The economics of local authority pest control.
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Group Processes↗
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Results for “Pest control”
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[Current problems in hospital pest control using dichlorvos].
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Animals↗
Pest control industry and vector control activities in Taiwan.
At the end of 1993, there were 117 private pest control companies in Taiwan, with 438 technical managers and 274 technicians. Their business includes the control of mosquitoes, cockroaches, fleas, rodents, termites, houseflies, etc. Pyrethroids and some organophosphates are employed. At present, no applications of insect growth regulators or microbial agents are used by private pest control operators. During dengue epidemics they assist the government in space spraying with insecticides. The Environmental Protection Administration, Executive Yuan, R.O.C., is responsible for the training and management of pest control operators. In addition, the Administration is also in charge of affairs concerning the manufacture, import, registration and sale of environmental pesticides and microbial agents. It establishes protocols for testing the efficacy of insecticides and promotes pest control on the community level.
Aedes↗
[Health effects and personal protection in pest control workers using organophosphorus insecticides].
One hundred and sixteen pest control workers (16 termite control workers (Sprayer I), 46 cockroach or fly-control workers (Sprayer II) and 56 both termite and cockroach or fly-control workers (Sprayer III)) were surveyed by a questionnaire and health examinations. Variety and quantity of pesticide used, personal usage of protective devices (respirator, gloves, work clothes, under wear), and conditions related to bathing were studied by a questionnaire. Relationships between protective devices and blood cholinesterase activity (ChE) were also analyzed. Significant findings were as follows: Most of the pest control operators wore gum gloves and gas masks when involved in termite control. However in the case of cockroach or fly-control, 38% did not wear gloves, and for respiratory protection 44% wore gas masks while 25% of them did not even use any form of respirators. In spite of having better protective practices than sprayers II and III, sprayer I showed significantly lower plasma ChE activity than both sprayer II and III. Plasma ChE activity in sprayers who put on simple respirators tended to be lower than those using gas masks. Plasma ChE activity was also significantly lower in those workers who had less frequent changes of work clothes compared to those with more frequent.
Adult↗
Cancer mortality among local authority pest control officers in England and Wales.
OBJECTIVE: To examine cancer mortality by tumour site among local authority pest control officers. METHODS: Prospective mortality study, and follow up to the end of 1994, of 1485 male pest control officers aged between 17 and 69 and employed in 296 local authorities in England and Wales for at least six months between January 1980 and April 1984. Observed numbers of deaths were compared with those expected on the basis of the rates for relevant calendar year, cause, sex, and age specific groups for England and Wales. RESULTS: 200 deaths occurred during the follow up period of which 65 were certified as due to malignant neoplasms. No tumour type showed significantly more deaths than expected. Total all cause, lung cancer, and respiratory disease mortality were significantly lower than expected. CONCLUSIONS: 15 year follow up of a group of men handling a wide range of pesticides did not show any significant risk of cancer. This may be partially explained by the healthy worker effect and also the limited power of the study to detect significant increases in the less common tumours. Further long term follow up of this cohort will continue. Chemical control of pests that can cause human disease and can contaminate food and water has been, and will continue to be, a major public health measure. It is important to ensure that the health of those applying pesticides is not at excess risk. Negative results are important.
Adolescent↗
Cancer mortality among municipal pest-control workers.
OBJECTIVES: This epidemiological study was carried out in order to investigate the hypothesis of a relationship between cancer occurrence and occupational exposure in a population of municipal pest-control workers exposed to a wide range of pesticides and other chemicals. METHODS: The study was designed as a mortality historical cohort study. The cohort comprised all subjects ever employed in a municipal pest-control service between 1979 and 1994. The follow-up period lasted from 1979 to 2000. The mortality rates of pest-control workers were compared with those of a regional population. A job exposure matrix was developed, which took into account four types of chemicals: formaldehyde, ethylene oxide, insecticides and rodenticides. RESULTS: None of the 181 subjects of the cohort, leading to 3,107 person-years, was lost to follow-up. Thirty-nine of them died, and all the causes of deaths were ascertained. The standardized mortality ratios (SMRs) for all causes of deaths and for all cancer causes were significantly greater than unity: 1.61 (1.14-2.20) and 2.24 (1.39-3.43), respectively. Non-significant excesses were observed for most cancer sites, except for lung cancer, which had a low SMR. We obtained significant excesses for cancer in workers with more than 20 years of employment [SMR = 2.42 (1.43-3.82)]. Cancer mortality tended to increase insignificantly with formaldehyde and rodenticides exposures, whereas no clear patterns were observed for ethylene oxide and insecticides. However, significant excesses were observed for the highest exposure levels of formaldehyde, insecticides and rodenticides. CONCLUSIONS: This study showed a statistically significant excess of cancer mortality in a population of municipal pest-control workers exposed to a wide variety of chemicals. These cancer sites might be related to occupational activities, since they tended to be more frequently observed when duration of employment increased.
Adolescent↗
Host-host-pathogen models and microbial pest control: the effect of host self regulation.
