The Chalcidoidea bush of life: evolutionary history of a massive radiation of minute wasps.

Chalcidoidea are mostly parasitoid wasps that include as many as 500 000 estimated species. Capturing phylogenetic signal from such a massive radiation can be daunting. Chalcidoidea is an excellent example of a hyperdiverse group that has remained recalcitrant to phylogenetic resolution. We combined 1007 exons obtained with Anchored Hybrid Enrichment with 1048 ultra-conserved elements (UCEs) for 433 taxa including all extant families, >95% of all subfamilies, and 356 genera chosen to represent the vast diversity of the superfamily. Going back and forth between the molecular results and our collective knowledge of morphology and biology, we detected bias in the analyses that was driven by the saturation of nucleotide data. Our final results are based on a concatenated analysis of the least saturated exons and UCE datasets (2054 loci, 284 106 sites). Our analyses support an expected sister relationship with Mymarommatoidea. Seven previously recognized families were not monophyletic, so support for a new classification is discussed. Natural history in some cases would appear to be more informative than morphology, as illustrated by the elucidation of a clade of plant gall associates and a clade of taxa with planidial first-instar larvae. The phylogeny suggests a transition from smaller soft-bodied wasps to larger and more heavily sclerotized wasps, with egg parasitism as potentially ancestral for the entire superfamily. Deep divergences in Chalcidoidea coincide with an increase in insect families in the fossil record, and an early shift to phytophagy corresponds with the beginning of the "Angiosperm Terrestrial Revolution". Our dating analyses suggest a middle Jurassic origin of 174 Ma (167.3-180.5 Ma) and a crown age of 162.2 Ma (153.9-169.8 Ma) for Chalcidoidea. During the Cretaceous, Chalcidoidea may have undergone a rapid radiation in southern Gondwana with subsequent dispersals to the Northern Hemisphere. This scenario is discussed with regard to knowledge about the host taxa of chalcid wasps, their fossil record and Earth's palaeogeographic history.

Transcriptome sequence-based phylogeny of chalcidoid wasps (Hymenoptera: Chalcidoidea) reveals a history of rapid radiations, convergence, and evolutionary success.

Chalcidoidea are a megadiverse group of mostly parasitoid wasps of major ecological and economical importance that are omnipresent in almost all extant terrestrial habitats. The timing and pattern of chalcidoid diversification is so far poorly understood and has left many important questions on the evolutionary history of Chalcidoidea unanswered. In this study, we infer the early divergence events within Chalcidoidea and address the question of whether or not ancestral chalcidoids were small egg parasitoids. We also trace the evolution of some key traits: jumping ability, development of enlarged hind femora, and associations with figs. Our phylogenetic inference is based on the analysis of 3,239 single-copy genes across 48 chalcidoid wasps and outgroups representatives. We applied an innovative a posteriori evaluation approach to molecular clock-dating based on nine carefully validated fossils, resulting in the first molecular clock-based estimation of deep Chalcidoidea divergence times. Our results suggest a late Jurassic origin of Chalcidoidea, with a first divergence of morphologically and biologically distinct groups in the early to mid Cretaceous, between 129 and 81 million years ago (mya). Diversification of most extant lineages happened rapidly after the Cretaceous in the early Paleogene, between 75 and 53 mya. The inferred Chalcidoidea tree suggests a transition from ancestral minute egg parasitoids to larger-bodied parasitoids of other host stages during the early history of chalcidoid evolution. The ability to jump evolved independently at least three times, namely in Eupelmidae, Encyrtidae, and Tanaostigmatidae. Furthermore, the large-bodied strongly sclerotized species with enlarged hind femora in Chalcididae and Leucospidae are not closely related. Finally, the close association of some chalcidoid wasps with figs, either as pollinators, or as inquilines/gallers or as parasitoids, likely evolved at least twice independently: in the Eocene, giving rise to fig pollinators, and in the Oligocene or Miocene, resulting in non-pollinating fig-wasps, including gallers and parasitoids. The origins of very speciose lineages (e.g., Mymaridae, Eulophidae, Pteromalinae) are evenly spread across the period of chalcidoid evolution from early Cretaceous to the late Eocene. Several shifts in biology and morphology (e.g., in host exploitation, body shape and size, life history), each followed by rapid radiations, have likely enabled the evolutionary success of Chalcidoidea.

