The Ichneumonidae is one of the most species rich families of all organisms with an estimated 60000 species in the world (Townes, 1969). Even so, many authorities regard this figure as an underestimate! (Gauld, 1991). An estimated 12100 species of Ichneumonidae occur in the Afrotropical region (Africa south of the Sahara and including Madagascar) (Townes & Townes, 1973), of which only 1927 have been described (Yu, 1998). This means that roughly 16% of the afrotropical ichneumonids are known to science! These species comprise 338 genera. The family Ichneumonidae is currently split into 37 subfamilies (including, Acaenitinae; Adelognathinae; Agriotypinae; Alomyinae; Anomaloninae; Banchinae; Brachycyrtinae; Campopleginae; Collyrinae; Cremastinae; Cryptinae; Ctenopelmatinae; Diplazontinae; Eucerotinae; Ichneumoninae; Labeninae; Lycorininae; Mesochorinae; Metopiinae; Microleptinae; Neorhacodinae; Ophioninae; Orthopelmatinae; Orthocentrinae; Oxytorinae; Paxylomatinae; Phrudinae; Phygadeuontinae; Pimplinae; Rhyssinae; Stilbopinae; Tersilochinae; Tryphoninae; Xoridinae) (Yu, 1998).
The Ichneumonidae, along with other groups of parasitic Hymenoptera, are supposedly no more species rich in the tropics than in the Northern Hemisphere temperate regions (Owen & Owen, 1974; Janzen, 1981; Janzen & Pond, 1975), although a number of hymenopteran families, for example the Chalcididae (Hespenheide, 1979) and Encyrtidae (Noyes 1989b) exhibit an increase in species richness with a decrease in latitude. Other hymenopteran taxa such as sawflies (Symphyta), gall-forming Cynipidae and bees (Apoidea) peak in species richness at mid or high latitudes (Michener 1979; Noyes 1989b; Kouki et al. 1994). Considerable debate has centred on the apparent species richness anomaly exhibited by a number of hymenopteran parasitoid taxa in the tropics (see Morrison et al. 1978; Gauld, 1991; Gauld & Gaston, 1994). Ichneumonids utilise a diverse array of insects and arachnids as their hosts and play an essential role in the normal functioning of most ecosystems, underlining the need to inventory their diversity. Ichneumonids have been used successfully as biocontrol agents and given the largely undocumented fauna there is a huge potential for their utilisation in managed biocontrol programmes (Gupta, 1991). Comprehensive quantitative biodiversity surveys will enable the identification of hotspots of species richness and endemism; essential base line data that will enable informed future conservation management decisions.
Identifying characteristics for the family Ichneumonidae include:
- Antennae apparently with 16 or more segments.
- Hind trochanters 2-segmented.
- Two recurrent veins.
- Usually larger than braconids; quite variable in color.
- Females often with long ovipositors.
- Species in the family Ichneumonidae are separated from those in Braconidae by having two, rather than one or zero recurrent veins.
- Ichneumons are important internal parasitoids of other insects. Common hosts are larvae and pupae of Coleoptera, Hymenoptera, and Lepidoptera.
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