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PubMedDate not supplied

[Standardization of a method for determining the irritability of mosquitoes (Diptera, Culicidae) to insecticides].

The method for determining mosquito irritability with insecticides recommended by the WHO has some drawbacks, which make the results less valuable. An improved method for determining the irritability is developed, in which WHO standard instruments and WHO insecticide paper are applied. It is suggested that the same specimens be used both in experiment and control, and spontaneously active females be removed from the experiment. It is recommended to calculate mosquito distribution from the degree of irritability. In determining the degree of irritability some motor activity in between flights should be taken into account. In each group average number of flights is calculated within 10 min. contact with insecticide. It is shown that a single experiment with every population is sufficient for obtaining true results if the size of experimental sample is 50 females.

Animals↗
PubMed1988

Laboratory assessment of poisoning with a carbamate insecticide.

We discuss a case of a 17-year-old white male who intentionally ingested a tick and flea insecticide and was admitted to the emergency room unconscious, with signs and symptoms of cholinergic toxicity. Capillary gas chromatography and electron-impact mass fragmentographic analysis of the patient's urine and serum demonstrated the presence of poly-ethylene glycol and propoxur (o-isopropoxyphenyl N-methyl-carbamate), a carbamate-based cholinesterase inhibitor commonly used in insecticides. The patient fully recovered, but only after a complicated hospital course. We also discuss the laboratory assessment and clinical treatment of poisoning with carbamate and organophosphate insecticides.

Adolescent↗
PubMed1986

Studies on wide mesh netting impregnated with insecticides against Culex mosquitoes.

Seven insecticides, fenitrothion, d-phenothrin, fenvalerate, permethrin, cyphenothrin and fenpropathrin, were each impregnated onto wide-mesh netting and bioassayed for insecticidal activity against Culex mosquitoes. After 9 months of aging, cyphenothrin was the most effective chemical. The movement of adult females through untreated nets was recorded. When the size of the opening of the mesh was less than the width of wing expanse, the mosquitoes were found to rest on the netting before they passed through, thus allowing them time to pick up a lethal dose of the insecticide.

Animals↗
PubMed1986

[Enzyme systems of insecticide detoxication in the Colorado beetle].

The activity of three enzymatic systems of xenobiotic metabolism (cytochrome P-450-dependent monooxygenases, non-specific esterases and glutathione S-transferases) was studied at different stages of development of the Colorado potato beetle (Leptinotarsa decemlineata). Significant sex and ontogenetic differences in the content of cytochrome P-450, position of maxima of CO-difference spectra of the cytochrome P-450 reduced form and substrate specificity of cytochrome P-450 were revealed. The activity of non-specific esterases was shown to increase depending on the age of larvae. The insecticide 1-naphtholenol methylcarbamate which is metabolized by the system of cytochrome P-450-dependent monooxygenases is more toxic in the larvae than at the imago stage, which is correlated with the activity of this system at different stages of ontogenesis. The microsomal monooxygenase inhibitor, piperonylbutoxide, increases the insecticide toxicity in the Colorado beetle imago more than 2-fold. The experimental results testify to different contribution of the detoxication systems to the sensitivity of the Colorado beetle to insecticides at various metamorphosis stages.

Animals↗
PubMed1985

Response of the mosquito Culex pipiens molestus in the Amman area of Jordan to certain insecticides.

The response of adult females of the mosquito Culex pipiens molestus to six insecticides was evaluated. Adults were collected from two locations in the Amman area from May to October 1983. The F1 generation was exposed to paper-impregnated insecticides using WHO test kits. At both locations, the most toxic insecticides were permethrin, propoxur and ferpropathrin. Malathion, dieldrin and DDT were far less effective.

Animals↗
PubMed1985

The parameters of comparative evaluation of insecticidal activity of preparations in aerosol containers.

