Adding microencapsulated pear ester to insecticides for control of Cydia pomonella (Lepidoptera: Tortricidae) in apple

BACKGROUND: The possibility of improving the efficacy of various insecticides for codling moth, Cydia pomonella (L.), by the addition of a microencapsulated formulation of pear ester, ethyl (2E, 4Z)‐2,4‐decadienoate (PE‐MEC, 5% AI), was evaluated in field trials in apple from 2005 to 2009. RESULTS: The addition of PE‐MEC (<3.0 g AI ha^?1) significantly lowered fruit injury with low rates of organophosphate and neonicotinoid insecticides. The addition of PE‐MEC (1.48 g AI ha^?1) to maximum label rates of insecticides with moderate activity for codling moth, such as ebamectin benzoate, spinosad and methoxyfenozide, significantly improved their effectiveness. However, PE‐MEC did not consistently improve the activity of maximum label rates of either rynaxypyr or spinetoram. The addition of PE‐MEC with seasonal spray programs of acetamiprid and azinphos‐methyl in combination with the use of sex pheromones for mating disruption provided the most effective control. CONCLUSION: The addition of PE‐MEC can improve the effectiveness of some insecticides for codling moth in apple. Insecticides active via dermal toxicity are more strongly improved by the addition of PE‐MEC. Season‐long use of PE‐MEC can also augment the effectiveness of mating disruption. Adding PE‐MEC to variable integrated management programs for C. pomonella should be further investigated. Published 2012 by John Wiley & Sons, Ltd.     

Potential of Heterorhabditis zealandica (Rhabditida: Heterorhabditidae) for the control of codling moth,Cydia pomonella (Lepidoptera: Tortricidae) in semi-field trials under South African conditions

Infection of codling moth, Cydia pomonella (L.), larvae by the entomopathogenic nematode, Heterorhabditis zealandica, was studied under semi-field conditions. Late-instar diapausing codling moth larvae, coccooned in perforated cardboard strips, were used in all trials to evaluate the nematode treatments involved. A morning application of 0.5, 1.0 and 1.5 MM infective juveniles (IJs) per tree resulted in 85%, 95% and 100% codling moth larval infection, respectively. Contrasting results were obtained for an evening application, with low levels of codling moth infection (<50%). Nematode treatment strips placed in direct sunlight resulted in almost no infection (<10%), opposed to strips attaining 67% infection placed in the shade.     

Targeting Cydia pomonella (L.) (Lepidoptera: Tortricidae) adults with low‐volume applications of insecticides alone and in combination with sex pheromone

BACKGROUND: Studies surveyed the toxicity of several insecticides against adult codling moth, Cydia pomonella (L.), and examined the field effectiveness of applying low‐volume (12 L ha^?1) sprays alone or in combination with a microencapsulated (MEC) sex pheromone formulation. RESULTS: Neonicotinyls, organophosphates and synthetic pyrethroids significantly reduced fecundity at concentrations nearly 100‐fold lower than their maximum labeled field rate. Field studies in 2005 demonstrated that six applications of esfenvalerate resulted in > 90% reduction in fruit injury versus the untreated check. The addition of the MEC pheromone formulation did not further improve control. Five sprays of esfenvalerate, phosmet and acetamiprid all significantly reduced levels of fruit injury compared with the untreated control in 2006. Esfenvalerate and acetamiprid mixed with the MEC pheromone significantly reduced fruit injury compared with the MEC‐only treatment. Significant increases in pest and decreases in predator mite densities occurred in plots treated with esfenvalerate in both years. Low‐volume sprays of phosmet and acetamiprid did not disrupt mites. CONCLUSION: Low‐volume insecticide sprays can effectively manage codling moth and are less disruptive of integrated mite management. Developing an effective ‘attract and kill’ technology with this approach will require optimization of the attractant(s) to maximize moth exposure to insecticide residues. Published 2010 by John Wiley & Sons, Ltd.     

