Sterile males helping keep mosquito population down

A pilot programme in Larnaca has seen numbers of the pests reduced

A programme to battle increasing numbers of mosquitos on the island is already showing results, with a notable decrease in disturbance caused by the pests, officials have told the Cyprus Mail.

In Cyprus there has been an infestation of the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), with the former carrying many diseases and being found in higher numbers on the island than other European countries.

Speaking to the Cyprus Mail, head of the Public Health Service Herodotos Herodotou said the pilot programme began in an area of Larnaca where the yellow fever mosquito is prevalent in June.

Sterile male mosquitoes are imported to Cyprus, where they are released to mate with females. The latter then lay empty eggs, thus controlling the population, and potentially leading to the mosquito’s disappearance from the island.

“Preliminary results have shown satisfaction among residents in the area [where the programme is being run],” Herodotou said, explaining they have reported the insects are less of a nuisance.

He added that research will finish at the end of the year, and results will be announced then.

The pilot programme saw 100,000 sterile male mosquitoes flown in from Austria.

Meanwhile, a similar programme to deal with the Asian tiger mosquito in Limassol is set to begin in March, and will see the males flown in from a lab in Italy.

Herodotou said that the Asian tiger mosquito has become prevalent in Limassol, while the yellow fever mosquito dominates in Larnaca.

The Asian tiger mosquito, he added, is more prevalent in Europe, while high number of the yellow fever mosquito are only seen in Cyprus among European nations. Herodotou said the programme started with the yellow fever mosquito in an effort to stop its spread elsewhere.

The pilot programme monitors two areas, Kiti and an area in Dromolaxia, where there is no programme being implemented as a control.

In the area where the programme is implemented, until July neither perfect insects nor eggs were detected, which demonstrates its success, Herodotou said.

The yellow fever mosquito can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents.

The Asian tiger mosquito is native to the tropical and subtropical areas of Southeast Asia. In the past few centuries, however, it has spread to many countries through the transport of goods and international travel. It is characterised by the white bands on its legs and body.

This species also spread some diseases including yellow fever and dengue fever.

As part of the programme, insects are collected from the local, wild population and transported to specially designed facilities abroad where they are reared and separated into males and females, where the males are sterilised.

The insects are then released from the ground (by car) or from the air (by drone). The mosquitoes are sterilised using the SIT (Irradiated Sterile Insect Technique), which uses ionised radiation, and “environmentally friendly” method targeting only the species of interest, which helps to reduce the need to use insecticides and where the insect population has developed resistance to insecticides.

The SIT method has been successfully applied in other countries, including Germany, Switzerland, France, Italy, Greece, Brazil, China, Cuba, and the Dominican Republic. In the case of Greece, the method was applied for the first time in 2018, with the results being evident from the first two weeks after initial release.