Chlorfenapyr resistance in the spider mite Tetranychus urticae: stability, cross-resistance and monitoring of resistance

The two-spotted spider mite, Tetranychus urticae Koch, is a key pest of many agricultural crops. Studies of stability of resistance, cross-resistance relationships and monitoring of chlorfenapyr resistance were carried out with T. urticae to provide basic information necessary to define effective acaricide resistance management strategies for this pest. Chlorfenapyr resistance was shown to be stable in the absence of selection pressure under laboratory conditions. The activities of seven different acaricides against chlorfenapyr-resistant and -susceptible strains of T. urticae were evaluated. The results indicated possible positive cross-resistance between chlorfenapyr and the acaricides abamectin, propargite and etoxazole. No cross-resistance was detected for the acaricides milbemectin, fenpyroximate and diafenthiuron. A possible negatively correlated cross-resistance was observed between chlorfenapyr and spiromesifen. The evaluation of 21 T. urticae populations from several crops in the States of São Paulo, Mato Grosso, Goiás, and Bahia, in Brazil, indicated that the susceptibility of mites to chlorfenapyr was variable, with percentages of resistant mites ranging from 0.0 to 86.5%. The highest resistance frequencies were observed in ornamental plants in the State of São Paulo. Some populations from cotton and papaya also presented high frequencies of chlorfenapyr resistance. This is the first report on chlorfenapyr resistance in T. urticae on cotton and papaya in Brazil. Strategies for the management of acaricide resistance are discussed.     

Genetic and biochemical analysis of a laboratory‐selected spirodiclofen‐resistant strain of Tetranychus urticae Koch (Acari: Tetranychidae)

BACKGROUND: Spirodiclofen is a selective, non‐systemic acaricide from the new chemical class of tetronic acid derivatives. In order to develop strategies to minimise resistance in the field, a laboratory‐selected spirodiclofen‐resistant strain of the two‐spotted spider mite, Tetranychus urticae Koch, was used to determine genetic, toxicological, biochemical and cross‐resistance data. RESULTS: Selecting for spirodiclofen resistance in the laboratory yielded a strain (SR‐VP) with a resistance ratio of 274, determined on the larval stage. The egg stage remained far more susceptible. No cross‐resistance was found against other established acaricides, except for spiromesifen. Based on synergist experiments and enzyme assays, it appeared that especially P450 monooxygenases, but also esterases and glutathione‐S‐transferases, could be involved in the metabolic detoxification of spirodiclofen. Genetic analysis showed that the resistance is inherited as an intermediate trait under control of more than one gene. CONCLUSIONS: Resistance to spirodiclofen exceeded by far the recommended field rate. A good acaricide resistance management programme is necessary to prevent fast resistance build‐up in the field. Spirodiclofen can be used in alternation with most established acaricides, except for other tetronic acid derivatives. Without selection pressure, resistance tends to be unstable and can decrease in the presence of susceptible individuals owing to the intermediate, polygenic inheritance mode. Copyright © 2009 Society of Chemical Industry     

Fumigant toxicity of lemon eucalyptus oil constituents to acaricide-susceptible and acaricide-resistant Tetranychus urticae

BACKGROUND: This study was aimed at assessing the fumigant toxicity of 14 essential oil constituents from lemon eucalyptus, Eucalyptus citriodora Hook, and another ten known compounds to females of acaricide‐susceptible, chlorfenapyr‐resistant, fenpropathrin‐resistant, pyridaben‐resistant and abamectin‐resistant strains of Tetranychus urticae Koch. RESULTS: Menthol (LC₅₀, 12.9 µg cm^?3) was the most toxic compound, followed by citronellyl acetate (16.8 µg cm^?3), against the susceptible females. High toxicity was also produced by β‐citronellol, citral, geranyl acetate and eugenol (LC₅₀, 21.7–24.6 µg cm^?3). The fumigant toxicity of these compounds was almost identical against females from either of the susceptible and resistant strains, indicating that the compounds and acaricides do not share a common mode of action or elicit cross‐resistance. CONCLUSION: Global efforts to reduce the level of highly toxic synthetic acaricides in the agricultural environment justify further studies on materials derived from lemon eucalyptus oil, particularly menthol and citronellyl acetate, as potential acaricides for the control of acaricide‐resistant T. urticae as fumigants with contact action. Copyright © 2011 Society of Chemical Industry     

