Evolution of the expansion of invading mosquitoes Aedes spp
Invader mosquitoes of the genus Aedes spp., have an anthropophilic tendency (to bite and feed on humans) are able to transmit different types of viruses and are showing an increase in their populations both in Europe and in the rest of the world as a result of variations in climatic conditions, among other factors. This indicator shows the evolution of the expansion of the invading mosquitoes of the genus Aedes spp. in the Basque Country since 2013.
- If these invasive mosquitoes do settle in an area, they can create discomfort associated with bites, and, in addition, their settlement in urban areas represents a potential risk of local transmission of viral diseases.
- Of the 5 invasive species existing in Europe, Aedes albopictus and Aedes japonicus have been identified in the Basque Country. Both show different characteristics in their activity, and climate change may affect them differently.
Relationship of the indicator to climate change
In general, warmer weather conditions will favour the expansion of tropical species, such as invasive mosquitoes of the genus Aedes. The increase in temperature could make mosquitoes already existing in the territory, such as, for example, the tiger mosquito (Aedes albopictus) active for a longer period along the year. In addition, the increase in temperatures would favor the development of its life cycle, being able to complete its cycle more times within the same year. This could cause an exponential increase in the abundance of these insects, increasing the problems in the well-being and health of citizens (Ryan et al., 2019; Iwamura et al. 2020).
It is estimated that by 2030 (under the RCP 4.5 scenario) the yellow fever mosquito (Aedes aegypti) could find favorable conditions in the Iberian Peninsula (Iwamura et al., 2020). However, Aedes japonicus populations, for example, may be negatively affected by the increase of temperatures (Cunze et al., 2016).
An increase in the percentage of positive municipalities denotes an upward progression in the expansion of invasive mosquitoes.
An increase in the percentage of positive samples denotes an upward progression in the implantation of invasive mosquitoes in the Basque Country.
This indicator shows the evolution of the expansion of invading mosquitoes of the genus Aedes spp. (Aedes albopictus, Aedes japonicus) in the Basque Country since the beginning of the Surveillance Programme in 2013. This indicator is based, on the one hand, on the percentage of municipalities with the presence of invasive mosquitoes and, on the other, on the percentage of samples with the presence of eggs from invasive mosquitoes.
To evaluate the presence of invading Aedes mosquitoes, ovitraps are used distributed throughout the territory. These systems are composed of a small black container with water in which a wooden splint is introduced, which serves as an oviposition substrate for the female mosquitoes of the genus Aedes (ECDC, 2012). Every 7-15 days the tablets of each ovitrap are replaced and analyzed in the laboratory in order to evaluate the presence of Aedes eggs. From the eggs, the existing species of mosquito is determined either by hatching and moulting up to the adult mosquito phase, or by molecular techniques. A municipality will be considered positive when the presence of eggs is detected at least in one of the investigated ovitraps.
As an indicator of the evolution of the expansion, the following measures are calculated:
- \[\text{Percentage of positive municipalities} = {\text{No.of positive municipalities} \over \text{No.of municipalities evaluated}} x 100\]
- \[\text{Percentage of positive samples} = {\text{No.of positive samples} \over \text{No.of samples evaluated}} x 100\]
Iwamura, T., Guzman-Holst, A. & Murray, K.A. Accelerating invasion potential of disease vector Aedes aegypti under climate change. Nat Commun 11, 2130. (2020). https://doi.org/10.1038/s41467-020-16010-4
Ryan SJ, Carlson CJ, Mordecai EA, Johnson LR Global expansion and redistribution of Aedes-borne virus transmission risk with climate change. PLOS Neglected Tropical Diseases 13(3): e0007213. (2019). https://doi.org/10.1371/journal.pntd.0007213
Cunze S, Koch LK, Kochmann J, Klimpel S. Aedes albopictus and Aedes japonicus - two invasive mosquito species with different temperature niches in Europe. Parasit Vectors 9(1), 573. (2016). doi: 10.1186/s13071-016-1853-2.
European Centre for Disease Prevention and Control. Guidelines for the surveillance of invasive mosquitoes in Europe. Stockholm: ECDC; 2012
The Basque Country
Aedes albopictus y Aedes japonicus
Most widespread species since 2013