Agriculture Reference
In-Depth Information
World War II, research on insect management rapidly shifted to a narrow focus
on chemical control. These long-lasting and highly effective insecticides seemed
a panacea, providing nearly complete control of even the most troublesome pests.
Unfortunately, near sole reliance on chemical controls resulted in the development
of insecticide resistance and decimation of natural enemy communities, and pest
outbreaks followed, as did growing concerns over environmental impacts.
As early as 1959, Vernon Stern and colleagues began to call for the integration
of chemical insecticides into a more holistic set of practices they termed “inte-
grated control” (Stern et  al. 1959). Their concept, now known as Integrated Pest
Management (IPM), sought to combine cultural, biological, and chemical pest con-
trol in a systems approach. In response, researchers developed IPM systems that
combined cultural tools like rotation and resistant varieties with biological con-
trols including importation, conservation, and augmentation of natural enemies.
Additionally, crops were regularly scouted and chemicals applied only after a pest
population exceeded an economic threshold, that is, the population level at which
action is needed to prevent an economic loss (Radcliffe et al. 2009).
More recently, the advent of genetically modified (GM) crops has once again
shifted the focus in pest management. The development of field crops with built-in
resistance to broad-spectrum herbicides—for example, glyphosate-tolerant soybean
and corn—allowed a very different approach to weed management. Rather than
scouting fields for weed species composition and growth stage and using selective
herbicides, growers can now spray a single broad-spectrum herbicide whenever
weeds reach critical levels. Moreover, farmers can also purchase “stacked” GM
crop seeds that not only contain genes for herbicide resistance but also genes for
producing bacterial toxins that confer resistance to multiple insect pests. Although
it has simplified pest management for farmers, reliance on such a small set of tools
has again yielded instances of resistance and concerns about environmental degra-
dation (Ferry and Gatehouse 2009).
Ecologically Based Pest Management
At the same time that agricultural scientists were developing new methods of pest
management, ecologists were beginning to study agriculture from an ecological per-
spective (Lowrance et al. 1984, Carroll et al. 1990, Gliessman 1998, Robertson et al.
2004). One aspect of agroecology has focused on the question of how the biodiver-
sity of cropping systems might be managed to achieve improved pest management
(Altieri 1994). The relationship between biotic diversity and ecological performance
has been a key question for ecologists for more than a half-century. Rooted in the
diversity-stability arguments of the late twentieth century (MacArthur 1955, Elton
1958, Odum 1959, May 1973) and more recently in the study of biodiversity and eco-
system function (Schulze and Mooney 1993, Loreau et al. 2002), our understanding
of the ways in which biodiversity influences ecosystem services continues to evolve.
The study of predator-prey interactions has produced a rich body of theoretical and
empirical work elucidating the influence of biotic diversity on herbivore population
regulation (Ives et al. 2005, Bruno and Cardinale 2008, Letourneau et al. 2009).
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