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The fitness of African malaria vectors in the presence and limitation of host behaviour

Lyimo, N. , Haydon, T. , Mbina, F., Daraja, A. , Mbehela, M., Reeve, and Ferguson, M. (2012) The fitness of African malaria vectors in the presence and limitation of host behaviour. Malaria Journal, 11 (425). ISSN 1475-2875

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Abstract

Host responses are important sources of selection upon the host species range of ectoparasites
and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors,
and assess its ability to predict their known host species preferences in nature.
Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis
and Anopheles gambiae s.s in the presence and limitation of host behaviour were conducted
in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials,
mosquitoes were released within the SFS and allowed to forage overnight on a host that was
free to exhibit a natural behaviour in response to insect biting. In the other, mosquitoes were
allowed to feed directly on from the skin surface of immobile hosts. The feeding success and
subsequent fitness of vectors under these conditions were investigated on six host types
(humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of
preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less
effective at preventing mosquito bites than those of common alternatives.
Anopheles arabiensis generally had greater feeding success when applied directly to host skin
than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae
sensu strictu obtained blood meals from free and restrained hosts with similar success from
most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and
post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free
to exhibit behaviour, than those who were immobilized during feeding trials.
Conclusions
Allowing hosts to move freely during exposure to mosquitoes was associated with moderate
reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of
mosquitoes that were able to feed upon them. This suggests that physical defensive
behaviours exhibited by common host species including humans do not impose substantial
fitness costs on African malaria vectors.

Item Type: Article
Keywords: Malaria Vector, ectoparasites, phytophagous, Anopheles gambiae s.s, Tanzania,Fitness, Feeding success, Host species range, Host behaviour, Natural selection
Subjects: Malaria > Vector control
Divisions: Ifakara Health Institute > Biomedical
Depositing User: Digital Library Manager
Date Deposited: 20 Dec 2012 07:05
Last Modified: 07 Jan 2013 07:38
URI: http://ihi.eprints.org/id/eprint/996

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