Effects of Microclimatic Changes Caused by Land Use and Land Cover on Duration of Gonotrophic Cycles of<i>Anopheles gambiae</i>(Diptera: Culicidae) in Western Kenya Highlands

TLDR

The study examined how deforestation‑induced microclimate changes affect the gonotrophic cycle length of *Anopheles gambiae* in western Kenya highlands. Researchers measured gonotrophic cycle duration in field‑collected F1A *Anopheles gambiae* females. Deforestation raised indoor temperatures by up to 1.8 °C, shortening the first and second gonotrophic cycles by 1.7–1.5 days (≈17–59 %) and increasing daily biting frequency, thereby enhancing vectorial capacity; it also reduced larval‑to‑adult development time and increased survivorship, further boosting malaria transmission potential.

Abstract

Studies were carried out at a malaria epidemic-prone highland site in western Kenya to determine the effects of deforestation-caused microclimate change on the duration of the gonotrophic cycle of the malaria vector Anopheles gambiae Giles. Gonotrophic cycle duration was measured using field-collected F1A. gambiae females. Average ambient temperature in the deforested area of Kakamega (elevation 1,430–1,580 m above sea level), western Kenya, was 0.5°C higher than that of the forested area over a 10-mo period. During the dry season, deforested areas showed an increased mean indoor temperature of 1.8°C, and a shortened duration of the mosquitoes' first and second gonotrophic cycles, by 1.7 d (59%) and 0.9 d (43%). During the rainy season, the average indoor temperature of houses located in the deforested area was 1.2°C higher than in houses in the forested area. The duration of the first and second gonotrophic cycles was shortened by 1.5 d (17%) and 1.4 d (27%), respectively, in the deforested highland site. A shorter mosquito gonotrophic cycle implies increased daily biting frequency and thus increased vectorial capacity. Together with evidence that deforestation reduced A. gambiae larva-to-adult developmental time and increased larval and adult survivorship, this study suggests that deforestation can further enhance malaria transmission potential in the highlands through increased indoor temperature and shortened gonotrophic cycle durations of A. gambiae mosquitoes.