Inheritance of resistance to pyrethroid insecticides in Tribolium castaneum (Herbst)

A strain of Tribolium castaneum, highly resistant to pyrethroids, was isolated (single-pair method) from a pyrethroid-resistant field strain and made isogenic with a susceptible laboratory strain. Insecticide assays were used to determine the mode of inheritance and linkage of pyrethroid resistance. Resistance to deltamethrin could not be measured directly but at a 2% mortality response was about 1600-fold. The responses of SR and RS hybrids to deltamethrin were intermediate between the resistant and susceptible parent strains; there was no significant difference between the SR and RS hybrids (P>0.05). Chi-square analysis of the observed responses of the F₁–backcross and F₂ progenies rejected the null hypothesis that a single gene was responsible for resistance. Successive backcrosses with selection indicated the involvement of more than one gene. Test crosses with visible mutant markers suggested that resistance was associated with linkage groups VIII and IX. Assays with deltamethrin applied to grain indicated that this resistance will be rapidly selected in the field resulting in control failures.     

Research Watch: Aquatic toxicity

Toxicity.     

Residue analysis of pyrethroid insecticides in cereal grains, milled fractions and bread

A procedure is described for the residual analysis of eight pyrethroid insecticides at levels of 2-5 micrograms/kg. Residues are extracted from cereal grains, flour or bread with a mixture of acetonitrile/water (2 + 1) and are partitioned into petroleum ether. Clean-up is performed by gel permeation chromatography on Bio-Beads S-X3 and an additional Florisil column. Electron capture gas liquid chromatography on a non-polar SE-30 capillary column separates the isomers of the compounds. Under the conditions used in the experiments with cyfluthrin, cypermethrin, deltamethrin, fenvalerate, and permethrin, the compound levels in rye and wheat did not decrease significantly. Losses during milling and baking were small. Consequently, pyrethroid insecticides remain effective in grain stored over a long period of time. However, considerable residues result in the milled fractions as well as in different types of bread.     

Synthetic pyrethroid insecticides as replacements for chlorinated hydrocarbons for the control of wood-boring insects

The need for effective contact insecticides to replace γ-HCH and dieldrin is discussed. Four synthetic pyrethroids, permethrin, cypermethrin, decamethrin and fenvalerate were evaluated for control of the house longhorn beetle,Hylotrupes bajulus and the common furniture beetleAnobium punctatum. Permethrin was also tested againssLyctus brunneus and the termiteReticulitermes santonensis. Initial toxic effectiveness of all 4 pyrethroids was similar to or in the case of decamethrin, markedly better than γ-HCH and with the exception of fenvalerate their persistence in wood was superior to γ-HCH. They offer hopeful potential replacements for chlorinated hydrocarbons but further evaluation is necessary.     

Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas

A nationally consistent approach was used to assess the occurrence and potential sources of pyrethroid insecticides in stream bed sediments from seven metropolitan areas across the United States. One or more pyrethroids were detected in almost half of the samples, with bifenthrin detected the most frequently (41%) and in each metropolitan area. Cyhalothrin, cypermethrin, permethrin, and resmethrin were detected much less frequently. Pyrethroid concentrations and Hyalella azteca mortality in 28-d tests were lower than in most urban stream studies. Log-transformed total pyrethroid toxic units (TUs) were significantly correlated with survival and bifenthrin was likely responsible for the majority of the observed toxicity. Sampling sites spanned a wide range of urbanization and log-transformed total pyrethroid concentrations were significantly correlated with urban land use. Dallas/Fort Worth had the highest pyrethroid detection frequency (89%), the greatest number of pyrethroids (4), and some of the highest concentrations. Salt Lake City had a similar percentage of detections but only bifenthrin was detected and at lower concentrations. The variation in pyrethroid concentrations among metropolitan areas suggests regional differences in pyrethroid use and transport processes. This study shows that pyrethroids commonly occur in urban stream sediments and may be contributing to sediment toxicity across the country.     

