diene) as the key step. Several refinements to the synthetic route were introduced in our laboratory this year. The thermal desulfonylation step utilising NaHCO to "unmask" the diene gave the desired ca 100% E (trans) stereochemistry to the delta-11 double bond under the conditions employed.
We utilized red rubber septa as the optimal trap bait component because it is reliable for aldehydes. In addition, since it is well known that these materials are relatively unstable and photolabile (subject to oxidation /polymerization), we began developing a method to stabilize the active ingredient in the septa (such as use of anti-oxidants and polymer stabilizers).
Preliminary GC/EAD (gas chromatography/ electroantennography) of excised virgin female glands revealed only activity at the E11,13–14:Ald retention time (confirmed by GC/MS); this early data suggests that no other major pheromone components exist. Minor components may still be present since gland titre, even for the major component, is very low; further analysis is underway.
Field trapping experiments clearly show that both 10 and 100 µg quantities of E11,13–14:Ald on red rubber septa are highly attractive to male Acleris variana (100 µg >10 µg ; P<0.05), with few other insects trapped, imparting high specificity to the trap and bait. The non-saturating Multipher traps gave reliable results, and their use is recommended for survey work with this insect. The comparison of the efficiency of trapping with milk carton traps (MCT) vs Multipher traps showed that either trap was equally effective in capturing males. MCTs have the drawback of easily and quickly saturating with males and, therefore, may not be useful at high insect densities.
Our data suggest that a trap bait of 100 µg of E11,13–14:Ald on red rubber septa in Multipher traps is a highly effective tool that can now be developed to monitor blackheaded budworm populations. An anti-oxidant such a BHT is essential, and a UV-protectant will likely be required as well to maintain the field life of this unstable compound both in trap baits and in other controlled release devices.