ABSTRACT
The Onchocerciasis Control Program of the World Health Organization is carrying out an extensive screening program in a search for new larvicides to be used for control of Simulium damnosum s.l. Emphasis has been given to finding a pyrethroid and a carbamate to supplement the organophosphates currently in use. These chemicals with differing modes of action, together with Bacillus thuringiensis H-14, are being used in an attempt to cope with the development and spread of resistance to the organophosphates temephos and chlorphoxim.
Subject(s)
Insect Control/methods , Insecticides , Simuliidae , Africa, Western , Animals , Carbamates , Chrysanthemum cinerariifolium , Insecticide Resistance , Larva , Organophosphorus CompoundsSubject(s)
Diptera , Insect Control , Animals , Apicomplexa , Carbaryl , Chlorpyrifos , DDT , Diptera/parasitology , Diptera/physiology , Fenitrothion , Fenthion , Fungi , Humans , Insect Bites and Stings/complications , Insect Vectors , Insecticide Resistance , Larva , Methoxychlor , Nematoda , Onchocerca , Onchocerciasis/transmission , Pest Control, Biological , Pupa , TemefosSubject(s)
Aircraft , Diptera , Insect Control , Insecticides , Aerosols , Ghana , Larva/drug effectsSubject(s)
Diptera/drug effects , Insect Control , Insecticides/pharmacology , Insecticide Resistance , New YorkSubject(s)
Encephalitis Viruses/isolation & purification , Aedes , Animals , Antibody Formation , Antigens , Arthropod Vectors , Blood Chemical Analysis , Cattle , Complement Fixation Tests , Culex , Culture Techniques , Deer , Diptera , Humans , Mice , Neutralization Tests , New York , Rabbits , Reptiles , Rodentia , Virus CultivationSubject(s)
Aedes , Malaria, Avian/microbiology , Plasmodium/growth & development , Thiotepa/pharmacology , AnimalsABSTRACT
The early discovery that DDT is extremely effective in controlling blackfly larvae led to its widespread use in control programmes. Recent evidence that DDT accumulates in the food chain has made it desirable to investigate the effectiveness of other, less persistent, insecticides in reducing populations of blackfly larvae.A method of testing larvicides in troughs was developed and tests were carried out with a number of insecticides both in the troughs and in streams in New York State. Fourfold or fivefold differences in the susceptibility of larvae to different formulations of the same chemical were noted. In the laboratory, emulsions were less effective than oil solutions or wettable-powder suspensions. The effectiveness of emulsions under field conditions, noted in the course of their widespread use in Africa, may be due to the ease with which they become uniformly distributed throughout the water even when no special effort is made to ensure even distribution. When aircraft are used to apply larvicides in oil solution the insecticide is similarly distributed in fine droplets resulting in control at unusually low dosages.In trough tests and in streams, methoxychlor and DDT in oil solutions were about equally effective; carbaryl in wettable-powder suspension was highly effective in the laboratory but relatively greater concentrations were required in streams. Abate in oil solution was effective at low dosages in the laboratory and, in a single test, in a stream.