Statewide investigation of the role of pyrethroid pesticides in sediment toxicity in California's urban waterways

A statewide investigation of urban creek sediment toxicity was conducted in California in recognition of increased incidences of toxicity linked to pyrethroid pesticides. The goals were to examine the spatial occurrence and magnitude of sediment toxicity in California urban creeks, and to examine the role of pyrethroids in toxic urban creek sediment samples. After a preliminary screening of 90 sites, 30 creeks were sampled in eight geographical regions. Sediment toxicity was assessed using 10 day bioassays with the resident amphipod Hyalella azteca. Bioassays were conducted at two test temperatures of 23 degrees C and at 15 degrees C to provide evidence of the cause of toxicity, and to more accurately reflect ambient environmental temperatures. Twenty-five of 30 samples were toxic when tested at 23 degrees C, and all 30 samples were toxic when tested at 15 degrees C. The magnitude of toxicity increased in samples tested at 15 degrees C suggesting the influence of pyrethroids, which are more toxic at colder temperatures. Pyrethroids were present in all sediment samples and were the only compounds detected at concentrations toxic to H. azteca. Bifenthrin was the pyrethroid of greatest toxicological concern, occurring in all 30 samples at concentrations up to 219 ng/g. Pyrethroid contamination of urban creeks was most severe in the Los Angeles, Central Valley, and San Diego regions, respectively. However, pyrethroids were also linked to urban creek aquatic toxicity in all regions sampled, including the less urbanized areas of the North Coast and Lake Tahoe.     

Pyrethroid insecticides and sediment toxicity in urban creeks from California and Tennessee

Pyrethroid pesticides have replaced organophosphates for many urban applications, including structural pest control, landscape maintenance, and residential home and garden use. This study was intended to determine if pyrethroids are detectable and widespread in diverse urban systems and if concentrations are high enough to cause associated aquatic toxicity. Urban creeks in California and Tennessee were tested on up to four occasions for pesticide residues in sediments, and aquatic toxicity was determined by acute toxicity tests using the amphipod, Hyalella azteca. In California, 12 of the 15 creeks tested were toxic on at least one sampling occasion, and sediment pyrethroid concentrations were sufficient to explain the observed toxicity in most cases. The pyrethroid bifenthrin, due to its high concentrations and relative toxicity as compared to other pyrethroids, was likely responsible for the majority of the toxicity at most sites. Cypermethrin, cyfluthrin, deltamethrin, and lambda-cyhalothrin also contributed to toxicity at some locations. The source of cypermethrin and deltamethrin was probably almost entirely structural pest control by professional applicators. Bifenthrin, cyfluthrin, and lambda-cyhalothrin may have originated either from professional structural pest control or from lawn and garden care by homeowners. None of the sediments collected from the 12 Tennessee creeks were toxic, and pyrethroids were rarely detectable. Regional differences between Tennessee and California are possibly attributable to climate, differences in types of residential development, and pesticide use practices.     

Selective treatments,including combinations of pyrethroid and organophosphorus insecticides. For control of stored product Coleoptera at two temperatures

Selective treatments, appropriate to simulated storage conditions, reinfestation pressures and species or strains of insects present in the wheat, required less insecticide than any “blanket” or all-purpose treatment. In particular, the pyrethroids bioresmethrin, synergized bioresmethrin or synergized pyrethrins were especially effective where Rhyzopertha dominica and especially a strain resistant to organophosphorus insecticides, was the only species present. Conversly, the organophosphorus insecticides dichlorvos, malathion, fenitrothion and pirimiphos-methyl were especially effective against Tribolium and Sitophilus species. There was no antagonism between any of the pyrethroids and any of the organophosphorus insecticides when they were applied in combination, in that the period of protection given by combinations was the period of protection given by the pyrethroid component against R. dominica and the organophosphorus component against Tribolium and Sitophilus species. As an example of the data required for selective treatments, bioassays were conducted at 20 and 30°C and it was found that the net effect of the lower temperature in reducing toxicity but increasing persistence was to increase the period of protection given by insecticides in cooled storages. It is suggested that the amounts of insecticides applied to grain could be considerably reduced if more consideration was given to grain conditions, if reinfestation pressures were more carefully examined and if less attention were given to surviving adults under conditions where progeny do not develop.     

