Effect of Insecticides on Natural-Enemies (original) (raw)
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Pesticides released to the environment can indirectly affect target and non-target species in ways that are often contrary to their intended use. Such indirect effects are mediated through direct impacts on other species or the physical environment and depend on ecological mechanisms and species interactions. Typical mechanisms are the release of herbivores from predation and release from competition among species with similar niches. Application of insecticides to agriculture often results in subsequent pest outbreaks due to the elimination of natural enemies. The loss of floristic diversity and food resources that result from herbicide applications can reduce populations of pollinators and natural enemies of crop pests. In aquatic ecosystems, insecticides and fungicides often induce algae blooms as the chemicals reduce grazing by zooplankton and benthic herbivores. Increases in periphyton biomass typically result in the replacement of arthropods with more tolerant species such as ...
Impact and Selectivity of Insecticides to Predators and Parasitoids
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Problems with the use of insecticides has brought losses, such as, negative impact on natural enemies. When these beneficial insects reduce cause the eruption of pests and resurgence it’s more common. Thus principles of conservation these arthropods are extremely important in the biological natural control of pests, so that these enemies may present a high performance. Because of the negative impacts caused by insecticides on agriculture and their harmful effects on natural enemies, the objective of this article is to approach two important subjects, divided into three parts. Part I relates to the description of the main crop pests and their natural enemies; Part II involves the impact of insecticides on predators and parasitoids and Part III focuses on the selectivity of several groups of insecticides to natural enemies. Before spraying insecticides, it is necessary to choose a product that is efficient to pests and selective to natural enemies. So, it is indispensable to identify ...
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Information about the side-effects of pesticides on biological control agents is an essential requirement of integrated pest management (IPM). Different methods to test the effects of pesticides on natural enemies have been used and new methods are being developed. In the past, evaluations were mostly based on individual level (lethal or sublethal) endpoints. Differences in the used methods and the measured endpoints make it difficult to compare the results. There is increasing emphasis on using standard methods to combine the lethal and sublethal effects to a total effect. Especially, population-level effects or demographic toxicology has been concluded as a better measure because of its ecological relevance and is the current centre of attention. Very recently, molecular and biochemical methods, primarily, have been developed for detecting potential damage to populations at early stages. But these types of responses (i.e. biomarkers) to toxic stress are only demographically relevant if the response can be linked to effects at higher organism levels. We describe the methods used to study the effects of pesticides on beneficial arthropods and the current status of the evaluation of side-effects. We also provide new suggestions. In addition to methodological discussion, in the last part we presented a table containing summary database on the effect of key classes of commonly used pesticides on various natural enemies. This data may be helpful for researchers or IPM users.
Impact of Legally Compliant Organic Pesticides on Natural Enemies
Twenty-nine studies were reviewed that examined the impacts of four commercially produced insect pathogens, spinosad ® , and neem/azadirachtin on 49 natural enemy species among 23 arthropod families (including insects, mites, and spiders). Results indicated that many toxins used in legally compliant organic pesticides have the ability to either kill or debilitate (via sublethal effects) many parasitoids and predators commonly found in agriculture. These results are mainly based on laboratory experiments with few studies conducted in the field. Greater than 20% mortality was caused to most species (42 of 49 [86%]) by the compounds/pathogens examined. Hippodamia convergens and Podisus maculiventris were the only species tested in all three toxin categories without > 20% mortality, but the latter species did exhibit sublethal effects following neem / azadirachtin exposure.
PeerJ, 2017
Pesticide application is the dominant control method for arthropod pests in broad-acre arable systems. In Australia, organophosphate pesticides are often applied either prophylactically, or reactively, including at higher concentrations, to control crop establishment pests such as false wireworms and earth mite species. Organophosphates are reported to be disruptive to beneficial species, such as natural enemies, but this has not been widely assessed in Australian systems. Neither has the risk that secondary outbreaks may occur if the natural enemy community composition or function is altered. We examine the abundance of ground-dwelling invertebrate communities in an arable field over successive seasons under rotation; barley, two years of wheat, then canola. Two organophosphates (chlorpyrifos and methidathion) were initially applied at recommended rates. After no discernible impact on target pest species, the rate for chlorpyrifos was doubled to elicit a definitive response to a le...
Pesticides do not significantly reduce arthropod pest densities in the presence of natural enemies
Ecology Letters, 2021
Chemical pesticides remain the main agents for control of arthropod crop pests despite increased concern for their side effects. Although chemical pesticide applications generally result in short-term decreases of pest densities, densities can subsequently resurge to higher levels than before. Thus, pesticide effects on pest densities beyond a single pest generation may vary, but they have not been reviewed in a systematic manner. Using mathematical predator-prey models, we show that pest resurgence is expected when effective natural enemies are present, even when they are less sensitive to pesticides than the pest. Model simulations over multiple pest generations predict that pest resurgence due to pesticide applications will increase average pest densities throughout a growing season when effective natural enemies are present. We tested this prediction with a meta-analysis of published data of field experiments that compared effects of chemical control of arthropod plant pests in the presence and absence of natural enemies. This largely confirmed our prediction: overall, pesticide applications did not reduce pest densities significantly when natural enemies were present, which concerned the vast majority of cases. We also show that long-term pesticide effectiveness is underreported and suggest that pest control by natural enemies deserves more attention.
The Sublethal Effects of Pesticides on Beneficial Arthropods
Annual Review of Entomology, 2007
Traditionally, measurement of the acute toxicity of pesticides to beneficial arthropods has relied largely on the determination of an acute median lethal dose or concentration. However, the estimated lethal dose during acute toxicity tests may only be a partial measure of the deleterious effects. In addition to direct mortality induced by pesticides, their sublethal effects on arthropod physiology and behavior must be considered for a complete analysis of their impact. An increasing number of studies and methods related to the identification and characterization of these effects have been published in the past 15 years. Review of sublethal effects reported in published literature, taking into account recent data, has revealed new insights into the sublethal effects of pesticides including effects on learning performance, behavior, and neurophysiology. We characterize the different types of sublethal effects on beneficial arthropods, focusing mainly on honey bees and natural enemies, and we describe the methods used in these studies. Finally, we discuss the potential for developing experimental approaches that take into account these sublethal effects in integrated pest management and the possibility of integrating their evaluation in pesticide registration procedures. 81 Annu. Rev. Entomol. 2007.52:81-106. Downloaded from arjournals.annualreviews.org by Dr. Axel Decourtye on 12/15/06. For personal use only. Pollinator: an organism that carries pollen from one flower to another IPM: integrated pest management LD 50 : lethal dose 50% Sublethal effect: an effect (physiological or behavioral) on individuals that survive an exposure to a pesticide (the pesticide dose/concentration can be sublethal or lethal)