Filter Paper Contact Test Research Articles

Joint toxic effects of cadmium and four pesticides on the earthworm (Eisenia fetida)

The contaminants, instead of single contaminants, are usually found as chemical mixtures in terrestrial environment. However, little information is now available about the joint effects of heavy metals and farm chemicals on the soil organism. Our current study aimed to assess the combined toxicity of cadmium (Cd) and four pesticides (atrazine, chlorpyrifos, lambda-cyhalothrin and abamectin) to the earthworm (Eisenia fetida) with binary, ternary, quaternary and quinquenary mixtures. Two distinct kinds of bioassay systems were applied in this study, including contact filter paper test and artificial soil test. Synergistic effects were observed from two quaternary mixtures (Cd-Atrazine-Chlorpyrifos-Lambda-cyhalothrin and Cd-Chlorpyrifos-Lambda-cyhalothrin-Abamectin) and one quinquenary mixture (Cd-Atrazine-Chlorpyrifos-Lambda-cyhalothrin-Abamectin) in both bioassay systems. Besides, two binary mixtures (Cd-Atrazine and Cd-Lambda-cyhalothrin) and three ternary mixtures (Cd-Atrazine-Chlorpyrifos, Cd-Atrazine-Lambda-cyhalothrin and Cd-Chlorpyrifos-Lambda-cyhalothrin) also exhibited synergistic effects on E. fetida by the soil toxicity test. It is more practical to evaluate the contaminant toxicities to earthworm by soil toxicity test. Therefore, the effects of chemical mixtures on soil invertebrates might be underestimated by data obtained from single toxicant. Our findings would offer a better understanding of the complex effects of chemical mixtures on non-target living creatures, and these findings provided valuable insights into the interplay of different chemicals in natural environment.

Toxic effects of new ethyl-carbamates on the morphology, mortality and acetylcholinesterase activity of Eisenia foetida

The toxicity of the ixodicidal carbamates ethyl-4-bromophenyl carbamate (LQM 919), ethyl-4-chlorophenyl carbamate (LQM 996) and propoxur on Eisenia foetida adults was evaluated to estimate their ecotoxic potential. The earthworm mortality and weight loss produced by the three evaluated carbamates showed a concentration-dependent effect (p < 0.0001) in the contact filter paper test (CFPT). In the artificial soil test (AST), mortality increased in relation to the exposure time (p < 0.0001) and the concentration (p < 0.01) of the carbamates. Only the earthworms exposed in the CFPT showed morphological alterations. According to the LC50 obtained in the CFPT, the three carbamates were classified as very toxic and, according to the LC50 obtained in the AST, the three carbamates were classified as highly toxic for E. foetida. The values of ki and kd indicated that LQM 919 and LQM 996 are weak inhibitors with lower affinity for the acetylcholinesterase of E. foetida than that of propoxur. The concentrations in the CFPT and AST at which 100% mortality was observed in E. foetida were 64- and 4-fold higher, respectively, than the egg hatching inhibitory concentration 99% reported for ticks.

Assessment of ammonium hydroxide effect on &lt;i&gt;Eisenia fetida&lt;/i&gt; (Savigny, 1826): acute toxicity and avoidance tests

In this study, acute toxicity and avoidance tests were conducted to assess the effect of ammonium hydroxide 'AH' on the brandling worm Eisenia fetida (Annelida: Lumbricidae). Adults' earthworms were exposed to an increasing concentration of AH (0.0001, 0.001, 0.01, 0.1, 1 and 10 mg.cm‒2) for contact filter paper test and (0, 0.05, 0.1, 0.5, 1 and 5 mg.g1 of soil) for soil and avoidance tests. Our results show that AH caused a high mortality rate and a decrease in biomass according to the increase of concentrations and exposure time, causing some physiological symptoms (bleeding and burns) and behavioural responses. The LC50 calculated for contact filter paper test after 48 h was 1.01 mg.cm‒2 and 1.05 mg.g‒1 for soil test after 14th days. Moreover, the EC50 obtained in avoidance test was 0.05 mg.g‒1, this means that the earthworms were able to immediately detect low concentration of AH in soils, avoiding it.

