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PubMed2004

Laboratory bio-assay of temephos and fenthion against some vector species of public health importance.

Laboratory studies carried out using Temephos and Fenthion, two commonly used larvicides under Urban Malaria Scheme (NMEP) and NFCP for the control of mosquito larvae. The results revealed that the LC50 and LC90 values for temephos against Aedes aegypti 0.0177 and 0.0559, Anopheles stephensi 0.0148 and 0.0472, Culex quinquefasciatus 0.0157 & 0.0480 and for Culex vishnui group of mosquitoes 0.043 & 0.0118 ppm respectively. The results obtained revealed that there is a 62.8 & 94.12 times increase in the LC50 & LC90 of Cx. Quinquefasciatus which indicates that the species has developed resistance to temephos. There were 6.32 & 8.34 fold increase in Ae. aegypti and 2.27 & 2.34 fold increase in LC50 & LC90 values of An. stephensi are indicative of development of tolerance against temephos. Similarly LC50 and LC90 values estimated for fenthion against Ae. aegypti 0.0173 & 0.0392, An. stephensi 0.0274 & 0.0992 and Cx. quinquefasciatus 0.03 & 0.0469 respectively. The slope values were found to be higher in fenthion as compared to temephos. It was recorded to be 2.72 times higher in Cx. quinquefasciatus and 1.54 times against An. stephensi. However, much difference was not observed in the slope values of temephos and fenthion in Ae. aegypti.

Aedes↗
PubMed2004

Studies on persistence of temephos in sandy loam soil under field and laboratory conditions.

Persistence of temephos was studied in soils under field and laboratory conditions in sandy loam soil to evaluate the effect of moisture and formulations on persistence. The insecticide was applied as 50 EC and 1 % S.G. granules @1 kg a.i. ha-1 on surface of the soil' and residues were determined spectrophotometrically. The soil was fortified separately with dilute emulsion of EC and suspension of granular formulation at 5 ppm level and incubated at different moisture levels at 25:1:1 degrees C for 90 days. The residues of temephos from both the formulations persisted upto 55 days in soil when applied @1 kg a.i. ha(-1). In 40 days 92 and 91.43 per cent temephos was dissipated from soil treated with EC and granular formulations, respectively. There was no leaching or downward movement of the toxicant beyond 7.5 cm. The half-life of temephos under field condition for EC and granular formulations were 18.14 and 20.44 days, respectively. Statistically, there was no significant effect of two formulations of temephos on its persistence. But at three different moisture conditions viz. airdry, field capacity and sub-merged, the difference was significant at 5% level.

Environmental Monitoring↗
PubMed2006

Uganda's successful Guinea Worm Eradication Program.

Having begun its national Guinea Worm Eradication Program (UGWEP) in 1991 (1991 population, 16.6 million) with the third-highest number of cases reported by any endemic country, and ranked as the second-highest endemic country in the world in 1993, by 2004, Uganda celebrated its first full calendar year with no indigenous cases of the disease. Systematic interventions began in 1992 and were gradually intensified until the final indigenous case occurred in July 2003. The favorable concentration of most cases in relatively few northern districts of the country was partly offset by chronic insecurity in much of the endemic area and by repeated importations of cases from neighboring Sudan. Strong support and dedicated leadership by government officials and external partners were keys to this program's dramatic success. This program cost approximately US dollar 5.6 million.

Animals↗
PubMed2005

Insecticide resistance development in Culex quinquefasciatus (Say), Aedes aegypti (L.) and Aedes albopictus (Skuse) larvae against malathion, permethrin and temephos.

