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At least 235 records · Page 13Linked to original sources
PubMed2000

Risk/risk trade-offs in pesticide regulation: an exploratory analysis of the public health effects of a ban on organophosphate and carbamate pesticides.

Efforts to reduce pesticide-related risks to consumers and farmworkers often neglect the possibility that measures to reduce the target risk may introduce or enhance countervailing risks. These may arise from substitute pesticides or pest-control practices, from increased levels of pests or pest-related hazards, from increased levels of toxic natural pesticides in plants, from increased costs and decreased consumption of health-enhancing fruits and vegetables, or from direct income effects on consumers and farmers. The effect of the countervailing risks may partially or completely offset the reduction in the target risk. A risk-trade-off analysis was conducted of a potential ban on the use of organophosphate and carbamate (OP/Carbamate) insecticides in U.S. agriculture. Although this scenario is extreme, it has the analytic virtue of dispensing with the infinite number of "next-best" OP/Carbamates that might be substituted for specific combinations of crops and pests should only selected uses be banned. The analysis relies on detailed descriptions of the alternative pesticides and pest-control measures that would be used for each of 14 major crops. The effects of pest-control cost changes on prices and consumption and effects on consumer and producer incomes are projected using a general-equilibrium economic model. Several countervailing risks that may be significant were found, including acute toxicity to farmworkers from substitute pesticides, cancer and noncancer risks from substitute pesticides, and mortality induced by changes in disposable income. Other countervailing risks are more difficult to estimate or weigh. Potential increases in natural plant pesticides following an OP/Carbamate ban are discussed but data are lacking to quantify the effects. Changes in diet following the ban have both positive and negative effects, and the ultimate change is difficult to estimate. Although a net risk cannot be estimated, several approaches were illustrated that would be useful in risk-trade-off analyses. Key factors complicating comprehensive analysis of risk/risk trade-offs for pesticides were also identified, including data gaps and shortcomings of current risk assessment methods.

Agriculture↗
PubMed2003

[Effects of bagging on the fruit quality in Litchi chinensis fruit and pesticide residues in it].

Different color bags were used to cover Litchi chinensis fruit to study the effects of bagging on its quality and pesticide residues. The results showed that bagging significantly improved the fruit color. Using bagging techniques, the I and II class fruit was accounted for 57.87% to 81.57%, 30% higher than that of control, and the weight per fruit increased significantly. Among the color bags used, white bag was the best. When the end of the bag was opened, it was benefit for decease control, but not good for pest control. When the end of the bag was closed, it was good for pest control, but bad for decease control. Bagging had no effects on the taste of Litchi chinensis fruit, but might increase the residues of fenpropathrin and trichlorphon. More study should to be carried out to select the suitable pesticides accompanied with bagging techniques.

Color↗
PubMed1964

ESTERASE INHIBITORS AS PESTICIDES.

Thirty years of testing has yielded over 120 esterase inhibitors in current use for pest control. Several hundred million pounds of these organophosphates and carbamates are employed each year as insecticides and acaricides and, to a much lesser extent, as anthelmintic agents, nematocides, and herbicides. Systemics or chemotherapeutic agents for control of insect pests of plants and animals first became practical with the organophosphates. Compounds of lower mammalian toxicity and other favorable biological properties continue to appear and displace established compounds and broaden the use areas. Problems of resistance and residues in certain areas of insect control by chlorinated hydrocarbons will result in a further shift to esterase-inhibitors for pest control. Interpretation of the potential hazards of pesticides to man is dependent on the availability of fundamental information on their modes of action combined with use experience; this knowledge is available for the organophosphates and carbamates that act as acetylcholinesterase inhibitors.

Animals↗
PubMed1992

[Integrated control of pests injuring Chinese hawthorn Crataegus pinatifida Bge. var. major N.E.Br. by nonpollution techniques].

