Many Southeast Asian countries, including Thailand, are experiencing warmer temperatures and irregular rainfall, and such conditions benefit the dengue-carrying mosquitoes, he said.
Scientists have found that the Aedes mosquitoe's life span has increased from one to two months.
Normally, the mosquitoes feed in the day, but Thailand's warmer climate allows them to feed at night too, Dr Rungrueng said. He suspects the changing climate has played a part in the changes in the mosquitoes' life cycle and behaviour.
Urbanisation and poor waste management in cities are also to be blamed.