A literature review of dispersal pathways of Aedes albopictus across different spatial scales: implications for vector surveillance

Abstract

Background: Aedes albopictus is a highly invasive species and an important vector of dengue and chikungunya viruses. Indigenous to Southeast Asia, Ae. albopictus has successfully invaded every inhabited continent, except Antarctica, in the past 80 years. Vector surveillance and control at points of entry (PoE) is the most critical front line of defence against the introduction of Ae. albopictus to new areas. Identifying the pathways by which Ae. albopictus are introduced is the key to implementing effective vector surveillance to rapidly detect introductions and to eliminate them.

Methods: A literature review was conducted to identify studies and data sources reporting the known and suspected dispersal pathways of human-mediated Ae. albopictus dispersal between 1940-2020. Studies and data sources reporting the first introduction of Ae. albopictus in a new country were selected for data extraction and analyses.

Results: Between 1940-2020, Ae. albopictus was reported via various dispersal pathways into 86 new countries. Two main dispersal pathways were identified: (1) at global and continental spatial scales, maritime sea transport was the main dispersal pathway for Ae. albopictus into new countries in the middle to late 20th Century, with ships carrying used tyres of particular importance during the 1980s and 1990s, and (2) at continental and national spatial scales, the passive transportation of Ae. albopictus in ground vehicles and to a lesser extent the trade of used tyres and maritime sea transport appear to be the major drivers of Ae. albopictus dispersal into new countries, especially in Europe. Finally, the dispersal pathways for the introduction and spread of Ae. albopictus in numerous countries remains unknown, especially from the 1990s onwards.

Conclusions: This review identified the main known and suspected dispersal pathways of human-mediated Ae. albopictus dispersal leading to the first introduction of Ae. albopictus into new countries and highlighted gaps in our understanding of Ae. albopictus dispersal pathways. Relevant advances in vector surveillance and genomic tracking techniques are presented and discussed in the context of improving vector surveillance.

Keywords: Aedes albopictus; Citizen science; Dispersal; Dispersal pathways; Genomics; Spatial scales; Vector surveillance.

Fig. 1

Aedes albopictus distribution range. Map indicates the year of first detections (interceptions and vector surveillance of Ae. albopictus) by country and whether established populations were formed (full colour). ‘Before 1940’ was based on published literature documenting the presence of Ae. albopictus populations in these countries before 1940. Establishment status was defined as persistent spatial and temporal published records. ‘Not established’ was defined as Ae. albopictus populations recorded sporadically after an incursion. In Australia, populations are only recorded in the Torres Strait, with no established populations on the Australian mainland. 'Unknown establishment’ was defined as no published records regarding its establishment after detections were made. ‘Not recorded’ was defined as no records of Ae. albopictus have been recorded for this country

Fig. 2

Number of first detections (interceptions and vector surveillance) of Ae. albopictus in a country by known and suspected dispersal pathways for the period 1940–2020. Publications reporting the first detection of Ae. albopictus in a new country were selected (Additional File 1: Table S1). "Unknown" dispersal pathway is defined from published scientific articles with insufficient evidence to prove or suspect otherwise

Fig. 3

Percent of first detections (interceptions and vector surveillance) of Ae. albopictus in a country by known and suspected dispersal pathways for the period 1940–2020. Publications reporting the first detection of Ae. albopictus in a new country were selected (Additional File 1: Table S1). "Unknown" dispersal pathway is defined from published scientific articles with insufficient evidence to prove or suspect otherwise