Invasive Process and Repeated Cross-Sectional Surveys of the Mosquito Aedes japonicus japonicus Establishment in Belgium

David Damiens,Wim Van Bortel,Thierry Hance,Veerle Versteirt,Audrey Ayrinhac,Wouter Dekoninck,Claudio R Lazzari

doi:10.1371/journal.pone.0089358

Abstract

When accidentally introduced in a new location, a species does not necessarily readily become invasive, but it usually needs several years to adapt to its new environment. In 2009, a national mosquito survey (MODIRISK) reported the introduction and possible establishment of an invasive mosquito species, Aedes j. japonicus, in Belgium. First collected in 2002 in the village of Natoye from a second-hand tire company, then sampled in 2003 and 2004, the presence of adults and larvae was confirmed in 2007 and 2008. A repeated cross-sectional survey of Ae. j. japonicus was then conducted in 2009 in Natoye to study the phenology of the species on two different sites using three kinds of traps: Mosquito Magnet Liberty Plus traps, BG sentinel traps and CDC Gravid traps. An analysis of the blood meals was done on females to assess the epidemiological risks. Five species of mosquitos were caught using the different kind of traps: Culex pipiens, Cx torrentium, Anopheles claviger, Aedes geniculatus and Ae. j. japonicus, Cx pipiens being the most abundant. The CDC gravid traps gave the best results. Surprisingly Ae. j. japonicus was only found on one site although both sites seem similar and are only distant of 2.5 km. Its population peak was reached in July. Most of the engorged mosquitoes tested acquired blood meals from humans (60%). No avian blood meals were unambiguously identified. Larvae were also collected, mostly from tires but also from buckets and from one tree hole. Only one larva was found in a puddle at 100 m of the tire storage. A first local treatment of Ae. j. japonicus larvae population was done in May 2012 using Bacillus thuringiensis subsp. israelensis (Bti) and was followed by preventive actions and public information. A monitoring is also presently implemented.

Highlights

The process of invasion by exotic species follows at least six well identified steps: 1) transport, 2) introduction, 3) colonization, 4) naturalization, 5) spread and 6) impact [1]
As we cannot be sure of these results, these positive samples for avian origin can not be taken into account. With this follow up study, we confirmed the presence of Ae. j. japonicus in Belgium [5]
In Natoye 1, the population presented its maximum abundance in July (39 females only caught in Gravid traps)

Summary

Introduction

The process of invasion by exotic species follows at least six well identified steps: 1) transport, 2) introduction, 3) colonization, 4) naturalization, 5) spread and 6) impact [1]. Notwithstanding this classification was first developed for plants, it is useful for animals, when they may become agricultural, medical or veterinary pests. This categorization can be limited to 3 main stages: initial dispersal, establishment of self-sustaining populations, and spread [2]. At least, 8-year presence, Ae. j. japonicus still seems to be in either the introduction [1] or initial dispersal phase [2]

Methods

Results

Conclusion