Statistical analysis of decay of organophosphorus and pyrethroid insecticides and carbaryl on paddy rice, maize, sunflowers and field peas

A model is developed to describe the decay of seven insecticides on stored paddy rice, maize, sunflowers and peas, and is shown to be more precise than each of six literature models on pesticide decay. It relates residues (R), as a ratio of applied concentration (R(0)), to time after insecticide application (t), modifying the usual first-order kinetics equation lnR=lnR(0)-kt by assuming that the rate constant k has a mixture of values according to a gamma distribution with mean K. The resulting equation is lnR=lnR(0)-Kcln(1+t/c), where c is a constant determined empirically. For large c, this model reduces to the first-order model with K=k. The parameter K is further modelled as linear in temperature for maize and rice. The rate of loss of protectants was found not to be seriously affected by co-application with other insecticides, and this is a useful finding for future studies on rates of loss of grain protectants. The apparent rate of loss was also not seriously affected by the method of analysis, whether by gas chromatography or high-performance liquid chromatography, and this finding supports previous validation of the methods.     

Analysis of polychlorinated biphenyls, pyrethroid insecticides and fragrances in human milk using a laminar cup liner in the GC injector

 Since 1970 the State Laboratory of Basle City has been periodically analyzing human milk from the region (the latest in 1998/99) as a bioindicator for the environmental load of organochlorine pesticides [1, 2]. The analysis of human milk is very complex including several clean-up steps and is therefore time consuming. The focus is mainly on organochlorine pesticides, polychlorinated biphenyls (PCB), and nitro-musk compounds; analytes which are easily detectable with gas chromatography and electron capture detection (ECD). Our aim was to minimize the clean-up steps for the analysis of ECD sensitive substances. Furthermore, analytes insensitive to EC detection that require MS detection, such as polycyclic musk substitutes, were of interest. With the help of a specially designed GC liner in the vaporizing injector of the gas chromatograph, the laminar cup liner, we have considerably reduced the time and effort in the sample preparation. With the described clean-up procedure we analyzed 53 human milk samples from the region of Basle for PCB, pyrethrins, and pyrethroid insecticides and fragrances (nitro-musk compounds and polycyclic musk substitutes). While PCB showed a general downward trend in mean concentrations since 1980, residues of the polycyclic musk substitutes galaxolide and tonalide were detectable in almost every sample (e.g., 73 μg/kg fat of HHCB, 74 μg/kg fat of AHTN). Pyrethrins and pyrethroid insecticides were detected only at low concentrations between 0.03 and 0.46 mg/kg fat. Received: 28 September 1999 / Revised version: 2 May 2000     

Presence of insecticides in shrimp farms adjacent to the sea of cortes: detection, quantification, and toxicity testing

The presence of insecticides in a shrimp farming park in Sonora, Mexico, was investigated. Sediment and water were from an estuary adjacent to the farming park and sediment, water, and shrimp from ponds were sampled and analyzed for insecticides using gas chromatography. Artemia salina acute toxicity assay and the Salmonella mutagenicity test were performed on insecticides found in shrimp and on insecticide-containing shrimp, respectively. All insecticides searched were found in shrimp samples, as well as in sediment and water from the estuary. Chlorpyrifos was found to cause >50% mortality at levels below those found in ponds. All insecticide-containing shrimp were not mutagenic towards Salmonella TA98 and TA100 tester strain. Results suggest that insecticides levels found in the farming environment might contribute to reduced production. Although insecticide-containing shrimp were no mutagenic, further toxicity testing is necessary to evaluate the risk for the consumer.     

