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The effects of two pyrethroids, fenvalerate and permethrin, were studied in field experiments on two soil types: organic soil and sandy loam. The objectives were to determine 1) the persistence of fenvalerate and permethrin in straw, 2) the effects of the pyrethroids on epigeal Arachnida and Collembola, and other soil animals and 3) the effects of the pyrethroids on the decomposition rate of straw. The residues of fenvalerate and permethrin in straw approximately 2 months after application varied between 0.1 to above 5 mg/kg straw in 1986, 1988 and 1989, but was less than 0.5 mg/kg straw at harvest in 1991. No pesticide residues were found in straw samples taken in the following summer in the 1991 experiment. The decomposition rate of straw did not differ between permethrin and fenvalerate- treated plots and control plots. The rate of decomposition was slightly higher in sandy soil than in organic soil, but the same on tilled and non-tilled plots. Fenvalerate and permethrin affected the numbers of epigeal Arachnida and Collembola in the field. Araneae were more numerous in pitfall samples taken from control plots than in insecticide-treated plots immediately after treatment. In organic soil the difference was marginally significant after harvest. The abundance of Acarina in pitfalls was significantly lower in insecticide-treated plots than in control plots. In the sandy soil experiment, less Collembola occurred in pitfalls of fenvalerate plots than in permethrin or control plots. There were no differences in any of the groups of soil animals in soil cores extracted with dry funnels between the treatments.
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)–pH–alkalinity–conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
SummaryA petrol driven machine, normally used to collect leaf litter, was modified to be used as a suction sampler for polyphagous predators in cereals and grassy habitats and aphids in cereals. Recovery efficiency of Araneae, Carabidae and Staphylinidae did not differ significantly between winter sampling from Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus or Lolium perenne although the structure of these grasses was very different. Summer sampling of aphids and their predators in winter wheat showed that the new sampler captured significantly more target organisms per unit area than did a traditional suction sampler. The machine was also lighter, cheaper and much easier to use than a traditional machine.
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)-pH-alkalinity-conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
Contiguous winter wheat fields of similar cropping history and soil type were used in a study of the responses of Collembola to summer sprays of cypermethrin and pirimicarb in southern England. Chlorpyrifos was included in the study as a toxic standard. Epigeic arthropods were captured by suction sampling and crop-inhabiting species obtained by dissecting wheat ears. Eight genera of Collembola responded significantly to the insecticide treatments. Collembolan abundance decreased after chlorpyrifos was applied but increased after use of cypermethrin. Negative effects of cypermethrin and pirimicarb on Collembola were not detected in this study. Effects of chlorpyrifos varied spatially as a result of faunal heterogeneity among the fields, despite apparent homogeneity of the site. Some species known to be susceptible to chlorpyrifos were absent from one or more of the fields. The implications of these findings for the interpretation of non-target pesticide effects and the potential use of Collembola as bioindicators in field studies with pesticides are discussed. (C) 1999 Society of Chemical Industry.
The book is organized into 10 chapters: general introduction; review of the literatire on springtails; evolution, systematics and biogeography; ecomorphology and anatomy; taxonomic methods and the species concept in Collembola; interactions between Collembola and the abiotic environment; interactions between Collembola and the biotic environment; reproduction, development and life histories; ecology and conservation; and ecotoxicology. There are three appendices: World genera of Collembola; regional checklists of Collembola; and laboratory/field studies on the effects of chemicals on Collembola.
Methodology was developed to assess effects of insecticides on parasitoids and predators of aphids. Small replicated plots gave limited results for beneficial species which are mobile or present in small numbers. Large (0·84 ha) unreplicated plots were therefore used and the effects of three insecticides—demeton-S-methyl, cypermethrin and pirimicarb—on non-target species were assessed in two successive seasons on the same field. Results validated the new methodology, clearly demonstrating the broad spectrum and systemic action of demeton-S-methyl, the selectivity of pirimicarb and the consequences of lack of systemic action by cypermethrin. Methods suggested by the International Organization for Biological Control for field assessment of side-effects of pesticides on natural enemies of insects and mites incorporate many aspects of the techniques reported here.