Assessment of ammonium hydroxide effect on Eisenia fetida (Savigny, 1826): acute toxicity and avoidance tests

In this study, acute toxicity and avoidance tests were conducted to assess the effect of ammonium hydroxide 'AH' on the brandling worm Eisenia fetida (Annelida: Lumbricidae). Adults' earthworms were exposed to an increasing concentration of AH (0.0001, 0.001, 0.01, 0.1, 1 and 10 mg.cm‒2) for contact filter paper test and (0, 0.05, 0.1, 0.5, 1 and 5 mg.g1 of soil) for soil and avoidance tests. Our results show that AH caused a high mortality rate and a decrease in biomass according to the increase of concentrations and exposure time, causing some physiological symptoms (bleeding and burns) and behavioural responses. The LC50 calculated for contact filter paper test after 48 h was 1.01 mg.cm‒2 and 1.05 mg.g‒1 for soil test after 14th days. Moreover, the EC50 obtained in avoidance test was 0.05 mg.g‒1, this means that the earthworms were able to immediately detect low concentration of AH in soils, avoiding it.

Untargeted metabolomics reveals transformation pathways and metabolic response of the earthworm Perionyx excavatus after exposure to triphenyl phosphate

Triphenyl phosphate (TPHP) is one of the most highly utilized organophosphorus flame retardants, and has been frequently detected in various environmental matrices, including soil. So far, limited information is known regarding the potential toxicity of TPHP to the earthworm-soil ecosystem. We investigated the metabolism of TPHP and the perturbation of the endogenous metabolome in the earthworm, Perionyx excavatus, using gas chromatography mass spectrometry (GC-MS) and liquid chromatography quadrupole time-of-flight (LC-QTOF)-based untargeted metabolomics approach after acute exposure to TPHP for one and two days through a filter paper contact test, as well as after chronic exposure for 28 days in a soil microcosm experiment. TPHP showed low bioaccumulation potential in the earthworm-soil ecosystem at concentrations of 10 mg/kg and 50 mg/kg. Identified phase I metabolites include diphenyl phosphate, mono-hydroxylated and di-hydroxylated TPHP. Two groups of phase II metabolites, thiol conjugates (including mercaptolactic acid, cysteine, cysteinylglycine, and mercaptoethanol conjugates) and glucoside conjugates (including glucoside, glucoside-phosphate, and C14H19O10P conjugates), were putatively identified. Only acute TPHP exposure caused significant perturbations of the endogenous metabolome in earthworms, featuring fluctuations in amino acids, glucose, inosine and phospholipids. These results reveal novel phase II metabolism and toxicity of TPHP in P. excavatus.

Toxicity of Heavy Metals to Mongoloniscus sinensis (Dollfus, 1901) (Crustacea: Isopoda: Oniscidea).

The bioaccumulation of and resistance to different heavy metals in soil was tested using Mongoloniscus sinensis, a terrestrial isopod endemic to china, and results show that: (1) the median lethal concentration (LC50) of Pb, Zn, Cd in the filter paper contact test after 48h was 197.6, 503.7, 448.0µgcm- 2, LC50 of Pb-Zn compounds was 173.8 and 440.8µgcm- 2 and after 14 days of soil contamination LC50 was 2917.0, 2977.9, 5048.4mgkg- 1, LC50 of Pb-Zn compounds was 1219 and 1463mgkg- 1. Thus Zn turned out to be less toxic than Cd in the filter paper contact test, while their sequence of toxicity was reversed during the soil exposure test, which shows that M. sinensis can tolerate a dose of Zn and Cd. (2) analysis of body burdens showed that the sequence of internalized metal concentrations was Pb < Cd < Zn, which indicates that heavy metals in soil can be enriched and absorbed by M. sinensis, and that it is much more efficient at absorbing Zn and Cd than Pb.

