The Mosquito Research and Control Unit employs the principles of Integrated Pest Management in order to bring about the control of mosquitoes in the Cayman Islands. The most apparent aspect of the department's work is the use of fixed wing aircraft and ground vehicles fitted with ground ULV equipment around sunset. However, each spray operation takes place as a result of a great deal of operational planning and scientific preparation.

All aspects of the department's mosquito control operations take place in so as to cause the least impact on the natural environment of the Cayman Islands. All insecticides employed meet with the approval process of the Environmental Protection Agency in the USA.

The breeding cycles of swamp breeding mosquitoes such are Aedes taeniorhynchus are dependent upon the fall and rise of water levels in the mangrove swamp and other areas subject to flooding. Management of the swamp water levels can be used to reduce the area of swamp that suitable for mosquitoes to breed in. A series of dykes and canals have been built in many areas of swamp. This improved water dynamic allows for better water exchange at high and low tide. Water can pumped into areas of swamp, flooding them so that mosquito eggs hatch. By allowing the water to drain into the sea before the larvae will either be consumed by predators such as fish or stranded on dry land before they can complete their development.

The system of canals and dykes in conjunction with periodic "hatch and strand" operations has considerably reduced the ability of the black salt-marsh mosquito to breed in very large numbers in many areas of mangrove swamp, without the use of insecticides.

There are a number of species of fish living in the mangrove swamp and MRCU's canal and ditches that feed on mosquito larvae. Those belonging to the genus Gambusia the "mosquito fish" are particularly voracious predators of mosquito larvae. These fish have been introduced to many ponds and pools on the island to help reduce mosquito numbers. In areas where they are abundant Gambusia act as a natural control measure, eating mosquito larvae before they get a chance to develop into adults.

MRCU started using aircraft for mosquito control purposes in 1972. Today, aerial applications form the backbone of our mosquito control operations. The use of fixed wing aircraft allows larger and less accessible areas of the island to be treated. Currently MRCU Operates two agricultural aircraft certified in the Aerial Work Category.

MRCU employs a number of truck mounted ground ULV space spray machines for the control of adult mosquitoes on all three islands. MRCU's newest ULV generators are the Clarke Grizzly cold aerosol ULV generator. These units use an 18Hp Briggs and Stratton IC engine and a high performance Laminar Air Flow nozzle. In addition to the standard remote cab flow control, we have fitted Adapco Monitor 3 units and are developing our own data management system using handheld computers.

Dengue fever, Dengue haemorrhagic fever and Yellow fever are all highly debilitating viral diseases transmitted to man by the bite of the mosquito Aedes aegypti and in some circumstances Aedes albopictus.

Ae. aegypti and Ae. albopictus are both species of mosquito that will use artificial containers as breeding sites. The female mosquito lays batched of eggs attached to the surface of the container, at or just above the water level. If not flooded immediately, the eggs may survive for some time (as long as 6 months) and hatch when flooded at a later date. Ae. aegypti and Ae. albopictus are commonly found in and around houses, where they use water filled man made containers in which to lay their eggs. Preferred sites for laying eggs include discarded car tyres, buckets, barrels, flowerpots, paint pots, cars, boats etc. Ae. albopictus can be found in treeholes and in the leaf axils of air plants and bromeliads near human habitation.

MRCU has a continual surveillance program to detect re-infestations as soon as possible so that action can be taken to prevent them from re-establishing in Cayman. Premises are constantly being inspected for mosquito larvae, a task that is becoming more time consuming as the number of properties rises. A network of over 300 ovitraps are checked weekly for egg laying. Almost every aircraft, vessel and container that enters Cayman is sprayed with insecticide by port disinsection officer from MRCU.