Abstract:
Malaria is a significant vector-borne disease transmitted by an infective bite of female
Anopheles mosquitoes. It poses one of the most complex public health challenges in tropical
and subtropical regions. Climate change can directly affect the patterns of vector-borne
diseases by influencing the distribution, abundance, and dynamics of vectors thus, altering
disease transmission patterns. This study aimed to investigate the effects of temperature and
relative humidity on the development, abundance, and survival time of Anopheles arabiensis,
a primary malaria vector widely distributed in Ethiopia. The mosquitoes were reared under
both variable and constant temperatures and humidity conditions. A total of four hundred
(400) An. arabiensis eggs were subjected to temperatures ranging from 14.5-34.35 ℃ and
relative humidity (RH) levels from 64%-84%. The development rate and survival of immature
and adults were examined under 20 different temperature and humidity regimes. Statistical
analyses were performed using Package for the Statistical package for social sciences
Version (SPSS)26, with linear regression analysis assessing egg hatchability, developmental
time, and survival rates. Ordinary Least Squares (OLS) and Quadratic regression equations
were used to evaluate the combined effects of temperatures and relative humidity. The study
revealed that the optimal conditions for 80% of egg hatchability were temperatures between
25.3-34.35℃ with relative humidity levels of 64-68%. Adult emergence occurred over a
broad temperature range (16-34℃, peaking at 80% between 28.37-29.65℃ with 70% RH
except under extreme conditions below 16℃ and 64% RH. The maximum time required for
larvae L1 to L2 stage was 13 days at temperatures between 14.55 and 15.62℃ with 83-86%
RH. The highest survival time for adult mosquitoes was 25 days at a temperature between
23.65-24.72°C with 68-69% RH. Fluctuations in temperature and relative humidity
significantly impacted the development of all stages of Anopheles arabiensis. The study
demonstrated that temperature variations and RH affect the population dynamics and
developmental time from egg to larvae, from one instar to subsequent instars, to pupae, and
from pupae to adults. Further research is needed to explore the effects of temperature and
humidity on the development survival, and of wild An. arabiensis populations in Ethiopia.
Such studies are essential for developing models to assess malaria transmission risk.
