Gavin R. Broad

Establishing the evidence base for maintaining biodiversity and ecosystem function in the oil palm landscapes of South East Asia

The conversion of natural forest to oil palm plantation is a major current threat to the conservation of biodiversity in South East Asia. Most animal taxa decrease in both species richness and abundance on conversion of forest to oil palm, and there is usually a severe loss of forest species. The extent of loss varies significantly across both different taxa and different microhabitats within the oil palm habitat. The principal driver of this loss in diversity is probably the biological and physical simplification of the habitat, but there is little direct evidence for this. The conservation of forest species requires the preservation of large reserves of intact forest, but we must not lose sight of the importance of conserving biodiversity and ecosystem processes within the oil palm habitat itself. We urgently need to carry out research that will establish whether maintaining diversity supports economically and ecologically important processes. There is some evidence that both landscape and local complexity can have positive impacts on biodiversity in the oil palm habitat. By intelligent manipulation of habitat complexity, it could be possible to enhance not only the number of species that can live in oil palm plantations but also their contribution to the healthy functioning of this exceptionally important and widespread landscape.

Endoparasitism in cereal aphids: molecular analysis of a whole parasitoid community

Insect parasitoids play a major role in terrestrial food webs as they are highly diverse, exploit a wide range of niches and are capable of affecting host population dynamics. Formidable difficulties are encountered when attempting to quantify host–parasitoid and parasitoid–parasitoid trophic links in diverse parasitoid communities. Here we present a DNA‐based approach to effectively track trophic interactions within an aphid–parasitoid food web, targeting, for the first time, the whole community of parasitoids and hyperparasitods associated with a single host. Using highly specific and sensitive multiplex and singleplex polymerase chain reaction, endoparasitism in the grain aphid Sitobion avenae (F) by 11 parasitoid species was quantified. Out of 1061 aphids collected during 12 weeks in a wheat field, 18.9% were found to be parasitized. Parasitoids responded to the supply of aphids, with the proportion of aphids parasitized increasing monotonically with date, until the aphid population crashed. In addition to eight species of primary parasitoids, DNA from two hyperparasitoid species was detected within 4.1% of the screened aphids, with significant hyperparasitoid pressure on some parasitoid species. In 68.2% of the hyperparasitized aphids, identification of the primary parasitoid host was also possible, allowing us to track species‐specific parasitoid‐hyperparasitoid links. Nine combinations of primary parasitoids within a single host were found, but only 1.6% of all screened aphids were multiparasitized. The potential of this approach to parasitoid food web research is discussed.

A thousand and one wasps: a 28S rDNA and morphological phylogeny of the Ichneumonidae (Insecta: Hymenoptera) with an investigation into alignment parameter space and elision

Abstract The internal phylogeny of the Ichneumonidae is investigated using parsimony analysis of a large data set including 1001 partial 28S ribosomal DNA sequences, 621 of which are newly reported, and a morphological data set of 162 characters scored variously at subfamily, tribe, genus group and genus levels and including only informative characters. The data set includes members of 630 named genera, representing all currently recognized subfamilies, all but four tribes and all but one of the taxa noted by Townes as being of uncertain placement. Sequences were aligned using clustal X, and a sensitivity analysis was performed varying gap-opening and gap-extension parameters. Alignments were appraised by reference to their ability to recover a range of traditional and morphologically recognized groups. Each alignment was analysed both independently and simultaneously with the morphological data set, and also with gap characters treated as both missing data and as informative. No single set of alignment parameters was found to be markedly better by this criterion, and different ranges of parameters led to the recovery of different recognized groups of taxa. Elision (combining all alignments into a single analysis) was therefore used, both with and without morphology and with both gap character treatments, to summarize the overall molecular signal. Analysis of the morphological matrix alone produced a number of results that are undoubtedly a consequence of convergence of morphological characters as the result of parallel evolution of similar life histories. Simultaneous analysis of the morphological data set with each of the 120 DNA alignments recovered most accepted subfamilies as monophyletic. Several currently recognized subfamilies are supported by most of the molecular analyses but some appear to be paraphyletic or polyphyletic. The Ctenopelmatinae are paraphyletic with respect to the Metopiinae. Robustly recovered results lead us to resurrect the Brachyscleromatinae to include Brachyschleroma and the Erythrodolius group of Phrudinae. The Neorhacodinae and the Phrudus group of Phrudinae are transferred to the Tersilochinae. Nonnus is transferred to the Nesomesochorinae. Hyperacmus is transferred to the Cylloceriinae. The major groupings of subfamilies that have recently been proposed (i.e. ichneumoniformes, pimpliformes and ophioniformes) were recovered as monophyletic, but their exact limits remain in question.

