Food Webs, Risks of Alien Enemies and Reform of Biological Control

摘要: As ilwasions of alien species mount, biological control ''''ill become an increasingly important tool conservation and agriculture. In effort to understand indirect interactions in control, we review food web ecology terms resource competition, trophic cascades, intra-guild predation, apparent omnivory a diverse set tri-trophic interactions. The most inclusive study suggests that webs are simpler than natural communities. Risks non-target created by have been studied seriously for only about 20 years, knowledge these risks is incomplete. greatest known be posed the organisms with broadest diets, such as vertebrates snail Euglandina rosea, which has probably caused extinction entire genus native snails Polynesia. Some parasitoid introduced sufficiently polyphagous attack insects, cases serious harm populations now coming light. However, continue imported control. One case point campaign against Russian wheat aphid, over 8.5 million individual invertebrates, including more 1 individuals 12 ladybird beetles new North America, were released past 15 little potential effects, direct or indirect. Another use black carp suppression pest industrial catfish ponds. This fish poses great high diversity molluscs Mississippi drainage. We argue risk flora © CAB International 2001 . Evaluating Indirect Ecological Effects Biological Control (eds E. Wajnberg, J.K. Scott P.c. Quimby) 57 58 O.R. Strong R. W. Pemberton weeds can judged before introduction. For New "Vorld, lowest comes from stenophagous insects no congeners. vVhen congeners, introductions even relatively led non-target, plants. Restraint key safe First must come judicious winnowing targets. Not every threat. not appropriate response pest, especially perceived pests. Second, available enemy promises relief. Importing multiple agents lottery search one might do job increases probability attacks upon biota. open discussion versus benefits What was basis choice large number aphid? "'bat calculus benefit dissemination delta? Regulation USA archaic. Oversight derives hotchpotch old legislation designed serve agriculture, protection under current regulatory frame,,,'ork deficient. Native terrestrial, aquatic marine, at structure, while plants had some, but full, foreign herbivores disseminated Although ecological economic value invertebrates widely appreciated, crucial integrity our wild, urban agricultural landscapes. among threatened species, contribute webs. sensible course extend Federal minimize all organisms. There also need pay attention after they released, restrict propagation re-release those damage ",lith invasive just many environmental issues, doing nothing neutral. Imported enemies last best hope parry some damaging exotic pests areas well absence reform, rational irrational opposition will grow. Only reform maintain public support this powerful tool.