A test battery for assessing the ecotoxic effects of textile dyes

The textile dyeing industry is one of the main sectors contributing to environmental pollution, due to the generation of large amounts of wastewater loaded with dyes (ca. 2–50% of the initial amount of dyes used in the dye baths is lost), causing severe impacts on human health and the environment. In this context, an ecotoxicity testing battery was used to assess the acute toxicity and genotoxicity of the textile dyes Direct Black 38 (DB38; azo dye) and Reactive Blue 15 (RB15; copper phthalocyanine dye) on different trophic levels. Thus these dyes were tested using the following assays: Filter paper contact test with earthworms (Eisenia foetida); seed germination and root elongation toxicity test (Cucumis sativus, Lactuca sativa and Lycopersicon esculentum); acute immobilization test (Daphnia magna and Artemia salina); and the Comet assay with the rainbow trout gonad-2 cell fish line (RTG-2) and D. magna. Neither phytotoxicity nor significant effects on the survival of E. foetida were observed after exposure to DB38 and RB15. Both dyes were classified as relatively non-toxic to D. magna (LC50 > 100 mg/L), but DB38 was moderately toxic to A. salina with a LC50 of 20.7 mg/L. DB38 and RB15 induced significant effects on the DNA of D. magna but only DB38 caused direct (alkaline comet assay) and oxidative (hOGG1-modified alkaline comet assay) damage to RTG-2 cells in hormetic responses. Therefore, the present results emphasize that a test battery approach of bioassays representing multiple trophic levels is fundamental in predicting the toxicity of textile dyes, aside from providing the information required to define their safe levels for living organisms in the environment.

Individual and combined effects of herbicide tribenuron-methyl and fungicide tebuconazole on soil earthworm Eisenia fetida

Earthworms are soil engineers that alter the soil bio-physical properties to favor plant growth whereas pesticides represent a significant threat to their abundance and soil health. Thus, we investigated the toxic effects of tribenuron-methyl (TBM) and tebuconazole (TEB) on the soil earthworm, Eisenia fetida. The TBM demonstrated low toxicity to E. fetida in the contact filter paper and artificial soil tests, with median lethal concentrations (LC50) of 135.6 μg cm−2 at 48 h and 511 mg kg−1 on day 14, respectively. Similarly, TEB also showed low toxicity to E. fetida in the artificial soil test with LC50 of 287 mg kg−1 on day 14. However, TEB was highly toxic to earthworm in the contact filter paper test with LC50 of 5.7 μg cm−2 at 48 h. The mixture of two pesticides had an antagonistic effect on the earthworm. Under 0.1 LC50 of TBM and TEB, either single or combined application of pesticides induced oxidative stress and inhibited cellulase activity in early days of the earthworm exposure. However, both pesticides did not damage the earthworm DNA. Our results suggest that pesticides can negatively affect soil earthworms and provide valuable information regarding the responses of soil biological engineers to the lethal agrochemicals.

Metabolism of tri-n-butyl phosphate in earthworm Perionyx excavatus.

Tri-n-butyl phosphate (TBP) is widely used in various industrial processes and has been detected in all environmental matrices. So far, little work has been done regarding the metabolism of TBP on terrestrial invertebrates. We investigated the metabolism of TBP in the earthworm, Perionyx excavatus, after acute exposure to TBP for one and two days in filter paper contact test, as well as after chronic exposure for 28 days in soil experiment. Biotransformation products were identified by using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry, and by exploiting the information dependent acquisition in tandem mass spectrometry. TBP exhibited low accumulation in earthworm-soil ecosystem at 10mg/kg and 50mg/kg. The presence of earthworms significantly enhanced TBP degradation at 50mg/kg in soil. Dibutyl phosphate and hydroxylated TBP were the major phase I metabolites. Three novel phase II metabolites were identified: ethanol dibutyl phosphate and its sulfate conjugate, and the phosphate conjugate of hydroxylated TBP. Hydroxylation and further phosphorylation dominated metabolism in chronic exposure. An extensive metabolic pathway of TBP in earthworm was proposed. This is the first report of TBP metabolism in terrestrial invertebrates and highlights the necessity to identify metabolites of contaminants when evaluating their bioaccumulation and toxicity.

