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PubMed1972

Toxicity of insecticides to tsetse flies.

New insecticides have been evaluated for toxicity to tsetse flies and compared with organochlorine compounds currently in use. The most toxic compounds and their estimated median lethal doses in nanograms per fly by topical application in solution to teneral Glossina austeni were: resmethrin 4, fenthion 8, dieldrin 10, propoxur 12, chlorfenvinphos 12, tetrachlorvinphos 20, and dichlorvos 20. There was little variation in the susceptibility of teneral male and female flies, young fed flies, and fed stud males with all the compounds tested (dieldrin, resmethrin, tetrachlorvinphos, bromophos, and propoxur) and increased tolerance in old fed pregnant flies occurred only with dieldrin and resmethrin. There was also little variation in the susceptibility of teneral flies of the two species G. austeni and G. morsitans. In contact toxicity tests with water dispersible powder deposits on plywood, propoxur was highly active initially but lost its effectiveness after only a few weeks, whereas tetrachlorvinphos was less active initially but more persistent.

Animals↗
PubMed1965

Toxicities of certain larvicides to resistant and susceptible Aedes aegypti (L.).

In a study of the toxicological characteristics of dieldrin-resistant and DDT-resistant strains of Aedes aegypti, combined with an evaluation of certain larvicides, 14 cyclodienes, 13 DDT-type compounds, 18 organophosphorus compounds, several carbamates and a number of other compounds were tested against larvae of A. aegypti. Telodrin and GC-9160 proved to be toxic against a highly dieldrin-resistant strain. Against highly DDT-resistant strains the toxicity of DDT could be enhanced by piperonyl butoxide, DMC or WARF, that of deutero-DDT by DMC, and that of methoxychlor by piperonyl butoxide. Prolan and Bulan were found to be slightly less effective than deutero-DDT against highly DDT-resistant strains. Among the more recent organophosphorus compounds found to exceed fenthion in toxicity are AC-52160, Stauffer N-2404, Folithion, Bayer 52957 and SD-7438. The effectiveness of dimethrin could be enhanced with piperonyl butoxide.

Aedes↗
PubMed1966

A simple laboratory method for testing the susceptibility of larvae of the Simulium neavei complex to insecticides.

Certain species of the Simulium neavei complex are important vectors of human onchocerciasis in Africa. Because of the association of the larvae of this complex with freshwater crabs, their insecticide susceptibility cannot be readily tested by any of the available methods. They are firmly attached to the crabs and can be removed only with difficulty and sometimes injury. The method described in this paper was developed, therefore, to obviate removal of the larvae from the crabs.Larvae of S. nyasalandicum de Meillon, from the Eastern Usambaras in Tanzania, were used in this investigation. In order to prevent the crabs from eating larvae which became detached during the test, and to facilitate transfer from one container to another, the crabs were confined in specially designed plastic cages.Preliminary tests with DDT and fenthion suggest that the method has considerable potentialities, but that certain aspects require further investigation.

Animals↗
PubMed1969

Results of fenitrothion selection of Culex pipiens fatigans Wied. and Anopheles albimanus Wied.

Laboratory selection of Culex pipiens fatigans (=C. quinquefasciatus) and Anopheles albimanus by fenitrothion pressure for 30 and 25 generations, respectively, resulted in only 2.2-fold and 1.1-fold increases in tolerance to this compound. Cross-resistance to arprocarb in Culex increased 12.2-fold but smaller increases in tolerance to fenthion, malathion, DDT, and dieldrin, may be manifestations of vigour tolerance. Since the essential conditions for selection are believed to have been fulfilled, the authors consider the negative results obtained to be of practical significance, as well as of academic interest.

Animals↗
PubMed1971

Insecticide resistance resulting from sequential selection of houseflies in the field by organophosphorus compounds.

Although cross-resistance in houseflies to the organophosphates has eliminated numerous potentially useful compounds from field use, the "subgroup" specificity of this phenomenon has permitted housefly control to be carried out for nearly a quarter of a century by changing from one toxicant to another within this class of insecticides. A question of considerable importance in insect control is whether the development of resistance to one subgroup of organophosphates will be at the expense of resistance to a subgroup applied previously. The development over several years of resistance in a field population selected sequentially by a number of organophosphates was studied. It was observed that the resistance spectrum expanded progressively to include, finally, organophosphates originally thought to belong to more than one subgroup-namely, malathion (resistance greater than 100 times), fenchlorphos (114 times), diazinon (163 times), coumaphos (greater than 100 times), Ciodrin (greater than 100 times), fenthion (18 times) and naled (9.3 times). Resistance to each compound continued to rise to levels considerably higher than those achieved at the time when the field use of the compound ended. The possible coexistence of subgroup cross-resistance in a population is discussed in the light of these results.

