Benefits and Costs of Controlling Rangeland Grasshoppers (Orthoptera: Acrididae) with Exotic Organisms: Search for a Null Hypothesis and Regulatory Compromise

Abstract

The rebuttal of Lockwood (1993, Environ. Entomol. 22:503–518) by Carruthers & Onsager (1993, Environ. Entomol. 22:[in press]) focuses on the elements of cost-benefit analysis and regulatory policy. I present the case that “native” has ecological, evolutionary, ethical, and legal meaning (hence the term neoclassical biological control is justified). In comparing the costs and benefits of grasshoppers (using only conditional values), the argument that costs of widespread damage and control exceed the benefits interms of sustained ecological and economic productivity is not supported by available data, whether we consider the interests of the rancher or the public. Moreover, when unconditional values are included, neoclassical control of rangeland grasshoppers becomes indefensible. Contrary to selected evidence presented by Carruthers & Onsager (1993), existing data show that native biological control agents are as or more effective in population regulation than the exotic agents. Host ranges of the exotic organisms are essentially unknown given the quality and quantity of available data, so ecological safety assurances are unfounded. A careful review of the data used to demonstrate the probability of success by the proposed exotic agents clearly demonstrates that these organisms have a very lowlikelihood of economic or ecological benefit. The essential ecological differences between various forms of biological control must be addressed in terms of regulatory policies and procedures. Existing federal laws may be sufficient to protect the agricultural and environmental interests of western rangeland, but only if these laws are interpreted and enforced from a sound ecological basis.