Apanteles fumiferanae, an important parasitoid wasp

Apanteles fumiferanae Viereck is one the most important Microgastrinae wasps in North America -at least from a forest pest management perspective. Based on specimens available in collections, it is the most common braconid parasitoid wasp reared from the spruce budworm Choristoneura fumiferanae (Harris) (Lepidoptera: Tortricidae), which in turn is one of the major forest pests in the region.

Very few pests rival the spruce budworm in importance, and thus this lepidopteran species has been extensively studied over the years. There are hundreds of papers covering details of its biology, ecology, damage and control (biological, chemical, integrated). As part of those studies, for many years its caterpillars have been collected and reared for parasitoids, providing perhaps the best information ever available for a single forest pest in the Neartic region. Still there are many details to be researched and understood.

Some recent papers summarize what we know until now. For example, an excellent analysis of the complex relationships between the spruce budworm and its parasitoids/hyperparasitoids/pathogens, was published by Eldon Eveleigh (Canadian Forest Service, CFS) and ten co-authors in 2007; it can be freely downloaded here (http://cfs.nrcan.gc.ca/pubwarehouse/pdfs/28040.pdf). That paper shows the complexities of food webs -even in a temperate forest. From a parasitoid perspective, John Huber, also from the CFS, led a team of four taxonomists to produce a series of papers covering all major groups of parasitoids of the genus Choristoneura in the Nearctic region: chalcid wasps (Huber, 1996), tachinid flies (O'Hara, 2005), ichneumonid wasps (Bennett, 2008) and braconid wasps (Fernández-Triana and Huber, 2010). Those works provided numerous illustrations, keys, and taxonomic notes to help identifying the large fauna of currently known parasitoids (230 species within 106 genera and 13 different families; see figures 155-157 and the discussion section in Fernández-Triana and Huber (2010). [Unfortunately those papers cannot be downloaded for free, except for their Abstracts].

As for Apanteles fumiferanae, the species is widely distributed in the Nearctic region (there is also a record from Poland, but that might be incorrect). It has been reared from caterpillars of 17 lepidopteran species representing 4 families (although some of those early records, from historical references, are likely to be wrong). Close to one hundred scientific papers have dealt with the biology/ecology of Apanteles fumiferanae. In fact, the species might actually comprise a complex of morphologically cryptic species (i.e. species that cannot be easily separate based on external morphology, yet are distinct biological entities).

This is nothing new. After the description of the species, in 1912, a couple of papers have already split A. fumiferanae into several, distinct species. Mason (1974) described four new species of Apanteles reared from Choristoneura, based on a study of several hundred specimens. Fernández-Triana and Huber (2010) mentioned another three different species -among samples of over 2,000 reared Apanteles examined. Two of those species were then described as new in another paper (which can be freely downloaded here: http://www.pensoft.net/journal_home_page.php?journal_id=1&page=article&S...).

Thus, we already know that what was thought to be one species (Apanteles fumiferanae) at the beginning of the XX century, it is actually several. Some of those species are host-specific (e.g., Apanteles huberi is only found in British Columbia parasitizing Choristoneura bienis). Others are not. Still, A. fumiferanae remains with too many associated hosts, which strongly suggest there might be additional species hidden under that name. In fact, that is implied when looking at data from DNA barcoded specimens: based on data from specimens deposited in several Canadian collections, there seems to be and additional couple of species within this complex awaiting discovery and description. And that does not include specimens from United States collections, which are likely to have additional species from southern areas in North America.

Because of its importance as a key parasitoid, Apanteles fumiferanae (and related taxa, including potentially cryptic and undescribed species) stands out as something to be studied with more details in the future. More rearing of forest caterpillars is needed and we plan to include details of those efforts in this site -hopefully in the near future.

[This post is an expanded article based on a post from a blog on Microgastrinae wasps (http://cncbraconidae.blogspot.ca/) that used to be written by one of us (Jose Fernandez-Triana). That blog is no longer active but its contents have been moved to this website].

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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith