Ichneumonid Subfamily Research Articles

Determinants of parasitoid abundance and diversity in woodland habitats

Summary Insect parasitoids comprise a large fraction of terrestrial biodiversity. Because of this diversity, species‐level conservation of most parasitoid species is impractical and habitat conservation must substitute. However, habitat indicators of parasitoid abundance and diversity are poorly known. To identify such habitat indicators, parasitoid wasps in four ichneumonid subfamilies were sampled in the field herb layer of 15 woodlands in the Vale of York, UK, using Malaise traps. The catch was related to vegetation characteristics. A total of 1543 individuals in 60 species was recorded, representing 36% of UK species in the taxa sampled. Parasitoids tended to be more abundant and species rich in woodlands with a high broadleaf content and tree species richness. This pattern was observed in the ichneumonid subfamilies Pimplinae, Poemeniinae and Diacritinae. However, the ichneumonid subfamily Diplazontinae was found to vary in abundance and richness within rather than between woodlands and showed no association with measured habitat variables. Reserve selection analyses indicated that coniferous woodlands, and woodlands with a low abundance and richness of parasitoids, none the less can contribute to maximizing parasitoid diversity at the landscape scale. Synthesis and applications. At the individual woodland scale, broadleaved woodlands with high tree species richness appear best for conserving parasitoid abundance and diversity. At a landscape scale however, a variety of woodland habitat types can maximize diversity of all parasitoid taxa. We hypothesize that the degree of association between parasitoid abundance and diversity, and characteristics of the vegetation within habitats will decrease with an increase in the number of trophic links that separate them.

The genus Nipponaetes (Hymenoptera: Ichneumonidae: Cryptinae) in Costa Rica, with a reassessment of the generic limits

Keywords. Ichneumonidae, Cryptinae, Tryphoninae, Nipponaetes, Zurquilla, 28S, host, spider, phylogeny, new synonymy Abstract. The endemic Costa Rican genus Zurquilla Gauld, 1997, is transferred from the ichneumonid subfamily Tryphoninae (tribe Oedemopsini) to the Cryptinae (tribe Phygadeuontini) and synonymised with Nipponaetes Uchida, 1933. This decision is justified using morphological and molecular (28S D2-3 ribosomal DNA sequence) evidence. We briefly discuss the phylogenetic utility of characters that led to the type species of Zurquilla being described as a tryphonine and provide a host record that indicates that Nip- ponaetes is a parasitoid of spider egg sacs.

The Eucerotinae: a Gondwanan origin for a cosmopolitan group of Ichneumonidae?

A new genus and species of the formerly monobasic and predominantly amphitropical, ichneumonid subfamily, Eucerotinae, is described from Chile. A phylogenetic analysis of the redefined Eucerotinae is undertaken. Barronia araucaria gen. et sp. n. has a sister-group relationship with Euceros. The southern hemisphere species of the latter genus were found to comprise a monophyletic clade, the sister group to all other Euceros species. Similarly all north temperate Euceros species form a monophyletic clade, the sister group of which occurs in Madagascar. Within the former clade, the North American species form a monophyletic group, the sister species of which is Palaearctic. Several other groups of Palaearctic taxa have a sister-group relationship to this lineage. These results suggest the Eucerotinae had an ancient origin on Gondwanaland in the lower Cretaceous, prior to the separation of the Indo-Madagascar terrane from the Australian-Antarctic-South American tectonic plate. We hypothesize the Palaearctic fauna colonized Eurasia following the impaction of India on to its southern margin, and that the North American fauna is derived from a single circum-polar dispersal from Eurasia. Our results do not support an earlier hypothesis that the Eucerotinae arose as hyperparasitoids of Symphyta. Evidence suggests the group arose as parasitoids of ophioniform ichneumonids attacking lepidopterous larvae feeding on gymnosperms or anemophilous angiosperm trees.