A model has been investigated of the dynamics of the interaction between two hosts that are both attacked by a common pathogen with free-living infective stages, where the hosts are also subject to self-regulation. If either host interacted with the pathogen alone, two types of dynamics would be possible: an uninfected state where the host settles at its carrying capacity, and an infected state where the host settles at, or cycles around, a density lower than the carrying capacity. The three possible combination of two hosts have been investigated: uninfected-uninfected (both hosts uninfected if alone with the pathogen), infected-uninfected and infected-infected. A range of dynamics is generated, depending on parameter values, including infected co-existence of the two hosts (arrived at by a variety of routes), uninfected co-existence of the two hosts, exclusion of one host by the other which remains in an infected state, and a number of outcomes contingent on the initial densities in the system. Free-living infective stages make uninfected co-existence more likely and introduce additional contingency into the dynamics. The implications for microbial pest control are into the dynamics. The implications for microbial pest control are markedly different from those derived from related models without host self-regulation. There appears to be little chance of a non-target host undermining pest control, relatively little chance of the non-target enhancing pest control and a small but non-negligible threat to non-targets when parameter values are appropriate. The application of the results is commended but great caution is urged.
Animals↗
Can satyrs control pests and vectors?
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Animals↗
You needn't build a better mousetrap to control pests.
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Animals↗
[Increased mortality from esophageal cancer, stomach cancer and skin melanoma in pesticide-exposed pest control operators in the DDR].
A retrospective mortality study on male pest control workers of the German Democratic Republic (GDR) was undertaken to evaluate the association of exposure to pesticides and development of malignant tumors. The cohort encompassed 1,214 male subjects with at least 5 years pest control work between 1945 and 1980. Informations on causes of death and cancer cases were obtained from death certificates and the cancer registry form. As control cohort for the standardized mortality ratios (SMR) served the general male population of the GDR. The SMR of 133 for the category of malignant tumors in the pesticide exposed cohort was significantly elevated. Among the other causes of death categories the SMR was less than 100. The tumor excess was statistically significant for the following tumor sites: esophagus, SMR = 430 (4 observed vs. 0.9 expected); stomach, SMR = 180 (14 observed vs. 7.8 expected) and skin melanoma, SMR = 588 (2 observed vs. 0.3 expected). Mortality from stomach cancer showed a linear rising trend by number of years licensed (less than 10 years, SMR = 118; 10-19 = 160; greater than 19 years, SMR = 260). The data suggest an etiological link between the pesticide exposure and increased mortality of esophagus cancer, stomach cancer and skin melanoma.
Esophageal Neoplasms↗
Pest control by the release of insects carrying a female-killing allele on multiple loci.
With recent advances in genetics, many new strategies for pest control have become feasible. This is the second article in which we model new techniques for pest control based on the mass release of genetically modified insects. In this article we model the release of insects carrying a dominant and redundant female killing or sterilizing (FK) allele on multiple genetic loci. If such insects are released into a target population, the FK allele can become widely spread in the population through the males while reducing the population each generation by killing females. We allow the number of loci used to vary from 1 to 20. We also allow the FK allele to carry a fitness cost in males due to the gene insertions. Using a model, we explore the effectiveness and optimal strategies for such releases. In the most ideal circumstances (no density-dependence and released insects equal in fitness to wild ones), FK releases are several orders of magnitude more effective than equal sized sterile male releases. For example, a single release of 19 FK-bearing males for every two wild males, with the released males carrying the FK allele on 10 loci, reduces the target population to 0.002% of no-release size. An equal sized sterile release reduces the target population to 5% of no-release size. We also show how the effectiveness of the technique decreases as the fitness cost of the FK alleles in males increases. For example, the above mentioned release reduces the target population to 0.7% of no-release size if each FK allele carries a fitness cost in males of 5%. Adding a simple model for density-dependence and assuming that each of the released males carries the FK allele on six loci, we show that the release size necessary to reduce the target population to 1/100 of no-release size in 10 generations of releases varies from 0.44:1 to 4:1 (depending on parameter values). We also calculate the optimal number of loci on which to put the FK allele under various circumstances.
Alleles↗
Fit of four curve-linear models to decay profiles for pest control substances in soil.
Experiments that investigate the pattern of degradation of pest control substances in soil are often undertaken to estimate the persistence of compounds in the environment. Mathematical models are typically fit to decay data to facilitate the interpretation of the results and make predictions concerning the environmental fate of xenobiotics in soil. Four mathematical models were fit to 61 data sets to compare their performance in conforming to empirical patterns of degradation of pest control substances in soil. The use of composite residual plots allowed comparisons of the performance of the different models over many data sets. While an exponential model, estimated using nonlinear regression, fit many data sets very well, a shift-log, biexponential, and Monod equation appears superior in many cases, and systematic deviations from data sets are often less evident with the latter models. A knowledge of the patterns of bias typically exhibited by each model across many data sets may be useful for selecting models with reduced bias when fitting individual data sets.
Linear Models↗
Sustainable pest regulation in agricultural landscapes: a review on landscape composition, biodiversity and natural pest control.
