The General Host Selection Behavior of Parasitoid Hymenoptera and a Comparison of Initial Strategies Utilized by Larvaphagous and Oophagous Species

The first third of this paper discusses the general host selection behavior of parasitoid Hymenoptera with some modifications of previous interpretations and presentations. This is followed by a section that includes a discussion of a slightly different interpretation of the detectability–reliability paradigm in relation to the role of experience (α-conditioning) and associative learning (β-conditioning) in the host selection process. Also some problems with the definition of koinobionts and idiobionts are briefly discussed. The remainder of the presentation focuses on a comparison of the strategies employed by larvaphagous and oophagous parasitoid Hymenoptera. The focus of the discussion of host location by larvaphagous parasitoids is on those species of parasitoids attacking herbivorous lepidopterous larvae. It is this parasitoid–host group which has received the most intense study over the past decade. The approach presented here first considers the biology of the host, which host stages are attacked, and how the host is utilized by the parasitoid. While the cues utilized by parasitoids attacking herbivorous larvae differ in their detectability and reliability, more recently published data suggest that reliability may be as high for both the highly detectable cues, i.e., synomones, as the less detectable cues, i.e., kairomones. Differences in host selection strategy may be influenced primarily by the developmental stage attacked rather than by the detectability or reliability of the host-associated cues. This difference can be attributed to differences in the utilization of hosts by koinobionts and idiobionts. A similar thesis, that developmental problems faced by egg parasitoids influence how these oophages locate hosts, is presented. One of the main issues for egg parasitoids is having enough time to develop in a short-lived resource. Several strategies are discussed, including both a search strategy and an ambush strategy