Acaricide resistance and resistance mechanisms in Tetranychus urticae populations from rose greenhouses in the Netherlands

BACKGROUND: Spider mites are important crop pests that rapidly develop resistance to acaricides. To investigate whether acaricide resistance is a threat to greenhouse rose culture in the Netherlands, the susceptibility of 15 strains of Tetranychus urticae was tested to several currently used acaricides, and resistance mechanisms were investigated. RESULTS: Although the observed levels of susceptibility differed between strains and acaricides, resistance was detected in most strains. The activity of detoxifying enzymes was significantly increased in most field‐collected strains, and a number of amino acid substitutions known to be involved in resistance were detected. CONCLUSIONS: Resistance levels to traditional acaricides such as bifenthrin and abamectin were prominent, and might result in control failure under field conditions. Resistance to more recently registered compounds was detected in several populations. Resistance levels were generally unstable in the laboratory without selection pressure. The toxicological, biochemical and genetic data in this study will be essential in devising an efficient resistant management for Dutch rose culture. Copyright © 2011 Society of Chemical Industry     

Spiromesifen toxicity to the spider mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis> and selectivity to the predator <Emphasis Type="Italic">Neoseiulus californicus</Emphasis>

Tetranychus urticae Koch (Acari: Tetranychidae) is a major pest of several agricultural crops and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is an important natural enemy of this pest mite. The objective of the study was to evaluate the effect of spiromesifen on the development and reproduction of T. urticae, and to assess the influence of spiromesifen and other acaricides on the population growth rates of the spider mite and its predator, N. californicus. Toxicity tests with spiromesifen at different life stages of T. urticae indicated that eggs less than 72 h old were more sensitive than other development stages. The oviposition rate of T. urticae was significantly affected by spiromesifen. Experiments on the effects of spiromesifen on the growth rates of T. urticae and N. californicus indicated that spiromesifen is innocuous to the predaceous mite but highly toxic to the spider mite, leading to population suppression in 10 days. Fenpropathrin, acephate and neem oil were not harmful to N. californicus, but were not so efficient as spiromesifen in controlling T. urticae, and had significantly less influence on the population growth rates of the spider mite. Among these three products, only neem oil caused significant reduction in the growth rate of T. urticae. Chlorfenapyr, abamectin, milbemectin and diafenthiuron significantly affected the population growth rates of T. urticae and N. californicus. Spiromesifen was the most promising acaricide for managing the two-spotted spider mite, when used in combination with N. californicus.     

Synergistic effect of Beauveria bassiana and spirodiclofen on the two-spotted spider mite (Tetranychus urticae)

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pests in agriculture. Due to its short life cycle and high reproductive rate, this pest has become resistant to most acaricides. Therefore, finding alternative control strategies for this damaging pest is necessary. Application of microbiological agents with minimum concentrations of acaricides is a very suitable tactic in integrated pest management. In the present study, lethal effects of a chemical acaricide – spirodiclofen, and an Iranian strain of the entomopathogenic fungus Beauveria bassiana, were evaluated on different life stages of the two-spotted spider mite on two host plants, bean and cucumber. In the next step, compatibility of acaricide with the fungus was studied regarding conidial germination and vegetative growth of the fungus in the presence of different concentrations of the acaricide. Finally, the acaricide at rates of LC₂₅ with the fungus at LC₅₀ were sprayed on adult female mites. The results showed that immature stages of T. urticae were more susceptible to the acaricide whereas the adults were more susceptible to the fungus. Also, mites reared on cucumber were significantly more susceptible to the acaricide and fungus than those reared on bean. Spirodiclofen and the fungus had a synergistic effect; percentage of mortality for fungus infection was 48.6% and 53.5% on bean and cucumber, respectively, while it was 80.6% on bean and 84.5% on cucumber when the mite was sprayed with both the fungus and the acaricide.     

