Succession in substrate colonisation by African blackfly larvae (Diptera: Simuliidae)

Artificial substrates exposed in a Nigerian river were colonised by succession of a blackfly larvae. Simulium cervicornutum had a peak of abundance at 14 days, S. hargreavesi had a peak at 18 days and S. vorax at 25 days. In each case, after the initial peak, the population declined. On the individual substrates, mean abundance of each species increased away from the point of attachment, but when comparing a row of 20 substrates, there was considerable variation in the larval abundance on each substrate, showing that each species had a clumped distribution. Most of the colonising larvae of S. hargreavesi were very young, but this was not so in S. squamosum and S. cervicornutum. This implies that S. hargreavesi may be more competitive than these species in remaining on the substrate, particularly since S. cervicornutum was also a much smaller species. -from Authors