Effects of co-habitation between Anopheles gambiae s.s. and Culex quinquefasciatus aquatic stages on life history traits.
BACKGROUND
The effective measures for the control of malaria and filariasis vectors can be achieved by targeting immature stages of anopheline and culicine mosquitoes in productive habitat. To design this strategy, the mechanisms (like biotic interactions with conspecifc and heterospecific larvae) regulating mosquito aquatic stages survivorship, development time and the size of emerging adults should be understood. This study explored the effect of co-habitation between An. gambiae s.s. and Cx. quinquefasciatus on different life history traits of both species under different densities and constant food supply in the habitats of the same size under semi-natural conditions.


METHODS
Experiments were set up with three combinations; Cx. quinquefasciatus alone (single species treatment), An. gambiae s.s. alone (single species treatment); and An. gambiae s.s. with Cx. quiquefasciatus (co-habitation treatment) in different densities in semi field situation.


RESULTS
The effect of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus was found to principally affect three parameters. The wing-lengths (a proxy measure of body size) of An. gambiae s.s. in co-habitation treatments were significantly shorter in both females and males than in An. gambiae s.s single species treatments. In Cx. quinquefasciatus, no significant differences in wing-length were observed between the single species and co-habitation treatments. Daily survival rates were not significantly different between co-habitation and single species treatments for both An. gambiae s.s. and Cx. quinquefasciatus. Developmental time was found to be significantly different with single species treatments developing better than co-habitation treatments. Sex ratio was found to be significantly different from the proportion of 0.5 among single and co-habitation treatments species at different densities. Single species treatments had more males than females emerging while in co-habitation treatments more females emerged than males. In this study, there was no significant competitive survival advantage in co-habitation.


CONCLUSIONS
These results suggest that co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in semi-natural conditions affect mostly An. gambiae s.s. body size. Hence, more has to be understood on the effects of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in a natural ecology and its possible consequences in malaria and filariasis epidemiology.
Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu 40100, Kenya. pat.kweka@gmail.com
Eliningaya J
EJ
Kweka
Goufa
G
Zhou
Leila B
LB
Beilhe
Amruta
A
Dixit
Yaw
Y
Afrane
Thomas M
TM
Gilbreath
Stephen
S
Munga
Mramba
M
Nyindo
Andrew K
AK
Githeko
Guiyun
G
Yan
D000818:Animals; D000852:Anopheles / Q000254:growth & development / Q000502:physiology*; D049628:Body Size; D003465:Culex / Q000254:growth & development / Q000502:physiology*; D017753:Ecosystem; D005260:Female; D005368:Filariasis / Q000517:prevention & control* / Q000635:transmission; D008018:Life Cycle Stages; D008288:Malaria / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D012744:Sex Ratio; D015996:Survival Rate