Phylogeny, host association and biogeographical patterns in the diverse millipede-parasitoid genus Myriophora Brown (Diptera: Phoridae).

Myriophora is the most species-rich group of parasitoids that attack toxic, chemically defended millipedes in the superorder Juliformia and order Polydesmida-a resource that few insect predators and parasitoids are able to exploit. Worldwide, there are an estimated 200 species of Myriophora, with the majority of the diversity centred in the Neotropical region. The phylogeny of Myriophora is unknown, biogeographical patterns are not documented, and known host associations have not been assessed in a phylogenetic context. We provide the first phylogenetic study of the genus from a data set composed of 52 taxa primarily from the Neotropical region including 10 outgroups, 40 morphological characters, and molecular data from three mitochondrial (16S, COI and ND1) and one nuclear marker (AK). We find that Myriophora dispersed from the New World to the Old World in a single event before subsequently spreading to the Afrotropical region. The ancestral hosts reconstructed for Myriophora are the benzoquinone-producing Juliformia, and this association has been retained in the Old World clade. In the Neotropical region, Myriophora that are associated with cyanide-producing polydesmidan millipedes are confined to a single clade that shows remarkably little genetic variation between clearly morphologically diagnosable species.

Torymidae (Hymenoptera, Chalcidoidea) revised: molecular phylogeny, circumscription and reclassification of the family with discussion of its biogeography and evolution of life-history traits.

A phylogeny of the Torymidae (Chalcidoidea) is estimated using 4734 nucleotides from five genes. Twelve outgroups and 235 ingroup taxa are used, representing about 70% of the recognized genera. Our analyses do not recover Torymidae as monophyletic and we recognize instead two families: Megastigmidae (stat. rev.) and Torymidae s.s. (stat. rev.). Within Torymidae s.s., we recognize six subfamilies and six tribes, including Chalcimerinae, Glyphomerinae and Microdontomerinae (subf. nov.), and two new tribes: Boucekinini and Propalachiini (trib. nov.). Seven unclassified genera (i.e. Cryptopristus, Echthrodape, Exopristoides, Exopristus, part of Glyphomerus, Thaumatorymus, Zaglyptonotus) are assigned to tribes within our new classification. Five genera are restored from synonymy-Ameromicrus and Didactyliocerus from under Torymoides (stat. rev.), Iridophaga and Iridophagoides from under Podagrionella (stat. rev.) and Nannocerus from under Torymus (stat. rev.)-and three genera are synonymized-Allotorymus under Torymussyn. nov., Ditropinotus under Eridontomerussyn. nov. and Pseuderimerus under Erimerussyn. nov. A Palaearctic or Eurasian origin for Torymidae is proposed. The ancestral area of Megastigmidae is indicated as the Australian region. The most probable ancestral life strategy for Torymidae s.s. is ectoparasitism on gall-forming Cynipidae. The life strategy and putative hosts of the common ancestor of Megastigmidae remain uncertain.

Millipede Defensive Compounds Are a Double-Edged Sword: Natural History of the Millipede-Parasitic Genus Myriophora Brown (Diptera: Phoridae).

Toxic defensive secretions produced by millipedes in the orders Julida, Spirobolida, Spirostreptida, and Polydesmida are highly repellent to most vertebrate and invertebrate natural enemies, but a few insects have evolved mechanisms to overcome these defenses. We demonstrate that highly specialized parasitic phorid flies in the species-rich genus Myriophora use volatile millipede defensive compounds as kairomones for host location. Of the two predominant quinone components in the defensive blend of juliform millipedes, 2-methoxy-3-methyl-1,4-benzoquinone alone was sufficient to attract adult flies of both sexes; however, a combination of 2-methoxy-3-methyl-1,4-benzoquinone and 2-methyl-1,4-benzoquinone increased attractiveness nearly threefold. We further discuss oviposition behavior, adult and larval feeding habits, life history parameters, and the potential competitive interactions between phorid flies in the genus Myriophora and other millipede-associated insects.