Agricultural intensification has resulted in a simplification of agricultural landscapes by the expansion of agricultural land, enlargement of field size and removal of non-crop habitat. These changes are considered to be an important cause of the rapid decline in farmland biodiversity, with the remaining biodiversity concentrated in field edges and non-crop habitats. The simplification of landscape composition and the decline of biodiversity may affect the functioning of natural pest control because non-crop habitats provide requisites for a broad spectrum of natural enemies, and the exchange of natural enemies between crop and non-crop habitats is likely to be diminished in landscapes dominated by arable cropland. In this review, we test the hypothesis that natural pest control is enhanced in complex patchy landscapes with a high proportion of non-crop habitats as compared to simple large-scale landscapes with little associated non-crop habitat. In 74% and 45% of the studies reviewed, respectively, natural enemy populations were higher and pest pressure lower in complex landscapes versus simple landscapes. Landscape-driven pest suppression may result in lower crop injury, although this has rarely been documented. Enhanced natural enemy activity was associated with herbaceous habitats in 80% of the cases (e.g. fallows, field margins), and somewhat less often with wooded habitats (71%) and landscape patchiness (70%). The similar contributions of these landscape factors suggest that all are equally important in enhancing natural enemy populations. We conclude that diversified landscapes hold most potential for the conservation of biodiversity and sustaining the pest control function.
Biodiversity↗
Controlled release effect of insecticide microcapsules and their results in common household insect pest control.
Since 1978 we have prepared microencapsulated insecticides by complex coacervation and interfacial polymerization for household insect pest control, fenthion being the main core element. A series of tests have been conducted against mosquitoes (Culex pipiens quinquefasciatus), cockroaches (Periplaneta americana) and bedbugs (Cimex lectularius), and the results indicate that microencapsulation can prolong persistent effects by 2-12 times, enhance safety and subdue offensive odour. Furthermore, the production cost is comparatively low.
Animals↗
Unexpected consequences of vertebrate pest control: predictions from a four-species community model.
Although indirect effects are important structuring forces in ecological communities, they are seldom considered in the design of pest control operations. However, such effects may cause unpredicted and deleterious changes in other populations that could reduce or even negate the benefit to endangered species for which control is undertaken. Furthermore, the complexity and nonlinearities inherent in interacting ecological communities may cause thresholds in the strength of pest control, on either side of which indirect effects could vary greatly in their magnitude and desirability. We constructed a four-species simulation model for a common pest community in New Zealand beech (Nothofagus spp.) forests: house mice, ship rats, stoats, and brushtail possums. When the model was perturbed to simulate common control techniques, marked increases in the abundance of nontarget pest species were observed at the next forest mast. Higher mouse numbers were observed following both toxin (1080) application and rat kill-trapping, and higher rat numbers were observed following stoat kill-trapping, due to a release from predation in all cases. In comparison, a marked decrease in stoat abundance at the next forest mast was observed following simultaneous control of rats and mice, due to the effects of decreased prey abundance on the stoat population. For rat control, the size of the indirect effect on mouse numbers increased monotonically with control strength. Because the curvature of the relationship is slight, the relationship between the direct benefits of control and the indirect costs incurred would remain relatively unchanged regardless of the strength of control employed. For simultaneous mouse and rat control, however, high levels of control (as initially simulated) were predicted to cause decreased peak stoat abundance at the next mast event, whereas intermediate and low levels of control were predicted to cause increased stoat abundance. Hence, this study demonstrates two points of concern for pest managers. First, indirect effects of control operations do have the potential to reduce the planned-for benefit. Second, thresholds in the strength of control employed can potentially occur, across which indirect effects switch from being of conservation benefit to being of conservation concern.
Animals↗
[Retrospective cohort study of the cancer incidence in pesticide-exposed male pest control workers].
A cohort of 1,214 pest control workers employed during 1945-1980 for at least 5 yr was investigated with regard to cancer mortality. Standardized Mortality Ratio (SMR) was significantly elevated for all malignant neoplasms (SMR = 133; 65 observed vs. 48.5 expected). Significantly elevated SMRs were also found for the following tumor sites: esophagus, SMR = 430 (4 observed vs. 0.9 expected); stomach, SMR = 180 (14 observed vs. 7.8 expected) and melanoma, SMR = 588 (2 observed vs. 0.3 expected). Mortality from stomach cancer showed a rising trend by number of years licensed (less than 10 years, SMR = 118; 10-19 years, SMR = 160; greater than 19 years, SMR = 260). The findings help clarify the role of occupational pesticide exposure as a risk factor for cancer.
Adenocarcinoma↗
[Sensitization and allergic pathology in a group of workers employed in insect breeding for biological pest control].
On the basis of the results of a previous study and immuno-allergological tests, a group of workers employed in breeding insects for biological pest control were studied to ascertain whether any new sensitizations to arthropods recently included in the work cycle occurred and whether any new allergic diseases were observed. The results confirmed a high sensitization to Ephestia kuehniella and to Orius, the latter probably due to contamination; sensitization to Tetranicus urticae and to Planococcus citri were observed, although to a lesser degree. It is concluded that the insects used in biological pest control are highly allergogenic and that the protective devices used up to the present were ineffective; the authors therefore recommend the use of closed or semi-closed cycles along with local ventilation equipment.
Adult↗