The suprageneric groups of the Pimplinae (Hymenoptera: Ichneumonidae): a cladistic re-evaluation and evolutionary biological study

The phylogenetic relationships of the suprageneric groups of the ichneumonid subfamily Pimplinae (Hymenoptera) are re-assessed using 166 morphological and biological characters for 162 species, representing all of the available described genera and subgenera. The cladistic analysis was repeated using abstracted genera, re-codedfrom the ­initial set of species, as terminal taxa. The topology of the resulting cladograms was similar. In the first (primary) analysis several genera (including Neotheronia, Itoplectis, Dolichomitus, Dreisbachia, Polysphincta, Oxyrrhexis and Zonopimpla) were not retrieved as monophyletic groups; however, all except the last were found to be monophyletic in the second analysis. These results suggest that using abstracted taxa may force a ‘false monophyly’ on the preselected groups. Thus we reject the use of such abstractions, preferring instead to use exemplar speciesthat together show much of the variation that occurs within a hypothesizedgenus. Within the Pimplinae three major groupings were recognized, the Delomeristini (including the Perithoini syn. nov.), the Pimplini and the Ephialtini. Within the Pimplini, two generic groups were recovered, the Xanthopimpla and Pimpla genus-groups, but a third postulated group, the Theronia genus-group, was found to be paraphyletic. Within the Ephialtini five groups wererecognized, the Pseudopimpla, Alophosternum, Camptotypus, Ephialtes and Sericopimpla genus-groups. The spider parasitizing complex of genera (the Polysphincta genus-complex) was found to nest within the Sericopimpla genus-group confirmingthe placement of Polysphinctini as a synonym of Ephialtini. Problems with the status of some existing genera are highlighted, but formal nomenclatural changes are not proposed. The ancestral Pimplinae are hypothesized to have been solitary ectoparasitic idiobiontson weakly concealed immature Hymenoptera. The major radiations within the Pimplinae are shown as: (1) a progressive exploitation of cocooned, then weakly cocooned, lepidopterous pupae in the Pimplini leading to idiobiont endoparasitism; (2) increasing specialization to attack hosts deeply concealed in wood in the Ephialtes genus-group, and (3) specialization on a variety of cocooned hosts, including spider egg sacs, leading to koinobiont ectoparasitism of spiders. A brief synopsis of the distribution of the group is given, and some biogeographical inferences drawn. The group is presumed to have originated and radiated on Laurasia; no evidence for trans-Antarctic relationships can be found.

The Labeninae (Hymenoptera: Ichneumonidae): a study in phylogenetic reconstruction and evolutionary biology

The internal phylogenetic relationships of the ichneumonid subfamily Labeninae (Hymenoptera) are re-assessed using 136 characters for 54 species representing all currently known species-groups. New character sets are used. These include a new form of seta (named the grossulariform setae) which are present on the inner surface of the hind coxa of some females, and the extensive structural modifications of the terminal segments of the female metasoma, which are described and structural homologies established. The monophyly of the Labeninae and of the four component tribes, Groteini, Poecilocryptini, Xenothyrini and Labenini, is demonstrated. The Groteini is shown to be the sister-group to the Poecilocryptini + (Xenothyrini + Labenini). Monophyletic genera are established, including three new genera: Ozlabium gen. nov. Gauld & Wahl (type-species O. arcadium sp. nov.) in the Groteini from Australia; Torquinsha gen. nov. Gauld & Wahl (type-species Certonotus invictus Porter) in the Labenini from Chile, and Gauldianus gen. nov. Lanfranco (type-species Gauldianus chilensis sp. nov. Lanfranco) in the Labenini from Chile. Apechoneura is removed from synonymy and re-instated as a valid genus for a complex of tropical American species. The biogeographic patterns shown by the Labeninae are discussed. Evidence suggests that the group radiated on Gondwanaland after the separation of Africa/India/Madagascar, but prior to the separation of Australia. Species occurring off the southern continental fragments, in North America, are shown to be members of highly derived lineages, a result consistent with the hypothesis that labenines colonized North America recently through Mesoamerica. Patterns of host utilization and mating behaviour are examined for the group. Members of the more derived lineages show progressively more female specializations for attacking hosts deeply concealed in woody substrates. Males in the more specialized lineages are shown to have a wider array of secondary sexual characteristics and genitalic ornamentations than more plesiomorphic taxa.

