Byers, J.A. and Castle, S.J. 2005. Areawide models comparing synchronous versus
asynchronous treatments for control of dispersing insect pests. Journal of
Economic Entomology 98:1763-1773.
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Abstract--
Integrated pest management (IPM) has the goal of combining several control methods
that reduce populations of pest insects and their damage to tolerable levels and thereby reduce the
use of costly pesticides that may harm the environment. Insect populations can be monitored during
the season to determine when the densities exceed an economic threshold that requires treatment,
often as an insecticide application. We developed a simulation model where insect populations varied
in exponential growth in fields and dispersed to adjacent fields each day of a season. The first model
monitored populations of individual fields in a grid of fields and treated any field with insecticide if
it exceeded a threshold population (asynchronous model) as done in traditional IPM. The second
model treated the entire grid of fields with insecticide when the average population of all fields
exceeded the threshold (synchronous model). We found that the synchronous model at all growth
and dispersal rates tested had average field populations during a season that were significantly lower
and required fewer treatments than the asynchronous method. Parameters such as percentage of
fallow fields, number of fields, and treatment threshold had little affect on relative differences between
the two models. The simulations indicate that cooperation among growers in areawide monitoring of
fields to obtain an average population estimate for use in treatment thresholds would result in
significantly less insect damage and fewer insecticide treatments. The synchronous method is more
efficient because population refugia are precluded from which dispersal could reintroduce insects.
Chemical Ecology