Animals↗
PubMed1983

Resistance to organophosphate and carbamate insecticides in Anopheles atroparvus.

Adult Anopheles atroparvus, from Cadiz, Spain (strain AT SPA) were resistant to several organophosphorus and carbamate insecticides. Separate lines of the AT SPA strain selected with propoxur, fenitrothion, fenthion and malathion were cross-resistant to these insecticides as well as chlorphoxim and bendiocarb. Lack of synergism between malathion and triphenyl phosphate (TPP), a carboxylesterase inhibitor and between fenitrothion and piperonyl butoxide (PB), a multi-function oxidase inhibitor, against the selected lines suggests that resistance to these insecticides may be non-metabolic. Lack of synergism of propoxur after 2 h exposure with PB, sensamex and SV1 (which all inhibit multi-function oxidases), may suggest that the same mechanism is involved here. However, all three synergists were effective in conjunction with 6 h exposure to propoxur. The postulated mechanisms are: a non-metabolic resistance, possibly an altered site of action, responsible for the non-synergizable resistance to organophosphorus insecticides and to a lesser extent the carbamates and a multi-function oxidase inhibitor-suppressed mechanism conferring resistance to propoxur.

Anopheles↗
PubMed1978

The efficacy of various insecticides against the larvae of Lucilia cuprina (Wied.), the green blowfly of sheep. I. In vitro tests using a resistant and susceptible strain.

In order to determine the larvicidal action of different insecticides against both susceptible and resistant blowfly strains in the Republic of South Africa, an attempt was made to find a suitable in vitro method for mortality counts and potency evaluations. After a series of preliminary trials the Australian method of Roxburgh & Shanahan (1973) was adopted as the most reliable for this purpose. A statistical analysis by computer of the basic data at Onderstepoort established the superiority of the LC50 value in biological assays over the LC99 or the closely related minimum lethal concentration (MLC). The insecticidal action of different blowfly compounds was evaluated for relative potency against both susceptible and resistant blowfly strains by comparing their LC50 values in their logarithmic form. Comparisons are fully justifiable where the individual regression coefficients of the insecticides under test do not deviate significantly from a common slope initially calculated (Finney, 1971). A diazinon formulation proved the most potent against susceptible blowflies and fenthion ethyl against the resistant strain from Riversdale. Relative insecticidal potencies varied from 0,07-0,62 in the former compound and from 0,35-0,66 in the latter.

Biometry↗
PubMed1993

Tolerance of sewage treatment plant microorganisms to mosquitocides.

Beneficial protozoa and rotifers collected from a wastewater treatment plant in Panama City, FL, were tested for tolerance to 11 commonly used mosquito larvicides and adulticides in the laboratory. The acute effects were assessed using selected concentrations of the adulticides fenthion, malathion, naled, permethrin, and resmethrin; and the larvicides Bacillus thuringiensis israelensis, Bacillus sphaericus, diflubenzuron, larviciding oil, methoprene, and temephos for the following microorganism taxa: ameoboids, flagellates, free-swimming ciliates, stalked ciliates, and rotifers.

Animals↗
PubMedDate not supplied

Susceptibility status of Culex quinquefasciatus in Patna to insecticides.

To obtain the base line data, a study conducted in district Patna, Bihar to note the susceptibility status of adult Culex quinquefasciatus against organochlorine, organophosphorous and synthetic pyrethroids. It was found that adult of Cx.quinquefasciatus developed double resistance to DDT and dieldrin but susceptible to O.P. compounds and pyrethroids. Cx.quinquefasciatus larvae are also found susceptible to O.P compounds like malathion, temophos, fenthion and fenitrothion.

Animals↗
PubMedDate not supplied

Insecticidal susceptibility status of Anopheles stephensi (Liston) in selected areas of Calcutta (West Bengal).

Susceptibility tests were carried out with insecticides like Organochlorine Organophosphorus and Synthetic pyrethroids using the WHO test kits against Anopheles stephensi larvae and adults, collected from malaria endemic wards of Calcutta in December, 1995 and January, 1996 Anopheles stephensi adults were found resistant to DDT, Propoxure, Malathion but susceptible to Fenthion and Deltamethrin.

Adult↗
PubMed1997

Recent epidemiological status of malaria in Calcutta Municipal Corporation area, West Bengal.