Contiguous winter wheat fields of similar cropping history and soil type were used in a study of the responses of Collembola to summer sprays of cypermethrin and pirimicarb in southern England. Chlorpyrifos was included in the study as a toxic standard. Epigeic arthropods were captured by suction sampling and crop-inhabiting species obtained by dissecting wheat ears. Eight genera of Collembola responded significantly to the insecticide treatments. Collembolan abundance decreased after chlorpyrifos was applied but increased after use of cypermethrin. Negative effects of cypermethrin and pirimicarb on Collembola were not detected in this study. Effects of chlorpyrifos varied spatially as a result of faunal heterogeneity among the fields, despite apparent homogeneity of the site. Some species known to be susceptible to chlorpyrifos were absent from one or more of the fields. The implications of these findings for the interpretation of non-target pesticide effects and the potential use of Collembola as bioindicators in field studies with pesticides are discussed.© 1999 Society of Chemical Industry
Effects of cropping on summer abundance and species composition of epigeic Collembola were investigated during a six-year study in which nine different arable crops were sampled. Crops were sited on three farms, each with a different rotation and soil type. Species composition was usually similar between fields on the same farm but differed markedly between farms. Arthropleona were generally favoured by a grass and wheat rotation on calcareous clay whereas Symphypleona were favoured by a mixed cereals and break crops rotation on calcareous loam. A mixed cereals and root crops rotation on stony sand consistently had the lowest collembolan abundance and taxonomic richness in all years. Analysis of combined data from all three farms indicated that, except for barley, winter-sown crops had higher abundance and taxonomic richness than spring-sown crops. This pattern was also evident when all crops within individual farms were compared, but the differences were statistically significant only at one farm. However, when comparisons were restricted to cereals, differences in collembolan abundance between spring and winter-sown cereals were inconsistent between farms. Several collembolan species had restricted spatial distributions among fields, independent of cropping and soil type. These findings, which are compared with previous work on effects of cropping on Collembola, have implications for the interpretation of field ecotoxicological studies.
Ecological monitoring is the purposeful observation, over time, of ecological processes in relation to stress. It differs from biological monitoring in that ecological monitoring does not consider the biota to be a surrogate filter to be analysed for contaminants, but rather has changes in the biotic processes as its focal point for observation of response to stress. Ecological monitoring methods aimed at detecting subtle or slow changes in ecological structure or function usually cannot be based on simple repetition of an arbitrarily chosen field measurement. An optimum method should be deliberately designed to be ecologically appropriate, statistically credible, and cost-efficient.
Ecologically appropriate methods should consider the ecological processes that are most likely to respond to the stress of concern, so that relatively simple and well-defined measurements can be used. Statistical credibility requires that both Type I and Type II errors be addressed; Type I error (a false declaration of impact when none exists) and Type II error (a false declaration that no change has taken place or that an observed change is random) are about equally important in a monitoring context. Therefore, these error rates should probably be equal. Furthermore, the error rates should reflect the large inherent variability in undomesticated situations; the optimum may be 10%, rather than the traditional 5% or 1% for controlled experiments and observations.
Field bioassays were conducted to assess the toxicity of three insecticides, chlorpyrifos, cypermethrin and pirimicarb, to four species of springtails, Isotoma viridis, Isotomurus palustris, Folsomia candida (Collembola: Isotomidae) and Sminthurus viridis (Collembola: Sminthuridae). Spray residues on two soil types (a sandy clay loam and a sandy soil) were obtained in the field, in the presence and absence of a wheat crop canopy, after spray application by a commercial tractor-mounted sprayer. Collembola were then confined for 24-h periods on the sprayed soils in a constant laboratory environment at 1, 2, 3, 8 and 15 days after treatment. Residual insecticide toxicity was compared between species, insecticides, soils and exposure conditions (crop or no crop) using the age of residue at which median mortality occurred (DAT50). Cypermethrin and pirimicarb residues were of low toxicity, causing less than 10% mortality, whereas residues of chloryprifos were toxic to all four species of Collembola on both soil types and in both exposure treatments. Interspecific differences in collembolan susceptibility to chlorpyrifos residues gave the ranking (from most to least susceptible) S. viridis>F. candida>Isotomurus palustris>Isotoma viridis. Residues on the sandy soil were more toxic than those on the sandy clay loam. These results are discussed in terms of how field bioassay approaches may be used to determine pesticide residual toxicity to microarthropods. We conclude that field bioassays offer a feasible method for evaluating the toxicity of pesticides and the persistence of toxic effects on Collembola. Advantages and disadvantages of this method are considered.
