736 Invasive Stink Bugs and Related Species (Pentatomoidea)
of natural enemies that were eliminated by insecticidal applications that targeted primary pest species,
and appearance of resistance, which required increased applications per year and increased amounts
per application. These developing problems were ignored or discounted by entomologists and the
general public, particularly those involved with selling pesticides. In fact, the rates at which these
negative effects were appearing were undoubtedly influenced significantly by the practice of preven-
tive control.
Another problem during this period was the increasing expectations of consumers for high quality
produce (i.e., no blemishes). As DeBach (1964) noted, the consumer had adopted the slogan that “the
only good bug was a dead bug” and, in doing so, thoroughly accepted “the advertising idea that shiny
clean fruit, etc., are better fruit. No thrips scars, not a scale insect, must be present. Quality and taste are
really forgotten to a large extent; appearance is of prime importance.”
How does one obtain perfect produce? With pesticides. Use of DDT and other chlorinated hydrocar-
bons produced perfect apples, tomatoes, and many other crops. The nonchemical methods (e.g., cultural
control, biological control) then available could not produce the same high quality and generally were
ignored (Turnbull and Chant 1961).
One characteristic of the chlorinated hydrocarbons that had been considered a positive attribute
in the beginning was that of a long residual action. However, it began to be viewed negatively as the
other concerns about pesticides mentioned above became more evident. Thus, the organophosphates
and carbamates were developed, which had a short residual action. These could be applied just before
crops were harvested and sent to market. Unfortunately, the organophosphates (OPs) generally are more
toxic to humans than the chlorinated hydrocarbons (malathion probably is the least toxic of the OPs).
Carbamates, as a class, generally are less toxic than the organophosphates, though both have a similar
mode of action (synaptic poisons) (Ware 1994).
Biological control plays a major role in pest management today. But, research on this tactic
already was being conducted when DDT was introduced to farmers in 1945 and had been shown to
be effective since the late 1800s in some cases (see above). However, up into the 1960s, there was
a reluctance by farmers to rely on biological control because it was much easier to use insecticides,
and biological control could not provide 100% control. This is because an effective parasitoid rarely
eliminates 100% of the host population. The result is there may be damage. The farmer, then, is
faced with one of two choices: (1) accept an increased risk that there will be insect damage and a
reduction in marketable yield and/or the price received for the harvested product or (2) continue to
use insecticides.
Biological control varies in its effectiveness depending on the type of injury caused by the pest species,
direct or indirect. Direct injury is damage to the part of the plant (e.g., fruit) targeted for harvest. Indirect
injury is damage to non-harvested parts of the plant (e.g., twigs, leaves, bark). Biological control is most
valuable for control of pests causing indirect injury because 100% control is not needed (Turnbull and
Chant 1961).
The turning point in blind reliance on pesticides and belief that there was no downside to their usage
was the 1962 publication of Rachel Carson’s book, “Silent Spring,” in which she dramatically and force-
fully brought to the attention of the public the dangers associated with these insecticides. Not only were
they hurting the environment, they could be deadly to those who used them. She not only discussed the
harmful effects of pesticides on vertebrates and invertebrates but was particularly critical of the long-
term effects of the chlorinated hydrocarbons because of their long residual characteristic and subsequent
biomagnification in food chains. To this can be added the off-site movement of pesticides to surface
waterways and ground water and pesticides on harvested products.
Rachel Carson’s book was viewed by many, including entomologists, with much hostility. But, today,
it is considered a landmark publication, which resulted in major changes in current pest control and how
pesticides are viewed by the public. Numerous changes in public policy, including changes in the regula-
tion of pesticides and their usage, occurred in both the United States and Europe. Today, pesticides are
viewed by some as a necessary evil and should not be used if there is an alternative. If they are used, they
should be used as infrequently as possible, exceptions being emergency situations (sudden outbreaks,
particularly diseases).