Resistance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), larvae in Michigan to insecticides with different modes of action and the impact on field residual activity

BACKGROUND: The codling moth is one of the principal pests of apple in the world. Resistance monitoring is crucial to the effective management of resistance in codling moth. Three populations of codling moth in neonate larvae were evaluated for resistance to seven insecticides via diet bioassays, and compared with a susceptible population. In addition, apple plots were treated with labeled field rate doses of four insecticides. Treated fruit were exposed to neonate larvae of two populations from commercial orchards. RESULTS: Two populations of codling moth expressed two‐ and fivefold resistance to azinphos‐methyl, seven‐ and eightfold resistance to phosmet, six‐ and tenfold resistance to lambda‐cyhalothrin, 14‐ and 16‐fold resistance to methoxyfenozide and sixfold resistance to indoxacarb, but no resistance to acetamiprid and spinosad. The impact of the resistance to azinphos‐methyl, measured as fruit damage, increased as the insecticide residues aged in the field. In contrast, fruit damage in methoxyfenozide‐ and lambda‐cyhalothrin‐treated fruit was observed earlier for resistant codling moth. No differences in efficacy were found for acetamiprid. CONCLUSIONS: Broad‐spectrum insecticide resistance was detected for codling moth. Resistance to azinphos‐methyl, lambda‐cyhalothrin and methoxyfenozide was associated with reduced residual activity in the field. Broad‐spectrum resistance presents serious problems for management of the codling moth in Michigan. Copyright © 2008 Society of Chemical Industry     

Toxicological and biochemical response to azinphos-methyl in Cydia pomonella L. (Lepidoptera: Tortricidae) among orchards from the Argentinian Patagonia

BACKGROUND: Azinphos‐methyl is the main insecticide used to control codling moth on apple and pears in Northern Patagonia. The aim of this study was to evaluate the toxicological and biochemical response of diapausing larvae of codling moth in orchards subjected to different insecticide selection pressure. RESULTS: Dose–mortality assays with azinphos‐methyl in diapausing larvae of Cydia pomonella L. showed significant differences between the LD₉₅ from a population collected in one untreated orchard (2.52 µg moth^?1) compared with that in a laboratory‐susceptible population (0.33 µg moth^?1). Toxicity to azinphos‐methyl in field populations of diapausing larvae collected during 2003–2005 was evaluated by topical application of a discriminating dose (2.5 µg moth^?1) that was obtained from larvae collected in the untreated orchard (field reference strain). Significantly lower mortality (37.71–84.21%) was observed in three out of eight field populations compared with that in the field reference strain. Most of the field populations showed higher esterase activity than that determined in both the laboratory susceptible and the field reference strains. Moreover, there was a high association between esterase activity and mortality (R² = 0.64) among the field populations. On the other hand, a poor correlation was observed between glutathione S‐transferase activity and mortality (R² = 0.33) among larvae collected from different orchards. CONCLUSIONS: All the field populations evaluated exhibited some degree of azinphos‐methyl tolerance in relation to the laboratory susceptible strain. Biochemical results demonstrated that esterases are at least one of the principal mechanisms involved in tolerance to this insecticide. Copyright © 2008 Society of Chemical Industry     

Plant volatile compounds shorten reaction time and enhance attraction of the codling moth (Cydia pomonella) to codlemone

BACKGROUND: The codling moth is the most serious pest of deciduous tree fruit (apples, pears, crabapples, walnuts, quince) worldwide. The high frequency of insecticide treatments per season has resulted in breakdown of codling moth control owing to insecticide resistance. As an alternative, integrated pest management includes mating disruption to achieve population suppression in orchards. Under this scheme, the sex pheromone of the codling moth, (E, E)‐8,10‐dodecadien‐1‐ol (codlemone), is released from dispensers in crops to hinder mating by luring males. Increasing the attractiveness of codlemone formulations to codling moth males can be regarded as a key to increasing the efficacy of mating disruption. With this aim, the effects of adding plant volatiles on the behavioural responses of codling moth males to codlemone were tested. RESULTS: Adding R(+)‐limonene, linalool, (E)‐β‐farnesene or ethyl (E, Z)‐2,4‐decadienoate to codlemone significantly increases the proportion of males flying to the pheromone source in a wind tunnel. The response level is equivalent to that of males responding to females releasing codlemone. Using real‐time recordings, it is shown how these four plant products also shorten the response time of males to codlemone under the behavioural criteria time to activation, time till upwind flight is induced and time to pheromone source contact. CONCLUSION: Shortening the response time and increasing source location by males of dispensers releasing codlemone with R(+)‐limonene, linalool, (E)‐β‐farnesene or ethyl (E, Z)‐2,4‐decadienoate added would enhance mating disruption through better engagement of males with dispensers, to the detriment of females. Copyright © 2011 Society of Chemical Industry     

Reduced egg viability in codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) following adult exposure to novaluron

