Newsletter of the Biological Survey of Canada (Terrestrial Arthropods)

An overview and update of the Microgastrinae (Hymenoptera: Braconidae) holdings in the Canadian National Collection, Ottawa

General information and editorial notes

News and Notes:

Bio-Blitz 2007

BSC Curation Blitz

Head of Biological Survey to retire

Summary of the Scientific Committee meeting

Hugh Danks retires as Head of the BSC

New Head of the BSC appointed

New electronic mailing list

Departing Editor's remarks

Project Update: Arthropods of Canadian Grasslands

The Quiz Page

An overview and update of the Microgastrinae holdings in the CNC, Ottawa

Selected future conferences

Quips and Quotes

List of Requests for Material or Information

With about 2,000 described species (Yu et al. 2005) and an estimate total of 5,000–10,000 species (Mason 1981, Whitfield 1997) the Microgastrinae (Hymenoptera, Braconidae) is one of the most specious groups of parasitic wasps. At present there are 135 species recorded in Canada (Marsh 1979, Yu et al. 2005), but it is estimated that 275 species actually occur here (Biological Survey of Canada 2007).

As part of several studies underway by the author on Nearctic Microgastrinae, a thorough review of the holdings in the Canadian National Collection of Insects, Ottawa (CNC) was carried out. The total number of specimens was estimated taking into account the number of drawers, and the number of specimens per drawer. The last figure varied considerably, so an average of 400 specimens per drawer was chosen as an approximation. All of the Nearctic species represented in the collection were counted and their presence was recorded for each Canadian province. Approximate numbers of specimens collected in Arctic North America were also recorded, as well as some particularly valuable collections (see below).

Apart from type material (housed in a separate area with the rest of the Braconidae types), there were 9 cabinets containing Microgastrinae; plus 6 more cabinets with miscellaneous Braconidae (conservatively, one third of which were Microgastrinae). Each cabinet has 29 drawers, but on average 15% of them were empty. Altogether this totals approximately 250 drawers and at least 100,000 pinned specimens of this subfamily. Compared with previous information (66,900 pinned specimens; Sharkey 1992) this means an almost 50% increase in the last 15 years.

Additionally, there is a significant alcohol-preserved collection; with samples stored at –20ºC (some of them kept in 95% alcohol, suitable for DNA studies). It is difficult to calculate with accuracy the number of specimens there, but the author searched all of the samples from Southeast Asia and some from the United States and Australia; and it is quite evident that there are several thousand Microgastrinae. Even using the most conservative estimate, the total figure for the subfamily in the CNC easily surpasses 150,000 specimens, making this one of the larger collections in the world – if not the largest.

The best represented region is the Nearctic, with approximately two thirds of the holdings. Specimens from the Neotropics, Palearctic, Australia, and Old World tropics are also significant. In summary, this is a collection with a major focus in North America but with a fairy good representation at a worldwide level. Most of the specimens added in the past few years were prepared by critical point drying and generally their quality is superb.

Of the 299 described species recorded in the Nearctic (data pooled from Yu et al. 2005; Whitfield 1995, 2006), the CNC has at least 266 of them (89%); including numerous primary types and paratypes (information about primary types summarized in Sarazin 1985). The collection is particularly well represented in diverse and difficult genera such as: Apanteles, Cotesia, Dolichogenidea, and Microgaster, each with over 90% of the known species represented in the collection. Microplitis is the most poorly represented genus, with 19 of 32 Nearctic species (60%); although numerous undetermined specimens are available for further study.

Table 1 provides an update of species number by province for Canada. Figures were obtained from careful and exhaustive collation of data for each named species (in some cases the specimens were sorted just to species-groups or the closest known species, stating that they were a new, but otherwise undescribed, species). Those determinations were made mostly by W. Mason, the past authority on Microgastrinae; and no intent is made in this paper to check potential mistakes and/or validity of those identifications. However, a thorough revision of those former identifications is currently in progress, and a complete checklist of Microgastrinae species of Canada will be soon published elsewhere. Although some correction to the present figures is certainly expected, all the numbers provided here are rather conservative.

The results show a significant increase for all provinces, ranging from a little less than half for Alberta to more than three times to Manitoba. This is an additional confirmation that the holdings of the CNC cover most of Canada – although many specimens still have to be studied. The Ontario figure (137) even surpasses the previous total for the entire country. As for the single species recorded for Yukon (Whitfield 2006) an almost completed work (Fernandez and Goulet, unpublished data) will increase the figure considerably.

Altogether, 73 new species for Canada were found. This does not include unsorted specimens (several thousand), which will surely increase those numbers even more. In comparison, the number of species currently known for the Nearctic is around 300 (Whitfield 1995, 2006; Yu et al. 2005), with 266 recorded within the US and the highest diversity for its states ranging from 73 to 89 species (Yu et al. 2005). This does not mean that Canada and/or Ontario are the Microgastrinae hot-spot in the Nearctic, but it clearly shows the potential of the resources and information available in the CNC.

