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PubMed1998

Effect of insecticides on vital activity, hepatic enzymes and red blood cell acetyl cholinesterase activity of rabbits in Makkah.

Developing animals and invertebrate are markedly more sensitive to acute toxicity through exposure to insecticides. Varieties of insecticides are used for hygienic control in Makkah holy places. The present study examines the acute effects of commonly used insecticides in Makkah area. Rosfin as an organophosphorus, Airlen as a pyrethroid and Sulvac as a carbamate derivative were tested for their effects on vital activities, hepatic transaminases, serum triglycerides and acetyl cholinesterase activity of rabbits. The insecticides were tested in same and double concentration used for insect control by Makkah's municipal authorities. Compressed air was used as a source of pressure for spraying wooden boxes designed for habitation of animals during the experiments. There were no significant changes in vital activities of rabbits in both concentrations. However, serum glutamate pyuvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT) showed irregular changes (mild decrease or increase) in all groups, while triglyceride showed mild rise after six days exposure in case of double concentration. Acetyl cholinesterase showed mild increase in activity after five minutes incubation time, but there was unnoticed increase in activity after 15, 25, 35 and 45 minutes of incubation. In case of Airlen, the activity increased after five minutes of incubation and decreased thereafter. In conclusion, insecticides used in the holy places of Makkah area have no apparent effects on vital activity, acetyl cholinesterase activity and showed no significant effect on rabbit hepatic transaminases and serum triglyceride.

Acetylcholinesterase↗
PubMed1976

The release of a compound-chromosome stock in a vineyard cellar population of Drosophila melanogaster.

The prospect of autocidal insect control was investigated in a cellar population of D. melanogaster using a compound-chromosome stock. The released stock was synthesized by irradiating virgin female progeny derived from the cellar and crossing to a second-chromosome compound laboratory stock. Incorporation of an appropriate genetic background into the compound stock was tested in laboratory studies. Larval development to adult emergence and adult survival studies indicated the compound release stock to be relatively similar to the wild population, while behavioral tests detected no mating isolation between wild or compound genotypes. An unstable equilibrium point of compound frequency 0.7 was observed in population cage experiments with the two genotypes. Adults were released into the cellar at a 50:1 ratio in favor of the compound. Five hundred newly hatched compound-chromosome larvae were also released. Adult, larval and pupal samples were regularly made. The compound stock successfully bred in the cellar maintaining an adult frequency of at least 90% for 108 days after the release. The rapid decline in compound frequency after this period is thought to be due to the migration of inseminated wild-type females from wine storage areas adjacent to the cellar. The results indicate that a compound stock may limit the rate of population expansion in an area and may be a useful mechanism of autocidal control. It cannot be overemphasized that the probability of a successful release will be related to the level of understanding of the adaptive strategy of the population into which the release is made.

Animals↗
PubMed1999

Rhodnius prolixus infected with Trypanosoma rangeli: In vivo and in vitro experiments.

Studies were carried out on the activation of the prophenoloxidase (proPO) in adults of Rhodnius prolixus infected by short and long epimastigote forms of Trypanosoma rangeli. The in vitro activation of the proPO cascade using l-DOPA as substrate was very low in the absence of fat body extract, hemolymph, and parasites. On the other hand, a higher PO activity was observed when short, but not long, epimastigotes of T. rangeli were incubated with fresh hemolymph, fat body extract, and l-DOPA. Supernatant from lysed long epimastigotes increased the PO activity at levels identical to those observed with supernatants from lysed short epimastigotes. Similarly, the PO activity of hemolymph obtained from inoculated insects with long epimastigotes of T. rangeli showed a very low activity when incubated with l-DOPA compared to the PO activity of hemolymph taken from insects inoculated with short epimastigotes of T. rangeli. Control insects inoculated with sterile PBS showed no PO activity. These data indicate the presence of (a) factor(s) in the hemolymph as well as in the fat body extract that may be released (or induced) by the presence of short epimastigotes of T. rangeli and which results in the activation of the R. prolixus proPO system. The implications of these findings are discussed in relation to the development of T. rangeli and its ability to overcome the proPO system, survive, and successfully colonize the hemolymph of R. prolixus.

