John A. Byers

Modeling of IPM Methods and Strategies

Modeling is helpful to understand integrated pest management (IPM) systems and to develop and test new methods of control. Most farmers use IPM on their fields and do not cooperate with neighbors. Each manager monitors his crops for insect populations levels that exceed an "action threshold" that causes him to treat his fields (usually insecticide spray) and knock down the pests. However, his neighbors may have lower densities so they wait a few days or weeks until they also have higher densities of pest and reach the threshold eliciting treatment. In the meanwhile, pest insects fly to the first managers fields and build up much faster than they would if all fields were treated when the first manager treated his fields. Later, if the treatments are asynchronous the pests from the first managers fields fly to the recently treated neighbors fields and innoculate them so they build up populations much earlier than otherwise. The models below show that synchronous treatments over a larger area would save cooperating farmers huge sums of money over the conventional IPM methods. Also, there would be less frequent insecticide sprayings. In the synchronous strategy, all farmers would monitor and when the average density reached the action threshold then all fields would be treated and reduce populations to a low level over the entire area. The populations would rebound but much slower than if new recruits could fly in from neighboring fields. The population growth is "S"-shaped and much slower at low populations (like right after treatment). Unfortunately, most farmers are humans and look out for their own fields and do not cooperate so they will probably pay for treatments much more often then necessary as indicated by the models. Maybe some will pay attention and consider starting a cooperative monitoring and treatment program but the organizational and momentum problems may not allow this idea to be accepted for some time. Well, we tried.


Areawide IPM Models Java applet of Areawide IPM models

Questions concerning these program areas can be directed to: