The MRCU uses water management techniques like the Hatch and Strand program to reduce mosquito populations by controlling water levels in the swamps. By flooding targeted areas during low tides, mosquito eggs are forced to hatch, and larvae are then washed out to sea or stranded in drying mud. This method, supported by a system of sluice gates and drainage canals, helps prevent large mosquito outbreaks when the rainy season begins.
Hatch and Strand (and the Canals)
The Hatch and Strand program is a water management technique developed by the MRCU to control mosquito populations by manipulating water levels in the swamp. During the dry season, swamp mosquitoes lay their eggs just above the waterline, and these eggs hatch in massive numbers when tides rise significantly or when rains begin.
In the spring, during periods of low tides, the MRCU blocks off sections of the swamp with sluice gates, and water is pumped into these areas to trigger hatching. The water is then held for several days to allow all larvae to emerge. After this, the sluice gates are opened, and the water flows out to sea, taking mosquito larvae with it and leaving the rest stranded in the mud, where they die.
The canal system further aids in mosquito control by allowing tidal variations to circulate water in and out of the swamp and helping with drainage following heavy rains.
Biorational Mosquito Control Products
Pesticides vary in their toxicity and in their potential ecological impact. Pest control materials that are relatively non-toxic to people with few environmental side effects are sometimes called “biorational” pesticides. These fit well into an integrated pest management strategy, which relies on monitoring for early detection of pests and emphasizes the use of selective products that provide control while preserving the ecological health of the farm and minimizing negative effects on beneficial insects that suppress pests. MRCU incorporates a number of these biorational products in their integrated mosquito control programme.
Bacillus Thuringiensis Subsp. Israelensis (Bti)
Bacillus thuringiensis subsp. israelensis (Bti) is a naturally occurring soil bacteria used as a microbial insecticide tocontrol the spread of vector-borne diseases, protect public health, and manage insect pest species. Bti was firstdiscovered in a stagnant pond in Israel in 1976 (Margalit and Dean 1985). Initial testing of Bti revealed acutetoxicity to mosquitoes (Goldberg and Margalit 1977) and black flies (Undeen and Nagel 1978). Further researchdemonstrated that Bti is nontoxic to humans, mammals, birds, beneficial insects, fish, plants, and most aquaticorganisms (EPA 1998 Bti EG2215 Factsheet). Bti an ideal pesticide with greatly reduced environmental impacts incomparison to man-made chemical insecticides. In addition, Bti is species specific, breaks down rapidly, limitednon-target impacts (de Barjac and Sutherland 1990), There are 26 Bti products in the United States with some ofthe following trade Names: Vectobac, Teknar, Aquabac, Bactimos, LarvX, etc.
Spinosad
Spinosad is natural product approved for use in organic agriculture by numerous national and international regulators including the US EPA. Spinosad has a good environmental profile and is an effective natural product for the integrated management of larval mosquitoes. It possesses a unique mode of action not shared by any other insecticide and is shown to be minimally disruptive to most non-target species tested. It is made by a soil bacterium named Saccharopolyspora spinosa and is a mixture of two chemicals called spinosyn A and spinosyn D.The genus Saccharopolyspora was discovered in 1985 in isolates from crushed sugar cane collected at an abandoned rum factory in the Caribbean Virgin islands. Evaluation of the bacterial actinomycete showed it to have powerful insecticidal properties. Spinosad has been registered for use in pesticides by the US Environmental Protection Agency (EPA) since 1997. MRCU has been using EPA approved spinosad based products since 2012. Spinosad is highly active against larvae of all mosquito species tested. The only spinosad based products currently available for mosquito control in the Caribbean region are sold under the trade name Natular. Natular products are the first larvicides evaluated as a Reduced Risk product by the EPA.Spinosad is highly active to mosquito larave, by both contact and ingestion. Spinosad affects the nervous system of insects that eat or come in contact with it, primarily targeting binding sites on nicotinic acetylcholine receptors of the insect nervous system and causing their muscles to flex uncontrollably. This ultimately leads to paralysis and death in 24-48 hours.
Methoprene
Methoprene is a growth regulator which prevents larvae by imitating the mosquitoes natural juvenile hormone. Because methoprene affects other insects but is safe for humans and mammals, it’s also formulated and sold for controlling a variety of other pests, from flies on cattle farms to fleas on dogs. Methoprene does not work by killing mosquito larvae directly; they will continue to live as larvae until they’re eaten by predators or die naturally but they will never turn into adult mosquitoes.