Efficacy of Inundative Releases

Abstract

The value of entomophaga for regulating and controlling agricultural pests has long been recognized (23), but conscious manipulation and utilization of arthropods was all but abandoned by most entomologists with the advent of modern pesticides in the 1940s (89). Subsequent concern about resistance, pesticide misuse, and contami­ nation (17) has reestablished the use of arthropods for pest control. The work up to the early 1960s has been summarized (26); therefore, this article is limited to research reported since that time. Two distinct categories for augmenting the use of beneficial arthropods have been recognized (26): inoculative and inundative releases. The former involves releasing relatively small numbers of beneficial arthropods as colonizing populations, with the purpose of providing relatively long-term pest regulation through in-field reproduc­ tion of the released species. Inundative releases, on the other hand, release large numbers to cause an immediate and direct mortality in the pest population, with no expectation of long-term regulation. It is this latter usage of entomophaga as biological insecticides to which this article is addressed . .In practice, however, it must be realized that the distinction between these categories is often vague. Inoculative releases may be made over several weeks and involve relatively large numbers of individuals released, whereas the inundative approach may only require, at certain times, a single release of relatively low numbers to achieve a ratio of predators or parasitoids to prey sufficient for control. There are numerous reviews available on inundative releases in the broader context of biological control and integrated pest management (6,25,27,45,78,90, 94,98, 101) and for specific crops or pest complexes (21, 29, 38, 61, 62, 92, 104, 117, 131, 135), therefore the purpose of this paper is not to give an exhaustive review