Novel and environmental friendly approach; Impact of Neem (Azadirachta indica) gum nano formulation (NGNF) on Helicoverpa armigera (Hub.) and Spodoptera litura (Fab.)

The future of this study was to prepare a natural pesticide which will not harm the environment and yet control pests. Neem gum nano formulation (NGNF), a novel biopesticide prepared from the Neem gum extract (Azadirachta indica) (NGE) was evaluated for its antifeedant, larvicidal and pupicidal activities against Helicoverpa armigera (Hub.) and Spodoptera litura (Fab.) at 100ppm. The NGNF showed significant (100%) antifeedant, larvicidal and pupicidal activities against H. armigera and S. litura. The LC50 values of 10.20, 12.49 and LC90 values of 32.68, 36.68ppm on H. armigera and S. litura, respectively at 100ppm. The NGNF treatments showed differences in the activities of detoxifying enzymes, carboxylesterases, glucosidases and glutathione S-transferases in the larval gut. Earthworm toxicity illustrated that 6.25ppm of chemical insecticides (cypermethrin) varied widely in their contact toxicities compared to 100ppm of NGNF and control in both contact filter paper and artificial soil test. The NGNF were characterized and confirmed by FTIR, XRD, SEM and EDX analysis. Ten compounds were identified from the Neem gum extract (NGE) by Gas Chromatography-Mass Spectrometry (GC–MS) analysis. The major compounds were fatty acids like Hexadecanoic acid, oleic acid, and ricinoleic acid. NGNF could be used as an agent to prepare novel bio-pesticides formulations.

Effects of perfluorooctanoic acid and perfluorooctane sulfonate on acute toxicity, superoxide dismutase, and cellulase activity in the earthworm Eisenia fetida.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the two best-known perfluorinated chemicals and have received much attention due to their ubiquity in the environment. In the present study, we evaluated the effects of PFOS and PFOA on acute toxicity, superoxide dismutase (SOD), and cellulase activities in Eisenia fetida. The results of acute toxicity testing using a filter paper contact test and a natural field soil test showed that PFOA and PFOS exhibited acute toxicity in earthworms, and the toxic effect of PFOS was greater than that of PFOA. The results also showed that avoidance behavior is a more sensitive and easy operation biomarker than acute toxicity and will give us information for early diagnosis of soil pollution, well before the lethal effect becomes apparent. Subchronic exposure to PFOA or PFOS resulted in changes in SOD and cellulase activities in E. fetida, and SOD activity was more sensitive than cellulase activity during early exposure. Based on these findings, we suggest that avoidance behavior and SOD activity in earthworms are suitable biomarkers for evaluating the toxicity of PFOA- and PFOS-contaminated soils. These results indicate that exposure to PFOA and PFOS has a potential impact on soil animals and their environment.

Acute Toxicity of Imidazole Nitrate Ionic Liquids with Varying Chain Lengths to Earthworms (Eisenia foetida).

When ionic liquids (ILs) first came into use, we thought that they were safe. However, upon further investigation, researchers found that ILs are not harmless. In this study, the model soil organism, earthworms (Eisenia foetida), were used to study the acute toxicity of imidazole nitrate ionic liquids with varying chain lengths from 2 to 12. The experiment used two different methods, a filter paper contact test (48h) and an artificial soil test (14 days), to determine the toxicity. These results demonstrated that the toxicity increased with the length of carbon chains until C8 and that the cut-off effect occurred at 1-octyl-3-methyl imidazole nitrates.Then, the toxicity began to increase again. At the same time, the concentrations of [C10mim]NO3 and [C12mim]NO3 were determined by high performance liquid chromatography and demonstrated that ILs were stable throughout the experiment. The present study revealed the acute toxicity of ILs with varying chain lengths.