On the basis of experimental data, the authors present a group of parameters for the purpose of unification of comparative evaluation of the insecticidal effect of preparations in aerosol containers designed for combatting flying and non-flying domestic insects. The advisability of evaluation of the effect of the preparations for combatting flying insects according to the concentration of insecticides ensuring death of flies in the course of 15 min and the corresponding expenditure of the mixture has been substantiated. Preparations designed for combatting non-flying insects should be evaluated according to the coefficients of acute action, ovicidal and residual effects. To facilitate analysis and evaluation of the preparations in aerosol containers, the authors propose their classification according to the parameters of the insecticidal effect. Classification of the preparations under study according to their parameters is presented. It has been demonstrated that compositions containing pyrethroids and their mixtures with DDVP--Neofos, Neofos-2 and Pif-Paf are the most efficient.

Aerosols↗
PubMed1971

Some factors affecting the distribution and rate of action of insecticides.

The amount of insecticide that reaches a critical site of action within an insect is affected by a number of physical and chemical processes both within and outside the insect. This paper reviews some of these processes, with particular attention to those external to the insect, whose action commences at the moment an insecticide is released into the environment. On the basis of research that has been conducted on such processes, conclusions are drawn as to the properties that are desirable, from the point of view of insecticidal efficiency, in new compounds.

1-Propanol↗
PubMed1969

The impact of insecticide-resistance on control of vectors and vector-borne diseases.

A questionnaire inquiring into the nature of schemes for the insecticidal control of disease vectors, the development of resistance in these vectors, and the effect of any such resistance on their control and on the extent of disease was sent to more than 100 health authorities throughout the world. The replies to the questionnaire are summarized in this paper.Until recently, the use of insecticides in public health has been largely based on three organochlorine compounds-DDT, HCH and dieldrin. However, in some countries resistance to these has now severely affected control both of many insect species and of the diseases they transmit (e.g., malaria, yellow fever, filariasis, typhus, plague). Certain other public health problems (onchocerciasis, Chagas' disease, trypanosomiasis, leishmaniasis) have not so far been greatly affected by resistance, but it is difficult to be sure of the continued reliability of the organochlorines.Research in the past 5 years, much of it sponsored by WHO, has shown the value of various organophosphorus and carbamate insecticides as replacements for the organochlorines, although resistance to them, too, can occur. Attention must therefore be focused on all facets of the use of these newer compounds and particular scrutiny made of possible instances of resistance to them.

Insect Control↗
PubMed1971

The WHO programme for the evaluation and testing of new insecticides.

For many years the World Health Organization has been engaged in a programme for the control of vector-borne diseases, and in 1960 established a programme for evaluating and testing new insecticides, the special objectives being to find new compounds that would overcome the problem of insecticide resistance and not lead to further contamination of the environment.This paper reviews the present status of control of some of the principal vector-borne diseases of man and describes the WHO programme for insecticide evaluation and testing and the results it has achieved.

Evaluation Studies as Topic↗
PubMed1971

Experience in the WHO field programme for evaluating the safety of new insecticides.

After careful laboratory evaluation every new insecticide is subjected to village-scale trials, under the WHO Scheme for Evaluating and Testing New Insecticides, before it can be recommended for general use. Several such trials have been conducted to obtain both entomological and toxicological information. The toxicological assessment includes both clinical observations and laboratory tests on both spray-men and residents.Laboratory tests should be of a kind suitable for field operations. So far only serum cholinesterase determinations have proved suitable: determinations are usually made before spraying, immediately after spraying, and again a few weeks later.THE FINAL EVALUATION OF THE SAFETY OF A NEW INSECTICIDE MUST ALWAYS TAKE INTO ACCOUNT THE CONDITIONS UNDER WHICH IT IS LIKELY TO BE USED: it must be remembered that it will be used in confined spaces, that it may contaminate bedding and food, that safety precautions by the spray-men will be negligible, and that the general supervision will be inadequate.

Anopheles↗
PubMed1975

[Thymus changes in chicks following treatment with small doses of insecticides].

