Corethrellidae are close relatives
of the Culicidae (mosquitoes) and Chaoboridae (phantom midges) and were
actually first placed in the Culicidae along with the chaoborids, then
just with the chaoborids and have only recently been recognized as a
separate family (since 1986)."Adults" share
For many years, specimens of
Corethrella were quite rare in collections and most species were
represented by only 1-3 specimens.
Pupae float at the water surface and are quite inactive. A few days are sufficient for the adults to emerge and fly away. As noted above, females are easily collected with a cassette player and I have found that running a nearby UV light trap may attract numbers of males (but only when the cassette player is running). Female adults readily lay eggs (which are beautifully sculptured and float singly on the water surface) and larvae are easily reared on small mosquito larvae or other moving aquatic organisms in small petri dishes. Overcrowding, though, will result in cannibalism.
In Costa Rica, I have identified 20 species of Corethrella (some unnamed and new to science). All of these are restricted to lower altitudes. Generally, adults may be very abundant (100 adults trapped in 1 hour) in lowland habitats and become scarce at 2400 meters. I haven't yet found any species above this elevation.
The relationship between Corethrella species and frogs is likely an ancient one. The most primitive Corethrella species lives in New Zealand, where some of the most primitive frogs in the world also reside. Furthermore, we now know of a fossil Corethrella in Lebanese amber 120-122 million years old which looks very similar to those living today.
Because specimens of Corethella were so difficult to collect for so many years, our knowledge of the group is actually quite poor. However, as mentioned above, it is now possible to easily collect and study the different species. The larvae and pupae are particularly rich in structural variation and this genus would be a fascinating group for someone interested in interpreting their phylogeny, behaviour and biology.
Although no one has yet investigated this aspect of their biology, it is quite possible that species of Corethrella transmit diseases among their frog hosts."Although no one has yet investigated this aspect of their biology, it is quite possible that species of Corethrella transmit diseases among their frog hosts" a Very recently, McKeever and French have reported that some Corethrella in the eastern United States transmit diseases between male frogs. Considering the global concern with the health of frog populations, this will be a fruitful line of further research.
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