The adaptive significance of host location by vibrational sounding in parasitoid wasps.

Vibrational sounding, which is a form of echolocation, is a means of host location by some parasitoid wasps. The wasp taps the substrate (wood, stem or soil) and detects the position of a potential host through the returning ‘echoes’. The deployment of vibrational sounding is inferred through the form of the subgenual organ in the female tibia in combination with the presence of modifications to the female antenna used for tapping the substrate. Vibrational sounding and its associated modifications were found in two families. The use of vibrational sounding by parasitoid wasps was positively correlated with the depth of the host in the substrate relative to the size of the parasitoid. There were also significant correlations between the use of vibrational sounding and parasitism of immobile and concealed hosts and between vibrational sounding and idiobiosis. The data suggested that vibrational sounding evolved under a variety of ecological conditions, being employed in the location of wood–boring, stem–boring, soildwelling and cocooned hosts and stem–nesting aculeates, often in situations in which the host does not produce vibrations itself.

Unprecedented ichneumonid parasitoid wasp diversity in tropical forests.

The megadiverse parasitoid wasp family Ichneumonidae (Hymenoptera) is classically considered an exception to the extensively studied latitudinal diversity gradient: the majority of ichneumonid species are described from temperate regions. The gradient has been hypothesized to be dependent on the biology of the wasps, but recently questions of sampling and description biases have been raised. Here, we show with primary data that the species richness of Ichneumonidae is markedly underestimated in tropical areas and that latitudinal diversity patterns in the family remain uncharacterized. We discovered a startling 177 likely undescribed orthocentrine species with relatively low sampling effort in the forests of Central America and Amazonian Ecuador, over three times the previously known orthocentrine diversity in the worlds tropics. Species accumulation curves reveal that we are just beginning to unveil the true extent of tropical orthocentrine diversity. We also found evidence for cryptic species; our DNA analysis revealed additional species not easily distinguishable using morphological characteristics. The difficulty in establishing species richness patterns of Ichneumonidae probably follows from the relative lack of taxonomic expertise and the low density of ichneumonid species throughout the landscape.

Direct optimization and multiple alignment of 28S D2–D3 rDNA sequences: problems with indels on the way to a molecular phylogeny of the cryptine ichneumon waSPS (Insecta: Hymenoptera)

A molecular phylogeny of the Cryptinae based on the D2–D3 region of the 28S rDNA gene, including 176 cryptines representing 139 genera and an additional 77 outgroup genera, is presented. Direct optimization and multiple alignment each with a range of gap/substitution parameters were employed. The informal higher grouping of the ichneumonids were supported, but the relationship of the Ichneumoninae and Cryptinae was not resolved. Cryptinae tribes were supported but many genera formed constant groups that did not follow earlier subtribal divisions. We investigated artifactual placements of, e.g., Agriotypinae and Brachycyrtinae, and showed that they do not possess molecular synapomophies with the Ichenumoninae where direct optimization places them. The sequences of anomalous placed taxa were markedly longer (or in some cases shorter) than those of most other taxa, and this is explained by homoplastic indels at “hot spots” in the absence of large numbers of informative substitutions. We show that multiple alignment generally resulted in taxa with large insertions or deletions being placed in more plausible positions. The relationship of the genus Alomya is also explored.