Field experiments on integrated control of pests injuring Chinese hawthorn by some nonpollution techniques including agricultural biological and physical methods, were carried out in Xinglong County, Hebei Province during 1989-1991. Satisfactory results were obtained. Compared with synthetic pesticides, the new techniques improve the control effect by 30%-60% generally, increase the number of natural enemies by 51.26%-68.51%, and enhance the yield by 47.58%. The test shows that the hawthorns from the field treated by the new techniques are either free of pesticide residual or with a residual 500-1000 times less than the residual standard fixed by FAO/WHO or the state.

Animals↗
PubMed2003

Modelling the spatial configuration of refuges for a sustainable control of pests: a case study of Bt cotton.

The 'high-dose-refuge' (HDR) strategy is widely recommended by the biotechnology industry and regulatory authorities to delay pest adaptation to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. This involves cultivating nontoxic plants (refuges) in close proximity to crops producing a high dose of Bt toxin. The principal cost associated with this strategy is due to yield losses suffered by farmers growing unprotected, refuge plants. Using a population genetic model of selection in a spatially heterogeneous environment, we show the existence of an optimal spatial configuration of refuges that could prevent the evolution of resistance whilst reducing the use of costly refuges. In particular, the sustainable control of pests is achievable with the use of more aggregated distributions of nontransgenic plants and transgenic plants producing lower doses of toxin. The HDR strategy is thus suboptimal within the context of sustainable agricultural development.

Bacillus thuringiensis↗
PubMed2005

Evaluation of cocoa- and coffee-derived methylxanthines as toxicants for the control of pest coyotes.

Methylxanthines were quantified in coffee, tea, and chocolate products. Tarajuilie tea from India, cocoa powder, and cocoa nibs contained the highest levels of methylxanthines. Theobromine, caffeine, and theophylline combined in the ratios observed in tea and chocolate were ingested by coyotes. Although both mixtures induced acute toxicity, the symptoms accompanying the chocolate methylxanthine mimic were preferable. Manipulation of the ratios of methylxanthines in the chocolate mimic led to the identification of a 5:1 theobromine/caffeine mixture as a promising coyote toxicant. This mixture was then administered to coyotes using the coyote lure operative device (CLOD). Mortality occurred in every coyote that ingested any portion of the CLOD contents. These results indicate that mixtures of theobromine and caffeine have the potential to be developed into a selective, effective, and socially acceptable toxicant for the control of pest coyotes.

Animals↗
PubMed2001

Mass production of entomopathogenic nematodes for plant protection.

Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are commercially used to control pest insects. They are symbiotically associated with bacteria of the genera Photorhabdus and Xenorhabdus, respectively, which are the major food source for the nematodes. The biology of the nematode-bacterium complex is described, a historical review of the development of in vitro cultivation techniques is given and the current use in agriculture is summarised. Cultures of the complex are pre-incubated with the symbiotic bacteria before the nematodes are inoculated. Whereas the inoculum preparation and preservation of bacterial stocks follow standard rules, nematodes need special treatment. Media development is mainly directed towards cost reduction, as the bacteria are able to metabolise a variety of protein sources to provide optimal conditions for nematode reproduction. The process technology is described, discussing the influence of bioreactor design and process parameters required to obtain high nematode yields. As two organisms are grown in one vessel and one of them is a multicellular organism, the population dynamics and symbiotic interactions need to be understood in order to improve process management. Major problems can originate from the delayed or slow development of the nematode inoculum and from phase variants of the symbiotic bacteria that have negative effects on nematode development and reproduction. Recent scientific progress has helped to understand the biological and technical parameters that influence the process, thus enabling transfer to an industrial scale. As a consequence, costs for nematode-based products could be significantly reduced.

Animals↗
PubMed2002

Changes in protease activity and Cry3Aa toxin binding in the Colorado potato beetle: implications for insect resistance to Bacillus thuringiensis toxins.

