Unprecedented ichneumonid parasitoid wasp diversity in tropical forests

Abstract

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 world's 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.

Diversity of parasitoid and parasitic wasps across a latitudinal gradient: Using public DNA records to work within a taxonomic impediment

“…However, some have questioned whether this apparent exception is a trend actually caused by limits in taxonomic and geographic sampling (Skillen et al 2000;Willig et al 2003;Jones et al 2009;Baselga et al 2010;Santos and Quicke 2011;Quicke 2012;Veijalainen et al 2012). For example, data from comparatively well-studied northern geographic regions such as North America and Europe (Santos and Quicke 2011) and data gathered over longer time periods may conflate our understanding of species richness (Willig et al 2003).…”

Optimising Capture Methods for the Evaluation of Parasitoid Wasp Diversity

“…Unfortunately, the development of such methods are more difficult for hyperdiverse taxa such as parasitoid wasps, where even modest efforts capture large numbers of species almost anywhere in the world (Veijalainen et al, 2012;Owen et al, 1981). The present study has demonstrated that it is possible to census two thirds of the parasitoid wasp diversity characterising local sites by employing an intensive Malaise-trapping regime over the summer.…”

“…They sampled a greater number of sites with less effort per site, but also captured just over 1 female specimen per Malaise-trap-day. Fraser et al (2007Fraser et al ( , 2008 2004), while they can be six times higher for Orthocentrinae (Veijalainen et al, 2012). Parasitoid assemblages are characterised by a high proportion of taxa represented by only one or two individuals, so by definition they require extra sampling effort compared to more even groups (Magurran, 2004).…”

“…Parasitoid species diversity is immense worldwide (Veijalainen et al, 2012). In Costa Rica, Gaston & Gauld (1993) caught 150 species from a single subfamily over a five year period.…”

New species ofMegastylus(Hymenoptera: Ichneumonidae: Orthocentrinae) reared from larvae of Keroplatidae fungus gnats (Diptera) in a Dutch orchid greenhouse

“…The West Palaearctic Megastylus species are rather well known (Förster 1871;van Rossem 1974van Rossem , 1983, but the Neotropical fauna of the genus Megastylus, as well as all orthocentrines, are still mostly unstudied (Veijalainen et al 2012(Veijalainen et al , 2013. Until now, only two Neotropical species of Megastylus have been described: Megastylus panamensis from Panama (Wahl 1996) and Megastylus kasparyani Humala from Mexico (Humala 2014), and the number of Megastylus morphospecies registered in the Neotropics is higher than the number of described species in the world (Veijalainen et al 2012). Hopefully, future studies of the Neotropical fauna will allow the newly described species to be found in its natural habitat and its origin can be clarified.…”