J. HYM. RES. 1(1), 1992 pp. 3-14 Phylogeny of the Non-Aculeate Apocrita and the Evolution of Parasitism in the Hymenoptera James B. Whitfield Department of Biology, University of Missouri, St. Louis, MO 63121, U.S.A. Abstract. — Recent interest in the higher-level phylogeny of Apocrita has led to the advancement of several competing hypotheses of relationships among major lineages. Nevertheless, some areas of agreement do exist among these hypotheses, providing a base from which further progress can be made. A well-corroborated phylogeny for the Apocrita would be extremely useful for interpreting the evolution of parasitism, among other features, within the Hymenoptera. Comparative studies of parasitoid / host biology are still at a relatively early stage. Most of what is known of parasitoid biology is derived from relatively few taxa of Ichneumonoidea, Chalcidoidea and Scelionoidea, and even within these groups data are extremely sparse. A number of specialized biological features associated with endoparasitoid groups show intriguing patterns of distribution among taxa, but so little is known of these features across all taxa that coherent evolutionary hypotheses concerning these features cannot yet be advanced. It is suggested that more emphasis be given to comparative parasitoid biology, especially within poorly-known groups. Interest in the evolution of the Hymenoptera is certainly not new; broad treatments of the phylog-eny of the order and the evolution of the food habits of its members span at least most of this century (e.g. Handlirsch 1907, Borner 1919, Brad-ley 1958, Malyshev 1968, Iwata 1976, Tobias 1976, Hennig 1981). Only within the past several de-cades, however, have relatively explicit and prac-tical methods of phylogenetic inference been avail-able so that studies of hymenopteran evolution have become repeatable and open to productive criticism. Even more recent is the wholesale recog-nition of the value of specific phylogenetic hypoth-eses for interpreting the evolution of biological traits (e.g. Coddington 1988, Donoghue 1989, Brooks and MacLennon 1991, Harvey and Pagel 1991). Although this by no means implies that studies of hymenopteran evolution prior to the last few years do not continue to be valuable (such careful studies as those of Oeser 1 961 and Brothers 1 975 on Aculeata, for instance, have held up remarkably well to further scrutiny), it is much easier to evalu-ate the more recent ones in the light of the actual evidence that is presented, so that one study builds upon another. In this brief overview I first hope to quickly cover some of the major findings and controversies of recent phylogenetic studies of the higher taxa of 1 Current address: Department of Entomology, University of Arkansas, Fayetteville, AK 72701, U.S.A. Hymenoptera, focusing especially on the non-ac-uleate Apocrita, which were often under-repre-sented and poorly understood in earlier studies. I will begin with the exhaustive literature review and analysis of Konigsmann (1976, 1977, 1978a,b) and continue to the present, attempting to consoli-date some areas of agreement among the various studies and to point out where disagreement is rampant and further study would be most valuable. In the second main segment of this paper I briefly review what is currently known about vari-ous comparative aspects of the parasitoid habit among the groups of non-aculeate Apocrita. I will first focus on the ways in which parasitoids have overcome the problems associated with an evolu-tionary transition from ectoparasitism (the puta-tive ancestral form of parasitic lifestyle in Hym-enoptera) to endoparasitism. There will follow a brief discussion of how some of these parasitoid "strategies" are distributed among hymenopteran higher taxa. Although an attempt will be made to illustrate the value of a phylogenetic perspective in interpreting such comparative data, the major goal of this review is to point out areas where new comparative biological data would add apprecia-bly to our understanding of the evolution of para-sitism in the Hymenoptera. It is one major virtue of a phylogenetic approach that the distribution and depth of comparative data among taxa must be made explicit so that areas of ignorance become clear.
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