First Occurrence Of Lasius Neglectus (Hymenoptera: Formicidae) In Zurich, Switzerland: Distribution And Control Measures

Abstract:
In July 2015 the Invasive Garden Ant, Lasius neglectus, was identified during control measures in an apartment house in the city of Zurich. This was the second finding of this species in Switzerland and the first finding in an inhabited area. In order to find out the distribution of the population, the surroundings were sampled for ants in October 2015. The population of L. neglectus was not considered to have strong invasive character yet. Knowing of the invasive potential of this species, the Urban Pest Advisory Service (UPAS) and the section Neobiota of the Environment Department Kanton Zurich nevertheless decided to carry out a survey to investigate the extent of the L. neglectus populations. The survey included a zone of 42 ha around the actual infestation and another 40 risk locations in the greater Zurich area. These included horticultural areas, demolition waste dumps, compost works, parks, cemeteries etc. In 2016, L. neglectus was only found in the infestation area of 4.2 ha, including parks with old trees, a school, apartment houses, small gardens, backyards and business buildings, but not in any of the other monitoring sites. In summer 2016 control measures were mainly taken outside, because by then ants were not a problem inside buildings. UPAS and the section Neobiota of the Kanton Zurich decided that eradication is a long-term objective and thus, the monitoring and control measures will continue in 2017.