The microimmersion bioassay: A novel method for the topical application of pesticides to spider mites

A novel and versatile method is described for measuring the contact activity of acaricides against spider mites. The microimmersion (MI) bioassay involves drawing batches of 25 mites into small pipette tips under vacuum, immersing them for 30 s in 35 μ1 of a test solution, and then confining the treated subjects on clean foliage in holding cells. Evaluations of amitraz, bifenthrin, chlorpyrifos and dicofol against susceptible strains of Tetranychus urticae Koch showed the MI bioassay to be equally applicable to formulated and technical acaricides (the latter dissolved in acetone + distilled water; 20 + 80 by volume), and to give LC₅₀ values that corresponded well with those from a conventional residual bioassay. The most important difference between bioassay methods was the consistently greater slope of probit lines from MI tests. Results were not highly sensitive to varying the immersion period between 15 and 60 s, and low control mortality was observed with ethanol or acetone concentrations of up to 500 ml litre^?1, and surfactant concentrations of up to 10 g litre^?1. The potential of this method for assessing the relative toxicity of both fast- and slow-acting acaricides, screening small quantities of experimental compounds for acaricidal activity, and improving the laboratory procedure for selection and characterization of acaricide resistance is discussed.     

Acaricide toxicity and resistance in larvae of different strains of Tetranychus urticae and Panonychus ulmi (Acari: Tetranychidae)

The toxicities of eight structurally different acaricidal compounds to six‐legged larvae (first motile stage) of three laboratory strains of the two‐spotted spider mite, Tetranychus urticae, and the European red mite, Panonychus ulmi, were evaluated following spray application. The larvae of five field‐derived strains of T urticae originating from France, Italy, Brazil, California and Florida were also tested for their susceptibilities to discriminating concentrations of several acaricides resulting in 95% mortality when applied to the organophosphate‐resistant laboratory reference strain WI. The spray bioassay used was robust and gave repeatable results with a wide range of acaricidal compounds, irrespective of their mode of action (ovo‐larvicides or primarily acting on motile life stages). Compounds tested were abamectin, azocyclotin, chlorpyrifos, clofentezine, deltamethrin, fenpyroximate, hexythiazox and pyridaben. Larvae of one of the laboratory strains of T urticae, AK, originally collected in Japan in 1996 and maintained without further selection pressure, exhibited 2000‐ and >4000‐fold resistance to the mitochondrial electron transport inhibitors pyridaben and fenpyroximate, respectively. Another strain of T urticae, AU, obtained from Australia and maintained in the laboratory under selection with hexythiazox and clofentezine since 1987 showed >770‐ and >1000‐fold resistance to clofentezine and hexythiazox, respectively. The same resistance pattern was observed against larvae of a laboratory strain of P ulmi, CE, also selected with hexythiazox. Larvae of one of the field‐derived strains of T urticae, BR, showed a lower susceptibility to a number of compounds, whilst the others were susceptible to all compounds except the organophosphates. © 2001 Society of Chemical Industry     

Het voorkomen van resistentie tegen organische fosforverbindingen bij de bonespintmijt (Tetranychus urticae) in Aalsmeer

