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The Biology of Pheromones

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In many respects. the mating disruption strategy for insect control seems to have been conceived with the western pine shoot borer, Eucosnm smmrmtnu Kcarfott. specifically in mind. This insect’s life history and habits make it generally immune to control by conventional methods but especially vulnerable to manipulation by mating disruption. Both aerial and ground application methods for use of mating disruption against borer populations have been successful. At this writing, Environmental Protection Agency registration and operational use of mating disruption to control the shoot borer appear imminent. Learn more about Alpha A314 pheromones | Pheromones-Planet.com

BIOLOGY

Considering the cryptic habits of the western pine shoot borer, it is not surprising that conventional pest control measures are ineffective. The adult moths are in flight for only a few weeks in early spring, at which time mating and oviposition occur. Eggs are deposited beneath bud scales,‘ and the larval stage is spent mining the pith of the elongating shoot.’ Depending on geographic location and seasonal temperatures, flight and oviposition may occur from February through May. The dominant leader shoot appears to be the preferred site for oviposition and feeding, although lateral shoots of the upper branches are often infested as well. Larval development roughly coincides with elongation of the new pine shoots. When larval development is completed, the insect moves to the ground to pupate and overwinter in the litter. Learn more at https://jail6letter.wordpress.com/2015/12/19/pheromone-stages/

There is a single generation per year. For successful mating disruption, the most significant biological characteristic of E. sonomana is the relatively low number of insects per hectare of pine plantation. Rarely is more than one larva found per pine shoot, and availability of leader shoots and suitable shoots on lateral branches apparently limits the numbers of insects that can potentially develop in a given location. Even in very heavy infestations, it is doubtful if the number of adults exceeds several hundred per hectare.

Pheromones emitted by the queen dictate the behavior of her workers. Usually eight or more worker attendants are present when a queen is stationary, but they tend to lose Contact as she walks rapidly over the comb. For example, an average of 6.2 attendants has been recorded (Allen, 1957) when the queen is moving, increasing to 8.7 when she is laying an egg and 10.8 when she is stationary. The amount young queens are licked and palpated increases as they become mated and lay eggs, but when they have grown old and are laying haploid eggs they receive less attention (Free er al., 1987a). This can be seen in the table below:

Type of queen Number of workers Number of workers licking queen palpating queen Virgin 0. 1 4.0 Newly mated 0.3 5.4 One—year-old mated 0.6 7.9 Old mated 0.4 5.7

This characteristic low-density, scattered population of adults is considered a strong advantage for the mating disruption approach to control, since it logically means that pheromone communication is more essential to successful reproduction than for a closely aggregated species. Tests with stored-product insects and observations in the field support the general view that mating disruption is more effective against lower density populations.” Learn more about pheromones at http://mpommett79.hatenablog.com/entry/2015/09/14/040259

III. DAMAGE POTENTIAL

The western pine shoot borer is known to infest ponderosa pine, Pinus ponderosa Laws., lodgepole pine, P. contorta Dougl., and Jeffrey pine, P. jeffreyi Grev. and Balf." Other apparent hosts are knobcone pine, P. attenuata Lemm., and Monterey pine, P. radiata D. Don.’ An extensive trapping study revealed that E. sonomana has a wide distribution throughout the western U.S.,7 and in a separate study it was also reported in western Canada.“

Larval boring within the pith of elongating shoots may stunt or even halt shoot and needle growth (Figure 1).‘ Occasionally, leader shoots are killed which may lead to forking or other multiple leader conditions that adversely affect tree form. Such forking can also result from laterals overtopping stunted leaders. Trees in the l.5- to l5-m height range appear to be most susceptible to damage, and it is not uncommon for trees to be infested repeatedly year after year.’ The cumulative damage could reduce tree height at harvest age by as much as 25%. Monetary loss would result from the pheromones. Learn more about Max Attraction Gold pheromones at http://youthbruce.com/2016/05/03/does-max-attraction-gold-work/

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