Fig 1.
Location of the study areas in south-eastern Côte d’Ivoire.
The study was carried out in the villages located in oil palm plantation areas belonging to the Sud-Comoé region. The study area covers the villages of Ehania-V1, Cité-cadre and Akakro situated at the interface between the industrial oil palm plantation and traditional agricultural smallholdings. The industrial exploitations are devoted to the monoculture of oil palm plantations (Eleasis guineensis) covering over 30,000 hectares managed by an integrated agro-industrial unit of PALMCI. In the industrial part, a primary rainforest of over 100 ha has been preserved intact and forbidden of any human activities. In the traditional lands, the agricultural exploitation systems are polycultures comprising oil palm trees, rubber trees, banana, taro, bromeliads, and cocoa growing in the same space. Several small villages averaging 20 people are dispersed in these smallholdings.
Table 1.
Classification of Aedes mosquito habitats sampled in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to October 2014.
Table 2.
Species composition of mosquitoes sampled in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to December 2014.
Fig 2.
Aedes mosquito species occurrence among the macrohabitats in oil in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to December 2014.
Error bars represent the standard error (SE). Letters indicate the results of the GLMM. Groups that do not share the same letter for the same sampling method are significantly different.
Table 3.
Aedes mosquito positivity patterns among the macrohabitats, and the study area in southeastern Côte d’Ivoire from January to December 2014.
Table 4.
Proportion (%) of each Aedes-positive microhabitat type among Aedes-positive microhabitats, macrohabitats, and study area in southeastern Côte d’Ivoire from January to December 2014.
Table 5.
Aedes species distribution and biodiversity among macrohabitats in oil palm-dominated landscapes in southeastern Côte d’Ivoire between January and December 2014.
Table 6.
Aedes mosquito abundance patterns in macrohabitats, and the study area in southeastern Côte d’Ivoire between January and December 2014.
Fig 3.
Monthly variations in the abundance of Aedes mosquitoes in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to December 2014.
Error bars represent the standard error (SE).
Fig 4.
Monthly variations in Aedes mosquito females’ host-seeking activities in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to December 2014.
Error bars represent the standard error (SE).
Fig 5.
Nycthemeral dynamics of Aedes mosquito females’ host-seeking activities in oil palm-dominated landscapes in southeastern Côte d’Ivoire from January to December 2014.
A: All species in all the macrohabitats and the study area, B: Prevalent Aedes species (> 1%) in the study area, C: Prevalent Aedes species (> 1%) in the polyculture, D: Prevalent Aedes species (> 1%) in the rural-housing areas.
Fig 6.
Synthesis of how agricultural land-use changes affect the dynamics of Aedes mosquitoes in oil palm-planted areas in southeastern Côte d’Ivoire.
f/p/d: female/person/day. Overall, there was a lack of Aedes microhabitats and species in the oil palm monoculture. In contrast, the highest abundance of Aedes mosquitoes was found in the polyculture. The rural housing area also hosted substantial numbers of Aedes mosquitoes. Conversely, the highest Aedes species richness was observed in the rainforest where the preference of Aedes females to feed on humans was very little. As a result, the polyculture and the rural areas increased Aedes vectors’ biting rates by 34.6 and 7.2 times compared with the original rainforest, respectively.
Fig 7.
Effects of land-use changes on distribution of Aedes mosquitoes and arboviruses’ transmission risks in oil palm-dominated landscapes in southeastern Côte d’Ivoire.
Human-induced land-use changes into the original tropical rainforests for their conversion in large industrial oil palm plantations have resulted in changes in land-covers creating four ecologically distinct macrohabitats: preserved rainforest (A), polyculture (B), oil palm monoculture (C), and rural housing area (D). The conversion of the original rainforests into large oil palm monoculture has led to the losses of the microhabitats and hosts of forest-dwelling Aedes mosquitoes thus increasing ecological pressure for searching alternative microhabitats and hosts in the three other macrohabitats, preserved rainforest, polyculture, and rural housing areas. Aedes mosquitoes found new microhabitats as anthropogenic containers abundantly encountered in the rural housing area and polyculture where humans (inhabitants and workers) were usually present thus resulting in higher abundance of vectors and high-risks of arboviruses’ transmission in these areas. In contrast, the arboviral transmission risks were very low in the oil palm monoculture due to the lack Aedes mosquitoes, and low in the rainforest due to the low anthropophagy of forest-dwelling Aedes species.