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PubMed1984

[Assessment of the exposure of pest control operators to organophosphorus pesticides. Organophosphorus pesticides in blood and alkyl phosphate metabolites in urine].

Pest control operators usually spray pesticides in small areas such as a kitchen in a restaurant and are exposed to various pesticides, especially those of the organophosphorus (OP) type. In order to evaluate their occupational exposure to OP pesticides during the work, OP pesticides in blood and alkyl phosphate metabolites in urine of these operators were analyzed and the relationship between pesticide exposure and analytical results were studied. OP pesticides in blood were analyzed by gas chromatography with flame photometric detector (FPD-GC) after separation of phospholipid in blood with silicagel column chromatography. OP pesticides were not detected in any blood samples (the limit of detection was 1 ng/ml). Dimethylphosphate (DMP) and dimethylthiophosphate (DMTP), being urinary metabolites of OP pesticides, were analyzed by FPD-GC after benzyl derivatization. This method eliminated interfering peaks in gas chromatograms. The ratio of two isomeric derivatives of DMTP was found to be constant. Both DMP and DMTP of the exposed group were significantly higher than those of the non-exposed group, DMP being higher than DMTP. The ratio of DMP to DMTP in the fenitrothion-dichlorvos-exposed group was significantly higher than that in the fenitrothion-exposed group. It was considered that the ratio might reflect a result of pesticide exposure. The urinary metabolites of OP pesticides tended to become lower with the lapse of time since the last exposure. However, small amounts were detected in a few samples even 5 days after the last exposure.

Adult↗
PubMed1977

[Present trends in the development of pest control methods with reference to environmental protection].

Problems are discussed which result from the present change in principles of parasite control. The main task is maximum limiting the damage caused by certain parasite species. But ecological stability should be disturbed at minimum level. Likewise the introduction of physiologically active alien substances in the ecosystem should be minimal. The solution of this task for practice is joined with research on natural regulation systems in populations and biocenoses, for such system determine the degree and number of species. Three main steps for this solution were shown: Ist: Evaluation of the scope of control; IInd: Evaluation of the strategy of control; IIIrd: Evaluation of a measures program to realize the chosen strategy.

Ecology↗
PubMed2003

Pyrethroids used indoors--immune status of humans exposed to pyrethroids following a pest control operation--a one year follow-up study.

A multiparametric analysis of immune components was performed in blood and serum of 61 voluntary persons before and after (1 day, 3 days, 4-6 months, 10-12 months) a professional pest control operation (PCO) using pyrethroids. Following parameters were included in the study (1) immunological parameters of the humoral defence, i.e. immunoglobulins of the classes A, G, M and E, complement components C3c and C4, acute phase proteins such as acid alpha 1-glycoprotein, haptoglobin, C-reactive protein; (2) mediators and receptors of immunity, i.e. neopterin, soluble interleukin-2 receptor (sIL-2R), soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor receptor (sTNF RII); (3) immunological markers of the cellular defence, i.e. white blood cell counts and lymphocyte (sub)populations such as total lymphocytes (CD2), mature lymphocytes (CD3), T-helper/inducer cells (CD4), T-suppressor/cytotoxic cells (CD8), B-cells (CD20), natural killer cells (CD56), as well as the ratio of CD4/CD8. The medians of all investigated immune components found before and for all time intervals after pyrethroid application were within the reference interval with respect to the total collective. Within this physiological range the investigated parameters showed a trend to lower values predominantly during the early phase (1 and 3 days) after PCO, partially being significant. Significant decreases were no more present in the late phase (6 to 12 month) after PCO indicating reversibility. Atopics did not differ in the immune response after PCO as compared to non-atopics. Obtained results suggest a modulation of immune components after a correct performed PCO within the physiological range towards lower values during the first days. However these immune changes are considered to be subtle and underlying compensatory mechanisms of immunoregulation.

Air Pollution, Indoor↗
PubMed2004

Evaluation of a contraction flow field on hydrodynamic damage to entomopathogenic nematodes-A biological pest control agent.