Revision of the Orasema festiva species group (Hymenoptera: Chalcidoidea: Eucharitidae).

The Neotropical Orasema festiva species group is revised, retaining O. festiva (Fabricius) and O. delicatula (Walker) as valid species, and describing four new species: O. alvarengai n. sp., O. caesariata n. sp., O. erwini n. sp., and O. reburra n. sp. The festiva-group is characterized by features that are unusual or unique in Orasema, including the presence of 8-11 labral digits, a smooth face, and a lateral petiolar carina. The egg of O. caesariata and the first-instar larva of O. delicatula are newly described and found to be similar to other species of Orasema.

Ancient host shifts followed by host conservatism in a group of ant parasitoids.

While ant colonies serve as host to a diverse array of myrmecophiles, few parasitoids are able to exploit this vast resource. A notable exception is the wasp family Eucharitidae, which is the only family of insects known to exclusively parasitize ants. Worldwide, approximately 700 Eucharitidae species attack five subfamilies across the ant phylogeny. Our goal is to uncover the pattern of eucharitid diversification, including timing of key evolutionary events, biogeographic patterns and potential cophylogeny with ant hosts. We present the most comprehensive molecular phylogeny of Eucharitidae to date, including 44 of the 53 genera and fossil-calibrated estimates of divergence dates. Eucharitidae arose approximately 50 Ma after their hosts, during the time when the major ant lineages were already established and diversifying. We incorporate host association data to test for congruence between eucharitid and ant phylogenies and find that their evolutionary histories are more similar than expected at random. After a series of initial host shifts, clades within Eucharitidae maintained their host affinity. Even after multiple dispersal events to the New World and extensive speciation within biogeographic regions, eucharitids remain parasitic on the same ant subfamilies as their Old World relatives, suggesting host conservatism despite access to a diverse novel ant fauna.

A phylogenetic analysis of the megadiverse Chalcidoidea (Hymenoptera).

Chalcidoidea (Hymenoptera) is extremely diverse with an estimated 500 000 species. We present the first phylogenetic analysis of the superfamily based on both morphological and molecular data. A web-based, systematics workbench mx was used to score 945 character states illustrated by 648 figures for 233 morphological characters for a total of 66 645 observations for 300 taxa. The matrix covers 22 chalcidoid families recognized herein and includes 268 genera within 78 of 83 subfamilies. Morphological data were analysed alone and in combination with molecular data from ribosomal 18S (2105 bp) and 28S D2-D5 expansion regions (1812 bp). Analyses were analysed alone and in combined datasets using implied-weights parsimony and likelihood. Proposed changes in higher classification resulting from the analyses include: (i) recognition of Eriaporidae, revised status; (ii) recognition of Cynipencyrtidae, revised status; (iii) recognition of Azotidae, revised status; (iv) inclusion of Sycophaginae in Agaonidae, revised status; (v) reclassification of Aphelinidae to include Aphelininae, Calesinae, Coccophaginae, Eretmocerinae and Eriaphytinae; (vi) inclusion of Cratominae and Panstenoninae within Pteromalinae (Pteromalidae), new synonymy; (vii) inclusion of Epichrysomallinae in Pteromalidae, revised status. At a higher level, Chalcidoidea was monophyletic, with Mymaridae the sister group of Rotoitidae plus the remaining Chalcidoidea. A eulophid lineage was recovered that included Aphelinidae, Azotidae, Eulophidae, Signiphoridae, Tetracampidae and Trichogrammatidae. Eucharitidae and Perilampidae were monophyletic if Eutrichosomatinae (Pteromalidae) was included, and Eupelmidae was monophyletic if Oodera (Pteromalidae: Cleonyminae) was included. Likelihood recovered a clade of Eupelmidae + (Tanaostigmatidae + (Cynipencyrtus + Encyrtidae). Support for other lineages and their impact on the classification of Chalcidoidea is discussed. Several life-history traits are mapped onto the new phylogeny.