Utility of the DNA barcoding gene fragment for parasitic wasp phylogeny (Hymenoptera: Ichneumonoidea): data release and new measure of taxonomic congruence

The enormous cytochrome oxidase subunit I (COI) sequence database being assembled from the various DNA barcoding projects as well as from independent phylogenetic studies constitutes an almost unprecedented amount of data for molecular systematics, in addition to its role in species identification and discovery. As part of a study of the potential of this gene fragment to improve the accuracy of phylogenetic reconstructions, and in particular, exploring the effects of dense taxon sampling, we have assembled a data set for the hyperdiverse, cosmopolitan parasitic wasp superfamily Ichneumonoidea, including the release of 1793 unpublished sequences. Of approximately 84 currently recognized Ichneumonoidea subfamilies, 2500 genera and 41 000 described species, barcoding 5′‐COI data were assembled for 4168 putative species‐level terminals (many undescribed), representing 671 genera and all but ten of the currently recognized subfamilies. After the removal of identical and near‐identical sequences, the 4174 initial sequences were reduced to 3278. We show that when subjected to phylogenetic analysis using both maximum likelihood and parsimony, there is a broad correlation between taxonomic congruence and number of included sequences. We additionally present a new measure of taxonomic congruence based upon the Simpson diversity index, the Simpson dominance index, which gives greater weight to morphologically recognized taxonomic groups (subfamilies) recovered with most representatives in one or a few contiguous groups or subclusters.

The parasitic wasp genera Skiapus, Hellwigia, Nonnus, Chriodes, and Klutiana (Hymenoptera, Ichneumonidae): Recognition of the Nesomesochorinae stat. rev. and Nonninae stat. nov. and transfer of Skiapus and Hellwigia to the Ophioninae

The ichneumonid wasp genera Skiapus Morley, Hellwigia Gravenhorst, Nonnus Cresson, Chriodes Förster, and Klutiana Betrem are each formally removed from the Campopleginae on the basis of morphological, molecular, and simultaneous analyses using PAUP* and the optimization alignment program POY. Skiapus and Hellwigia are shown to form a monophyletic group with the Ophioninae to which they are transferred. Nonnus is treated as comprising the Nonninae stat. nov. and Chriodes and Klutiana (sometimes treated as a junior synonym of Chriodes) are treated as comprising the Nesomesochorinae stat. rev. The status of Nesomesochorinae and Nonninae is not fully resolved as they are not consistently recovered as separate groups, forming a single clade in some analyses. We keep them separate because of this uncertainty. Molecular synapomorphies within the D2–3 expansion region of the 28S rDNA gene show the utility of this gene region in determining subfamily‐level placement within the higher Ophioniformes.

Altitudinal trends in species richness and diversity of Mesoamerican parasitoid wasps (Hymenoptera: Ichneumonidae)

Utilising short‐term but geographically extensive sampling in Guatemala, Honduras, and Nicaragua, we examined altitudinal trends in species richness and diversity of ichneumonid parasitoid wasps. This study covered 19 subfamilies, including four globally large subfamilies that have not yet been taxonomically revised in the Neotropics. Sampling was done at 25 sites classified into three elevational categories on the basis of the average elevation of traps at each site (low 34–659 m a.s.l., middle 1033–1709 m a.s.l., and high 1930–2565 m a.s.l.). A total of 2847 ichneumonid individuals were captured and sorted into 751 morphospecies, most of which were identified to the genus level. We found a clear compositional gradient in ichneumonid communities along the elevational gradient, as the majority of species were restricted to either one elevational zone or two adjacent zones. In our data, mid‐ and high‐elevation sites had generally higher ichneumonid species richness and diversity than low‐elevation sites. These trends were largely similar to those found in larger scale Mesoamerican ichneumonid studies. Yet, the low ichneumonid richness at low elevations may partly be a sampling artefact. This provides a new piece of evidence for the suggestion that extensive sampling is needed for uncovering the real diversity of ichneumonids in tropical lowland forests, and that the reputation of Ichneumonidae as a notable example of a reversed latitudinal diversity gradient may be undeserved.

First record of Acaenitinae (Hymenoptera, Ichneumonidae) from South America with description of a new species and a key to the world species of Arotes Gravenhorst

Abstract A new species of Acaenitinae, Arotes ucumari Castillo & Sääksjärvi, sp. n., is described and illustrated representing the first record of the subfamily from South America. The new species was collected from a premontane tropical rain forest in the Peruvian Andes at 1500 m. A key to the world species of Arotes Gravenhorst,1829 is provided. The subspecies Arotes albicinctus moiwanus (Matsumura, 1912)is raised to species rank, Arotes moiwanus stat. n.