The Labeninae (Hymenoptera: Ichneumonidae): a study in phylogenetic reconstruction and evolutionary biology

The internal phylogenetic relationships of the ichneumonid subfamily Labeninae (Hymenoptera) are re-assessed using 136 characters for 54 species representing all currently known species-groups. New character sets are used. These include a new form of seta (named the grossulariform setae) which are present on the inner surface of the hind coxa of some females, and the extensive structural modifications of the terminal segments of the female metasoma, which are described and structural homologies established. The monophyly of the Labeninae and of the four component tribes, Groteini, Poecilocryptini, Xenothyrini and Labenini, is demonstrated. The Groteini is shown to be the sister-group to the Poecilocryptini + (Xenothyrini + Labenini). Monophyletic genera are established, including three new genera Ozlabiumgen. nov. Gauld & Wahl (type-species O. arcadiumsp. nov.) in the Groteini from Australia Torquinshagen. nov. Gauld & Wahl (type-species Certonotus invictus Porter) in the Labenini from Chile, and Gauldianusgen. nov. Lanfranco (type-species Gauldianus chilensissp. nov. Lanfranco) in the Labenini from Chile.Apechoneura is removed from synonymy and re-instated as a valid genus for a complex of tropical American species. The biogeographic patterns shown by the Labeninae are discussed. Evidence suggests that the group radiated on Gondwanaland after the separation of Africa/India/Madagascar, but prior to the separation of Australia. Species occurring off the southern continental fragments, in North America, are shown to be members of highly derived lineages, a result consistent with the hypothesis that labenines colonized North America recently through Mesoamerica. Patterns of host utilization and mating behaviour are examined for the group. Members of the more derived lineages show progressively more female specializations for attacking hosts deeply concealed in woody substrates. Males in the more specialized lineages are shown to have a wider array of secondary sexual characteristics and genitalic ornamentations than more plesiomorphic taxa.

Cladistics of the genera of Mesochorinae (Hymenoptera: Ichneumonidae)

Abstract. A cladistic analysis is presented for the genera of the ichneumonid subfamily Mesochorinae. Nine genera are recognized as valid. Previous work on larval morphology is reviewed and a number of larvae are newly illustrated and discussed. Four new synonyms are proposed: Oncocotta, Piestetron, Plectochorus and Rhaibaspis are all synonymized with Mesochorus, and Stictopisthus is placed back as a synonym of Mesochorus. Four new genera are described: Artherola from South Africa, Chineater from Chile, Thamester from Japan, and Varnado from Morocco. A new key is provided to the mesochorine genera of the world.

The New Zealand species of the subfamily Metopiinae (Hymenoptera: Ichneumonidae)

Abstract The New Zealand species of the ichneumonid subfamily Metopiinae are revised. Three new species are described, Hypsicera nelsonensis, Sciron glaber, and S. enolae. One cosmopolitan species, Hypsicera femoralis Geoffroy is recorded from New Zealand. Carria nigripes (Cameron) is synonomised with C. fortipes (Cameron). A key to species is included.

The biology, egg and larvae of Acaenitus dubitator (Panzer) (Hymenoptera, Ichneumonidae: Acaenitinae)

Abstract Acaenitus dubitator (Panzer) is found to be a koinobiont endoparasitoid of the larva of an endophytic beetle, Cleonis piger (Scopoli) (Curculionidae), in Britain, suggesting a similar mode of development for the ichneumonid subfamily Acaenitinae as a whole. The parasitoid can overwinter in its cocoon in one of two ways. Individuals overwintering as essentially unaltered mature larvae do not become adult the following summer, while those that overwinter as morphologically distinct prepupae are committed to pupate and become adult immediately afterwards. The change from mature larva to prepupa takes place in late summer, soon after the time of cocoon formation, but a proportion of mature larvae lie over in the first year, and perhaps subsequently. This appears to be an adaptation to life in a particularly harsh and uncertain environment. The egg, prepupa, and first, second and final instar larvae are described and figured. Previous interpretations of the cephalic sclerites of final instar acaenitines are revised.

Further notes on family‐group names of Ichneumonidae (Hymenoptera)

AbstractThe name Phygadeuontinae Foerster, 1868 is chosen, from those available, for the ichneumonid subfamily known previously as the Hemitelinae, Gelinae or Cryptinae. These latter three names are incorrect under the International Code. The operation of the first reviser principle in this case is explained. Other additions and corrections to the treatment of family‐group names of Ichneumonidae recently published by the same authors are also given.