Laboratory-bred females of Culex quinquefasciatus, Aedes aegypti and Aedes albopictus from the insectarium, Unit of Medical Entomology, Institute for Medical Research were used in the experiment. The late third stage of the F0 larvae which survived the high selection pressure of malathion, permethrin and temephos were reared and colonies were established from adults that emerged. Cx. quinquefasciatus larvae were subjected to selection by malathion and permethrin for 40 generations, Ae. aegypti larvae to malathion, permethrin and temephos for 32 generations and Ae. albopictus larvae were selected against malathion and permethrin for 32 generations and 20 generations against temephos. The rate of resistance development was measured by LC50 value. Cx. quinquefasciatus larvae developed higher resistance to malathion and permethrin compared to Ae. aegypti and Ae. albopictus. On the whole, permethrin resistance developed at a faster rate than malathion and temephos.

Aedes↗
PubMed2005

Weekly variation on susceptibility status of Aedes mosquitoes against temephos in Selangor, Malaysia.

Larvae of Aedes aegypti and Aedes albopictus obtained from 6 consecutive ovitrap surveillance (OS) in Taman Samudera and Kg. Banjar were evaluated for their susceptibility to temephos. Larval bioassays were carried out in accordance with WHO standard methods, with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos respectively. Aedes aegypti and Ae. albopictus obtained from six OS in Taman Samudera showed resistance to diagnostic dosage of temephos with percentage mortality between 5.3 to 72.0 and 9.3 to 56.0, respectively, while Ae. aegypti and Ae. albopictus obtained from Kg. Banjar showed resistance to temephos with percentage mortality between 16.0 to 72.0 and 0 to 50.6, respectively. Only two strains of Ae. aegypti from Kg. Banjar were susceptible to temephos with 93.3% (OS 2) and 100% (OS 3) mortality. The 50% mortality at lethal time (LT50) for all strains of Ae. aegypti and Ae. albopictus tested against operational dosage of temephos showed range between 36.07 to 75.69 minutes and 58.65 to 112.50 minutes, respectively, and complete mortality was achieved after 24 hours. Our results indicated that there is weekly variations of the resistance status for Ae. aegypti and Ae. albopictus. Aedes susceptibility to temephos is changing from time to time in these two study sites. It is essential to continue monitoring the resistance of this vector to insecticides in order to ensure the efficiency of program aimed at vector control and protection of human health.

Aedes↗
PubMed2005

Susceptibility of Aedes aegypti and Aedes albopictus to temephos in four study sites in Kuala Lumpur City Center and Selangor State, Malaysia.

Larvae obtained from Taman Samudera (Gombak, Selangor), Kampung Banjar (Gombak, Selangor), Taman Lembah Maju (Cheras, Kuala Lumpur) and Kampung Baru (City centre, Kuala Lumpur) were bioassayed with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos. All strains of Aedes aegypti and Aedes albopictus showed percentage mortality in the range of 16.00 to 59.05 and 6.4 to 59.50 respectively, after 24 hours. LT50 values for the 6 strains of Ae. aegypti and Ae. albopictus were between 41.25 to 54.42 minutes and 52.67 to 141.76 minutes respectively, and the resistance ratio for both Aedes species were in the range of 0.68 to 1.82 when tested with operational dosage, 1 mg/L temephos. These results indicate that Aedes mosquitoes have developed some degree of resistance. However, complete mortality for all strains were achieved after 24 hours when tested against 1 mg/L temephos.

Aedes↗
PubMed1990

The elimination of dracunculiasis in Igbon, Oyo State, Nigeria: the success of self-help activities.

Guinea worm disease, dracunculiasis, is widespread in rural Nigeria, where an estimated 2.5 million cases occur every year. This study documents the use of multiple intervention strategies, based on community self-help in collaboration with health researchers, to eliminate Guinea worm in the village of Igbon, in Oyo State, Nigeria. In November 1978 the village had a point prevalence rate of 59% at the height of the period of patency and disease transmission. Advised by the university-based researchers who conducted the survey, villagers combined in a series of cooperative efforts which culminated in the construction of wells which provided them with a protected water supply. Since 1982 no cases of Guinea worm have been recorded in the village. Igbon is now free from its annual 'festival of agony', the village has increased in population, and economic activities flourish. Self-help activities such as those carried out in Igbon could be a very useful part of the current Guinea worm eradication campaign in Nigeria.

