Mosquito resistance

Only countries with political clout and political sense about DDT, notably South Africa, China, and India, still use it. South Africa had stopped using DDT in 1996 under pressure to join the world s Green community and switched to the next best alternative, the synthetic pyrethroids, which are three times the price and are effective over a shorter time span. Four years later, in 2000, South Africa decided to resume DDT spraying after malaria cases jumped by 1,000 percent because of mosquito resistance to the synthetic pyrethroids. 

Malaria affects an estimated 270 million people and causes 2—3 million deaths annually, approximately one million of which occur in children under the age of five. While primarily an affliction of the tropics and subtropics, it has occurred as far north as the Arctic Circle. The disease essentially has been eradicated in most temperate-zone countries, but some 1100 cases of malaria in U.S. citizens returning from abroad were reported to the Centers for Disease Control during 1990. Malaria is seen today in Southeast Asia, Africa, and Central and South America. It is on the increase in Afghanistan, Brazil, China, India, Mexico, the Philippines, Sri Lanka, Thailand, and Vietnam. Escalation of the disease is because of the discontinued use of the insecticide DDT which effectively kills mosquito larvae, but has been found to be toxic to Hvestock and wildlife. Also, chloroquine (6), a reUable dmg for the prophylaxis and treatment of falcipamm malaria, is ineffective in many parts of the world because of the spread of dmg-resistant strains. 

One reason for the rapid growth in the use of pesticides worldwide has been the "Green Revolution" (5), Although there have been some benefits from pesticide use in agriculture, they also cause significant environmental and public health problems. The same is true in public health where Insecticides have been used to control malaria. However, today Increased resistance to insecticides in mosquitoes and Increased resistance to drugs by the malarial parasite are resulting in an explosive increase of malaria worldwide (5). 

Another extremely important military characteristic is effectiveness against many different species of insects without the development of resistant strains. Every insecticide that must be added to the military list of supplies geometrically increases the difficulties of procurement and distribution. At the present time, nineteen different insecticides and insect repellents and four different rodenticides are issued by the Army Quartermaster. These figures do not include the different formulations of insect repellents issued under the same stock number. The three basic insect repellents are dimethyl phthlate, Indalone, and Rutgers 612. These repellents are issued either alone or in various combinations, further complicating the supply situation because of the variation in efficiency of these substances against different species of mosquitoes in different parts of the world. 

There are many examples of this effect of pesticide use, which can seem unexpected at first glance. Epidemiologists achievements in using pesticides to suppress malaria-carrying mosquitoes are well known. Before pesticide use, 40 million people contracted malaria in India annually after mass pesticide treatments in the 1950s, this number decreased to 40,000 annually. However, 10-15 years later, the mosquitoes showed resistance to... 

INVERTEBRATES Mosquito, Aedes nigromaculis Multi-resistant strain, fourth-stage larvae 5.6 g/ha (0.005 pounds/acre) 58% reduction 6 h after treatment 3... 

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