Why Microgastrinae and why they may interest you

When rearing caterpillars, it is common to find some small parasitoid wasps (1.5-8 mm long), often black or yellow and with rather short "abdomen". They belong to the subfamily Microgastrinae (Order Hymenoptera, Family Braconidae), and are one of the most important groups parasitizing butterflies and moths (Order Lepidoptera). These wasps are key components in the biological control of agriculture and forestry pests; and have also been extensively used in biodiversity, ecological, behavioral and molecular studies. However, its narrow host specificity and extraordinary diversity (more than 2,200 described species, with an estimate of 20-40,000 worldwide) presents an immense challenge. 

Addressing the need of more information about those fascinating insects is the main reason of this website. Tips to recognize different genera, species profiles, new biological data, distribution records, and other comments will be provided in following posts. Also, the readers are encouraged to send any question and/or contribution they may have about microgastrines (or any braconid wasp) parasitizing caterpillars. 

Detailed distribution of species and their host records will be compiled from different sources (mostly mined from the large and rich collection available in the Canadian National Collection of Insects, as well as other collections I have visited and/or borrowed material from). Contents intend to be useful to anyone already working or just interested in rearing caterpillars and their parasitoids. It will hopefully interest workers on biological control, bioinformatics, biodiversity researchers, wasp taxonomists, conservation authorities and entomological societies looking for information of species in particular areas. 

What do we know about the largest Apanteles species in North America?

In a previous post it was mentioned that the braconid wasps of the subfamily Microgastrinae comprise specimens ranging from 1.5 to 8.0 mm of body length. The truth is that most of the microgastrines are rather small, usually 2.0 to 3.5 mm long. The "record" of 8 mm is reserved for "giant" specimens of Larissimus, a tropical genus in South America. However, in North America there are very few species that surpass the 4 mm mark, and most of those species are in the genera Microgaster and Protomicroplitis...

Among the largest specimens of microgastrine wasps in North America, the species Apanteles crassicornis stands on its own with around 5 mm of length. That species is also noteworthy because of its elongate face and enlarged glossa, which is supposedly related to the gathering of pollen or nectar. 

Apanteles crassicornis (Provancher, 1866). Antennae and legs are missing some segments. Photo of the holotype of the species, deposited in Laval University, Quebec.

An overview of braconid wasps in Canada

Braconid wasps are the second largest group within Hymenoptera (the insect order that comprises bees, stinging wasps, ants, sawflies and parasitoid wasps). The last version of Taxapad records 956 described species of Braconidae for Canada. Of course, that is just the total of species that have been given scientific names by taxonomists. But it does not account for the many undescribed and/or unrecorded species that remain to be discovered. How many species are actually out there in the Great White North?  

Main subfamilies of Braconidae (Hymenoptera) in Canada. Total number of species: 956 [based on Taxapad (2012)].

While it is impossible to be certain, it is likely that at least twice the current figure, or about 2,000 species of braconid wasps will be found in Canada when all is said and done. 

Think about that for a second. The only group of living things (excluding perhaps microorganisms) that is more diverse than braconids wasps is yet another group of parasitoid wasps: Ichneumonidae, which happens to be the sister group to braconids. Ichneumonid wasps currently comprise almost 3,000 species in Canada (2,834, according to Taxapad). Nothing else comes even close to those figures -and the same situation is probably found in most other areas of the planet. We are talking here about the biodiversity heavy-weights.

Two thousand species of braconid wasps in Canada is a great number, and it amazes to think that we are still missing ONE THOUSAND species to be recorded -let alone studied in detail! The vast majority of those tiny wasps play a capital role in the natural regulation of herbivores -which might otherwise become pests of our crops and forests. Thus, this is not only a matter of scientific inquiry, but also a practical issue with economical implications.