The discovery and development of the pyrethroid insecticides represents a major advance in the techniques of crop protection and disease vector control. These compounds combine outstanding efficacy against a broad spectrum of noxious insects with low toxicity to birds and mammals. This paper considers the effects of pyrethroids on other components of the terrestrial non-target fauna, with particular reference to effects on ‘beneficial’ organisms, including natural pest-control agents, pollinators, and organisms responsible for the maintenance of soil structure and fertility. This paper uses laboratory and field data to identify which groups of organisms may be potentially at risk from the use of pyrethroids, and draws on extensive field data to consider the significance of such hazards under conditions of normal use. Emphasis will be placed throughout on the evaluation of these compounds under practical conditions, including both crop and non-crop usages. Limitations to, and opportunities for, the use of pyrethroids are discussed, and the potential for further development is considered.
Nine insecticides were evaluated in lucerne for control of the lucerne flea, Sminthurus viridis. Carbaryl, chlorpyrifos, omethoate and isofenphos were the most effective. Each gave immediate control and the highest levels of persistence. Efficacy data of the insecticides against aphids, leafhoppers, earth mites and total numbers of predators are also given. Omethoate and chlorpyrifos were the most effective chemicals overall, although further information on their effects on the predator complex is required to support their recommendation. Carbaryl and fenvalerate showed promise for differentiating between damage by three major pests.
Species sensitivity distributions (SSD) and 5% hazardous concentrations (HC5) are distribution-based approaches for assessing environmental risks of pollutants. These methods have potential for application in pesticide risk assessments, but their applicability for assessing pesticide risks to soil invertebrate communities has not been evaluated. Using data obtained in a systematic review, the present study investigates the relevance of SSD and HC5 for predicting pesticide risks to soil invertebrates. Altogether, 1,950 laboratory toxicity data were obtained, representing 250 pesticides and 67 invertebrate taxa. The majority (96%) of pesticides have toxicity data for fewer than five species. Based on a minimum of five species, the best available endpoint data (acute mortality median lethal concentration) enabled SSD and HC5 to be calculated for 11 pesticides (atrazine, carbendazim, chlorpyrifos, copper compounds, diazinon, dimethoate, γ-hexachlorocyclohexane, lambda-cyhalothrin, parathion, pentachlorophenol, and propoxur). Arthropods and oligochaetes exhibit pronounced differences in their sensitivity to most of these pesticides. The standard test earthworm species, Eisenia fetida sensu lato, is the species that is least sensitive to insecticides based on acute mortality, whereas the standard Collembola test species, Folsomia candida, is among the most sensitive species for a broad range of toxic modes of action (biocide, fungicide, herbicide, and insecticide). These findings suggest that soil arthropods should be tested routinely in regulatory risk assessments. In addition, the data indicate that the uncertainty factor for earthworm acute mortality tests (i.e., 10) does not fully cover the range of earthworm species sensitivities and that acute mortality tests would not provide the most sensitive risk estimate for earthworms in the majority (95%) of cases.
We provide a test protocol to evaluate the effects of plant protection products on mortality and reproductive performance
ofHypoaspis aculeifer (Acari: Laelapidae). The test design is in compliance with standard characteristics of extended laboratory studies as formulated
by international expert panels dealing with non-target arthropod testing schemes. Potential effects on survival rates are
evaluated by assessing mortality after an exposure period of 14 days that starts with protonymphs. The reproductive performance
of surviving mites is studied by following the egg production of individually isolated females over a 7-day period. The hatching
success of these eggs is assessed subsequently. Using several years’ data obtained from water control treatments, we propose
criteria to evaluate the validity of individual experiments.