Phytotoxicity due to the agricultural use of urban wastes. Germination experiments

The inhibitory effect on germination by the organic fraction of different urban wastes was studied in two experiments: on barley (Hordeum vulgare L cv Reinete) seeds in petri dishes and on ryegrass (Lolium perenne L cv Argo) seeds in containers. The urban wastes were mixed with a calcareous soil. Fresh sewage sludge almost totally inhibited germination of barley seeds when used as substrate; fresh municipal solid waste also inhibited germination, although to a lesser degree. Both inhibitory effects were less pronounced when the products had been composted previously. Similar results were obtained when the experiments were carried out with water extracts although overall inhibition was less. Correlation between germination indices and various parameters of the products used showed that the highest indices were obtained when the organic matter of the samples was the most stable (a smaller proportion of labile carbon, carbon extracted with Na₁P₂O⁷, carbon precipitated at pH 2 and water soluble carbon in the materials and extracts). Inhibition was greater when there were greater quantities of NH^?₄, polyphenols and organic acids of low molecular weight. Yields of ryegrass obtained from high doses of urban wastes (180 t ha ^?1) mixed with a calcareous soil were less than those of the control at the first harvest, these yields being influenced negatively by the same factors as above; at the second harvest the yields with most of the products used were higher than those of the control, probably as a result of their maturation in the soil. When the water extracts of the products were added to the soil, no significant differences from the control were noted at the first harvest.     

Organophosphorus insecticides in agricultural and residential runoff: field observations and implications for total maximum daily load development

Development of total maximum daily loads (TMDLs) for nonpoint source pollutants requires mass flux estimates for targeted compounds from contributing sources. We measured organophosphorus insecticide concentrations in surface runoff from agricultural and residential land-use sites in a southern Californian watershed over the course of runoff-producing irrigation and rainfall events. Event mean concentrations (EMCs) for chlorpyrifos, diazinon, and malathion exhibited considerable variability among irrigation and storm runoff events at agricultural sites; residential storm runoff EMCs for these compounds were considerably less variable. Event loads and EMCs were higher for runoff events following reported insecticide applications. Organophosphorus insecticide EMCs were not consistently correlated with hydrologic characteristics of runoff events. Our results indicate that on an area basis, loads from residential land may exceed those from sites planted in row crops for a given rainfall depth, suggesting that residential land use warrants explicit consideration in TMDL development and implementation. No consistent first flush effect was discernible for organophosphorus insecticides in storm or irrigation runoff. A relative potency factor approach is introduced to permit evaluation of organophosphorus insecticides on a common toxicological basis and allow development of TMDLs and pollutant control strategies for these compounds as a class.     

Aquatic toxicity of nine aircraft deicer and anti-icer formulations and relative toxicity of additive package ingredients alkylphenol ethoxylates and 4,5-methyl-1H-henzotriazoles

Characterization of the effects of aircraft deicer and anti-icer fluid (ADAF) runoff on aquatic organisms in receiving streams is a complex issue because the identities of numerous toxic additives are proprietary and not publicly available. Most potentially toxic and endocrine disrupting effects caused by ADAF are due to the numerous additive package ingredients which vary among manufacturers and types of ADAF formulation. Toxicity investigations of nine ADAF formulations indicate that endpoint concentrations for formulations of different manufacturers are widely variable. Type IV ADAF (anti-icers) are more toxic than Type I (deicers) for the four organisms tested (Vibrio fischeri, Pimephales promelas, Ceriodaphnia dubia, and Selenastrum capricornutum). Acute toxicity endpoint concentrations ranged from 347 to 7700 mg/L as ADAF for Type IV and from 1550 to 45,100 mg/L for Type I formulations. Chronic endpoint concentrations ranged from 70 to 1300 mg/L for Type IV and from 37 to 18,400 mg/L for Type I formulations. Alkylphenol ethoxylates and tolyltriazoles are two known classes of additives. Nonylphenol, nonylphenol ethoxylates, octylphenol, octylphenol ethoxylates, and 4,5-methyl-1H-benzotriazoles were quantified in the nine ADAF formulations, and toxicity tests were conducted with nonylphenol ethoxylates and 4,5-methyl-1H-benzotriazoles. Toxicity units computed for glycol and these additives, with respect to toxicity of the ADAF formulations, indicate that a portion of ADAF toxicity can be explained by the known additives and glycols, but much of the toxicity is due to unidentified additives.     

