One shortcoming of the pheromone trap is that the catch each day is affected by weather, especially temperature and humidity. However, if trapping is continued throughout the whole flight period, 3-4 weeks in late June and July, daily differences are probably compensated for.

Trap location also affects their pheromone efficiency, catches are highest at the top of the tree canopy, an inconvenient location for placement and retrieval. However, provided catches are adequate at lower levels there is no need to strive for maximum catches. The same consideration applies to trap design; cost and ease of handling are of prime importance and, if a simple inexpensive trap provides adequate results, costly design improvements are unnecessary. Learn about human pheromones at

The discovery of trans-1-tetradecenal as a synthetic attractant provided the opportunity to test the feasibility of using sex attractant traps in extensive surveys in 1972. Green Sectar 1* traps were placed out in 272 permanent sample plots in eastern Canada. Check out human pheromones at

Pheromone population estimates are made annually in these plots by beating foliage, allowing comparisons to be made between the two sampling meth- ods. Each trap was baited with a polyethylene vial stopper containing 2 mg Sprudamone (Zoécon** trade name for trans-1 l-tetradecenal), which should have approximated the attractiveness of a single virgin female (table 22.4). Results show- ed a poor correlation between the larval counts and adult male catches. With a log—l0g transformation a straight line of the equation log Y = 0.46 +0.49 logX (where Y = moths per trap, X = larval counts) gave a correlation coefficient of 0.54.

However, which method gave the better pheromone estimate could not be resolved. Results were disappointing, in that too many of the plots gave zero catches (80 out of 272), a situation which the earlier adult female trapping indicated should not have happened. Concurrent tests showed that the bait used was only about 10% as effective as a virgin female, and reasons for this discrepancy are being investigated. A short- coming of the polyethylene vial stoppers is that the release-rate of the aldehyde (as determined by weight-loss studies) falls off very quickly over time, giving a tenfold difference over a three week period. Learn more about pheromones for men 2016 |

Although preliminary results indicate that the pheromonal response of the male budworm is fairly constant over a considerable range of release-rates, this is a variable which can confound the interpretation of the results. There is therefore a definite need in the future for a wick which provides a more uniform release rate throughout the budworm flight period.

Prospects for Pheromone control

Investigations into the use of sex attractants and pheromones inhibitors in the control of spruce budworm populations have barely begun. It is considered unlikely that they will ever be of use in high density populations. Trapping would require an impractical number of traps, and mating disruption would be unlikely to succeed where there is a high probability of insects encountering each other by accident. Control strategy will have to involve the early detection of an ominous increase in endemic numbers followed by immediate treatment to check the increase. Possibly as few as 70 traps per hectare would be required to give 50% reduction in mating success at endemic population densities; but this is still a large number if applied to thousands of hectares. Because the spruce budworm are active throughout the canopy, pheromone traps would also have to be distributed in a vertical plane throughout the foliage which presents problems.