Comments on Population Dynamics of Exotic Insects

Abstract

This paper is a commentary on the recent article “Population Dynamics of Exotic Insects” by A. D. Turnbull (1967) which treats largely of the competitive displacement principle, DeBach (1966), DeBach and Sundby (1963). Dr. Turnbull has used this latest publication as a vehicle to reiterate his concern over the possible adverse effects of competition on biological control agents. In an earlier publication, Turnbull and Chant (1961), this concern was expressed in relation to the multiple introduction of entomophagous species which they considered bad practice. Now competitive displacement has been seized upon as perhaps another illustration of the unfavorable effects of competition. But in exploiting a situation that seemingly supports this position the author appears to have sacrificed perspective, which in turn has led into serious error. Honest error is understandable, even excusable, and Dr. Turnbull's errors would not be particularly bothersome if they comprised the only flaw in his paper. But error in this case has led to certain statements and implications concerning biological control which if left unchallenged stand to do considerable and perhaps permanent harm to that highly important field of pest control. This is what has induced me to expend time and effort in rebuttal.