Animals↗
PubMedDate not supplied

[The efficacy of a new insecticide ethofenprox (Trebon) for controlling different types of insects].

The insecticidal action of the new compound ethofenprox (trebon) in the form of 10 and 30% flow concentrate against house flies, cockroaches, bed bugs, rat fleas, mosquito imagines and larvae of Aedes and Culex genera was studied in the laboratory and in the field. The effective doses and the methods of spraying were established. 10% flow trebon is allowed by the USSR Ministry of Health to be useful in medical disinfection.

Animals↗
PubMed1999

Controlled release of insect sex pheromones from paraffin wax and emulsions.

Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin.

Air↗
PubMed1998

Exposures from indoor spraying of chlorpyrifos pose greater health risks to children than currently estimated.

Recent findings of indoor exposure studies of chlorpyrifos indicate that young children are at higher risks to the semivolatile pesticide than had been previously estimated [Gurunathan et al., Environ Health Perspect 106:9-16 (1998)]. The study showed that after a single broadcast use of the pesticide by certified applicators in apartment rooms, chlorpyrifos continued to accumulate on children's toys and hard surfaces 2 weeks after spraying. Based on the findings of this and other research studies, the estimated chlorpyrifos exposure levels from indoor spraying for children are approximately 21-119 times above the current recommended reference dose of 3 microg/kg/day from all sources. A joint agreement reached between the U.S. Environmental Protection Agency and the registrants of chlorpyrifos-based products will phase out a number of indoor uses of the pesticide, including broadcast spraying and direct uses on pets. While crack and crevice treatment of insects (such as cockroaches and termites) by chlorpyrifos will still continue, it appears prudent to explore other insect control options, including the use of baits, traps, and insect sterilants and growth regulators. To ensure global protection, adequate dissemination of appropriate safety and regulatory information to developing regions of the world is critical, where importation and local production of chlorpyrifos-based products for indoor uses may be significant.

Air Pollution, Indoor↗
PubMed1990

Specificity and efficacy of purified Bacillus thuringiensis proteins against agronomically important insects.

The host range and relative efficacy of three purified Bacillus thuringiensis insect control proteins were determined against 17 different agronomically important insects representing five orders and one species of mite. The three B. thuringiensis proteins were single gene products from B. thuringiensis ssp. kurstaki HD-1 (CryIA(b)) and HD-73 (CryIA(c)), both lepidopteran-specific proteins, and B. thuringiensis ssp. tenebrionis (CryIIIA), a coleopteran-specific protein. Seven insects showed sensitivity to both B. thuringiensis ssp. kurstaki proteins, whereas only 1 of the 18 insects was sensitive to B. thuringiensis ssp. tenebrionis protein. The level of B. thuringiensis ssp. kurstaki protein required for 50% mortality (LC50) varied by 2000-fold for these 7 insects. A larval growth inhibition assay was developed to determine the amount of B. thuringiensis ssp. kurstaki protein required to inhibit larval growth by 50% (EC50). This extremely sensitive assay enabled detection of B. thuringiensis ssp. kurstaki HD-73 levels as low as 1 ng/ml.

Animals↗
PubMed1983

Control of the northern fowl mite on inanimate objects by fumigation: field studies.

Field studies were conducted to determine the efficacies of methyl bromide and sulfur dioxide as fumigants for northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), on egg flats and egg cases. Both fumigants killed the mites within 24 hr; however, sulfur dioxide had a repulsive irritating odor, which was retained in the cardboard egg flats and egg crates and persisted for several days after exposure to the gas. When used in accordance with the manufacturer's recommendations for fumigating enclosed trailers and vans to control insects that attack food products, methyl bromide gave excellent control of northern fowl mites infesting inanimate materials.

Animals↗
PubMedDate not supplied

Insecticide metabolism and selective toxicity.

Current research is focused on means to improve the environmental acceptability and selective toxicity of existing classes of insecticides and the search for new and species selective modes of insecticidal action. The study of species differences in metabolism and its modulation by changes in chemical structure is a vital component of this effort. The importance of metabolism is illustrated by examples from the major classes of insect control chemicals, namely organophosphorus and carbamate insecticides, DDT, pyrethroids and insect growth regulators.