BACKGROUND: The codling moth, Cydia pomonella (L.), is one of the principal pests of pome fruits in the world. The effects of novaluron, a benzoylurea chitin synthesis inhibitor insecticide registered for use on apples in the USA, on fecundity and egg viability in codling moth were studied under laboratory conditions. Three different exposure methods were investigated: ingestion, contact and topical spray. Additionally, the duration of novaluron sublethal effects was measured subsequent to the three modes of exposure. RESULTS: The fecundity of codling moth adults was not significantly affected by novaluron with any of the exposure methods. However, novaluron did cause significant reductions in the proportion of egg hatch with all three exposure methods. The duration of sublethal effects was 9 days or more for all modes of exposure, but with the topical spray these effects began to diminish after 6 days. CONCLUSION: Novaluron does not affect fecundity in codling moth, but has significant sublethal activity by reducing egg viability subsequent to adult exposure. The topical, contact and ingestion exposures all induce sublethal effects after exposure, and these persist to various degrees throughout codling moth oviposition. A more complete understanding of novaluron's lethal and sublethal activities will help IPM practitioners optimize its use for management of the codling moth. Copyright © 2008 Society of Chemical Industry     

Control of the codling moth (cydia pomonella) in apple and pear orchards in Israel by mating disruption

Control of the codling moth,Cydia pomonella (L.) (Lepidoptera: Tortricidae), by pheromone-mediated mating disruption, was studied in Israel using two types of dispensers: Shin-Etsu twist-tie (normal and long-life) and TNO matrix formulation (square wafers). Factors affecting mating disruption: initial pest population density, timing of the pheromone application, early season insecticide treatments and monitoring of the pest, were evaluated. Efficacy of mating disruption was assessed by comparing catch of males in pheromone traps located in pheromone-treated and chemically sprayed control plots. Fruit infestation during the season and at picking time was the major criterion to assess mating disruption. The preferred time for pheromone application was before the first flight of the moth. When pheromones were applied at a later stage, one or two early insecticide sprays had to be used to reduce the initial level of the codling moth population. In all tests, trap catch in pheromone-treated plots was drastically reduced as compared with respective control plots. In pheromone-treated plots where total seasonal trap catch (after pheromone application) was less than 12 males/trap, fruit infestation was less than 1.5%; zero trap catch resulted in 0.1-0.3% infestation. At high population levels, mating disruption was ineffective, with the rate of infestation at picking-time being similar in pheromone-treated and control plots. All the field tests indicated that mating disruption with either Shin-Etsu ropes or TNO squares can control codling moth infestations in apple and pear orchards, at relatively low densities of the pest, as efficiently as commercial insecticide sprays.     

Cross‐resistance between azinphos‐methyl and acetamiprid in populations of codling moth,Cydia pomonella (L.) (Lepidoptera: Tortricidae), from Washington State

BACKGROUND: Codling moth, Cydia pomonella (L.), has been intensely managed with the organophosphate insecticide azinphos‐methyl for 50 years, and populations have developed resistance. New management programs have been developed and implemented that rely more heavily on other classes of insecticides. A prerequisite for developing effective resistance management strategies for these compounds is to establish their current levels of effectiveness. Adult and neonate larval assays were conducted to assess the response of field‐collected codling moth populations from apple in Washington State. RESULTS: Male codling moth populations exhibited a range of responses to a discriminating concentration of azinphos‐methyl in a survey of 20 populations. Populations from certified organic orchards were more susceptible than those from conventional orchards. Mean fecundity was inversely related to azinphos‐methyl tolerance. Male responses to azinphos‐methyl and acetamiprid varied significantly among populations and were correlated. The residual effectiveness of field applications of both insecticides varied significantly against neonate larvae. Neonate bioassays with insecticide‐dipped fruit found significant differences among populations with azinphos‐methyl, acetamiprid, methoxyfenozide and spinosad, but not with esfenvalerate. CONCLUSION: These results support a concern that alternation of insecticides with different modes of action may not be a sufficient strategy to avoid the evolution of broad‐spectrum insecticide resistance by codling moth. Published 2010 by John Wiley & Sons, Ltd.     

