Behavioural Adaptations of Malaria Vectors: Evaluating Vector and Human Interactions on Malaria Vector Abundance and Biting Dynamics Post LLINS Intervention in Atatam, Southern Ghana

Abstract

Deployment of malaria control interventions including long-lasting insecticidal nets (LLINs), and indoor residual spraying (IRS) remain the mainstay of current vector control efforts and provide protection against indoor biting and resting mosquitos. This study investigated the abundance, biting activity and human behavioural influence on malaria transmission after the implementation of LLINs in Atatam, a small farming community in the Adansi-Asokwa District of the Ashanti region. The standard Human Landing Catches (HLC) technique was used to collect 7,109 anophelines, which were used to estimate outdoor and indoor vector abundance and peak biting time activity of malaria vectors. A cross-sectional study surveyed thirty (30) households via questionnaire and interviews to assess human activity and sleeping patterns in the community. The study found Anopheles gambiae s.l 83.9 % (5,963) and Anopheles funestus s.l 16.1 % (1,146) to be the predominant vector species biting humans in Atatam. The seasonal abundance of Anopheles gambiae s.l. was significantly higher than Anopheles funestus s.l. (p < 0.05). Similar to Anopheles funestus s.l. the abundance of Anopheles gambiae s.l. outdoors was higher than their abundance indoors. However, this was not statistically significant (p > 0.05). Late night (22 – 04 h) peak biting activity indoor and outdoor which is the historical biting time was exhibited by Anopheles gambiae s.l with early morning (04 – 06 h) peak biting activity also observed for An. funestus s.l. The survey showed 93.3 % LLINs coverage/ownership and 100 % usage amongst households in Atatam. The shift in biting time from the historical late night to early morning indoor and outdoor biting of An. funestus could be due to pressure from LLINs or people spending more time outside unprotected.