Enhancing the potential use of microparticulate insecticides through removal of particles from raw grain

The current study presents the design and evaluation of a laboratory device combining mechanical motion of wheat grain and turbulent air streaming inside a positive pneumatic conveyor system. The device recovers microparticulate nano-engineered alumina insecticide powders (NAIP) from treated grain. The particle removal efficiency of the conveying system was experimentally quantified by using a laboratory prototype assembled by attaching an electrostatic filter (EF) to the conveyors exhaust. Then, the NAIP particles detached from the grain inside the conveyor were drawn by the conveyors’ exhaust air stream into the EF, where particles bound to the electrodes due to electric charge differences. The NAIP particle load bound to the EF electrodes was removed and weighed to determine the efficiency of the wheat grain cleaning process. Our experimental results, under laboratory conditions, show that the recovery efficiency of the prototype averaged 98.0% (±1.4). Thus, the present study provides an innovative strategy to remove NAIP insecticide particles after storage, once their role as insecticide in stored grain has been fulfilled. This technology provides advancement in grain technology allowing the possibility to provide insecticide-free grain to the food market.     

Additivity of action of three organophosphorus insecticides to some pests of stored grain, and the use of linear programming to identify minimum cost mixtures

Dust formulations of malathion, pirimiphos methyl and etrimfos and their 1:1 w/w mixtures were bioassayed against six species of stored product beetle pests, including a specifically malathion resistant strain of Tribolium castaneum. The bioassay data was consistent with the hypothesis of additive action of the mixtures against the species tested. The use of linear programming to identify minimum cost insecticide mixtures in cases where the components act additively against a number of target pest species is illustrated     

水生动物酶在水产品加工应用中的研究进展

综述了水生动物酶在水生生物的选择性组织降解、鱼腌制发酵及在水解蛋白制品中应用的研究进展,并展望了其发展方向。     

Laboratory assessment of the residual toxicity of commercial formulations of insecticides to adult Oryzaephilus surinamensis (Coleoptera: Silvanidae) exposed for short time intervals

Adult Oryzaephilus surinamensis from an insecticide resistant and a susceptible strain were exposed for fixed periods of time (within the range 0.5, 1, 2, 4, 8, 16, 24 and 32 min; 1, 2, 4, 8, 16 and 24 hr) to filter papers treated with commercially formulated insecticides of fenitrothion, chlorpyrifos-methyl, pirimiphos-methyl or etrimfos at a dose of 250 mg active ingredient per m². The emulsion concentrate (ec) and wettable powder (wp) formulations of fenitrothion produced a delayed toxic response, but were the most toxic insecticide formulations to the laboratory susceptible strain, the ET₉₉ (exposure time) being 0.54 and 0.38 hr respectively at the 24 hr assessment period. Etrimfos 50% ec was the most toxic formulation to the 0213 resistant strain, with an ET₉₉ value of 6.9 hr, whereas the other formulations required much longer exposures, the ET₉₉ values being > 16 hr. The 0213 strain was resistant to all the formulations tested, with a high level of resistance to fenitrothion ec (× 31) and wp (× 162) at the ET₉₉ level. Wettable powder formulations of fenitrothion and chlorpyrifos-methyl required shorter exposures than their respective ec formulations for kill of the susceptible strain. The implications of these results on the survival of O. surinamensis in grain stores are discussed.     

拟除虫菊酯类农药残留检测技术的研究进展

近年来,随着拟除虫菊酯类农药的广泛使用,其残留问题也日益突出。拟除虫菊酯类农药的大量使用给我国的出口贸易以及人类健康带来重大隐患。加强拟除虫菊酯类农药残留检测技术的研究是解决其残留超标问题的重要步骤。文中主要对用于拟除虫菊酯农药残留检测的气相色谱法、液相色谱法、质谱技术、分光光度法、生物传感器等技术进行了综述,并对其发展趋势进行了展望。