A new genus of Eucharitidae (Hymenoptera: Chalcidoidea), with notes on life history and immature stages.

Neolirata new genus (Eucharitidae: Eucharitini) is recognized based on males and females, with new descriptions of eggs, planidia and pupae. Redescriptions are provided for N. alta (Walker) and N. daguerrei (Gemignani) (comb. nov. transferred from Lirata) and a new description of N. furcula sp. nov. is presented. Females of N. alta deposit their eggs on the underside of leaves of Pseudabutilon virgatum (Cav.) Fryxell (Malvaceae) and N. daguerrei on the underside of Urvillea chacoensis Hunz (Sapindaceae). A key to species is included.

A review of the family Eucharitidae (Hymenoptera: Chalcidoidea) of Egypt.

The species of Eucharitidae (Hymenoptera: Chalcidoidea) of Egypt are reviewed. Three species of Eucharis Westwood are reported, Eucharis (Eucharisca) bytinskisalzi Boucek, E. (Psilogastrellus) cuprea (Blanchard) and E. (Psilogastrellus) punctata F6rster. Primary type material of E. bytinskisalzi and E. cuprea is illustrated through macrophotography and a key to separate the three species is provided. Eucharis bytinskisalzi is listed as a new record for the Egyptian fauna.

Convergence of dominance and neglect in flying insect diversity.

Most of arthropod biodiversity is unknown to science. Consequently, it has been unclear whether insect communities around the world are dominated by the same or different taxa. This question can be answered through standardized sampling of biodiversity followed by estimation of species diversity and community composition with DNA barcodes. Here this approach is applied to flying insects sampled by 39 Malaise traps placed in five biogeographic regions, eight countries and numerous habitats (>225,000 specimens belonging to >25,000 species in 458 families). We find that 20 insect families (10 belonging to Diptera) account for >50% of local species diversity regardless of clade age, continent, climatic region and habitat type. Consistent differences in family-level dominance explain two-thirds of variation in community composition despite massive levels of species turnover, with most species (>97%) in the top 20 families encountered at a single site only. Alarmingly, the same families that dominate insect diversity are 'dark taxa' in that they suffer from extreme taxonomic neglect, with little signs of increasing activities in recent years. Taxonomic neglect tends to increase with diversity and decrease with body size. Identifying and tackling the diversity of 'dark taxa' with scalable techniques emerge as urgent priorities in biodiversity science.

Phylogenetic relationships among superfamilies of Hymenoptera.

The first comprehensive analysis of higher-level phylogeny of the order Hymenoptera is presented. The analysis includes representatives of all extant superfamilies, scored for 392 morphological characters, and sequence data for four loci (18S, 28S, COI and EF-1α). Including three outgroup taxa, 111 terminals were analyzed. Relationships within symphytans (sawflies) and Apocrita are mostly resolved. Well supported relationships include: Xyeloidea is monophyletic, Cephoidea is the sister group of Siricoidea + [Xiphydrioidea + (Orussoidea + Apocrita)]; Anaxyelidae is included in the Siricoidea, and together they are the sister group of Xiphydrioidea + (Orussoidea + Apocrita); Orussoidea is the sister group of Apocrita, Apocrita is monophyletic; Evanioidea is monophyletic; Aculeata is the sister group of Evanioidea; Proctotrupomorpha is monophyletic; Ichneumonoidea is the sister group of Proctotrupomorpha; Platygastroidea is sister group to Cynipoidea, and together they are sister group to the remaining Proctotrupomorpha; Proctotrupoidea s. str. is monophyletic; Mymarommatoidea is the sister group of Chalcidoidea; Mymarommatoidea + Chalcidoidea + Diaprioidea is monophyletic. Weakly supported relationships include: Stephanoidea is the sister group of the remaining Apocrita; Diaprioidea is monophyletic; Ceraphronoidea is the sister group of Megalyroidea, which together form the sister group of [Trigonaloidea (Aculeata + Evanioidea)]. Aside from paraphyly of Vespoidea within Aculeata, all currently recognized superfamilies are supported as monophyletic. The diapriid subfamily Ismarinae is raised to family status, Ismaridae stat. nov. © The Will Henning Society 2011.

