Malaria Mosquito Larvae in Competition for Limited Resources

Abstract

The mosquitoes of the Anopheles gambiae species complex are the primary vectors of malaria in Africa. These Anopheles species demonstrate large geographical overlap and their larvae often inhabit the same small aquatic pools in nature. To understand how larval interactions between these mosquito species might affect development and success in the field, I studied larval competition between three members of the An. gambiae complex: An. arabiensis, An. quadriannulatus, and two strains of An. coluzzii (Suakoko and Mopti) in resource limited conditions. To quantify competitiveness I measured larval survivorship and time to adult emergence. When raised on a limited food diet, An. arabiensis demonstrated the lowest larval survivorship. Survivorship of An. quadriannulatus, An. coluzzii Mopti and An. coluzzii Suakoko was all significantly higher than An. arabiensis, but there was no significant difference among these three species. Surprisingly, when I competed An. arabiensis against An. coluzzii Suakoko and Mopti in these same conditions, it outcompeted both with significantly higher survivorship. Additionally, An. quadriannulatus and An. arabiensis survivorship increased when the two competed against each other compared to competition against siblings. The increased survivorship of An. arabiensis when in competition with An. coluzzii species suggests a competitive interaction is present that may influence their population sizes and ranges in the field.