English

Earthworms might be limited in their activities on soil by pesticides used at important rates in agriculture and human pathogenic micro-organisms introduced in soil by excreta. This study using a modified toxicity filter paper contact test from Organisation for Economic Co-operation and Development (OECD), aimed at assessing the toxicity of six pesticides formulations and six micro-organisms on the earthworm Eisenia fetida. The study performed over 7 months at the laboratory QAlEA (University of Caen Normandie, France), analysed the mortality every 24 h for 96 h and at 96 h of E. fetida when exposing to pesticides and microbial suspensions. The statistical test used is the Student’s t-test at the significant level of 0.05. No mortality of earthworms was observed when testing these pesticides at their recommended agricultural concentrations. Toxicity order from the highest to the lowest, based on LC50, was Capiscol, Stratos Ultra Jardin, Polyvalent, Roundup GT Plus, Polyflor and KB Limace. Among tested micro-organisms, only Enterobacter cloacae (culture broth) and Listeria monocytogenes (culture broth and supernatant) generate mortalities of E. fetida. Finally, all these tested pesticides do not lead to E. fetida mortality if they are used at their recommended agricultural concentrations. Earthworms species E. fetida are also stressed by some micro-organisms. Furthermore, the filter paper contact test OECD might be used as a tool to evaluate the response of E. fetida to abiotic and biotic stresses. Key words: Stress, toxicity, pesticides, micro-organisms.

Combined toxicity of imidacloprid and three insecticides to the earthworm, Eisenia fetida (Annelida, Oligochaeta).

Although the earthworm Eisenia fetida has been used in many ecotoxicological studies in recent years, most of these studies have only focused on assessing the effects of individual insecticides. In the present study, we aimed to compare the individual and combined toxic effects of imidacloprid and three insecticides (phoxim, chlorpyrifos, and lambda-cyhalothrin) on E. fetida. We showed that imidacloprid had the highest intrinsic toxicity to the worms in filter paper contact test, followed by phoxim and lambda-cyhalothrin, while the least toxicity was found from chlorpyrifos. Moreover, 14-day soil toxicity test revealed that the highest toxicity was still detected for imidacloprid with an LC50 value of 2.82 (2.61∼3.17) mga.i.kg-1 dry weight (DW), followed by chlorpyrifos with an LC50 value of 384.9 (353.5∼440.3) mga.i.kg-1 DW. Meanwhile, a relatively less toxicity was found for lambda-cyhalothrin with an LC50 value of 560.3 (475.9∼718.5) mga.i.kg-1 DW, while the lowest toxicity to E. fetida was observed for phoxim with an LC50 value of 901.5 (821.3∼1017) mga.i.kg-1 DW. In addition, significant synergistic responses were found from the ternary mixture of imidacloprid-phoxim-lambda-cyhalothrin and quaternary mixture of imidacloprid-phoxim-chlorpyrifos-lambda-cyhalothrin in both bioassay systems. Therefore, our findings highlighted that the simultaneous presence of several insecticides in the soil environment might lead to increased toxicity, resulting in serious damage to the nontarget organisms compared with individual insecticides.

Toxicity of A Novel Neonicotinoid Insecticide Paichongding to Earthworm Eisenia fetida

ABSTRACTTraditional neonicotinoid insecticides are used worldwide. Paichongding (IPP), as a novel neonicotinoid pesticide, has been widely used in China. However, the ecotoxicity of IPP to non-target invertebrates in soil ecosystem has not been reported yet. In this study, acute toxicity of IPP to earthworm Eisenia fetida, as well as the antioxidant response after IPP exposure, was evaluated. In the filter paper contact test, the LC50 at 24 hr and 48 hr for IPP were 14.98 μg/cm2 and 7.59 μg/cm2, respectively. In artificial soil test, the LC50 (lethal concentration) at 14 days and 28 days for IPP were 541.07 mg/kg and 238.51 mg/kg, respectively. The LC50 of IPP is much higher than that of traditional neonicotinoid insecticides. However, earthworm body weight assessment demonstrated that the growth of earthworm was inhibited by extended exposure to IPP at sublethal doses. The activities of antioxidative enzymes superoxide dismutase and catalase in earthworms were significantly induced after IPP exposure. Malondialdehyde, a biomarker of lipid peroxidation, was also increased after IPP exposure. Although the results indicated that IPP had potentially adverse effect on earthworms, its toxicity was much lower than traditional neonicotinoids.