Cholinesterase Inhibitors↗
PubMedDate not supplied

Vectors control importance on leishmaniasis transmission.

We reviewed the control of transmission of leishmaniasis regarding chemotherapy, reservoirs elimination, vaccination and insect control through the use of chemical insecticides. We also discussed complementary measures like monitoring traps, impregnated bednets and curtains, repelents, pheromones, biological control, etc. A cost comparison of insecticide interventions through the use of products belonging to the four main chemical groups was also done, comparing together conventional formulations versus a slow-release insecticide developed by the Núcleo de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro. We finally did recommendations on the situation that would justify an insecticide intervention to control sandflies.

Animals↗
PubMed1994

Glucose metabolism in an insect Manduca sexta and effects of parasitism.

The metabolism of [1-13C]glucose was examined during the last larval stadium of an insect Manduca sexta (Lepidoptera: Sphingidae) parasitized by Cotesia congregata (Hymenoptera: Braconidae). Following injection, the isotopically substituted glucose was metabolized at a significantly lower rate by parasitized larvae than by normal, control insects. 13C enrichment was principally observed in [1-13C]trehalose in both groups. Randomization of the label at the triose phosphate step was evidenced by incorporation of 13C into C6 of trehalose. Parasitized and control larvae both synthesized [1,6-13C]glycogen but the relative amount of label observed in parasitized larvae was greater. The ratio of C6/C1 enrichment in trehalose and glycogen was significantly less in parasitized larvae. The rate of labelled trehalose and glycogen synthesis was relatively high when compared with the estimated rate of glycolytic glucose oxidation, and the difference in C6/C1 enrichment ratio between normal and parasitized insects was, therefore, not reflective of a difference in the rate of substrate cycling, but rather, was due to the increased synthesis of [1-13C]glycogen in parasitized larvae when compared with controls. Inhibition of glycolysis by administration of iodoacetate to normal larvae resulted in an increase in the incorporation of 13C into glycogen relative to glucose metabolized, suggesting that inhibition of glycolysis may be responsible for the higher level of glycogen synthesis observed in parasitized insects. In control larvae, significant 13C enrichment from [1-13C]glucose was observed in fat, but no evidence of lipogenesis was observed in parasitized insects. Iodoacetate had no observable effects on the relative amount of 13C incorporated into fat. Malonic acid and cyanide resulted in accumulation of 13C from [1-13C]glucose in several TCA cycle intermediates of normal larvae, but had little effect on the relative enrichments of trehalose, glycogen and fat.

Animals↗
PubMed1975

The control of bluetongue in an enzootic situation.

On account of the wide host range of bluetongue virus and its biological transmission by insects, control of the disease in an enzootic situation is based primarily on the active immunisation of susceptible animals as well as on the prevention of contact between the insect vectors and the susceptible hosts. In spite of their unquestionable value, the egg attenuated vaccines which are currently employed for prophylactic immunisation, have certain shortcomings. The existence of 16 known serotypes of bluetongue virus makes it difficult to achieve a very wide spectrum of immunity in sheep vaccinated once or twice only. The problems which are experienced with the immunisation of lambs born in spring are indicated. The present vaccine can also present problems when used in breeding animals. Furthermore, the costs involved in the annual vaccination of large numbers of animals are considerable. The need for a vaccine for cattle is indicated. Work is also being conducted at present on the development of an inactivated vaccine for use in sheep. The use of novel virological techniques may aid in the future development of absolutely safe and highly efficient vaccines against bluetongue.

Animals↗
PubMed1987

The biotechnology of Bacillus thuringiensis.

One of the challenges in the application of biotechnology to pest control is the identification of agents found in nature which can be used effectively. Biotechnology offers the potential of developing pesticides based on such agents which will provide environmentally sound and economically feasible insect control alternatives. Such an agent, the insect pathogen Bacillus thuringiensis, is the subject of intense investigations in several laboratories. Insecticides which use the entomocidal properties of B. thuringiensis are currently produced and sold worldwide; new products are currently in the development stage. Herein, the biology and genetics of B. thuringiensis and the problems associated with current products are critically reviewed with respect to biotechnology. Moreover, the economic and regulatory implications of technologically advanced products are evaluated.

Amino Acid Sequence↗