Widespread commercial use of Bacillus thuringiensis Cry toxins to control pest insects has increased the likelihood for development of insect resistance to this entomopathogen. In this study, we investigated protease activity profiles and toxin-binding capacities in the midgut of a strain of Colorado potato beetle (CPB) that has developed resistance to the Cry3Aa toxin of B. thuringiensis subsp. tenebrionis. Histological examination revealed that the structural integrity of the midgut tissue in the toxin-resistant (R) insect was retained whereas the same tissue was devastated by toxin action in the susceptible (S) strain. Function-based activity profiling using zymographic gels showed specific proteolytic bands present in midgut extracts and brush border membrane vesicles (BBMV) of the R strain not apparent in the S strain. Aminopeptidase activity associated with insect midgut was higher in the R strain than in the S strain. Enzymatic processing of toxin did not differ in either strain and, apparently, is not a factor in resistance. BBMV from the R strain bound approximately 60% less toxin than BBMV from the S strain, whereas the kinetics of toxin saturation of BBMV was 30 times less in the R strain than in the S strain. However, homologous competition inhibition binding of (125)I-Cry3Aa to BBMV did not reveal any differences in binding affinity (K(d) approximately 0.1 microM) between the S and R strains. The results indicate that resistance by the CPB to the Cry3Aa toxin correlates with specific alterations in protease activity in the midgut as well as with decreased toxin binding. We believe that these features reflect adaptive responses that render the insect refractory to toxin action, making this insect an ideal model to study host innate responses and adaptive changes brought on by bacterial toxin interaction.

Aminopeptidases↗
PubMed2002

Parasitoid secretions provoke ant warfare.

Insect social parasites are extreme specialists that typically use mimicry or stealth to enter ant colonies to exploit the rich, but fiercely protected, resources within their nests. Here we show how a parasitic wasp (parasitoid) contrives to reach its host, itself an endangered species of social parasite that lives inside the brood chambers of ant nests, by releasing semiochemicals to induce in-fighting between worker ants, locking the colony in combat and leaving it underprotected. Four of these chemicals are new to biology and have the potential to control pest species by inducing different agonistic behaviours in ants.

Aggression↗
PubMed2002

[Ecological effects of cover crops].

This paper reviewed the effects of cover crops in reducing soil loss, surface runoff, NO3- leaching and water pollution, and elucidated roles of cover crops in controlling pest insects, weeds and diseases, and increasing soil nutrients. The potential roles and appropriate application of cover crops in sustainable development of agriculture were also discussed.

Biological Availability↗
PubMed1985

Hyperimmune serum in the control of peste des petits ruminants.

The value of administration of hyperimmune serum in the control of peste des petits ruminants was investigated in goats at different stages of the disease. A group of the goats was given hyperimmune serum intravenously at the fever stage of temperature of 40.5 degrees C or above; another group showing no elevation of temperature but with other clinical signs of the disease were also given hyperimmune serum. Results indicated that hyperimmune serum was very effective in reversing the process of the disease if administered at the fever stage but not in animals that had progressed past the fever stage. The goats given the hyperimmune serum survived for 10 days before showing evidence of reinfection.

Animals↗
PubMed2005

Role of neonicotinyl insecticides in Washington apple integrated pest management. Part I. Control of lepidopteran pests.

Three neonicotinyl insecticides, acetamiprid, thiacloprid and clothianidin, were evaluated for their impact on four species of lepidopteran pests of apple in Washington, the codling moth, Cydia pomonella (L.), the Pandemis leafroller, Pandemis pyrusana Kearfott, and the obliquebanded leafroller, Choristoneura rosaceana (Harris), and Lacanobia subjuncta (Grote & Robinson). None of the neonicotinyl insecticides demonstrated sufficient activity against P. pyrusana, C. rosaceana, or L. subjuncta to warrant field trials. Conversely, all had some activity against one or more stages of C. pomonella. Acetamiprid was highly toxic to larvae in laboratory bioassays, and had relatively long activity of field-aged residues (21 days). It also showed some toxicity to C. pomonella eggs (via topical exposure) and adults. Acetamiprid provided the highest level of fruit protection from C. pomonella attack in field trials conducted over five years in experimental orchards with extremely high codling moth pressure. Thiacloprid performed similarly in bioassays, but fruit protection in field trials was slightly lower than acetamiprid. Clothianidin showed moderate to high toxicity in bioassays, depending on the C. pomonella stage tested, but poor fruit protection from attack in field trials. None of the neonicotinyl insecticides were as toxic to larvae or effective in protecting fruit as the current standard organophosphate insecticide used for C. pomonella control, azinphosmethyl. However, both acetamiprid and thiacloprid should provide acceptable levels of C. pomonella control in commercial orchards where densities are much lower than in the experimental orchards used for our trials. The advantages and disadvantages of the neonicotinyl insecticides as replacements for the organophosphate insecticides and their role in a pest management system for Washington apple orchards are discussed.