In Calcutta, Plasmodium falciparum cases and death due to malaria show remarkably increasing trend since 1990. The incidence of P. falciparum malaria has increased more than eleven folds in 1996 in comparison to 1990, with 0, 0, 0, 3, 7, 52 and 17 deaths in 1990, 1991, 1992, 1993, 1994, 1995 and 1996 respectively. Situation is more serious than what it is projected in official records as annual blood examination rate (ABER) in Calcutta Municipal area is poor, varying from 1.5 to 3.9 in 1993 and 1996 respectively. This is further evident from the fact that in a study area in 19 months (January 1995 to July 1996) the slide positivity rate (SPR) was 47.94% on an average 28.72% suffer from P. falciparum infection (as low as 0.5% in June 1996 and as high as 71.5% in November 1996). For the first time resistance of P. falciparum to chloroquine has been noted at RII and RIII level. The response of the same parasite strain to sulfa-pyrimethamine combination drug is very much promising. Fresh infection is occurring in all the months of the year and the favourable period is from July to November 1995 that is corroborating with Container index and Breteau index related to the vector mosquito Anopheles. Susceptibility status of An. stephensi indicates that the mosquito species has acquired resistance to DDT, BHC, propoxure and malathion but is still susceptible to fenthion and deltamethrin.

Animals↗
PubMed1994

[Status of insecticide resistance in 4 strains of Musca domestica collected in animal farms].

Resistance to insecticides made from different chemical compounds were studied in 4 strains of Musca domestica collected from 2 poultry farms and 2 cow farms following WHO methodology. A high resistance to malathion was observed (resistance factor values ranging from 102X to 252X), and moderate, to diazinon, fenthion, dichlorvos, DDT, and propoxur. Resistance to the deltametrine and permethrin pyreturins was not observed.

Animal Husbandry↗
PubMed1997

Correlation between overall pesticide effects monitored by shrimp mortality test and change in macrobenthic fauna in a river.

The relationship between change in benthic fauna in the Suna River and shrimp mortality in the river water samples (test was conducted two times per week from May to September) was investigated to assess the insecticide impact on the benthic community. The river was selected because pesticide application had been restricted for a long time in the upper reaches, while aerial insecticide spraying had been done four times on paddy fields in the lower reaches in summer. Species richness and density of benthos were high at the stations in the upper reaches. High shrimp mortality was measured in the water samples collected from a downstream station during the pesticide spraying period, from late July to late August. Species richness and density of benthos markedly decreased at the stations in the lower reaches in that period. However, several species of chironomids, Cheumatopsyche (Trichoptera), which demonstrated tremendous insecticide resistance, and Baetis sahoensis (Ephemeroptera), which has a high recovery potential, were not affected, even in the insecticide spraying period. The benthic fauna in the lower reaches tended to recover from autumn to spring, although not sufficiently. It is considered that the temporal recovery of the benthic community was brought about through recruitment from the benthic community in the 5-km upper reaches. A close correlation was found between the high mortality of shrimp in the water samples and the deterioration in the benthic fauna in this river which was contaminated with insecticides during the summer.

Animals↗
PubMed1990

Prompt recovery from severe cholinesterase-inhibitor poisoning--remarks on classification and therapy of organophosphate poisoning.

In organophosphate intoxication the assessment of both the degree of severity of poisoning and the initial dose of pralidoxime and atropine are as yet based only on clinical symptoms. We present three patients with clinically severe organophosphate poisoning in whom a prompt recovery from central nervous symptoms occurred after the administration of low doses of atropine and pralidoxime. It is suggested that the true severity of organophosphate intoxication as well as the initial therapy should be determined by the amount ingested, the propensity for aging, and the pharmacodynamic properties of the organophosphorus compound, as well as by the time interval between exposure and initiation of appropriate treatment, as far as these data can be verified in the individual patient.

Acetylcholinesterase↗
PubMed1990

A simple method for screening assessment of acute toxicity of chemicals.

We proposed a simple method for screening assessment of acute oral and dermal toxicity using only three rats and mice of each sex at each dose level. Animals were first treated with chemicals at a dose of 2000 mg/kg and were carefully observed for compound-related morbidity and mortality. If none of the animals died, the following toxicity tests were suspended. If some of the animals died, toxicity tests at doses of 200 and 20 mg/kg were performed. The approximate LD50 values calculated by this method showed little difference between two separate laboratories and were in good agreement with LD50 values reported in the literature. Our toxicological data also showed that LD50 values were about 2-2.5 times the MNLD (maximum non lethal dose) in acute oral and dermal toxicity. This meant that a chemical could be regarded as having an LD50 of about 4000 mg/kg or higher when there was no mortality at the dose of 2000 mg/kg. A chemical with such low toxicity would not require further testing for lethal effects. Therefore, this simple method combining the fixed-dose procedure with the limit test is suitable for determination of approximate LD50 values of chemicals and for screening for necessity for classical full LD50 test using many animals.

Ammonium Sulfate↗