Phoresy Among Entomophagous Insects

Abstract

The term phoresie was proposed by P. Lesne in 1896 to designate the transport of certain insects on the bodies of other insects for purposes other than direct parasiti­ zation. The subject was reviewed by Ferriere (30), although a large part of his discussion related to species other than those of entomophagous habit. Shortly thereafter, Howard (36) cited a number of examples of this relationship among the parasitic Hymenoptera and proposed the anglicized form of the term, phoresy, which has been in general use in English language publications since that time. Numerous additional examples of phoresy in a number of families have come to light since Howard's account, and this review of the subject summarizes the infor­ mation available to the present time (1973). See also a brief review by Roussy (66), which deals mainly with phoretic mites carried by Hymenoptera. We are concerned here only with those aspects of phoresy that are exhibited by insect parasites and predators of other insects. Lesne's definition of the term specifies transport of an insect upon the body of another, but this is unduly restrictive in the light of present knowledge. Accordingly, in this discussion, the definition is extended to include also transport internally in an insect other than the host, provided such transport is essential or is of common occurrence in the developmental cycle of the insect being transported. This modification in definition of the term to include internal transport is made necessary by the occurrence of both means of transport in the same families, attacking the same host groups, and serving the same purpose. Accidental or causal carriage of one insect by another, without apparent object or purpose and not involving the species on which development is to take place, is not considered to constitute a true phoretic relationship. Feeding on the carrier by the parasite stage being transported, in the rare in­ stances in which this occurs, is only incidental; the primary objective is transport to the host stage in which or on which feeding and development will take place, in lieu of direct search. In some instances, widespread dispersion of the entomorpha­ gous species is incidental to the main function of transport.