Aims: The fitness of adult malaria mosquitoes, defined by size and survivorship, is influenced by density-dependent processes at the larval stage, and simultaneously by density-independent (environmental) processes. Understanding the roles of density-dependent and independent influences is essential for predicting the response of mosquito populations to larval control. Evidence for the existence of density dependent effects on An farauti, the primary vector in the Solomon Islands will be presented together with data on the physical, chemical and biological characteristics of larval habitats and their association with productivity.
Methods: Human landing catches were carried out across the Solomon Islands with the wings of the collected mosquitoes measured to determine size variation within the adult population. As well as adult collections, the aquatic stage was also investigated looking at the chemical, physical, and biological factors associated with the presence or absence of the Anopheles farauti larvae as well as the productivity of each potential habitat.
Results: Size variation was confirmed within the adult mosquito population, and significant factors found that act on the larvae with water temperature (P<0.0001*), pH (P=0.0002*), nitrate (P<0.0001*), ammonia (P=0.0190*), and phosphate (P<0.0001*) associated with increases in larval density. However, there does not appear to be any single dominant factor associated with habitat utilisation and productivity.
Conclusion: In conclusion, a lot of information is unknown regarding the aquatic stages of anophelines in the Solomon Islands. This is especially evident for Anopheles farauti which is concerning considering the impact it has on human health due to its association with malaria. Looking at the relationship between the larval habitat, larval density, and adult fitness could help influence future control methods to complement the use of insecticide treated nets for malaria control.