Agriculture Reference
In-Depth Information
regime for a whole season, plus a vigorous sanitation program, including
the removal of bins, brush, unpicked fruit, wood piles, general debris,
and abandoned apple, pear, apricot, quince, crabapple, hawthorn, and
walnut trees, to prevent re-infestation. In a few cases, the pest popula-
tions were so high that it merited an organophosphate application
after
the fruit had been picked to reduce populations to the point they could
be managed with pheromones alone the following spring. Historical non-
pesticide tactics included the use of corrugated cardboard (size Flute A,
18-inch rolls) collars around the base of trees to capture pupae in the
winter, which are removed in the winter and burned. Some organic
growers have used this effective, albeit labor-intensive, supplement to
sanitation, and a few conventional growers are considering it again.
Insecticides leave undeniable evidence: dead insects. Initially scientists
and PCAs had to monitor the effects of mating disruption on pest popu-
lations by inspecting fruit for damage, but very quickly they developed a
“supercharged” monitoring lure with ten times the pheromones. This
trap emitted chemicals that would “punch through” the background
level of pheromones. It worked well most of the time, but that is not
good enough for production agriculture, so researchers developed a
kairomone lure that mimics the volatile odor of ripe Bartlett pears. PCAs
now typically use these in tandem.
In recent years, scientists have investigated various explanations of the
precise mating-disruption mechanisms. The false plume theory holds
that the males follow the odor boundary of the manufactured
pheromones to a dead end. The camouflage theory suggests that the
manufactured products drown out the female pheromones. Some had
proposed the sensory overload theory: the volume of pheromone in an
orchard is so great as to overload the senses of the males and disorient
them completely. The success of the supercharged lure confirmed that
insect antennae adapt and filter out levels of overwhelming levels of
pheromones. Finally, the distortion theory holds that the pheromone
product disorients the navigational capacity of the insect. As of this writ-
ing, scientists agree that disruption is complex and observe that better
control is achieved when mating-disruption technologies take advantage
of several mechanisms.
The Randall Island Project was one of the first efforts to deploy
synthetic coddling moth pheromones at a field scale, but Welter collabo-