Effects of small doses of insecticides (Fenclorfos and Heptaclor) upon the thymus of chickens were followed. Treatment began at the age of 3 weeks and continued during 4 or 8 weeks. Doses used were: 1 ppm for Heptaclor and 1 ppm and 0.5 ppm for Fenclorfos. Total nucleic acid, total protein, RNA, DNA, and amino acid nitrogen contents were determined, as well as GOT and GPT activities and weight of the organ. Results are interpreted as being due to the action of insecticides on the hypothalamus-hypophysis-adrenals axis. They depend on the nature and dosis of insecticide, as well as on the duration of the treatment.

Adrenal Glands↗
PubMedDate not supplied

Interrelationships of oxygen consumption and insecticide sensitivity.

The circadian rhythms of oxygen consumption and insecticide sensitivity (to dichlorvos, a rapid-acting organophosphate) in adult confused flour beetles (Tribolium confusum du Val) were determined using a LD 12:12 lighting regimen and other standardized conditions. Analysis included fitting a 24 h cosine curve to the data to estimate rhythm characteristics. Relationships between rhythms in oxygen consumption and insecticide sensitivity were evaluated on the basis of each rhythm's acrophase (timing of high point). The acrophase of oxygen consumption occurred on the average about 3 h after the middle of the daily dark span. Maximum insecticide sensitivity, based upon the reciprocal of the LC70, occurred about 2 h earlier. Although the times are fairly close, the difference between the two acrophases was statistically significant.

Animals↗
PubMed1982

DNA content in the mouse spermatogonia B and spermatid nuclei during treatment with insecticides.

The DNA content in nuclei of germ cells: spermatogonia B and spermatides in the maturation phase of male mice receiving commercial insecticide preparations commonly used in this country was cytophotometrically measured. The following insecticides were tested: 1% Metox-30 solution, containing 30% of methoxychlorine (p,p-dimethoxydiphenyltrichlorethane), 0,3% solution of Sadofos-30 containing 30% of malathione (1,2-dicarboethoxyethyl-0,0-dimethyldithiophosphate) and 0,3% solution of Foschlor-50 containing about 50% trichlorfon (2,2,2-trichloro-1-hydroxyethyl-0,0-dimethyl-diphosphonate). It was found that a statistically significant number of spermatogonium B and spermatide nuclei in the phase of maturation of the animals treated with the insecticides exhibited an abnormal DNA content as compared with the nuclei of control animals. The chromatin of these nuclei is also more sensitive to acid hydrolysis in Feulgen reaction.

Animals↗
PubMed1983

[Effect of temephos on acetylcholinesterase activity in the brain of Tilapia guineensis. 3: Comparative effect of temephos and 3 substitute insecticides].

The Onchocerciasis Control Programme (OCP) is realized in the major part of the treated area by weekly applications of temephos in biotopes of simulles larvae. This insecticide is very effective and its impact on the aquatic fauna is evaluated by means of periodic samplings of the fauna. Therefore, the most sensitive way of tracking down fish poisoning is by studying the brain acetylcholinesterase depression. Evaluated on Tilapia guineensis this lowering is moderate when operational doses are used by OCP. The discovery of resistence to temephos incited researchers of OCP to try remplacement insecticides. Among these, chlorphoxim, chlorpyrifos-methyl and pirimiphos-methyl proved to be the most effect of these three organophosphorus compounds to that of temephos on the acetylcholinesterasic activity of the brain of Tilapia but using a much higher dosage (0,05 mg/l during 24 hrs that is 144 times more than for temephos). The results demonstrate that the three remplacement insecticides have on inhibitive effect plainly more important than that of temephos and that the retour to normal activity requires a much longer time.

Acetylcholinesterase↗
PubMedDate not supplied

Cellular lesions in the central nervous system of Periplaneta americana following insecticide treatment in vitro and in vivo. I. Nerve cell bodies and the neuropile.

