Tuesday, 13 October 2009

Featured insect: Tossinola pamianorum (Hymenoptera: Ichneumonidae)

When the word 'wasp' is mentioned, people get scared as the image of angry yellow jackets or paper wasps is conjured up. When I tell people that I'm interested in them, they tend to respond with a sense of bewilderment and treat me as if I'm crazy.

The order Hymenoptera is one of the largest insect orders, being beaten only by the beetles. Of that, only a small proportion sting, bite or otherwise make a nuisance of themselves, the others minding their own business and performing their vital services to the environment. A good many of them are parasitoids of other insects, their young developing in eggs, larvae, pupae or adults of other species. Frequently, species are host-specific in that one species of parasitic wasp will only develop in a single species of insect.

The featured insect for today, Tossinola pamianorum was recently described from Colo-i-suva in Fiji by Andrew Bennett as a result of the Fijian Terrestrial Arthropod Survey. It is in the subfamily Banchinae of the family Ichneumonidae, which is not only one of the major wasp families, but is one of the largest families of insects in general. A rare species, it was described from seven species from the total haul of the survey. While the host is not yet known, other species in the same group lay their eggs in caterpillars. One particularly gruesome feature in this instance, is that the caterpillars continue to move, eat and grow despite being inhabited by a parasitic wasp...

What is particularly interesting about this species of wasp is that it is the first time this subfamily has been found in Fiji. The genus is also known from the Philippines, Central Asia and West Africa, so there's some huge gaps in the distribution of this species. The subfamily has no other representatives in the South Pacific, though there are a number in Australia and New Zealand, so it may well be that people haven't looked for them rather than that there are none there.

This is not surprising, as the Ichneumonidae has been very poorly worked on despite (or perhaps because of?) it's size and economic importance. A great thing about this paper is that it not only starts to reveal some of the ichnemonid diversity of the South Pacific, but it also provides a useful entry into the fascinating world of Ichneumonidae taxonomy in general. A very interesting and worthwhile publication.

Bennett AMR. 2009. The Ichneumonidae (Hymenoptera) of Fiji: keys to subfamilies and genera with a review of the species of Anomaloninae, Banchinae, Brachycyrtinbae and Diplazontinae. In: Evenhuis, N.L. & Bickel, D.J. (eds.), Fiji Arthropods XIV. Bishop Museum Occasional Papers 105: 3-68.

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