Molecular and cellular response of earthworm Eisenia andrei (Oligochaeta, Lumbricidae) to PCDD/Fs exposure.

The acute toxicity of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) was investigated in the earthworm Eisenia andrei using filter paper toxicity test. Protein content, catalase (CAT) activity, and histology of intestinal wall (chloragogen cells and intestinal epithelium) were investigated in earthworms exposed for 48h to 0 (control), 0.5, 1.0, and 1.5ng/cm2 PCDD/Fs. The results showed an increase in the total protein content 1.56- (p=0.104), 1.66- (p=0.042), and 2.26-fold (p<0.001), respectively, compared to control. The average ± standard deviation of tissular CAT activity showed no significant differences; it was 36.01±7.65, 36.17±9.45, 36.08±9.80, and 40.01±6.98U/g tissue, respectively. However, the average specific activity of CAT ± standard deviation was significantly decreased (p<0.001) at all doses compared to control; it was 2.93±0.42, 1.93±0.53, 1.80±0.38, and 1.53±0.44U/mg protein, respectively. There was a progressive damage in both of the intestinal villi and the chloragogenous tissue associated with the incrementing doses. Since the toxic mixture altered the investigated biomarkers of E. andrei within 48h, the cellular and molecular alterations resulted from the filter paper contact test could be utilized as a rapid toxicity assessment tool of environmental contamination with dioxins/furans and to assess consequent potential adverse effects on soil biota and other organisms in the ecosystem.

Lethal and sub-lethal effects of triclosan toxicity to the earthworm Eisenia fetida assessed through GC–MS metabolomics

Triclosan (TCS) is a ubiquitous contaminant in municipal biosolids, which has also been detected in soils and earthworms sampled from agricultural fields amended with biosolids. The goal of this study was to evaluate the toxicity of TCS to earthworms using a metabolomics-based approach for an improved interpretation of toxicity. Toxicity of TCS was assessed using the OECD Method 207 filter paper contact test measuring the endpoints of weight loss, mortality, and ten metabolites determined by GC–MS. Eight earthworms were exposed as individual replicates to six concentrations of triclosan (0, 0.0001, 0.001, 0.01, 0.1, and 1mg TCS cm−2) on filter paper, with mortality assessed after 6, 24 and 48h. Mortalities were first observed at 24h, with 100% mortality in the 1 and 0.1mgcm−2 treatments. Worms at 1mgcm−2 lost most of their coelomic fluid before they could be sampled. The 48h LC50 for triclosan was estimated to be 0.006 and 0.008mgcm−2 by a linear and logistic model, respectively. Based on the LC50, triclosan is relatively more toxic to earthworms than a number of other emerging contaminants, but is less toxic than other chlorophenols and many pesticides. Alanine, valine, leucine, serine, phenylalanine, putrescine, spermidine, mannitol, and inositol were significantly different between treatments, although changes were most often associated with mortality rather than triclosan exposure. An increase in putrescine and decrease in amino acids, polyols, and spermidine were associated with mortality, suggesting decomposition had begun. Principal components analysis did not reveal evidence of metabolic impacts at sub-lethal concentrations. However, there were changes in the pattern of correlations between metabolite pairs in surviving worms at both 0.0001 and 0.001mgcm−2 exposure compared to the control.

Developmental response of Spodoptera litura Fab. to treatments of crude volatile oil from Piper betle L. and evaluation of toxicity to earthworm, Eudrilus eugeniae Kinb.