Samenvatting Bij een onderzoek naar de gevoeligheid voor acariciden van spintpopulaties, afkomstig van verschillende bedrijven in Aalsmeer, bleek in 20 van de 22 onderzochte gevallen een resistentie te bestaan tegen organische fosforverbindingen. Deze resistentie bleek ook te bestaan ten opzichte van organische fosforverbindingen, die nooit eerder tegen de onderzochte spintpopulaties gebruikt waren. De resistentie tegen demeton (Systox) bleek bij enkele populaties niet even groot.Tegen acariciden op basis van gechloreerde koolwaterstoffen zoals kelthane en chloorbenzilaat, werd nog geen resistentie bij de onderzochte populaties aangetroffen.Een onderzoek naar de gevoeligheid voor acariciden van spintpopulaties, welke in de directe omgeving buiten de kassen op onkruiden e.d. voorkomen, leidde tot de conclusie dat resistente spintmijten niet buiten de kas voorkomen. De resistentie van spintpopulaties is op de verschillende bedrijven in Aalsmeer zelfstandig spontaan opgetreden. Er bleek geen correlatie te bestaan tussen de verschillende waardplanten (roos, anjer enGerbera) en het optreden van resistentie.Summary During the year 1958 the susceptibility to acaricides of a number of populations of the two-spotted spider mite (Teranychus urticae Auct.) occurring in several nurseries in Aalsmeer (fig. 5) was studied at the Experimental Station for Floriculture at Aalsmeer, The Netherlands.The susceptibility of a population was examined by placing 50 adult female mites on a bean plant, treated with an acaricide. The percentage mortality was determined after four days.In these experiments both spider mite populations in the greenhouses (on roses, carnations andGerbera) and those in the open air near the greenhouses (on weeds) were studied. Fig. 1 gives the susceptibility of the different populations for water, parathion, diazinon, demeton (Systox) and kelthane. Of the 22 populations from glasshouses 20 proved to be resistant to organic P-compounds. Of those collected from weeds growing outside the greenhouses, not a single one proved to be resistant, so that it may be taken for granted that the resistant red spider mite, found in the greenhouse, does not survive outside.A number of populations were examined for their susceptibility to some other acaricides (fig. 2). In this experiment the resistance to those organic P-compounds with which the populations had never been treated before, such as phosdrin, thiometon and phenkapton was observed. It clearly illustrates that there is no question of resistance to a definite acaricide, but to the group of organic P-compounds. Resistance to demeton did not prove to be equally strong for every population.In all cases examined chlorinated hydro-carbons, such as kelthane and chlorobenzilate, proved to be normally active. Resistance to this group of acaricides has not yet been found in Aalsmeer.A special case is stated in fig. 3, where the spider mite population in a cucumberhouse, in which no chemical control had been applied, is compared with a population on nettles outside the glasshouse and a resistant population in a rosehouse of the same nursery.An experiment, repeated on several dates over a period of 13 months (fig. 4), shows that there was no important shift in the susceptibility of the population studied. It is clear that the resistance of two-spotted spider mites to organic P-compounds has been developed in Aalsmeer independently in more than twenty separate glasshouses.In no case the host plant (carnation, rose,Gerbera) proved to have an appreciable influence on the appearence of resistance.     

Purification and partial characterization of a glutathione S-transferase from the two-spotted spider mite, Tetranychus urticae

Glutathione S-transferases (GSTs) are known to catalyze conjugations by facilitating the nucleophilic attack of the sulfhydryl group of endogenous reduced glutathione on electrophilic centers of a vast range of xenobiotic compounds, including insecticides and acaricides. Elevated levels of GSTs in the two-spotted spider mite, Tetranychus urticae Koch, have recently been associated with resistance to acaricides such as abamectin [Pestic. Biochem. Physiol. 72 (2002) 111]. GSTs from acaricide susceptible and resistant strains of T. urticae were purified by glutathione-agarose affinity chromatography and characterized by their Michaelis-Menten kinetics towards artificial substrates, i.e., 1-chloro-2,4-dinitrobenzene and monochlorobimane. The inhibitory potential of azocyclotin, dicumarol, and plumbagin was low (IC₅₀ values > 100 μM), whereas ethacrynic acid was much more effective, exhibiting an IC₅₀ value of 4.5 μM. GST activity is highest in 2-4-day-old female adults and dropped considerably with progressing age. Furthermore, molecular characteristics were determined for the first time of a GST from T. urticae, such as molecular weight (SDS-PAGE) and N-terminal amino acid sequencing (Edman degradation). Glutathione-agarose affinity purified GST from T. urticae strain WI has a molecular weight of 22.1 kDa. N-terminal amino acid sequencing revealed a homogeneity of ≈50% to insect GSTs closely related to insect class I GSTs (similar to mammalian Delta class GSTs).     

