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PubMed1991

Extended selections for pyrethroid resistance in the German cockroach (Dictyoptera: Blattellidae).

Selection experiments with a pyrethrins-susceptible and a pyrethrins-resistant strain of German cockroaches, Blattella germanica (L.), were conducted for 17 generations with either permethrin or fenvalerate as the selecting agent. Large nymphs were left on treated glass surfaces for extended periods of time each generation. Mortality was assessed at 24 h. The level of resistance was determined periodically by time-mortality testing. The VPI-susceptible strain served as the basis for comparison. The pyrethrins-susceptible strain developed resistance to pyrethrins early in the selection process; this strain ultimately became resistant to allethrin, phenothrin, permethrin, fenvalerate, cyfluthrin, and cypermethrin. Fenvalerate caused faster development of resistance than did permethrin. The pyrethrins-resistant strain, selected with fenvalerate, quickly became resistant to allethrin, permethrin, phenothrin, and fenvalerate. Ultimately, it developed resistance to all nine pyrethroids tested.

Animals↗
PubMed1991

Effects of several insecticide formulations on oothecal drop and hatchability in German cockroaches (Dictyoptera: Blattellidae).

Formulations used for control of German cockroaches, Blattella germanica (L.), were investigated. The insecticides tested on gravid females were bendiocarb, chlorpyrifos, cyfluthrin, cypermethrin, fenvalerate, hydramethylnon, malathion, propetamphos, propoxur, and pyrethrins. Exposure to each insecticide increased the frequency of oothecal drop and reduced the percentage oothecal hatch. The percentage of oothecae that were dropped increased as a curvilinear function of insecticide concentration. An LD50 of propoxur to female German cockroaches resulted in the greatest oothecal drop (83.50%); fenvalerate caused the least drop (22.60%). LD50's of cypermethrin, propetamphos, and propoxur resulted in 29.60, 31.807, and 37.30% hatch from dropped oothecae, respectively. The smallest percentage hatch from retained oothecae was caused by LD50's of propoxur (1.5%) and cyfluthrin (7.70%). Retained oothecae from females treated with an LD50 of fenvalerate (68.70%) or pyrethrins (68.70%) had the greatest percentage hatch. Total percentage hatch (dropped and retained oothecae) declined exponentially as the insecticide concentration increased. An LD50 of cypermethrin limited total oothecal hatch to 24.50%, whereas LD50's of fenvalerate, malathion, and pyrethrins resulted in 53.60, 52.20, and 58.90% hatch, respectively. Mean time to oothecal hatch increased linearly with increasing insecticide concentration for all insecticides tested.

Animals↗
PubMed1990

[The appearance of insecticide resistance in Blattella germanica in the German Democratic Republic].

A review is given on the situation of resistance in the German cockroach (Blattella germanica) to insecticides during the last 15 years in the GDR, and conclusions are drawn for the future. From 23 samples trapped in various localities and subsequently reared in the laboratory, susceptibilities were measured against lindane, pyrethrin + PBO, trichlorfon, dichlorvos, and propoxur, the most used insecticides against cockroaches in our country. Detection of resistance was done with discriminating doses and the degree of resistance was measured with the doses-mortality method in deposit tests. In no case we found any resistance to propoxur but, for the first time, strains with a low resistance to dichlorvos. There was a distinct increase in the resistance to lindane, trichlorfon and pyrethrins + PBO during the lost years. A strain selected with pyrethrins in the laboratory showed marked group resistance to all tested pyrethroids (permethrin, cyfluthrin, cypermethrin, tetramethrin, deltamethrin, bioresmethrin, bioallethrin), but no cross resistance to the other insecticides.

Animals↗
PubMed1990

Toxicity of several insecticide formulations against adult German cockroaches (Dictyoptera: Blattellidae).

Toxicity of bendiocarb, chlorpyrifos, cyfluthrin, cypermethrin, fenvalerate, hydramethylnon, malathion, propetamphos, propoxur, and pyrethrins against the adult German cockroaches, Blattella germanica (L.), was investigated. At LD50, cyfluthrin was the most toxic insecticide to adult males (0.53 microgram/g), adult females (1.2 micrograms/g), and gravid females (0.85 microgram/g). Malathion was the least toxic insecticide to adult males (464.83 micrograms/g), adult females (335.83 micrograms/g), and gravid females (275.90 micrograms/g). Males and gravid females were generally more sensitive than nongravid females to the insecticides that we tested. In tests with malathion, however, males were more tolerant. The order of toxicity of the insecticide classes varied among the stages of adult German cockroaches. The order of toxicity for males and nongravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates = amidinohydrazone. The order of toxicity for gravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates greater than amidinohydrazone. These differences in toxicity suggest that sex differences should be considered when determining insecticide toxicity for German cockroaches.

