Mosquito surveillance in AmsterdamUrban ecology, mosquito presence & nuisance perception

Jan Buijs1, Chantal Vogels2, Daniela Cianci3, Wietse den Hartog4,

Sander Koenraadt2 & Arjan Stroo4

In 2014 the Public Health Service of Amsterdam1

started a survey together with WageningenUniversity2, Utrecht University3 and the Dutch Centre for Monitoring of Vectors4 to studymosquito distributions and abundances within Amsterdam (the Netherlands).

Research questions

1. Which mosquito species are present?2. Which microhabitats can be identified

as breeding sites?3. Is there a relationship between microhabitats,watertype and mosquito species?

4. Is there a relationship between city ecotypes, mosquito species distributions and abundances?

5. Is there a pattern in nuisance reports that can be explained by the observed mosquito presence?

- Larval sampling (dipping)- Liberty Plus Mosquito Magnet 3100 trap for the adults. Followed by:

- Morphological identification

Culex pipiens-complex identificationLarval samples are morphologically identified up to species level (torrentium vs. pipiens), and subsequently pipienssamples are analyzed (partly) for biotypes pipiens and molestus or hybrids with a Realtime PCR. For adult mosquitoes the whole complex is analyzed with that technique (notwithstandig efforts to recognize Cx. torrentium).

Results

Urban ecotypes % larvae # sites present

Old Residential areas 56 91 New Residential areas 47 111Industrial area 38 32Urban green space (parks) 31 71Suburban rural area 24 34

Methods

Old Residential areas (< 1950)

New Residential areas (> 1950)

Suburban rural area

Urban green space (parks)

Industrial area

City ecotypes

94 locations, spread over the 5 ecotypes are sampled. Within each ecotype the sample sites are assigned according to a Stratified Random Sampling Design. One sampling site is randomly selected in every km2 of industrial and suburban area, whereas two sampling sites are randomly selected in every km2 of the residential areas and urban green space . Fieldwork is being carried out from May until November. Per site, all possible microhabitats within a search radius of 50 meters are being sampled.

At each site, 5 addresses are selected for interviews to assess nuisance perception. From these 5 personspermission for investigationof the balcony, garden and/or basement was asked, to find additional breedingsites.

Species found in Amsterdam in 2014

larvae adults(May-Aug.) (Jul.–Aug.)

Anopheles claviger 6 4Anopheles maculipennis s.l. 10 132Anopheles plumbeus 5Coquillettidia richardii 314Culiseta annulata 29 580Culex pipiens 724Culex torrentium 254

pipiens/torrentium 80 163Culex territans 1

Aedes cinereus, Culiseta morsitans, Ochlerotatus cantans, O. dorsalis, O. leucomelas and O. punctor have been found by CMV in Amsterdam in previous years, but probably have been missedso far, due to the late start this season with the MM3100-traps. Finding those species as larvae might require adjustment of the larval sampling strategy.

Water type % larvaepresent

Rain water 49Drainage 55Mixed 26Surface water 11Other 12

The success rate of larval catches increases towards the city centre. This nicelycorrelates with nuisance reports (1-5):

Acknowledgements: Marjolein van Adrichem, Rens van den Biggelaar, Marian Dik, Adolfo Ibañez-Justicia, Bram van de Straat and Nienke Hartemink.

Correspondence: Arjan Stroo (c.j.stroo@nvwa.nl)

Based on larval sampling, the relative abundance of the Culex pipiens complex is highest in residential areas, whereas most other species are found more periferal. Biotype molestus and hybrids are often found together with biotype pipiens and/or Cx. torrentium, but seem to be relatively more numerous towards the centre.

Conclusions

• Within-city patterns are found in species distributions, abundances and nuisance.

• Differences in results between the sampling strategies (adult vs larval) are large (see for instance Culiseta annulata)

• The larval sampling strategy adds valuable insights, such as distribution over the water types, but the methodology needs further development to account for a broader selection of species.

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