Dracunculiasis↗
PubMed1990

Monitoring of temephos (abate) application as a cyclopicide under the guineaworm eradication programme in India.

Temephos application in unsafe water sources at a dose of 1ppm, which started in 1986, is an important activity of the guineaworm eradication programme in India. During March 1989, monitoring of temephos application was carried out in six villages in each of the five guineaworm endemic districts: Kurnool (Andhra Pradesh), Gulbarga (Karnataka), Dhar (Madhya Pradesh), Thane (Maharashtra) and Jhalawar (Rajasthan), selected for the study. Out of 62 unsafe water sources targeted in the sampled villages for temephos treatment, 43 were treated during 1989 in the five districts (coverage 69.35 per cent). Out of these 43 treated sources 79.1 per cent were free of cyclops and the rest 20.93 per cent showed a variable cyclops count. 117 adult cyclops identified from these sources included Mesocyclops byalinus (82) and M. leuckarti (35). People's perception of utility of chemical treatment of water sources varied from negligibly low to moderate levels. Those areas which received timely application of temephos during the preceding year, al sharp decline in the number of cases in 1989 was observed. However, in those villages where no temephos was applied or where application was started as late as April or May, there was no impact on prevalence of the disease.

Animals↗
PubMed1990

[Campaign against the vectors of onchocerciasis in the surroundings of a refugee camp located in a savanna zone of Cameroon].

In view of the risks of onchocerciasis facing Chadian refugees who have settled in a camp in a savanna hyperendemic area of northern Cameroon, the authors concluded that a vector control directed against the black fly larvae located on small seasonal tributaries of the main water course of this area should be carried out during the four to five months of the rainy season, i.e., during the whole period of transmission of this disease. The operations were undertaken during two consecutive rainy seasons. The first year consisted in developing ground-based control techniques and evaluating the larvicidal efficacy at the larval level. The second year was, particularly, devoted to the study of the impact of the vector control on the biting rate and on the transmission of onchocerciasis. Every week, three of the tributaries close to the camp were treated with an Emulsifiable Concentrate of temephos. Throughout the rainy season, the larvicide eliminated almost all the pre-adult black fly stages on these water courses. At the point in a high onchocercal endemicity area, it also reduced the biting rate by 60% and the Annual Transmission Potential by 72%, i.e., to values corresponding to the lower meso-endemicity threshold. Since these results were obtained at a very unfavourable point from the standpoint of black fly density and onchocerciasis transmission, the authors consider that vector control carried out under these conditions protects the local populations and the Chadian refugees effectively from black fly bites and a risk of severe onchocerciasis.

Animals↗
PubMed1991

Insecticide susceptibility of Aedes aegypti from Santo Domingo, Dominican Republic.

The insecticide susceptibility of Aedes aegypti adults and larvae from Santo Domingo, Dominican Republic, was investigated using World Health Organization standard procedures. A field strain was more resistant to insecticides than a colony strain that originated from the same place. Larvae produced from ovitrap-collected eggs were resistant to temephos (78.2% mortality on exposure to 0.025 mg/liter). Mortality rates after exposure of adults to discriminating concentrations showed that wild populations were resistant to DDT, malathion, propoxur, permethrin and deltamethrin. The problem of resistance was considered serious enough to warrant consideration of control measures other than the use of chemicals.

Aedes↗
PubMed1990

Laboratory evaluation of some larvicidal agents against Anopheles culicifacies in Pune.

A laboratory study to evaluate some larvicidal agents against Anopheles culcifacies was carried out. The findings of this study brought out that the larvae of this species were highly susceptible to temephos, fenthion, Paris green and Mosquito Larvicidal Oil (MLO) in that order. The LC50 values in respect of these larvicides were 0.0009 ppm, 0.0081 ppm, 0.029 ppm and 0.015 ml respectively and LC90 values were 0.0018 ppm, 0.022 ppm, 0.11 ppm and 0.046 ml respectively.