Animals↗
PubMed1970

Evaluation of compounds for insecticidal activity on adult mosquitos. 5. Toxicity to adult mosquitos and residual properties of some pyrethroids.

New pyrethrin-like compounds are compared with earlier synthetic pyrethroids and natural pyrethrins for intrinsic toxicity to adult mosquitos and for residual contact activity. Two of the compounds are at least as toxic as pyrethrin I to female Anopheles stephensi and Aedes aegypti. Residues of these compounds are very persistent in the dark or in very subdued lighting but they decompose on exposure to normal intensities of daylight and rapidly lose their insecticidal activity.

Animals↗
PubMed1990

The binding properties of pyrethroids to human skin fibroblast androgen receptors and to sex hormone binding globulin.

The pyrethroids are a class of natural and synthetic pesticides which were associated with an epidemic of gynecomastia in Haitian men in 1981. In the present study we tested several pyrethroids for their ability to interact with androgen binding sites in dispersed, intact human genital skin fibroblasts and in human plasma to sex hormone binding globulin (SHBG). All the pyrethroids tested inhibited fibroblast binding of [3H]methyltrienolone (R1881) at 22 degrees C with the following rank order of potency:pyrethrins greater than bioallethrin greater than fenvalerate greater than fenothrin greater than fluvalinate greater than permethrin greater than resmethrin. 50% displacement of [3H]R1881 binding to fibroblast androgen receptors was achieved by 1.5-44 x 10(-5) M concentrations of the competitors, respectively. Previous studies with cimetidine, a known inhibitor of androgen receptor binding, showed 50% competition at a concentration of 1.4 x 10(-4) M in this system. Scatchard analysis of binding experiments performed with increasing concentrations of [3H]R1881 in the presence of the pyrethroids indicated that the binding inhibition was competitive. On the other hand, of the pyrethroids examined only the pyrethrins (50% inhibition) and bioallethrin (43% inhibition) were able to displace [3H]testosterone from SHBG when tested at a concentration of 10(-4) M. These data indicate that a novel class of non-steroidal compounds, the pyrethroids, can interact competitively with human androgen receptors and SHBG. These findings provide a mechanism by which chronic exposure of humans or animals to pesticides containing these compounds may result in disturbances in endocrine effects relating to androgen action.

Fibroblasts↗
PubMed1990

Influence of insecticide treatment on German cockroach (Dictyoptera: Blattellidae) movement and dispersal within apartments.

Two similar studies were done to investigate effects of insecticide treatments on German cockroach, Blattella germanica (L.), movement and dispersal within individual units in multifamily housing. In the first study, Whitmire PT-565 Pyrethrum Insect Fogger (pyrethrins), Diazinon 4E (diazinon), Protector (permethrin), and Baygon 1.5 (propoxur) did not induce any significant changes in cockroach distribution, and rates of movement within apartments decreased. In the second study, populations treated with sublethal doses of pyrethrins and resmethrin settled to their original distribution 24 h after treatment. Results from both studies indicate that thorough insecticide applications do not significantly affect German cockroach population dispersal or movement patterns within apartments.

Animals↗
PubMed1979

Demographic study of head lice infestations in Sacramento County school children.

Head lice infestations have become a problem in school children in Sacramento County. An open study was conducted to determine how widespread head lice infestations were among preschool and elementary school children in Sacramento County and to see how effective a newly marked ever-the-counter pediculicide containing 0.3% pyrethrins synergized by 3.0% piperonyl butoxide was. The public health nurse for this study visited the homes of all reported patients infested with head lice. She verified and provided the pyrethrins-based treatment for 248 children, aged 6 months to 12 years. The children were Caucasian, Mexican-American, black and other ethnic backgrounds and from low, middle and upper income levels. All the patients were successfully treated, and the school children were able to return to their classs in a short time.

California↗
PubMed1987

Treatment of pediculosis pubis. Clinical comparison of efficacy and tolerance of 1% lindane shampoo vs 1% permethrin creme rinse.

