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-An Integrated Pest Management is formulated as a threshold policy. It is shown that when this strategy is applied to a food web consisting of generalist, specialist predators and endemic and pest prey, the dynamics can be stable and useful from the pest control point of view, despite the dynamical complexities inherent to the application of biocontrol only. In addition, pesticide toxicity depends rather on the species intrinsic parameters than on the chemical agent concentration.

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Yodzis discusses how the differing biological assumptions as to predator interference on the forms of predator-prey models can influence the conclusion to be drawn from multispecies population models with respect to the way predators affect human harvesting of natural populations. To deal with these intricacies related to biological assumptions and fishery management policies, a specific management strategy called threshold policy is proposed. It is shown that its application to the same models analysed by Yodzis leaves the behaviour of the managed population less sensitive to the underlying biological features and assumptions as well as parameter uncertainties. The same management strategy is proposed for the same models in the context of the timely issue of predator culling in fisheries. Interestingly, the fishery yield for each model is exactly the same despite their different biological assumptions.