联肼·乙螨唑对蔬菜优势叶螨产卵发育的影响及其田间防效

为明确新型复配杀螨剂联肼·乙螨唑对目前蔬菜田常发生的2种优势叶螨二斑叶螨Tetranychus urticae和截形叶螨T. truncatus的杀螨活性,于室内采用离体叶碟法测定其对这2种叶螨产卵及发育的影响,于室外采用活体植株评价该药剂对2种叶螨的田间防效。结果表明,经复配杀螨剂联肼·乙螨唑及其单剂处理2种叶螨雌成螨24 h后,死亡率为20.50%～54.98%,均显著高于清水对照;联肼·乙螨唑处理较清水对照显著降低了2种叶螨卵发育至若螨期的比率,联肼·乙螨唑处理后二斑叶螨和截形叶螨的若螨率分别为4.91%和1.63%。田间试验中联肼·乙螨唑对2种叶螨具有一定的速效性,药后3 d对二斑叶螨和截形叶螨的防效分别达95.74%和89.83%,药后7 d防效分别为98.03%和99.44%,显示了优良的防控效果及持效性。表明复配杀螨剂联肼·乙螨唑可用于田间蔬菜优势叶螨种群的高效防控。     

Effects of azadirachtin on Tetranychus urticae (Acari: Tetranychidae) and its compatibility with predatory mites (Acari: Phytoseiidae) on strawberry

BACKGROUND: The spider mite, Tetranychus urticae, is the major strawberry pest in Brazil. The main strategies for its control comprise synthetic acaricides and predatory mites. The recent register of a commercial formula of azadirachtin (Azamax^® 12 g L^?1) can be viable for control of T. urticae. In this work, the effects of azadirachtin on T. urticae and its compatibility with predatory mites Neoseiulus californicus and Phytoseiulus macropilis in the strawberry crop were evaluated. RESULTS: Azadirachtin was efficient against T. urticae, with a mortality rate similar to that of abamectin. In addition, the azadirachtin showed lower biological persistence (7 days) than abamectin (21 days). Azadirachtin did not cause significant mortality of adult predatory mites (N. californicus and P. macropilis), but it did reduce fecundity by 50%. However, egg viability of the azadirachtin treatments was similar to that of the control (>80% viability). The use of azadirachtin and predatory mites is a valuable tool for controlling T. urticae in strawberry crop. CONCLUSIONS: Azadirachtin provided effective control of T. urticae and is compatible with the predatory mites N. californicus and P. macropilis. It is an excellent tool to be incorporated into integrated pest management for strawberry crop in Brazil. Copyright © 2012 Society of Chemical Industry     

Synthesis of some new ether derivatives of hydroquinone and their ovicidal activity against the two-spotted spider mite (Tetranychus urticae Koch)

A new class of compounds derived from hydroquinone ethers showed high and predominantly ovicidal activity against the two-spotted spider mite, Tetranychus urticae Koch. The sequence of compounds synthesised and the factors which appeared to have contributed most to the discovery of these promising acaricides are presented.     

Acaricides Against Boophilus microplus (Canestrini) on Holstein Cattle in Trinidad

Abstract

Small scale field trials were conducted to compare toxicity and residual activity on Holstein cattle of seven acaricides against Boophilus microplus (Canestrini) in Trinidad. Tick populations were assessed before and after a single spraying at which the makers' recommended dilutions of acaricides were used. The effects were examined on a basis of a) initial kill of immature ticks, b) effects on the viability of engorged females, c) residual effect in preventing larval reattachment.

Dioxathion had the longest residual activity of seven days. Chlorfenvinphos had an initial quick kill and short residual action similar to carbaryl. Ethion and chlorpyrifos were considered as equivalent to dioxathion except for a shorter residual activity. Both crotoxyphos and pyrimithate, although effective against immature ticks, did not show equivalent activity against engorged females. Chlorfenvinphos and dioxathion were considered the best alternatives to carbaryl in Trinidad. The need to relate choice of acaricide to cost effectiveness as well as technical efficiency was emphasised. The possible usefulness of the trial to other Caribbean islands is mentioned.     