Evaluations of biological effects of (Pb-CVO) the crude volatile oil of Piper betle leaves on the tobacco cutworm Spodoptera litura were conducted. Pb-CVO was subjected to GC-MS analysis and twenty vital compounds were isolated from the betel leaf oil. Pb-CVO was tested at four different concentrations (0.25, 0.5, 1.0 and 1.5%) against S. litura. The treated insects exhibited dose depended mortality. The mortality rate was significantly higher at the 1.0 and 1.5% Pb-CVO. The LC50 (Lethal concentration) were observed at 0.48% Pb-CVO. Larval and pupal durations increased in all treatment concentrations (0.25, 0.3, 0.4 and 0.5%) whereas, pupal weight decreased compared to control. Adult longevity of S. litura was reduced in all treatments but predominantly in the 0.4 and 0.5% Pb-CVO. Correspondingly, mean fecundity rate was reduced at all concentrations compared to control. Histological studies of larvae mid-gut profiles of S. litura were severely damaged in 1.0 and 1.5% and showed abnormalities in mid-gut cells with 0.25 and 0.5% Pb-CVO treatments. Earthworm toxicity illustrated that 0.1% of chemical insecticides (monocrotophos and cypermethrin) varied widely in their contact toxicities compared to 0.5 and 1.0% Pb-CVO and control in both contact filter paper and artificial soil test. These findings suggest that twenty essential compounds of betel leaf oil were significant inhibitors of the development and caused behavioral changes of S. litura. Treatment with betel leaf oil at these concentrations had no adverse effect on earthworm populations.

Acaricidal activity of commercialized insecticides against Haemaphysalis longicornis (Acari: Ixodidae) nymphs

The acaricial activity of 13 commercialized insecticides in Korea against the hard tick nymphs Haemaphysalis longicornis collected in a field was tested using nymph dipping and folded filter paper methods and a spraying-residual assay. In a nymph dipping bioassay, 100% mortality at all tested doses was observed in insecticides containing active ingredients such as phthalthrin 8%+d-phenothrin 2%+piperonyl butoxide 20%, deltamethrin 1.5%, pyrethrum 0.5%, lambda-cyhalothrin 5.5%, alpha-cypermethrin 10% and teflubenzuron 50%, whereas the insecticide containing etofenprox 5%+octachlorodipropyl ether 11% at recommended dose (RD) and 0.5 times RD showed 97 and 90% activity, respectively. Other insecticides containing alpha-cypermethrin 5%, polyoxyethylene isostearylether 10%, etofenprox 5%, bistrifluron 10% and Bti did not show any significant activity. In the folded filter paper contact test with nymph H. longicornis at RD, polyoxyethylene isostearylether 10%, deltamethrin 1.5% and alpha-cypermethrin 10% showed 100% mortality at 1day after treatment (DAT). At 7 DAT, polyoxyethylene isostearylether 10%, deltamethrin 1.5% and lambda-cyhalothrin 5.5% exhibited 100, 93 and 87% mortality. Although the selected 5 insecticides showed strong mortality under laboratory conditions, their residual effect sprayed on field grown lawn leaves significantly decreased depending on DAT. Etofenprox 5% mixture (+octachlorodipropyl ether 11%) only showed 93 and 80% mortality at 1 and 2 DAT, respectively. Polyoxyethylene isostearylether 10% gave 0% mortality at even 1 DAT and the other insecticides also showed 60–70% mortality at 1 DAT. These results indicate that pyrethroid insecticides gave good activity against the H. longicornis nymphs but their residual effect is within 1 DAT under field conditions.

Bioaccumulation and Elimination of the Herbicide Clomazone in the Earthworms Eisenia fetida

Acute toxicity, bioaccumulation, and elimination of herbicide clomazone in the earthworm Eisenia fetida were investigated in the different exposure systems. The LC50 values of clomazone on earthworms were 5.6 μg cm(-2) in the contact filter paper test (48 h), 174.9 mg kg(-1) (7 days) and 123.4 mg kg(-1) (14 days) in artificial soil test, respectively. Clomazone could rapidly bioaccumulate in earthworms and reached the highest concentration after 3 days exposure, with the maximum concentrations of 9.0, 35.3 and 142.3 mg kg(-1) at 10.0, 40.0 and 160.0 mg kg(-1) of clomazone, respectively. Clomazone uptake showed a good correlation with exposure concentration. After the 14th day, clomazone declined to minimum value. About 74%-80% of accumulated clomazone was eliminated within 1 day after exposed to clomazone-free soil. However, a trace amount of clomazone persisted for a relatively long time in earthworms.