Effects of biological control on long-term population dynamics: identifying unexpected outcomes

摘要: Summary 1. Attempts to control natural systems through management have often met with success but also led unexpected and undesirable outcomes. Unfortunately, the ultimate result of such programmes may not be apparent until long after efforts begun. This is particularly true for forest-defoliating species that exhibit longperiod cycles as invasive gypsy moth Lymantria dispar, which causes widespread damage in some years rare other years. 2. We studied effects two commonly employed biocontrol agents on dynamics using a series field-tested empirically parameterized mathematical models, allowed us examine various potential strategies assess long-term effects. 3. In non-spatial model, addition either manufactured version same baculovirus involved epizootics, or general bioinsecticide Bacillus thuringiensis var. kurstaki (Btk), directly kills fraction population, decreases amplitude between boom bust portions cycle. 4. However, ill-planned applications can increased densities over term. Thus, maintain pest populations at unexpectedly high numbers, could constant forest defoliation. 5. spatial two-patch where one patch sprayed left untreated, there considerable danger migration patches drive unsprayed population levels 6. Synthesis applications: Perturbations host–pathogen results, driving maintaining multiple including those far from desired goals. It assumed any strategy short term beneficial, our results show outcomes occur. The mechanisms we describe apply many undergo outbreaks regulated by density-dependent processes, disease pesticide application used control. suggest successful should closely monitor responses immediately following ensure are being maintained artificially compared historic data.