Field and laboratory experiments on the response and development of resistance to pesticides and population density ofTetranychus cinnabarinus in ISRAEL

Dosage mortality data for 12 pesticides were determined with females of an insecticide-susceptible strain of the carmine spider mite,Tetranychus cinnabarinus (Boisd.), by the slide dip method; for four of the pesticides which are specific acaricides, also the Munger cell method was used. The LC₅₀s ranged from 0.00078% to 0.041%, with the synthetic pyrethroids being more toxic than the specific acaricides. There were no differences in results between the two assay methods. Four synthetic pyrethroids that were very active againstT. cinnabarinus in laboratory tests were examined in an unsprayed apple orchard for their effect on the population density of spider mites. An upsurge of tetranychid mites was noted 4 weeks after a single application     

Induction of cytochrome P450 monooxygenase activity in the two-spotted spider mite Tetranychus urticae and its influence on acaricide toxicity

Detoxification by cytochrome P450 monooxygenases is an important mechanism involved in pesticide resistance in insects and mites. The activity of these enzymes can be induced by a variety of chemicals. The aim of this study was to evaluate the effect of six P450 inducers (phenobarbital, barbital, 3-methylcholanthrene, geraniol, isosafrole, pentamethylbenzene), known to have an inducing activity in insects and mammals, on the O-deethylation activity in the two-spotted spider mite Tetranychus urticae. Treatment with barbital, phenobarbital and geraniol resulted in a dose-dependent increase in activity. Neither 3-methylcholanthrene, isosafrole nor pentamethylbenzene were effective inducers. Time course studies showed that induction by geraniol and barbital started rapidly within a period of 1-4 h after initiation of the treatment, while maximal activity was reached within 4 and 48 h, respectively. In addition, it was shown that induction with xenobiotic compounds can alter the monooxygenase-mediated acaricide tolerance in a susceptible strain of T. urticae. Although barbital induced higher levels of P450 activity, geraniol proved to be a better compound to decrease toxicity of the tested acaricides.     

Untersuchungen zur Akarizidresistenz an Populationen der Obstbaumspinnmilbe, Panonychus ulmi KOCH (Acari: Tetranychidae) aus dem Bodenseegebiet

One of the major acarine pest species of deciduous fruit trees like apple and plum is the European red mite, Panonychus ulmi KOCH (Acari: Tetranychidae). Feeding damage by P. ulmi results in leaf bronzing followed by an early defoliation and a reduction in yield, which is usually prevented by the application of acaricides. A problem often associated with mite control is the (sometimes rapid) development of resistance due to their high reproductive potential, a short life cycle allowing numerous generations per season and frequent applications of acaricides. Therefore a resistance monitoring is considered to be an essential part within resistance management strategies where only compounds providing full efficacy at recommended rates should be used. Once a new acaricide is considered for market introduction a so-called baseline susceptibility study is requested by the European authorities. Such a baseline study was also conducted for the new acaricidal compound spirodiclofen (Envidor^®), which is known to inhibit lipid biosynthesis and particularly active against juvenile stages of tetranychid mite pests such as P. ulmi. However, a strong reduction of female adult fecundity results in excellent residual efficacy. Here we report on the baseline susceptibility of 15 European red mite populations against spirodiclofen, which were collected in 2005 in apple orchards at Lake Constance, Germany. The baseline data were combined because of a low population-to-population variation in response to spirodiclofen and a composite dose effect calculation revealed a diagnostic concentration (LC₉₅) of 5?mg/liter (ppm) for future monitoring purposes in P. ulmi larvae. Furthermore we checked the susceptibility of the very same field populations against pyridaben, hexythiazox and abamectin. This helps to identify candidates for a balanced resistance management strategy avoiding the implication of cross-resistance issues.     

