The Evolution of Body Size, Antennal Size and Host Use in Parasitoid Wasps (Hymenoptera: Chalcidoidea): A Phylogenetic Comparative Analysis

Abstract

Chalcidoid wasps represent one of the most speciose superfamilies of animals known, with ca. 23,000 species described of which many are parasitoids. They are extremely diverse in body size, morphology and, among the parasitoids, insect hosts. Parasitic chalcidoids utilise a range of behavioural adaptations to facilitate exploitation of their diverse insect hosts, but how host use might influence the evolution of body size and morphology is not known in this group. We used a phylogenetic comparative analysis of 126 chalcidoid species to examine whether body size and antennal size showed evolutionary correlations with aspects of host use, including host breadth (specificity), host identity (orders of insects parasitized) and number of plant associates. Both morphological features and identity of exploited host orders show strong phylogenetic signal, but host breadth does not. Larger body size in these wasps was weakly associated with few plant genera, and with more specialised host use, and chalcidoid wasps that parasitize coleopteran hosts tend to be larger. Intriguingly, chalcidoid wasps that parasitize hemipteran hosts are both smaller in size in the case of those parasitizing the suborder Sternorrhyncha and have relatively larger antennae, particularly in those that parasitize other hemipteran suborders. These results suggest there are adaptations in chalcidoid wasps that are specifically associated with host detection and exploitation.

Molecular phylogeny of Pompilinae (Hymenoptera: Pompilidae): Evidence for rapid diversification and host shifts in spider wasps

“…In parasitoid wasps, our knowledge of host-range evolution is very limited due to a lack of reliable host records in many groups and lack of robust species-level phylogenies (Quicke, 1997;Quicke, 2012). Recent molecular studies have advanced our knowledge of host-use evolution in a phylogenetic framework (Symonds and Elgar, 2013;Taekul et al, 2014;Tschopp et al, 2013), but few studies have specifically addressed the diversification of parasitoids.…”

A comparative morphometric study of sensory capacity in geometrid moths

“…The first of these findings, that breeding strategy is of higher relevance, is rather surprising, as diet breadth (host specificity) has traditionally received much more research attention as an explanatory variable in ecological studies (cf. Davis et al., ; Symonds & Elgar, ).…”

“…Females of geometrids have simple, filiform antennae, as do males in some species, whereas in other species, males have feathery (pectinate or plumose) antennae. The ecological basis for such a dichotomy in antennal form among males (present also in several other moth families) is still poorly understood, but antennal size, both total length and length of the setae on feathery antennae, can be assumed to reflect sensory capacity of these organs (Allen, Zwaan, & Brakefield, ; Loudon & Koehl, ; Symonds & Elgar, ; Symonds, Johnson, & Elgar, ). Certainly, other antennal features are of significance (e.g.…”

“…To our knowledge, this is the first phylogenetic comparative study which relates sensory capacity to the degree of capital breeding, one of the first which relates sensory capacity to diet breadth (but see Shultz, Bradbury, Evans, Gregory, & Blackburn, ; Symonds & Elgar, ; MacLean et al., ; Farris & Roberts, ), and also, the first to detect any ecological correlate of feathery antennae in moths. Although previous studies have comprised wider phylogenetic spectra, we believe that our within‐family comparison carries the extra advantage of minimizing confounding lineage‐specific factors.…”

Coccinellid host morphology dictates morphological diversity of the parasitoid waspDinocampus coccinellae

“…Importantly, several studies have shown that the morphological characteristics of adults and fecundity of female parasitoids are affected by host characteristics, for example, host species (Nicol et al, 1999), host life stage (Traynor et al, 2005), host instars (Cloutier et al, 2000), and host size (Harvey et al, 2006; Mackauer et al, 2001). The size and species of hosts have been shown to greatly influence the evolutionary history of morphological characteristics in parasitoids (Brandl et al, 1987; Belshaw et al, 2003; Charnov et al, 1984; Bakker K et al, 1985; Moore et al, 2002; Symonds et al, 2013). It has been hypothesized that host-parasitoid co-evolution could eventually lead to increased fitness of parasitoids allowing them to parasitize multiple species (Charnov et al,1984; Ellers et al, 2002; Sampaio et al, 2008).…”