Effect of land-use changes on the abundance, distribution, and host-seeking behavior of Aedes arbovirus vectors in oil palm-dominated landscapes, southeastern Côte d’Ivoire

Abstract

BackgroundIdentifying priority areas for vector control is of considerable public health relevance. Arthropod-borne viruses (arboviruses) spread by Aedes mosquitoes are (re)emerging in many parts of the tropics, partially explained by changes in agricultural land-use. We explored the effects of land-use changes on the abundance, distribution, and host-seeking behavior of Aedes mosquitoes along a gradient of anthropogenic disturbance in oil palm-dominated landscapes in southeastern Côte d’Ivoire.MethodologyBetween January and December 2014, eggs, larvae, pupae, and adults of Aedes mosquitoes were sampled in four types of macrohabitats (rainforest, polyculture, oil palm monoculture, and rural housing areas), using standard procedures (bamboo-ovitraps, metallic-ovitraps, larval surveys, and human-baited double-net traps). Immature stages were reared and adult mosquitoes identified at species level.Principal findingsA total of 28,276 Aedes specimens belonging to 11 species were collected. No Aedes-positive microhabitat and only four specimens of Ae. aegypti were found in oil palm monoculture. The highest abundance of Aedes mosquitoes (60.9%) was found in polyculture, while the highest species richness (11 species) was observed in rainforest. Ae. aegypti was the predominant Aedes species, and exhibited high anthropophilic behavior inflicting 93.0% of total biting to humans. The biting rate of Aedes mosquitoes was 34.6 and 7.2-fold higher in polyculture and rural housing areas, respectively, compared to rainforest. Three species (Ae. aegypti, Ae. dendrophilus, and Ae. vittatus) bit humans in polyculture and rural housing areas, with respective biting rates of 21.48 and 4.48 females/person/day. Unexpectedly, all three species were also feeding during darkness. Aedes females showed bimodal daily feeding cycles with peaks at around 08:00 a.m. and 05:00 p.m. Host-seeking activities were interrupted between 11:00 a.m. and 02:00 p.m. in rural housing areas, while no such interruption was observed in polyculture. Some rainforest-dwelling Aedes species displayed little preference to feed on humans.ConclusionsIn southeastern Côte d’Ivoire, the agricultural land-use/land-cover changes due to the conversion of rainforest into oil palm monocultures influence the abundance, distribution, and host-seeking behaviors of anthropophagic and non-anthropophagic Aedes vectors. As a result, there is higher risk of humans to arbovirus transmission in polyculture and rural housing areas. There is a need for integrated vector management, including landscape epidemiology and ecotope-based vector control.

Mosquito-borne viral diseases in the Democratic Republic of the Congo: a review

“…It was reported that mosquitoes which are known to be zoophilic and sylvatic have invaded the peridomestic and periurban settlements and started to feed on humans [53]. Similar observations from the Ivory Coast illustrated the impact of land-use modifications on the abundance, distribution, and hostseeking behaviour of Aedes mosquitoes [54]. A study in the Amazon concluded that deforestation is responsible for the increase in malaria incidence [55].…”

Aedes Mosquitoes and Aedes-Borne Arboviruses in Africa: Current and Future Threats

“…Studies in rural areas have found that within oil palm-dominated landscapes in Côte d’Ivoire Ae. aegypti was more abundant in polycultures than monocultures [ 72 ].…”

Impact of deforestation on the abundance, diversity, and richness of Culex mosquitoes in a southwest Cameroon tropical rainforest

“…This is interesting in terms of interspecies competition that will be worth to observe how this might change with time in the palm plantation. In their study, Zahouli et al () recorded four species of Culex in oil palm‐dominated landscapes in southeastern Cote d'Ivoire, of which Culex nebulosus from the Culiciomyia subgenus were also caught in our study area in both forest and young palm plantations. All these observations confirm that Culex species could easily adapt to environmental degradation following complete deforestation.…”