Three Decades: A Reduction from 19 to 3 Species of Black Flies Juveniles

Abstract

Anthropological and environmental influence can be contributory factors to ecological speciation within and among insects. However, identifying specific survival strategy responsible for the colonization of an environment by all comers to survival of the fittest between species, for instance high rate of fecundity, adapting/resistance to changes in the environment, or cyclic or non-cyclic life history remains challenging. Here, we report an extraordinary case where we conducted a study of an environment where the population of the generics of some Black flies species (Simulium) were earlier reported to be nineteen (19) species and uncovered it reduced to three (3) species over a period of three decades. Via prospective studies, we were able to understand that physical parameters such as changes in hydrogen potential of water and water velocity, oviposition cues and possibly human activities could have been agents to the reduction in population of the same type of species of insects. Identification of the available larval species collected in five micro-niches at Assop fall indicated that the three predominant larvae were Simulium damnosum, Simulium vorax and Simulium hargreavesi. Our data suggest clear signs of sympatric distribution in larvae species synchronizing with the loss of adult species and probably the ability of the few species to survive in that area despite control measures put in the past to stem the transfer of Onchocerciasis with the attack on the vector species. We propose an ecological model that generational competition could be responsible for the ability of certain species of insects to out-compete others and probably develop certain innate survival strategy to remain viable in an environment.