Pediculosis pubis (PP) is a common sexually transmitted disease. Current therapy with 1% lindane or various synergized pyrethrins as a single dose has been accepted as adequate by the medical community. We treated 53 men with the diagnosis of PP with either 1% lindane (Kwell) shampoo for four minutes or 1% permethrin (Nix) creme rinse for ten minutes, according to random assignment. All patients combed with fine-toothed combs immediately after therapy. They were examined for tolerance and efficacy at 24 to 48 hours and again at ten days (eight- to 12-day range). In the lindane group, ten (40%) of 25 subjects were infested at the final assessment. In the permethrin group, 12 (43%) of 28 subjects were infested at the final assessment. The difference was not statistically significant. Both treatments were well tolerated, with one mild adverse reaction in each group. We concluded that both agents were equivalent in the treatment of PP. On the basis of the high failure rate, we propose that the therapy of PP with any agent should include a second treatment at ten days.

Adult↗
PubMed1991

Pesticides and the Third World.

Many developing countries are importing industrial processes that make use of toxic chemicals. By the same token, pesticides, which are toxic by design, are also used increasingly in agriculture and in public health programs to control pests and vector-borne diseases. Recent estimates suggest that pesticides account for more than 20,000 fatalities yearly, and that most of these will have occurred in developing countries. This may actually be a gross underreporting. Although organophosphate and carbamate insecticides are still responsible for many of those poisoning cases, herbicides such as paraquat are also increasingly being implicated in fatal poisoning cases. Newer pesticides such as the synthetic derivatives of pyrethrin, which were believed to be relatively safe to humans, now appear to be implicated in some serious cases of intoxication. Community-based pest control using locally available botanical pesticides could have severe consequences unless the toxicity of these compounds is carefully assessed relative to nontarget organisms. A high proportion of pesticide intoxications appear to be due to lack of knowledge, unsafe attitudes, and dangerous practices. The technology available to small farmers for pesticide application is often inappropriate: faulty sprayers, lack of protective equipment adapted to tropical conditions, nonexistent first-aid provisions. Agricultural extension is often not oriented to the transfer of information relative to the dangers inherent in the use of pesticides. The lack of information at all levels may be one of the most important causative factors of chemical intoxication in developing countries. Research should at this time concentrate on behaviors leading to chemical intoxication. This should be done concurrently with proper prospective and retrospective surveys of poisonings in developing country communities. More information should be sought relative to the decision processes of import, legislation, and licensing. Research and development efforts in appropriate technology and safety devices are also critically needed.

Animals↗
PubMed1992

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Animals↗
PubMed1991

Stimulation of vitellogenesis by pyrethroids in mated and virgin female adults, male adults, and fourth instar females of Ornithodoros moubata (Acari: Argasidae).

The effects of several pyrethroids on vitellogenesis, i.e., vitellogenin (Vg) synthesis and ovarian development in unfed mated female adults of Ornithodoros moubata were investigated. Survival of ticks treated with pyrethrin, resmethrin, and etophenprox was very low. Ticks treated with cypermethrin (CyM), fenvalerate (Fev), and flucythrinate (Flu) survived even when high concentrations were used. Vg titer in the hemolymph of unfed mated females was the same level on day 5 and about three times higher on day 10 after treatment with CyM, Fev, and Flu, as that of engorged adult females. CyM was the most effective in inducing vitellogenesis and was further evaluated in unfed virgin females, males, and fourth instars. CyM was shown to stimulate vitellogenesis in unfed virgin females adults. Oviposition did not occur but ovaries were well developed. CyM also was shown to stimulate Vg in the hemolymph of unfed and fed adult males; however, the Vg levels were very low compared to that of engorged adult females. Extremely high concentrations of Vg were observed in the hemolymph of female nymphs (fourth instar), particularly engorged nymphs, treated with CyM (10 micrograms). No ovarian development was observed in these nymphs. Vg stimulated by CyM was shown to be immunologically and electrophoretically the same as that of normal engorged females.

Animals↗
PubMed1988

Pediculosis capitis: why prefer a solution to shampoo or spray?

Two hundred and sixty-eight children with pediculosis capitis took part in a comparative study to test the efficacy of five different pediculocides commonly used in Israel. The preparations used were pyrethrin shampoo, pyrethroid spray, malathion solution, carbaryl shampoo and carbaryl lotion. Carbaryl lotion and malathion solution were much more efficient when compared to the shampoo and spray preparations.

Carbaryl↗