Transovarial biotransference of etoxazole through a terrestrial trophic web

BACKGROUND: Transovarial transport is defined as the passage of chemicals from the maternal body to eggs within the ovaries. Little is known about the effects of transovarial transport on non‐target species. This study evaluates etoxazole (a transovarial acaricidal compound) on a terrestrial trophic web consisting of a ubiquitous phytophagous mite, Tetranychus urticae Koch, and three species of predatory mites. RESULTS: Predatory mite females that consumed eggs laid by etoxazole‐treated T. urticae also produced infertile eggs. There was a negative relationship between the proportion of etoxazole‐treated T. urticae females and the instantaneous rate of predatory mite increase at the population level (r² = 0.86). Reduced fertility of etoxazole‐treated T. urticae females continued for 18 days following application. Eggs laid by etoxazole‐treated T. urticae females remained toxic to predatory mite females for 42 days after treatment. CONCLUSIONS: Transovarial transport could lead to magnification in the ecosystem by enhancing both bioavailability and movement of an active ingredient. The potential for enhancement of residual activity by terrestrial organisms and its significance once reaching the food web should be taken into account for new classes of acaricides and insecticides. Copyright © 2012 Society of Chemical Industry     

Compatibility of traditional and novel acaricides with bumblebees (Bombus terrestris): a first laboratory assessment of toxicity and sublethal effects

BACKGROUND: This project assessed the potential hazards of different classical and novel acaricides against an important non‐target and beneficial insect for the pollination of wild flowers and cultivated crops, the bumblebee Bombus terrestris (L). Twenty‐three acaricides used commercially in the control of phytophagous mites (Acari) were tested in greenhouses and/or the open field. Side effects included acute mortality and also sublethal effects on nest reproduction. The different compounds were administered in the laboratory via three different worst‐case field scenario routes of exposure: dermal contact and orally via the drinking of treated sugar water and via treated pollen. The compounds were tested at their respective maximum field recommended concentration (MFRC), and, when strong lethal effects were observed, a dose–response assay with a dilution series of the MFRC was undertaken to calculate LC₅₀ values. RESULTS: From the different acaricide classes, several chemistries caused high levels of acute toxicity in bumblebee workers, especially bifenthrin and abamectin which resulted in 100% mortality by contact. In addition, several acaricides tested were found to have a detrimental effect on drone production. For oral exposures via treated sugar water, the dose–response assay showed the LC₅₀ values for abamectin, bifenazate, bifenthrin and etoxazole to be 1/15 MFRC (1.17 mg AI L^?1), 1/10 MFRC (9.6 mg AI L^?1), 1/83 MFRC (0.36 mg AI L^?1) and 1/13 MFRC (4.4 mg AI L^?1) respectively, indicating that their use should be carefully evaluated. CONCLUSION: Overall, the results suggest that most of the acaricides tested are compatible with bumblebees, with the exceptions of abamectin, bifenazate, bifenthrin and etoxazole. However, the risks also depended on the type of treatment. As a result, the sugar water treatment seems to present the worst‐case situation of exposure, indicating that this approach is suitable for determining the hazards of pesticides against bumblebees. Finally, it is suggested that future tier testing under more field‐related conditions is required for a final decision of their risks. Copyright © 2010 Society of Chemical Industry     

大环内酯类新化合物天维菌素杀螨活性及田间防治效果

为明确新化合物天维菌素的杀螨活性,采用叶碟喷雾法测定了在室内天维菌素对朱砂叶螨Tetranychus cinnabarinus、柑橘红蜘蛛Panonychus citri及二斑叶螨Tetranychus urticae的毒力,并研究了其制剂对螨类害虫的田间防治效果。结果表明,天维菌素对朱砂叶螨若螨和雌成螨均具有较高的毒力,其LC50分别为0.011、0.11 mg(a.i.)/L,杀螨活性优于弥拜霉素、阿维菌素,但杀卵活性较差。田间试验中2%天维菌素微乳剂具有良好的速效性且具有一定的持效期,在有效成分8~40 mg/kg剂量下,对朱砂叶螨和二斑叶螨药剂处理14 d的防治效果分别为83.22%~92.77%和85.49%~92.64%,有效控制期在14 d以上;在有效成分75 mg/kg剂量下,对柑橘红蜘蛛防治效果最好,处理1、3、7、14 d的防治效果分别达96.53%、97.72%、98.05%和91.42%。表明天维菌素具有作为杀螨剂的潜力。