Animals↗
PubMed1990

Effects of sublethal dosages of Abate upon adult fecundity and longevity of Aedes aegypti.

Sublethal concentrations of Abate (temephos) were applied to F2 generation Aedes aegypti larvae, and fecundity and longevity were recorded in the emerged adults. Females exposed to Abate oviposited only in the first 2 gonotrophic cycles, meanwhile control females laid a few eggs after taking the third blood meal. Dosages of 0.009, 0.013 and 0.015 mg/liter of Abate decreased the mean egg production per gonotrophic cycle 37, 47 and 69%, respectively, in relation to the control. Females that were exposed as larvae to Abate lived longer than the control females.

Aedes↗
PubMed1991

Acute toxicity of mosquitocidal compounds to young mosquitofish, Gambusia affinis.

Toxicity of Florida mosquito larvicides and adulticides to 3-5 day old Gambusia affinis was determined in the laboratory. After 24-h exposure, the larvicides, temephos, fenoxycarb and petroleum distillates had LC50 values of 5.60, 1.05 and 593.4 ppm, respectively. After 24 h the adulticides resmethrin, fenthion, naled and malathion had LC50 values of 0.007, 2.94, 3.50 and 12.68 ppm, respectively. The only compound toxic to young mosquitofish at maximum field application rates was resmethrin. However, in the light of earlier tests, aerially applied adulticides generally reach the water surface at reduced concentrations and thus probably pose little or no risk to mosquitofish populations.

Animals↗
PubMed1991

Residual concentration and efficacy of three temephos formulations for control of larval Aedes aegypti.

The residual concentration and efficacy of Abate 5CG (impregnated in celatom granules) and plaster pellets impregnated with either Abate 4E or technical temephos were compared against late 3rd-instar Aedes aegypti larvae. Both plaster pellet formulations resulted in 100% larval mortality during the 6-wk test, compared with 2 wk for a similar level of mortality for the celatom formulation. The maximum temephos concentration in water treated with the celatom formulation occurred 30 min after treatment at 0.071 ppm. Temephos concentration of water treated with the 4E plaster formulation peaked at 12 h at 0.148 ppm while the concentration of the technical plaster formulation peaked at 48 h at 0.30 ppm.

Aedes↗
PubMed1991

[Evaluation of the efficacy of temephos in the campaign against dracunculosis].

Efficacy of water source treatment with temephos 200 EC had been tested with three methods after treatment of a natural reservoir in a temporary river bed. 1. Residual pesticide in water treatment was measured with a biological test based on the pesticide toxicity on mosquito larvae from a laboratory stock for which the standard LD50 for the considered pesticide is stable and accurately known. After pesticide treatment, samples of the treated source water were taken. 30 larvae were placed in 200 ml of the treated water either pure or diluted in untreated water (ten dilutions tested). The mortality rate of larvae after 24 hours was observed and marked on a probit scale. The LD50 was read directly from the curve. The corresponding dilution of the water sample that contained one standard LD50 was expressed in mg.l-1, using the value of the standard LD50. This method was found reproducible and sensitive (up to 0.001 p.p.m.), depending on the value of the standard LD50. 2. Lethality of cyclopides was measured by numeration of survivals in 10 liters samples and compared to the natural population of a close untreated water reservoir in the higher part of the same river. Results showed that half-life of temephos was shorter than 3 days and the concentration corresponding to the LD50 for cyclopides was reached a week after treatment. Two or three weeks after treatment the cyclopide population was significant and further pesticide application was needed. 3. Decrease of incidence of dracunculiasis was compiled by weekly examination of the population during the season of transmission. Authors observed an incidence of 37% during the 86/87 season.(ABSTRACT TRUNCATED AT 250 WORDS)

Aedes↗