Mechanized production and delivery of biological pesticides presents challenges because the biological agents must remain viable during these processes. This study evaluates the effect of flow through an abrupt contraction, where flow characteristics similar to that found within bioprocesses and spray equipment are developed, on damage to a benchmark biological pest control agent, entomopathogenic nematodes (EPNs). An opposed-pistons, contraction flow device generated volumetric flow rates ranging between 8.26 cm(3)/s and 41.3 cm(3)/s. Four EPN species were evaluated: Heterorhabditis bacteriophora, Heterorhabditis megidis, Steinernema carpocapsae, and Steinernema glaseri. Damage was quantified by counting living and dead EPNs. Optical and cold field emission scanning electron microscope (CFE-SEM) images provided qualitative information to describe how the damage occurred. The experimental flow field was completely described using FLUENT, a computational fluid dynamics program. Local flow parameters computed in FLUENT were compared to EPN damage. The type and extent of damage varied between EPN species. Damaged Heterorhabditis spp. generally remained whole with an internal rupture located near the center of the body, while Steinernema spp. most often broke into several pieces. The fast-transient stress field generated at the entrance to the contraction caused a momentary tensile loading and then relaxation that damaged the EPNs. At high flow rates, the tensile stresses became large enough to cause failure of the EPN structural membrane. The relative elasticity of the EPN structural membrane may explain the differences in damage observed between the species. It is speculated that the internal rupture of the Heterorhabditis spp. occurred during the processes of stretching and relaxing at the contraction entrance. Appreciable damage was observed at lower average energy dissipation rates for H. bacteriophora (1.23E + 8 W/m(3)), H. megidis (1.72E + 8 W/m(3)), and S. glaseri (2.89E + 8 W/m(3)) compared to S. carpocapsae (3.70E + 8 W/m(3)). Energy dissipation rates within an equipment component should be kept below 1E + 8 W/m(3) to avoid hydrodynamic damage to EPNs. The relationship between average energy dissipation and EPN damage provides important information for future simulation efforts of actual spray equipment components.

Animals↗
PubMed1990

Entomopathogenic rhabditid nematodes and pest control.

Imagine an insecticide that is effective against insects in cryptic habitats, has a wide spectrum of efficacy, is cheaply produced by high technology or cottage industry and hence is suitable for developing and developed countries, is non-toxic to vertebrates and plants, and persists at low levels in natural habitats. This is not a dream. These properties apply to a group of entomopathogenic nematodes belonging to the rhabditid families Steinernematidae and Heterorhabditidae. Bill Hominick reviews developments in the use of these nematodes for the control of insect pests. His article represents a departure in philosophy for parasitologists, in that entomophilic nematologists are devoted to increasing, rather than decreasing the number of nematodes in the environment.

Journal Article↗
PubMed2003

Comparison of linear and nonlinear regression for modeling the first-order degradation of pest-control substances in soil.

First-order kinetic models are often used to profile the degradation of pest-control compounds in soil. This approach is based on enzyme theory and is often favored due to its simplicity and its requirement by regulatory agencies. Here, linear and nonlinear regression approaches to modeling first-order decay are compared. Composite residual plots of many soil degradation data sets are presented on a normalized scale. These plots illustrate the general error structure for the data and are useful for detecting common mis-specifications of the models. Results indicate that a nonlinear regression approach to modeling first-order decay of compounds in soil more accurately describes most data sets when compared with a linear approach. Specifically, the observed error structure does not support the broad use of a logarithmic transformation to stabilize the variance. In addition, models generated using the linear approach generally exhibit more dramatic systematic deviations from the observations as compared with models generated using the nonlinear approach. The analysis methods described here may be useful for comparing alternative models in this and other research areas.

Enzymes↗
PubMed1983

Exposure of professional pest control operator to dichlorvos (DDVP) and residue on house structures.

Each of the 13 human volunteers carried out a 1-day urban pest control work in 4 homes using 10-14 aerosol cans (230-330 g dichlorvos (DDVP] and 18-22 pints of 0.5% emulsion spray (40-50 g DDVP). Average residue levels of 75.85 micrograms/ft2, 40.9 micrograms/ft2 were found on the applicator's back, chest and respirator filter, respectively. Residue on the house structure was 219.7 micrograms/ft2 on the first day, which fell to 50.9 micrograms/ft2 by the end of 5 days. Blood and urine analyses revealed no changes in various clinical parameters, including serum cholinesterase levels.

Acetylcholinesterase↗
PubMed1997

Perceptions of veterinary clinics and pest control companies regarding tick-related problems in dogs residing in Texas cities.

OBJECTIVE: To determine the extent and source of tick-related problems encountered by veterinary clinics and pest control company (PCC) clientele experiencing residential tick infestations in urban/suburban environments and to determine which tick-related diseases in dogs were diagnosed and treated at veterinary clinics. DESIGN: Cross-sectional survey. SAMPLE POPULATION: Veterinary clinics and PCC in Dallas/Fort Worth and Austin/San Antonio, Tex. PROCEDURE: Surveys were made into professionally printed booklets and mailed to participants. RESULTS: Dallas/Fort Worth and Austin/San Antonio clinics indicated that tick-related problems comprised 21 and 15%, respectively, of their canine-based business. The most frequently observed species was the brown dog tick. Tick infestations were most common during May through August. Immature tick populations were seen by the greatest number of clinics in May and June, and engorged female ticks were encountered most often in June and July. Ticks were most commonly found around homes and adjacent yards or lots. Greenbelts were perceived by all 4 study groups to be the principal place in the community where ticks were acquired by clients' dogs. Canine ehrlichiosis was the most common tick-related disease diagnosed and treated at clinics, followed by anemia caused by tick infestation. CLINICAL IMPLICATIONS: Identification of ticks is important, because different tick species transmit different disease agents and different ecologic factors may be associated with exposure and subsequent treatment. Knowledge of temporal activity patterns of ticks, where they are acquired and where populations become established, combined with improved cooperative efforts between veterinary clinics and PCC, would aid in more effective control and management of ticks.

