The role of heterogenous environmental conditions in shaping the spatiotemporal distribution of competing Aedes mosquitoes in Panama: implications for the landscape of arboviral disease transmission

Abstract

Monitoring the invasion process of the Asian tiger mosquito Aedes albopictus and its interaction with the contender Aedes aegypti, is critical to prevent and control the arthropod-borne viruses (i.e., Arboviruses) they transmit to humans. Generally, the superior ecological competitor Ae. albopictus displaces Ae. aegypti from most geographic areas, with the combining factors of biology and environment influencing the competitive outcome. Nonetheless, detailed studies asserting displacement come largely from sub-tropical areas, with relatively less effort being made in tropical environments, including no comprehensive research about Aedes biological interactions in Mesoamerica. Here, we examine contemporary and historical mosquito surveillance data to assess the role of shifting abiotic conditions in shaping the spatiotemporal distribution of competing Aedes species in the Republic of Panama. In accordance with prior studies, we show that Ae. albopictus has displaced Ae. aegypti under suboptimal wet tropical climate conditions and more vegetated environments within the southwestern Azuero Peninsula. Conversely, in the eastern Azuero Peninsula, Ae. aegypti persists with Ae. albopictus under optimal niche conditions in a dry and more seasonal tropical climate. While species displacement was stable over the course of two years, the presence of both species generally appears to fluctuate in tandem in areas of coexistence. Aedes albopictus was always more frequently found and abundant regardless of location and climatic season. The heterogenous environmental conditions of Panama shape the competitive outcome and micro-geographic distribution of Aedes mosquitoes, with potential consequences for the transmission dynamics of urban and sylvatic zoonotic diseases.

Supplementary information: The online version of this article (10.1007/s10530-021-02482-y).

Keywords: Aedes mosquitoes; Arbovirus transmission; Ecological niche; Environmental gradient; Geographic species displacement; Interspecific competition; Panama.

Fig. 1

a The presence of Ae. aegypti (orange corregimientos, i.e. counties), Ae. albopictus (blue corregimientos) and species co-occurrence (yellow corregimientos) recorded by extensive sampling with oviposition traps during the wet season months from 2016 through to 2018 in comparison to b Species occurrence data recorded from 2005 through 2017 through active surveillance by the Ministry of Health in Panama. Provinces are indicated by the black boundaries

Fig. 2

Sampling locations in the a Azuero Peninsula of Panama in relation to b life zones based on Holdridge (1967) (map modified is from the Smithsonian Tropical Research Institute www.stri.si.edu) c the underlying forest cover and land use of the area (sourced from the open source STRI GIS data portal https://stridata-si.opendata.arcgis.com) and d topography and altitude (map modified from the open source site topographic-map.com)

Fig. 3

a The proportion of sampled sites positive for Ae. aegypti and Ae. albopictus and b the median abundance of each species at each location across the dry (January–April) and wet (May–December) season months. The network of highways and roads across the Azuero Peninsula is shown in solid dark lines

Fig. 4

Weighted ensemble species niche distribution map for a Ae. aegypti and b Ae. albopictus showing habitat suitability across Panama with higher values indicating higher suitability. The region of the Azuero Peninsula is indicated in b. The niche distribution map for Ae. albopictus is shown in detail for the Azuero Peninsula in c. The map indicates areas where only Ae. albopictus was documented (hashed fill) and areas where both Ae. aegypti and Ae. albopictus were found (dotted fill) by the present study

Fig. 5

Density of occurrence of avaliable climates in the range of Ae. aegypti (red) and Ae. albopictus (blue) with niche overlap indicated by the purple area. The avaliable environment is shown as a dark blue line (Ae. albopictus) and dark red line (Ae. aegypti)