Dynamics of immature stages of Anopheles arabiensis and other mosquito species (Diptera: Culicidae) in relation to rice cropping in a rice agro-ecosystem in Kenya
Loading...
Date
2006
Authors
Mwangangi, Joseph
Shililu, Josephat
Muturi, Ephantus
Gu, Weidong
Mbogo, Charles
Kabiru, Ephantus
Jacob, Benjamin
Githure, John
Novak, Robert
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
We determined changes in species composition and densities of immature stages of Anopheles arabiensis
mosquitoes in relation to rice growth cycle in order to generate data for developing larval control strategies in rice ecosystems.
Experimental rice paddies (6.3m x 3.15m) exposed to natural colonization of mosquitoes were sampled weekly for two
rice growing cycles between February 2004 and March 2005. Overall, 21,325 Anopheles larvae were collected, of which
91.9% were 1st and 2nd instars and 8.1% were 3rd and 4th instars. An. arabiensis was the predominant species (84.1%) with
other species, An. pharoensis (13.5%), An. funestus (2.1%), An. coustani (0.3%), and An. maculipalpis (0.1%) accounting
for only a small proportion of the anophelines collected. Culex quinquefasciatus (65.7%) was the predominant species
among the non-anopheline species. Others species collected included: C. annulioris (9.9%), C. poicilipes (7.3%), C. tigripes
(7.2%), C. duttoni (0.6%), Aedes aegypti (5.3%), Ae. cumminsii (3.5%), and Ae. vittatus (0.7%). The densities of the major
anopheline species were closely related to rice stage and condition of the rice field. An. arabiensis, the predominant species,
was most abundant over a three-week period after transplanting. Low densities of larvae were collected during the late
vegetative, reproductive, and ripening phases of rice. An increase in larval density ten days post-transplanting was found to
correlate with the application of fertilizer (sulphate of ammonia). Culicine and aedine species densities were significantly
higher during the post-harvesting period. Our results suggest that the transplanting stage is favorable for the growth of
immature stages of An. arabiensis and provides a narrow window for targeted larval intervention in rice
Description
Research Article
Keywords
Rice growth cycle, Anopheles larval species, Rice height, Tillers, Water depth, Larval control