Tiger mosquitoes outpace control efforts in Basel region

Efforts to curb the Asian tiger mosquito have failed this year in the Basel region, where researchers have recorded far more mosquitoes than last year, SRF reports. The hot, dry summer helped the insects reproduce, and some are still laying eggs that can survive the winter.

Pie Müller, head of research at the Swiss TPH, said the fight against the mosquito had not gone well this year. He urged residents to eliminate standing water and start prevention in spring, before the mosquitoes become active.

Swiss TPH monitors and controls the mosquitoes with traps, while the canton works to prevent breeding sites. Müller said those measures were not enough and that researchers hoped to target adult mosquitoes more directly next year by releasing sterile males, preventing females from producing offspring. The method is already being used in Ticino.

Most breeding sites are thought to be on private property, said Noemi Danhieux of the Basel-Stadt cantonal laboratory. The canton distributes flyers and puts up posters, particularly in allotment gardens, and provides larvicide free of charge to treat drains and prevent larvae from hatching.

The Asian tiger mosquito is active during the day, unlike native mosquitoes, and can transmit tropical diseases. No such transmission has been recorded in Switzerland, although researchers in Basel detected dengue virus in a mosquito two years ago. Müller said viruses such as dengue and chikungunya were thought to be circulating, with several cases reported in nearby countries. Danhieux said the risk of infection in the region was low.

Falling temperatures are expected to bring fewer mosquitoes in the coming days, but Müller believes they have laid many eggs this year. Winter is likely to offer only a temporary break.