Agriculture↗
PubMed1997

The impact of insecticides on beneficial arthropods in cotton agro-ecosystems in South Africa.

The unique diversity of beneficial arthropods in South Africa can be regarded as an important natural resource in agro-ecosystems as it plays an important role in the natural control of insect pests. Insecticide applications reduce the ability of these beneficials to regulate cotton pests. In the absence of insecticides, average daily predation rates of 37% and 30% of bollworm eggs and larvae respectively were found in exclusion experiments. By minimizing the number of pesticide applications the combination of the direct negative effect of pesticide application on predator populations and secondary pesticide effects such as the stimulation of red spider mite populations as a result of predator suppression, can be avoided. This would open the option to fully utilize the full pest control potential of the natural enemy complex.

Animals↗
PubMed2005

Integration of insect parasitic nematodes (Rhabditida steinernematidae) with insecticides for control of pest mole crickets (Orthoptera: Gryllotalpidae: Scapteriscus spp.).

To develop a successful integrated pest management program for pest mole crickets (Orthoptera: Gryllotalpidae: Scapteriscus spp.), it is important to ascertain the compatibility of infective juveniles of insect parasitic nematodes and chemical insecticides. Aqueous solutions of five pesticides (acephate, bifenthrin, deltamethrin, fipronil, and imidacloprid) used in turfgrass to control mole crickets were tested for compatibility with Steinernema scapterisci Nguyen & Smart (Rhabditida: Steinernematidae) in the laboratory. Survival of S. scapterisci was >95% in solutions of acephate, bifenthrin, and imidacloprid. Infectivity of S. scapterisci in adult Scapteriscus vicinus Scudder was >60% in acephate and bifenthrin; however, infectivity was <40% in imidacloprid. The entomopathogenic nematode was compatible with most insecticides tested without significantly reduced survival or infectivity.

Animals↗
PubMed1994

What role for insecticides in vector control programs?

Vector-borne diseases including dengue, yellow fever, Japanese encephalitis, malaria, leishmaniasis, and filariasis remain severe public health problems in most of the countries in which they are endemic. In some cases, their incidence is increasing and they are spreading to new geographic areas. For a number of the infections, the most effective manner of controlling their transmission is through control of their vectors. However, in some instances, such as dengue and Chagas' disease, there is no alternative. Most countries that are endemic for vector-borne diseases maintain vector control services, and most large tropical and semitropical cities also have pest control programs, mainly against pest mosquitoes. Virtually all of the vector and pest control programs depend on the use of insecticides formulated as larvicides, adulticides, baits, or insecticide impregnated bed nets. For many years, the development of new insecticides for use in public health programs was encouraged and supported by multilateral and bilateral health agencies, including the implementation of field trials in endemic areas. Due to the development of insecticide resistance, toxicologic and environmental considerations, and the cost of development and of registration, the number of compounds available for use has declined while the number of new insecticides submitted for laboratory and field trials to the World Health Organization has dwindled even more. The recrudescence of vector-borne diseases, the rapid pace of urbanization, lagging development of environmental services in many tropical cities, and difficulties encountered in ensuring the community's cooperation in its own protection through environmental measures make imperative the continued availability of pesticides for public health use. Since only the pesticide manufacturing industry has the combination of technical and financial resources to promulgate the research and development of new pesticides and pesticide groups, it is suggested that governments, bilateral, and multilateral organizations explore the manner in which they can assist industry in the development of new compounds and guarantee the continued availability of effective and safe pesticides for vector-control programs.

