Overriding Principles

Predator—prey relationships are not chaotic, but are based upon time-tested principles with constant refining and generation of new approaches. Principles for prey include: (1) it is better to avoid attack than to defend against an attack; (2) the higher the cost or penalty suffered by a predator, the greater protection gained by the prey; and (3) avoid sharing time and space with as many potential predators as possible. Combinations of these principles form the basis for most successful defenses of insects. However, the story is complex: insects usually face not just one, or even a few, species of predators, but rather a whole suite of potential predators. And the biggest, fiercest predator usually is not the one that poses the greatest risk. To be successful, insect populations must maximize their defensive success against the summation of all predator attacks encountered. This is the combination of the probability of attack by each potential type of predator and the probability of success in countering the attack. Herein lies the experimentalist's dilemma: how can we know all of the predators that have impacted the evolution of an insect's defenses, the frequency of the attacks by each predator type, the success of the attacks by each predator type, and whether "phantom" predators, predators that might have posed serious threats in the past or become threats only at very infrequent intervals, exist. In addition, to access accurately the role of predators, the effects of predators during both bottleneck and outbreak periods of the insect's population must be evaluated. A clever experimentalist is an outstanding observer of natural history and the biology of the insect in question and successfully controls as many variables as possible to resemble nature.

0 0

Post a comment