The phenomenon of insecticide-induced resurgence of arthropod pests has long been known to occur in response to a reduction in natural enemy populations, releasing the pest population from regulation. However, studies of resurgent populations infrequently examine other mechanisms, although numerous alternative mechanisms such as physiological enhancement of pest fecundity, reduction in herbivore-herbivore competition, changes in pest behaviour, altered host-plant nutrition, or increased attractiveness may also cause, or enhance the probability of, resurgence. Additionally, many studies that have identified natural enemy mortality as the primary cause of resurgence do not document a priori regulation by natural enemies and, therefore, are correlative in nature. In this paper, a universal definition of resurgence is proposed and criteria for determining the occurrence of resurgence are listed. Both of these are essential to rigorous evaluation of this important phenomenon. Alternative mechanisms for resurgence and potential areas of future research are identified. It is argued that insecticide resistance is not a mechanism underlying resurgence; rather, it simply enhances the probability that resurgence may occur. The similarity of resurgence to some insect outbreaks is discussed. In some cases natural outbreaks differ only in the initiating factor. The importance of resurgence management to plant protection is that resurgence is totally contradictory to the intended outcome of insecticidal application. This conflict strengthens the need to identify specifically the causal factors for each case of resurgence in order to manage this detrimental phenomenon effectively.
Cypermethrin (Ripcord) and demeton-S-methyl (Duratox) were each applied to large fields of winter wheat by fixed-wing aircraft. The numbers of soil surface- and foliar-dwelling arthropods were estimated at intervals before and after treatment in both the treated and an untreated control field, using pitfall traps and a D-Vac suction sampler. Cereal aphids were the major group of phytophagous insects collected from all of the trial sites. Both compounds caused an initial decline in their numbers immediately after spraying but a significant "resurgence" in aphid populations was observed in the demeton-S-methyl-treated field towards the end of the study. The major groups of entomophagous arthropods collected from the fields were Carabidae, Staphylinidae, Linyphiidae, Empididae, and Braconidae. With the exception of the effects of cypermethrin on linyphiids and demeton-S-methyl on empids, both of the treatments had only minor, short-lived effects on these entomophages. Neither of the compounds had any significant, long-term effects on general feeding (e.g., detritivorous) arthropods.
When house crickets, Acheta domesticus (L.), were reared under suboptimum conditions, their growth was increased by certain coneeutrations of most of the 14 pesticides tested. These results are in agreement with the hormoligosis hypothesis, which predicts that subharmful quantities of any stressing agent will be stimulatory to the organism by providing it increased sensitivity to respond to changes in its environment and increased efficiency to develop new or better systems to fit a suboptimum environment. The concentration of these pesticides which was stimulatory was about 1/84 (range of 1/10 to 1100) of the lethal (LD100)dose. This prediction of the action of pesticides on crickets suggests that the hypothesis may be useful as a biological law in understanding and eventually helping control phenomena of biology sllch as "flare back." Possible mechanisms arc suggested.
During a 6‐year study, effects of two contrasting regimes of pesticide use on pitfall and suction catches of Collembola were monitored in an arable field under a rotation of grass and winter wheat. Current farm practice (CFP) represented conventional fungicide and herbicide use plus applications of organophosphorus (OP) insecticides, whereas reduced input approach (RIA) utilised minimum inputs of fungicides and herbicides and excluded any use of insecticides. Compared with RIA, the CFP regime caused a substantial decline in the abundance and diversity of Collembola in the field, including the local disappearance of one species, without recovery during the study. At the field edge, which was protected during OP applications by a 6‐m unsprayed buffer zone, effects of the CFP regime were less severe, and were not persistent in the long term. Some Collembola species occurred only in field‐edge samples. Pitfall and suction sampling yielded remarkably similar patterns of catches, indicating that pitfall trapping may be appropriate for detecting long‐term changes in collembolan abundance caused by intensive agricultural management practices.
© 2002 Society of Chemical Industry
Faunal health is largely dependent on their soil environment and available litter quality. So the effects of different soil habitats and pesticides on citrate synthase (CS) activity of soil fauna and its population were studied.
The soil animals were collected from different pedoecosystems for habitat study. Whereas Vigna radiata based system was selected for pesticidal observations. The field was divided into five equal plots for control and treatment of gamma-BHC, quinalphos, carbaryl and cypermethrin. Soil fauna was collected by quadrat method and extracted by Tullgren funnel. Individuals of a species having similar sizes were collected for the estimation of CS activity. They were homogenized and fractions were obtained by differential centrifugation. The activity of CS was assayed spectrophotometrically.