Animals↗
PubMed2004

Effectiveness of personal protective equipment: relevance of dermal and inhalation exposure to chlorpyrifos among pest control operators.

This study assessed the effectiveness of a custom fit personal protective equipment (PPE) program aimed at reducing occupational exposure to pesticides. The intervention study was carried out on 15 pest control operators (PCOs) during mixing/loading and application of chlorpyrifos. Each worker was measured twice; first while the worker used PPE as normal (baseline measurement), and second after making some adjustments to the PPE (postintervention measurement). The applied intervention consisted of a tight-fitting, full-face respirator, fit-testing, long gloves, chemical-proof boots, a Tyvek hood, and an instruction video that was shown prior to putting on the PPE. A comprehensive evaluation program was used for the within-subject comparisons, including assessment of potential dermal exposure, actual dermal exposure, inhalation exposure, and internal dose as measured by the urinary metabolite 3,5,6-trichloro-2-pyridinol (TCP). The PPE program resulted in a significant increase in fit factors from a mean of 670 to 132,000. Actual dermal exposure levels decreased on average by fourfold after implementation of the PPE program (baseline AM = 132.1 microg; postintervention AM = 32.6 microg). The TCP levels in urine collected 24-32 hours after spray activities were lower in the postintervention data set (AM = 21.2 microg TCP/g creatinine vs. AM = 13.9 microg TCP/g creatinine). However, it is impossible to attribute these differences totally to the PPE program since workers had significant and varying urinary TCP levels before onset of spraying activities. Linear regression models showed that dermal exposure was only a predictive parameter for TCP levels in urine in the baseline data set. Although the results should be interpreted cautiously this study suggests a protective effect of the evaluated PPE program.

Administration, Cutaneous↗
PubMed2004

[Study on the potential use of baculoviruses to eradicate insects in pest control].

The biological activity of baculovirus AcMNPV and its recombinant SPX were determined on cockroaches Blattella germanica, pharaoh's ants Monomorium pharaonis and flies Musca domestica--species very difficult to eradicate. Baculovirus AcMNPV is one of the best known viruses of wide host range. Its recombinant SPX contained the gene for natural toxin. It is known that this toxin paralyses nervous system of insects by blocking sodium channels. The studies on the influences of baculoviruses showed in the case of cockroaches Blattella germanica L. the disturbances of development. The result of using high concentration baculoviruses SPX 2 x 10(7) pfu/ml for a long time of exposition 8 weeks it was.

Animals↗
PubMed1992

Evaluation of methods for detecting ecological effects from genetically engineered microorganisms and microbial pest control agents in terrestrial systems.

This report summarizes and evaluates research from several laboratories that deals with the detection of ecological effects induced through exposure of microbes or plants to genetically engineered microorganisms (GEMs) and microbial pest control agents (MPCAs). Some 27 potential endpoints for measuring effects have been studied. Perturbations induced by GEMs have been detected in about one-half of these endpoints. Detectable effects have been recorded for over half of the 16 species of bacteria and fungi studied. The effects caused by GEMs and MPCAs include inhibition of beneficial mycorrhizal fungi growing on Douglas fir seedling roots, depression in plant root and shoot growth, inhibition of predatory soil protozoa, accumulation of a toxic metabolite during biodegradation that inhibits soil fungi, increased microbial community respiration due to rapid lignin breakdown in soil, and the displacement of a broad group of gram-negative bacteria that inhabit the root surface of cereal crops. These effects were usually, but not always, of short duration. However, some of the changes were irreversible during the observation time of days, weeks, or in one case, months.

Journal Article↗
PubMed2002

Insect pheromone olfaction: new targets for the design of species-selective pest control agents.

Insects communicate extensively with chemical signals specific to their species (pheromones). The highly sensitive and selective olfactory system involved in detection of these signals has attracted attention as a target for the design of novel pest control agents. This review summarizes efforts in understanding the structure-activity relationships of pheromone olfaction and in the design of compounds that selectively interfere with transport, recognition and degradation of pheromones in the peripheral olfactory system. Pheromone olfaction inhibitors are potential environmentally benign insect control agents.

Animal Communication↗
PubMed2006

Recent developments and future prospects in insect pest control in transgenic crops.

The adoption of insect-resistant transgenic crops has been increasing annually at double-digit rates since the commercial release of first-generation maize and cotton expressing a single modified Bacillus thuringiensis toxin (Bt) nine years ago. Studies have shown that these Bt crops can be successfully deployed in agriculture, which has led to a decrease in pesticide usage, and that they are environmentally benign. However, the sustainability and durability of pest resistance continues to be discussed. In this review, we focus on the science that underpins second- and third-generation insect-resistant transgenic plants and examine the appropriateness and relevance of models that are currently being used to determine deployment strategies to maximize sustainability and durability. We also review strategies that are being developed for novel approaches to transgenic insect pest control.

Bacterial Toxins↗