MRCU takes aim at larvae ahead of rain

(CNS): Ahead of the first major rainfall of the year, the Mosquito Research and Control Unit has begun the annual pre-hatch treatment of mosquito larvae across the Cayman Islands’ major breeding sites. This is a preventative control method that kills the pests before they develop into biting adults looking for a blood meal. 

Due to the nature of this operation, larviciding only takes place during daylight hours and requires several passes of the MRCU aircraft over a particular area.

“The pre-hatch treatment allows us to apply larvicide products to known breeding sites with the intent of killing mosquito larvae when they hatch after flooding,” said MRCU Director Dr Alan Wheeler.

The two main products they use, methoprene and spinosad, are applied as pellets to the breeding areas. They are biorational products, which are low-impact substances, typically biologically derived, with relatively low toxicity, causing little damage to the environment.

“Mosquitoes emerge when the eggs are submerged and hatch after flooding. This may be by high tides or rainfall,” Dr Wheeler said.

“It is important that the community understands that MRCU cannot control these events. By conducting preventative control operations, such as larviciding. we can minimise the number of adult mosquitoes emerging. However, MRCU supplements this work by also conducting its adulticiding operations as a responsive control measure to quickly control biting mosquitoes,” he added.

Those operations only happen at dusk or in the evening and can take several days, based on the size of the emergence, Wheeler said.

Pre-hatch treatment has already been completed for the Sister Islands, and work started on Grand Cayman on 17 May. It will take ten to fourteen days to complete, depending on weather and resources.

For more information or to file a mosquito-related complaint, contact the MRCU on 949-2557.

Visit the MRCU website to see the full list of products the unit uses to tackle mosquitoes.