General Insect Management 741
the shorter harvest schedule is to harvest the alfalfa in strips, always maintaining a portion of the alfalfa
field in a state that is attractive to the bugs, thereby minimizing any migration into cotton (Sevacherian
and Stern 1975, Summers 1976).
16.3.1.1.11 Host Plant Resistance (Non-GMOs)
Selecting crop varieties based on their tolerance or resistance to pests can be considered another form of
cultural control. Many crop-breeding programs have been focused on developing commercially accept-
able varieties that are resistant to a wide range of pests. Differences in pest susceptibility among crop
varieties can be based on pest evasion, antixenosis, antibiosis, or crop tolerance.
Pest evasion is a reduction in damage by not having the susceptible stage of the plant present when the
pest is abundant. For example, an early-maturing variety of soybean can appear to be resistant to late-
season migratory pests [e.g., fall armyworm, Spodoptera frugiperda (J. E. Smith); and soybean looper,
Chrysodeixis includens (Walker)] because it matures before these pests arrive. However, if an early-
maturing variety intended for a pest evasion approach is planted in a situation where the pest is present
when the plant is susceptible, this variety is just as susceptible as other varieties.
Antixenosis, or non-preference, is a form of host plant resistance that has the biggest benefit when pests
have a choice of hosts (Kogan and Ortman 1978). It has a genetic basis with less desirable morphological
(e.g., thorns, leaf hairs) or physiological (chemical deterrents) features for the pest. These features do not
actually kill the pest, but cause the pest to preferentially feed on other hosts when available. However, in
large, monocrop situations, this type of host plant resistance has minimal impact because the pest has no
choice, feeds on the plant, and can develop normally.
Antibiosis is the goal of most host plant resistance breeding programs. In this case, the pest is adversely
impacted by feeding on the plant. This may be due to the presence of one or more toxic metabolites or
a sub-optimal amount of some essential nutrient. Although this type of host plant resistance often pro-
vides the highest level of pest control, it also is the type of control that pests are most likely to overcome
by developing resistance to it. Because those that are most susceptible to the resistance mechanism are
killed, those that survive and mate are those that are most resistant, creating a situation where contin-
ued selection for resistance to a toxin eventually creates a population that can overcome the host plant
resistance.
The last form of host plant resistance is tolerance to the pest. In this case, the plant has no impact on
the pest, but the plant is able to compensate for pest damage and, therefore, the economic impact of the
pest on the plant is reduced. For example, a variety of corn that grows extra corn roots may not be as
susceptible to corn rootworm (Diabrotica spp.) feeding as other varieties (Owens et al. 1974, Ivezic et al.
2006).
16.3.1.2 Physical/Mechanical Control
Physical or mechanical control of insects involves altering the environment in some physical manner to
make it undesirable or uninhabitable to insect pests (Banks 1976). Several strategies are discussed here
generally and specifically when related to stink bugs or closely related groups.
16.3.1.2.1 Electricity
Ever since the invention of electricity, attempts at using electrical power to eliminate pests have been
endless. One of the most successful strategies for killing insects with electricity involves the combined
use of attractive light and energized metal wires. Traps designed to lure and kill insects with electricity in
this manner have been in use for decades. Although most of these trap types primarily lure and kill flying
insects, they are relatively non-selective, killing pestiferous and beneficial species, and are not generally
effective in killing a targeted species (Heinen et al. 2003). Furthermore, electrocuting insect traps might
actually release into the environment bacteria and viruses carried by insects when their bodies disinte-
grate (Broce 1993, Urban and Broce 2000). Finally, electric stink bug traps can be helpful for monitoring
general population trends, but there is no evidence that enough bugs can be attracted to actually reduce
population density in an outdoor setting.