Animals↗
PubMed2001

First steps to improve cotton crop management in Thailand.

Thai cotton growers yearly face serious pest problems consisting of heavy infestation associated with resistance to pesticides leading to expensive and harmful pest control practices. Thanks to a multi discipline research work carried out from 1991 to 1996, a decision-oriented model for cotton crop management was developed and compared to farmers' practices during the 1988 cotton growing season 1998 in Klang Hat district, Thailand. This model, based on plant monitoring, involved a new cotton cultivar (DORA 11 as a replacement for Sri Samrong 60), seed treatment with imidacloprid (at 3.5 g of a.i./kg of seeds), a threshold-based spray of mepiquat chloride, a cotton growth regulator (Pix at 1.5 l/ha) and a set of rules to selectively control with chemical and biological insecticides the major pests the American bollworm (Helicoverpa armigera Hübner) and the cotton leafhopper (Amrasca biguttula biguttula Ishida). This package was more friendly towards environment than farmers' practices since seed treatment does not harm beneficials at the beginning of cotton growing season while 1 and 5 sprays were saved against respectively the American bollworm and sucking pests and more than 50% of the sprays directed against American bollworms involved biological insecticides (Bacillus thuringiensis toxins potentialized by a low dosage of endosulfan). Threshold-based sprays against the main pests, the use of a cotton growth regulator, earliness of cotton cultivar and seed treatment were accountable for savings in pesticide sprays. Involving a biological insecticide and endosulfan at the beginning of cotton growing season and using the same quantity of active ingredient at each spray during the cotton growing season also improved the management of pyrethroid resistance in American bollworm populations was also. There was no significant difference between yields inside farmers' fields and innovation plots. However, thanks to cheaper pest control practices economic results were better. Lastly few improvements of this package are proposed.

Agriculture↗
PubMed2002

Insect-resistant transgenic plants in a multi-trophic context.

So far, genetic engineering of plants in the context of insect pest control has involved insertion of genes that code for toxins, and may be characterized as the incorporation of biopesticides into classical plant breeding. In the context of pesticide usage in pest control, natural enemies of herbivores have received increasing attention, because carnivorous arthropods are an important component of insect pest control. However, in plant breeding programmes, natural enemies of herbivores have largely been ignored, although there are many examples that show that plant breeding affects the effectiveness of biological control. Negative influences of modified plant characteristics on carnivorous arthropods may induce population growth of new, even more harmful pest species that had no pest status prior to the pesticide treatment. Sustainable pest management will only be possible when negative effects on non-target, beneficial arthropods are minimized. In this review, we summarize the effects of insect-resistant crops and insect-resistant transgenic crops, especially Bt crops, from a food web perspective. As food web components, we distinguish target herbivores, non-target herbivores, pollinators, parasitoids and predators. Below-ground organisms such as Collembola, nematodes and earthworms should also be included in risk assessment studies, but have received little attention. The toxins produced in Bt plants retain their toxicity when bound to the soil, so accumulation of these toxins is likely to occur. Earthworms ingest the bound toxins but are not affected by them. However, earthworms may function as intermediaries through which the toxins are passed on to other trophic levels. In studies where effects of insect-resistant (Bt) plants on natural enemies were considered, positive, negative and no effects have been found. So far, most studies have concentrated on natural enemies of target herbivores. However, Bt toxins are structurally rearranged when they bind to midgut receptors, so that they are likely to lose their toxicity inside target herbivores. What happens to the toxins in non-target herbivores, and whether these herbivores may act as intermediaries through which the toxins may be passed on to the natural enemies, remains to be studied.

Animals↗