Citrate synthase (CS) activity of beetle (Rasphytus fregi), woodlouse (Porcellio laevis) and centipede (Scolopendra morsitans) varied significantly with respect to changes in different soil habitats. Though the CS activity of R. fregi, P. laevis, and S. morsitans differed among themselves but the highest activity of CS in these animals was in V. radiata and lowest in A. nilotica based pedoecosystem. The aerobic capacity of centipede was maximum followed by woodlouse and beetle. The treatment of gamma-BHC, quinalphos, carbaryl and cypermethrin significantly reduced the CS activity of these animals. Gamma-BHC showed maximum reduction in CS activity indicating highly toxic effect of organochlorine on aerobic metabolism of soil fauna. However, minimum reduction was observed in response to carbaryl (in beetle) or cypermethrin (in woodlouse/centipede) leading to impairment of aerobic capacity. The differences in pesticide effects might be assigned to the differences in chemical nature of pesticides and their interactions with below-ground fauna. Treatment of gamma-BHC and quinalphos reduced the population of Acari, Coleoptera, Collembola, other arthropods as well as total soil fauna. Acari was least affected by gamma-BHC and maximally affected (72%) in response to quinalphos. The effect of gamma-BHC was fairly similar on Coleoptera, Collembola, other arthropod and total soil fauna suggesting almost similar sensitivity to this pesticide. Likewise, quinalphos was similarly effective on Collemobola and other soil arthropods. Application of carbaryl decreased Acari and Coleoptera population but increased Collembola, other arthropods and total faunal populations. However, application of cypermethrin significantly reduced the population of Acari, Coleoptera, Collembola and total soil fauna and increased the population of other soil arthropods. In both the cases, acarine population was least affected.
The observations show the habitat-specific variation in aerobic capacity of soil fauna. However, pesticide-dependent loss in population might be due to impairment of aerobic capacity of soil inhabiting animals in desert.
Pesticides can modify invertebrate movement and feeding behaviour which could reduce predation in agroecosystems. Previous assays have exposed the spider Pardosa amentata (Clerck) to the synthetic pyrethroid cypermethrin and monitored prey items consumed in small containers (requiring very little movement to capture prey). The current study used larger arenas containing artificial 'vegetation' (a plastic analogue) to encourage spiders to hunt and capture prey. The period 24 h after exposure produced greatest variability in prey item consumption between treatments and was used to examine treatment effects. At this time, cypermethrin reduced prey consumption rates but these effects did not persist. Findings did not suggest that the presence of artificial vegetation in arenas modified prey consumption rates, which was consistent for individuals treated with cypermethrin and a control group. This is despite the majority of pesticide-treated individuals exhibiting both ataxia and paralysis of the hind legs (these effects persisting for a maximum of 3 and 6 days respectively). These findings were consistent for both sexes. Spider longevity under starvation conditions was not significantly reduced by cypermethrin exposure but overall females survived longer than males. The findings are discussed in the context of the arenas used and the ecology of this common predator.
A systematic review was carried out to investigate the extent to which higher-tier (terrestrial model ecosystem [TME] and field) data regarding pesticide effects can be compared with laboratory toxicity data for soil invertebrates. Data in the public domain yielded 970 toxicity endpoint data sets, representing 71 pesticides and 42 soil invertebrate species or groups. For most pesticides, the most frequent effect class was for no observed effects, although relatively high numbers of pronounced and persistent effects occurred when Lumbricidae and Enchytraeidae were exposed to fungicides and when Lumbricidae, Collembola, and Arachnida were exposed to insecticides. No effects of fungicides on Arachnida, Formicidae, or Nematoda or of herbicides on Lumbricidae, Formicidae, or Nematoda were observed in any studies. For most pesticides, higher-tier no-observed-effect concentration or lowest-observed-effect concentration values cannot be determined because of a lack of information at low pesticide concentrations. Ten pesticides had sufficient laboratory data to enable the observed higher-tier effects to be compared with 5% hazardous concentrations (HC5) estimated from acute toxicity laboratory data (atrazine, carbendazim, chlorpyrifos, diazinon, dimethoate, gamma-hexachlorocy-clohexane, lambda-cyhalothrin, parathion, pentachlorophenol, and propoxur). In eight cases, higher-tier effects concentrations were within or below the 90% confidence interval of the HC5. Good agreement exists between the results of TME and field tests for carbendazim, but insufficient information is available for a comparison between TME and field studies for other pesticides. Availability and characteristics (e.g., taxonomic composition and heterogeneity) of the higher-tier effects data are discussed in terms of possible developments in risk assessment procedures.
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