Biologically Based Technologies for Pest Control Page: 41
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Chapter 3 The Technologies I 41
biological control. Few BBTs are yet in use
against plant pathogens.
I Applications
The goals of pest management vary with the
application site. Application sites also differ in
who practices pest control and in the range of
available, acceptable, or feasible pest control
technologies. The necessary or desired level of
pest suppression is higher under some circum-
stances than others; for example, blemish-free
fruit production requires very low rates of insect
damage, whereas greater pest abundance may be
tolerated in forests or rangelands. BBTs may be
easier to adopt in the latter circumstance because
the technologies usually suppress, but do not
locally eliminate, pests. Other pest control tech-
nologies that compete with BBTs are more com-
mon in some applications, such as major crops.
These factors, combined with the uneven avail-
ability of BBTs, have generated today's hit-or-
miss pattern of BBT use.
Arable Agriculture
Current use of BBTs in arable agriculture (culti-
vated lands) is confined almost completely to
insect pests. A number of major food processors
and growers have begun to rely on BBTs in "bio-
intensive" IPM systems (figure 3-2). From 1990
to 1993, for example, the Campbell Soup Com-
pany worked closely with Mexican tomato grow-
ers to eliminate all uses of chemical insecticides.
The resulting system combined monitoring, Bt,
pheromones, and Trichogramma wasp releases
to provide comparable control of insect pests at a
lower cost (30).
Millions of acres of U.S. crops are currently
protected from one or more pests by the intro-
duction of classical biological control agents
which have provided some level of suppression
for 63 arthropod pests (123,411). Most of these
biological control agents were introduced some
time ago, but others are fairly recent; for exam-
ple, introduction of parasites against the alfalfa
weevil (Hypera postica) from 1980 through 1992contributed significantly to a reduction in that
pest's abundance and impacts (174).
Augmentative releases of natural enemies by
farmers occur primarily in vegetable, fruit, and
nut crops (table 3-1) (377). Many of these uses
are relatively recent. However, augmentation is a
long-standing practice in some areas. In the
1930s a number of California citrus growers
formed the Filmore Citrus Protective District, a
cooperative that now produces natural enemies
for use against citrus pests such as mealybugs
and scales on more than 9,000 acres (173).
Augmentative use of natural enemies in green-
house agriculture is growing (411). The approach
is widespread in Europe, where cultivation of
vegetable crops in greenhouses is more common.
Greenhouse agriculture in the United States
occurs on only several hundred acres. The green-
house industry for ornamental plants is much
larger (valued at $2.5 billion in 1993), but the
potential for use of natural enemies here is lower
because less pest damage is tolerated on the
products and new chemicals may provide signifi-
cant competition (box 3-2) (411).
Few data quantify how frequently farmers
deliberately modify farming practices to con-
serve natural enemies on U.S. croplands. Inter-
cropping, modification of cropping practices,
and selection of crop varieties to enhance natural
enemies all look promising to researchers but
have not been widely adopted (411). Some Cali-
fornia vineyards and almond growers report that
certain vegetation practices enhance natural ene-
mies of arthropod pests and plant pathogens
(257,258). Other management practices that inci-
dentally conserve natural enemies are more
broadly used. One example is the routine moni-
toring of natural enemies and pests in commer-
cial orchards; farmers delay use of insecticides if
the ratio of predators to pests is high enough to
prevent pest damage (411). Vegetable, potato,
and cotton growers commonly consider the
effects of pesticides on natural enemies when
deciding which chemicals to use and when to
apply them (table 3-1) (377). Similar practices
are widespread among Pennsylvania apple grow-
ers (282).
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United States. Congress. Office of Technology Assessment. Biologically Based Technologies for Pest Control, report, September 1995; [Washington D.C.]. (https://digital.library.unt.edu/ark:/67531/metadc39770/m1/47/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.