Friday, June 7, 2013

School Malaise findings 5 - Midges and a dancing fly

Non-biting Midges (Chironomidae)
Chironomus plumosus
Chironomidae is a large family of flies whose members look much like mosquitoes. However, they do not possess the needle-like mouthparts of mosquitoes, so these midges do not bite! The males are easily recognized by their feathery antennae and are often seen in large swarms over a landmark such as a rock or bush. Their larvae are very common in many aquatic environments, where they usually feed on algae or decomposing plant material. The flying adults have a short lifespan in which males often assemble into huge swarms. Females join these swarms to mate, and shortly after the males die. The adults rarely eat as their lifespan is so short - they must focus on reproduction. The family Chironomidae is very diverse with over 8000 named species so far. As a result they are common in aquatic habitats around the world. They are notoriously difficult to identify to species level. Up to the point DNA methods became more accessible, the cytotaxonomical analysis of polytene chromosome banding patterns had been considered to be the only reliable method of Chironomid species identification. However, the method is time-consuming and requires considerable expertise, in particular for the interpretation of those banding patterns.

This family of midges also proved to be dominant in the School Malaise Trap Program as they were the most abundant and most diverse family of insects in the collections. Some 7000 sequences representing likely 250 species. Only about 1/5 matched records on BOLD that had a species name. The rest has not been identified so far or represents a new addition to the DNA Barcode library. 

Waltzing Fly (Prochyliza xanthostoma)
Prochyliza xanthostoma (credit
The Waltzing Fly  is a carrion fly commonly found in North America.  The larvae of this fly species often develop inside the bones of freshly killed animals (e.g. deer, moose) and in their final stages, they fall into the surrounding soil to pupate and soon after, emerge as adult flies. In Ontario's Algonquin Park, waltzing flies typically breed in early spring on the carcasses of moose that did not survive the Winter. In March and early April, they are one of the most plentiful insect species in the Algonquin forest. Males and females look quite different, with the male having larger antennae, head and forelegs compared to the female. These differences are due to the male’s unique courtship and combat behaviours. Males battle to defend their territory (see video) and dance to attract mates hence the name Waltzing Fly.

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