Evolution of the hymenopteran megaradiation.

The Hymenoptera--ants, bees and wasps--represent one of the most successful but least understood insect radiations. We present the first comprehensive molecular study spanning the entire order Hymenoptera. It is based on approximately 7 kb of DNA sequence from 4 gene regions (18S, 28S, COI and EF-1α) for 116 species representing all superfamilies and 23 outgroup taxa from eight orders of Holometabola. Results are drawn from both parsimony and statistical (Bayesian and likelihood) analyses, and from both by-eye and secondary-structure alignments. Our analyses provide the first firm molecular evidence for monophyly of the Vespina (Orussoidea+Apocrita). Within Vespina, our results indicate a sister-group relationship between Ichneumonoidea and Proctotrupomorpha, while the stinging wasps (Aculeata) are monophyletic and nested inside Evaniomorpha. In Proctotrupomorpha, our results provide evidence for a novel core clade of proctotrupoids, and support for the recently proposed Diaprioidea. An unexpected result is the support for monophyly of a clade of wood-boring sawflies (Xiphydrioidea+Siricoidea). As in previous molecular studies, Orussidae remain difficult to place and are either sister group to a monophyletic Apocrita, or the sister group of Stephanidae within Apocrita. Both results support a single origin of parasitism, but the latter would propose a controversial reversal in the evolution of the wasp-waist. Generally our results support earlier hypotheses, primarily based on morphology, for a basal grade of phytophagous families giving rise to a single clade of parasitic Hymenoptera, the Vespina, from which predatory, pollen-feeding, gall-forming and eusocial forms evolved.

Combined molecular and morphological phylogeny of Eulophidae (Hymenoptera: Chalcidoidea), with focus on the subfamily Entedoninae.

A new combined molecular and morphological phylogeny of the Eulophidae is presented with special reference to the subfamily Entedoninae. We examined 28S D2-D5 and CO1 gene regions with parsimony and partitioned Bayesian analyses, and examined the impact of a small set of historically recognized morphological characters on combined analyses. Eulophidae was strongly supported as monophyletic only after exclusion of the enigmatic genus Trisecodes. The subfamilies Eulophinae, Entiinae (=Euderinae) and Tetrastichinae were consistently supported as monophyletic, but Entedoninae was monophyletic only in combined analyses. Six contiguous bases in the 3e' subregion of the 28S D2 rDNA contributed to placement of nominal subgenus of Closterocerus outside Entedoninae. In all cases, Euderomphalini was excluded from Entiinae, and we suggest that it be retained in Entedoninae. Opheliminae n. stat. is raised from tribe to subfamily status. Trisecodes is removed from Entedoninae but retained as incertae sedis in Eulophidae until its family placement can be determined new placement. The genera Neochrysocharisstat. rev. and Asecodesstat. rev. are removed from synonymy with Closterocerus because strong molecular differences corroborate their morphological differences. Closterocerus (Achrysocharis) germanicus is transferred to the genus Chrysonotomyian. comb. based on molecular and morphological characters.

Read between the lineata: A revision of the tattooed wasps, Zagrammosoma Ashmead (Hymenoptera: Eulophidae), with descriptions of eleven new species.