Cellular lesions in the metathoracic ganglion of P. americana following insecticide treatment have been examined. Treatment of the isolated ganglia with dieldrin (10 microM) and bioresmethrin (5 microM) induced mitochondrial damage in the neuropile and nerve cell bodies. The mitochondria in treated nerve cells were swollen with broken cristae and devoid of normal morphological appearance. Following in vivo treatment of cockroaches with these insecticides, this type of mitochondrial damage was observed even at the onset of poisoning. In the prostrate cockroaches, however, the mitochondrial swelling was accompanied by the accumulation of electron dense granules. In addition, the neuropiles of insecticide-treated ganglia contained secondary lysosomes which increased in size and number with the progress of poisoning and showed signs of depletion of synaptic vesicles. The action of dieldrin upon the ultrastructure was completely abolished by pretreatment of ganglia with 10 mM Mg2+. On the other hand, pretreatment of ganglia with tetrodotoxin and pentobarbital-sodium had very little effect on the action of dieldrin though these compounds blocked the action of bioresmethrin. The results of this study suggest that cellular lesions in the insect CNS, caused by dieldrin, are due to an enhanced uptake of calcium into nerve terminals which may occur independent of membrane depolarization. The effects of bioresmethrin upon the ultrastructure of the CNS are apparently mediated by nerve excitation and membrane depolarization. It is concluded that treatment of intact cockroaches with dieldrin and bioresmethrin initiates catabolic processes in the nerve cells leading to cellular lesions which are indicative of neuronal degeneration.

Animals↗
PubMedDate not supplied

Cellular lesions in the central nervous system of Periplaneta americana following insecticide treatment in vitro and in vivo. II. Glial cells.

Glial cell damage in the central nervous system of P. americana following insecticide treatment has been studied. Treatment of isolated metathoracic ganglia with 10 microM dieldrin caused an increase in the electron opacity of the inner and outer glial cells without effecting such a change in the structure of glial cells in the ventral connectives. Glial cells in the ganglia and ventral connectives treated with 5 microM bioresmethrin were found to be swollen and even more electron lucent than the control cells. In the prostrate cockroaches (24 hr after the treatment) the action of bioresmethrin and dieldrin upon peripheral glial cells was identical. Both insecticides caused vacuolation and darkening of outer glial cells; their effects extended to include glial cells in the ventral connectives. At the onset of poisoning, 20-30 min following the application of dieldrin, outer glial cells exhibited slight increase in electron opacity while the inner glial cells showed increase in lysosomal activity. The observed action of dieldrin upon the ultrastructure of glial cells was prevented by pretreatment of the nervous tissue with 10 mM Mg2+. Though tetrodotoxin and sodium-pentobarbital had very little effect upon the action of dieldrin, these drugs blocked bioresmethrin-induced alterations in the fine structure of glial cells. The results of this study suggest that alterations in the ultrastructure of insect neuroglia following treatment with insecticides tested in this study are probably due to perturbations in the neural element of the nervous system.

Animals↗
PubMed1983

Regeneration of hydra damaged by zolone PM insecticide.

The zolone PM (phosalone) insecticide in the suspensions used destroys parts of the hypostome, ruins many buds and budless hydras. In the insecticide suspension a hydra shrinks and assumes the smallest surface. It is due to this that the surface mucous layer thickens and epidermal and gastrodermal cells become highly squeezed together. The insecticide penetrates the hypostomal opening and destroys hypostomal cells but does not act specifically upon a certain type of cells. Gradually, other cells replace the destroyed ones. They arrive from the gastrodermal region. Among them, zymogen cells, capable of differentiation und dedifferentiation into other types of cells, play the most significant part.

Animals↗
PubMed1983

Insecticidal properties of permethrin and permethrin-based agents.

A study of some insecticidal properties of a new pyrethroid, permethrin, showed that it was a highly effective insecticide at contact, superior in this respect to neopinamin for German cockroaches, houseflies and bedbugs and superior to sumithrin for German cockroaches. Combinations of permethrin with neopinamin displayed synergism. The most active combination contained permethrin and neopinamin in a ratio of 9:1. This combination surpassed in insecticidal activity the most effective combination of sumithrin with neopinamin.

Animals↗