There are four particularly valuable collections of Microgastrinae in the CNC that have not been carefully studied yet. Each is briefly mentioned below with some additional remarks:

1) Fauna north of 60º N:
The CNC holdings comprise an estimated of + 5,000 specimens, with close to 2,000 from Yukon, but with all northern Territories (as far north as Ellesmere Island) and Alaska also well represented. Altogether, this is the most valuable collections of Microgastrinae in the Arctic region of North America, and it will certainly provide an excellent baseline for further studies. As stated above, the Yukon fauna is currently under revision (with about 40 species already identified), and plans are underway to continue with all remaining Arctic samples from other areas.

2) Unidentified specimens reared from lepidopterans from both agricultural and forestry sites across Canada:
There are several hundreds, perhaps even thousands, of microgastrinae from past rearing programs; especially, but not exclusively, the Forest Insect Survey. Most of them have not been studied and lack complete identification (some are sorted to the genus level). It is likely that significant and new biological information can be extracted from those specimens, with the potential to provide new information for biological control efforts.

3) Microgastrinae from an exhaustive sampling program in an agricultural site:
Some 20,000–30,000 specimens, collected weekly during 4 years in two apple orchards in Frelighsburg, Quebec. This huge series of specimens will not only provide an excellent overview to the true diversity of Microgastrinae in a single ecosystem, but will also help to associate sex in difficult species complexes, as well as yield considerable of ecological information. Work is already underway, with about 3,000 specimens studied and some 30 species so far identified. There are also other smaller collections from agricultural sites but with much less coverage.

4) Non-Nearctic collections:
Alcohol samples from several southeastern Asian countries are particularly rich in microgastrinae braconids (with several hundred to perhaps a few thousand specimens), and will help to improve basic taxonomic knowledge of microgastrinae in that region. As a direct result of sorting through this valuable material, the genus Philoplitis is currently under review. Other valuable collections are from Australia and the Neotropics. Most of the tropical specimens still need to be mounted, making their study more time consuming.

Based on observations of the CNC microgastrinae collection, significant improvements could be made in three areas given the opportunity, resources, and personnel. First, there are species located under two different names in the collection, especially some of the former Apanteles that were transferred by Mason (1981) to the new genera he erected. This is confusing and also a waste of space. However, organizing those specimens should be done by a person with at least a minimum of knowledge of the group, to avoid making the situation worse. Second, there are long series of specimens representing a few species (mainly from the Frelighsburg collection) that could be reduced. A particularly useful way to do this is to exchange them for material from elsewhere. Potential places of interest to ask for this exchange would include Europe, Japan, the U.S., and some Latin America collections. That way some important gaps in the CNC, especially of the Palearctic fauna, could be filled. Last but not least, a great opportunity exists to produce illustrated keys to some groups, to create a database with the valuable information stored in the collection, and to carry out faunistic / zoogeography analysis. With over a hundred species already used and / or investigated worldwide in the biological control of pest Lepidoptera (Whitfield 1995) this group of parasitic wasps will undoubtedly require more attention and study in the near future.

Acknowledgements
Reviews by John Huber and Henri Goulet significantly improved the manuscript. The support and encouragement of all Hymenoptera staff at the CNC has allowed me to work on this and several projects related to the Nearctic fauna of Microgastrinae during the last 14 months.

Literature cited
Biological Survey of Canada. 2007. Canada’s Insect Fauna. Hymenoptera, Braconidae. http://www.biology.ualberta.ca/bsc/english/faunalanalysis.htm. Accessed on April 2007.

Marsh, P. 1979. Braconidae. Aphidiidae. Hybrizontidae, pp. 144–313. In: K. Krombein, P. Hurd, D. Smith, and B. Burks (eds.) Catalog of Hymenoptera in America North of Mexico. Smithsonian Institution Press, Washington.

Mason, W.R.M. 1981. The polyphyletic nature of Apanteles Foerster (Hymenoptera: Braconidae): A phylogeny and reclassification of Microgastrinae. Memoirs of the Entomological Society of Canada 115: 1-147.

Sarazin, M. 1985. Primary types of Braconidae (Hymenoptera) in the Canadian National Collection. The Canadian Entomologist 117: 1177–1222.

Sharkey, M. 1992. Braconidae holdings in the Canadian National Collection. Ichnews 13.

Whitfield, J. 1995. Annotated checklist of the Microgastrinae of North America north of Mexico (Hymenoptera: Braconidae). Journal of the Kansas Entomological Society 68(3): 245–262.

Whitfield, J. 1997. Microgastrinae, pp. 333-366. In: R. Wharton, P. Marsh, and M. Sharkey (eds.) Manual of the New World Genera of the Family Braconidae (Hymenoptera). International Society of Hymenopterists (Special Publication 1), Washington.

Whitfield, J. 2006. Revision of the Nearctic species of the genus Pholetesor Mason (Hymenoptera: Braconidae). Zootaxa 1144: 1-94.

Yu D.; K. van Achterberg, and K. Horstmann. 2005. World Ichneumonoidea 2004. Taxonomy, Biology, Morphology and Distribution. CD/DVD. Taxapad, Vancouver.

Composite photo of Canadian Microgastrinae housed at the Canadian National Collection (photograph by J.L. Fernandez)