The genus Zagrammosoma Ashmead (Hymenoptera: Eulophidae) is revised. Twenty-six species are recognized, of which 23 have been molecularly verified in a phylogenetic context using 28S, ITS2, and COI. Zagrammosoma is recovered as monophyletic, worldwide in distribution, and morphologically distinct from Cirrospilus Westwood. Zagrammosoma interlineatum Girault stat. rev. is elevated from synonymy. The following synonymies are proposed: Zagrammosoma mirum Girault under Zagrammosoma flavolineatum Crawford n. syn., Zagrammosoma dulanense Cao Zhu under Zagrammosoma talitzkii Boucek n. syn. The following species are described as new: Zagrammosoma calvini Perry n. sp. (Argentina, Chile), Zagrammosoma deliae Perry n. sp. (Peru), Zagrammosoma fisheri Perry n. sp. (USA), Zagrammosoma galapagoense Perry n. sp. (Ecuador: Galapagos Islands), Zagrammosoma headricki Perry n. sp. (Mexico, USA), Zagrammosoma metallicum Perry n. sp. (USA), Zagrammosoma occidentale Perry n. sp. (Mexico, USA), Zagrammosoma triangulum Perry n. sp. (USA), Zagrammosoma trifurcatum Perry n. sp. (Belize, USA), Zagrammosoma villosum Perry n. sp. (Nearctic, Neotropical), Zagrammosoma yanegai Perry n. sp. (Thailand). The following new combination is proposed: Cirrospilus variegatus (Masi) n. comb, from Zagrammosoma. Descriptions, distribution maps, host associations, and a key to all known species are provided.

Taxonomic description and phylogenetic placement of two new species of Spalangiopelta (Hymenoptera: Pteromalidae: Ceinae) from Eocene Baltic amber.

Spalangiopelta is a small genus of chalcid wasps that has received little attention despite the widespread distribution of its extant species. The fossil record of the genus is restricted to a single species from Miocene Dominican amber. We describe two new fossil species, Spalangiopelta darlingi sp. n. and Spalangiopelta semialba sp. n. from Baltic amber. The species can be placed within the extant genus Spalangiopelta based on the distinctly raised hind margin of the mesopleuron. 3D models reconstructed from µCT data were utilized to assist in the descriptions. Furthermore, we provide a key for the females of all currently known Spalangiopelta species. The phylogenetic placement of the fossils within the genus is analyzed using parsimony analysis based on morphological characters. Phylogenetic and functional relevance of two wing characters, admarginal setae and the hyaline break, are discussed. The newly described Baltic amber fossils significantly extend the minimum age of Spalangiopelta to the Upper Eocene.

The New World ant parasitoid genus Orasema (Hymenoptera: Eucharitidae).

A key is provided to 16 recognized species groups, plus several species not assigned to species group, of Orasema Cameron (Eucharitidae), a widespread New World genus of myrmicine ant (Formicidae: Myrmicinae) parasitoids ranging from northern Argentina to southern Canada. Eight of the species groups are revised, of which five are newly established; keys are given to the species of each treated group, 22 species are newly described, and detailed life histories of several well-documented species are discussed. Revised are the Orasema coloradensis group (four species: O. coloradensis Wheeler, O. iridescens n. sp., O. scaura n. sp., and O. violacea Ashmead), the Orasema bakeri group (six species: O. bablyi n. sp., O. bakeri Gahan, O. dubitata n. sp., O. polymyrmex n. sp., O. taii Chien Heraty, and O. texana Gahan), the Orasema tolteca group (two species: O. castilloae n. sp. and O. tolteca Mann), the Orasema sixaolae group (newly established, with four species: O. brachycephala n. sp., O. nebula n. sp., O. sixaolae Wheeler Wheeler, and O. tinalandia n. sp.), the Orasema acuminata group (newly established, with two species: O. acuminata n. sp. and O. cerulea n. sp.), the Orasema peraltai group (newly established, with two species: O. chrysozona n. sp. and O. peraltai n. sp.), the Orasema johnsoni group (newly established, with two species: O. johnsoni n. sp. and O. spyrogaster n. sp.), and the Orasema heacoxi group (newly established, with two species: O. heacoxi n. sp. and O. masonicki n. sp.). Newly described or treated species not placed to species group are O. brasiliensis (Bréthes), O. cirrhocnemis n. sp., O. monstrosa n. sp., O. mutata n. sp., O. psarops n. sp., and O. roppai n. sp. Species concepts and relationships are based on morphology and a recently published molecular phylogeny.

Novel lepidopteran sex pheromone components from Marmara gulosa (Lepidoptera: Gracillariidae).

Marmara gulosa Guillén & Davis (Lepidoptera: Gracillariidae) is a sporadic pest of citrus and a number of other crops in southern and central California. Coupled gas chromatographic-electroantennogram detection analyses of headspace volatiles collected by solid phase microextraction from virgin female moths revealed at least four related compounds in the extracts that elicited significant antennal responses from antennae of male moths. These compounds were identified as (8E,10E)-tetradecadien-1-ol, and the corresponding aldehyde, acetate, and formate ester, representing the first report of a formate as a lepidopteran pheromone component. The four compounds were consistently found in headspace volatiles collected from virgin female moths from different regions of the state and from M. gulosa collected from different host plants (citrus and squash). Repeated field trials determined that the formate ester alone was as attractive or more attractive than any blend of the formate with one or more of the remaining compounds. Although large numbers of moths were caught in some field trials, trap catches were not consistent. Thus, the pheromone may be useful for detection of the moth and setting an initial biofix, but it remains unclear whether the pheromone can be used as a reliable and accurate tool for monitoring densities of M. gulosa populations.

Counties not countries: Variation in host specificity among populations of an aphid parasitoid.

Parasitic wasps are among the most species-rich groups on Earth. A major cause of this diversity may be local adaptation to host species. However, little is known about variation in host specificity among populations within parasitoid species. Not only is such knowledge important for understanding host-driven speciation, but because parasitoids often control pest insects and narrow host ranges are critical for the safety of biological control introductions, understanding variation in specificity and how it arises are crucial applications in evolutionary biology. Here, we report experiments on variation in host specificity among 16 populations of an aphid parasitoid, Aphelinus certus. We addressed several questions about local adaptation: Do parasitoid populations differ in host ranges or in levels of parasitism of aphid species within their host range? Are differences in parasitism among parasitoid populations related to geographical distance, suggesting clinal variation in abundances of aphid species? Or do nearby parasitoid populations differ in host use, as would be expected if differences in aphid abundances, and thus selection, were mosaic? Are differences in parasitism among parasitoid populations related to genetic distances among them? To answer these questions, we measured parasitism of a taxonomically diverse group of aphid species in laboratory experiments. Host range was the same for all the parasitoid populations, but levels of parasitism varied among aphid species, suggesting adaptation to locally abundant aphids. Differences in host specificity did not correlate with geographical distances among parasitoid populations, suggesting that local adaption is mosaic rather than clinal, with a spatial scale of less than 50 kilometers. We sequenced and assembled the genome of A. certus, made reduced-representation libraries for each population, analyzed for single nucleotide polymorphisms, and used these polymorphisms to estimate genetic differentiation among populations. Differences in host specificity correlated with genetic distances among the parasitoid populations.

Development of a strategy for selective collection of a parasitoid attacking one member of a large herbivore guild.

Selectively collecting a single natural enemy species that parasitizes one member of a guild of herbivores that attack the same host plants can be a challenging problem during development of biological control programs. We present here a successful strategy for the collection of a strain of the egg parasitoid Avetianella longoi Siscaro (Hymenoptera: Encyrtidae), that parasitizes eggs of the longhorned borer Phoracantha recurva Newman (Coleoptera: Cerambycidae). This cerambycid is one member of a large guild of woodborers that simultaneously infest dying and fallen Eucalyptus in Australia, and it has become a major pest of Eucalyptus in many areas of the world where Eucalyptus has been introduced. Adult P. recurva of both sexes were caged on freshly cut Eucalyptus logs, and the resulting egg masses were marked and then left exposed to natural parasitization in the field. Parasitized egg masses were then harvested and held in the laboratory until adult parasitoids emerged. Parasitoids were identified as A. longoi by morphological comparisons with reference specimens, and with molecular markers. This strain of A. longoi readily accepted and had high survival rates in eggs of P. recurva. In contrast, the strain of A. longoi that has been used for biological control of P. semipunctata in California since the 1990s strongly prefers eggs of eucalyptus longhorned borer, Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae), and has relatively low rates of survival to adulthood in eggs of P. recurva. The causes of these behavioral and physiological differences between the two strains are not yet known.