Prospects of monosodium glutamate use for enhancement of spinosad toxicity against codling moth neonates

It was demonstrated that neonates of the codling moth,Cydia pomonella (L.), feed on ‘Red Delicious’ apple leaves and successfully molt to the second instar. Next, using a non-choice bioassay, we targeted codling moth neonates feeding on apple leaves, with standard concentrations of a culinary taste enhancer, monosodium glutamate (MSG), and Success®, which contains 22.8% spinosad as its active ingredient. The addition of 25 ppm MSG increased feeding by 20–30%. Stimulatory properties of MSG were preserved in the presence of 12.5 ppm Success, and mortality from a 12.5 ppm Success + 25 ppm MSG combination increased by factors of 3.1–1.6 compared with Success alone. In a field experiment without rain, MSG maintained its stimulatory properties for 24 h, increasing feeding by 37%. Consistently, without rain, MSG increased the toxicity of Success in the field by a factor of × 3.5. However, the stimulatory properties of MSG dropped to 19% with 4.3 mm of rain, and to zero with 9.6 mm of rain. Increased Success toxicity by MSG was reduced to × 1.6 with 4.3 mm of rain, and dropped to zero after 9.6 mm of rain. It is concluded that MSG seems to be a promising feeding stimulant, enhancing the toxic properties of Success which itself is a good candidate for codling moth control. However, field persistence of MSG needs to be improved, either by formulating the Success + MSG combination into some field-stable matrix, or by employing a sparingly water-soluble substance mimicking MSG’s action as a feeding stimulant in codling moth neonates.     

苹果蠹蛾在辽宁省彰武县梨树上的发生规律

为明确辽宁省苹果蠹蛾Cydia pomonella(Linnaeus)的发生规律,于2014—2016年连续3年对辽宁省彰武县哈尔套镇10个村59个不同梨园采用三角屋胶粘式诱捕器进行了雄成虫数量消长动态的监测,并对幼虫蛀果率、老熟幼虫数量及化蛹行径、蛹期进行调查。结果表明,在辽宁省彰武县,从4月下旬至9月下旬,苹果蠹蛾成虫共有2次发生高峰:第1次为5月下旬,第2次为7月中下旬;苹果蠹蛾在2016年全年内有3次明显的蛀果高峰期:第1次为6月下旬至7月上旬,第2次为8月上旬,第3次为8月下旬。老熟幼虫更趋向于脱果后直接掉落到地上再从地上沿着树干往上爬并在老翘皮下寻找合适位置化蛹;苹果蠹蛾经人工饲养的蛹期为9.95 d。研究表明,苹果蠹蛾在辽宁省彰武县1年发生2代,第1代从5月中旬到9月下旬,越冬代从7月中旬到翌年6月下旬。     

Parasitoids on codling moth Cydia pomonella (Lepidoptera: Tortricidae) in apple and walnut orchards in Syria

A survey was performed between 2007 and 2013 to investigate the complex of parasitoids on Cydia pomonella (codling moth) in apple and walnut orchards in Syria. This study showed the presence of 17 species belonging to 7 families from two orders (Hymenoptera and Diptera). The families Ichneumonidae and Braconidae were most common, comprising 8 and 4 species, respectively. Mastrus ridibundus and Neoplectops pomonella were new records for Syria.     

Development of a rapid resistance monitoring bioassay for codling moth larvae

BACKGROUND: The codling moth, Cydia pomonella (L.), is one of the most important pests of apple worldwide. Use of insecticides for management of this insect has been extensive and has resulted in resistance development. There are a number of different bioassay methods to monitor for codling moth resistance; however, many are not applicable to new insecticides and most are time consuming. A novel 16‐well plasticware bioassay plate containing lyophilized diet was developed for rapid resistance monitoring of codling moth. RESULTS: The contact insecticides acetamiprid and azinphosmethyl were significantly more toxic to neonates than to fourth instars. However, there was no significant difference in LC₅₀ values between neonates and fourth instars to the ingestion insecticides chlorantraniliprole, methoxyfenozide, novaluron and spinetoram. Field colonies of codling moth were significantly more resistant to methoxyfenozide than susceptible populations. A diagnostic dose of 20 µg mL^?1 (LC₉₉) was established to monitor for codling moth resistance to methoxyfenozide. CONCLUSIONS: The results presented here demonstrate that a novel and rapid bioassay can be used to monitor for codling moth resistance to methoxyfenozide. The bioassay method is relevant to both ingestion and contact insecticides, but a single diagnostic dose, regardless of larval age, is only relevant to ingestion insecticides. Age‐dependent diagnostic doses are likely necessary for contact insecticides. Copyright © 2011 Society of Chemical Industry     

迷向防治技术对苹果蠹蛾的田间防治效果

选取甘肃省12个苹果蠹蛾发生县区,研究了迷向防治技术对苹果蠹蛾的防治效果。结果表明:在种群密度较低(平均蛀果率在1%以下)的果园(连片面积17hm~2),采用迷向防治技术,即在诱捕到第1头苹果蠹蛾成虫(4月末5月初)后进行第1次悬挂迷向条(120~150根/hm~2),7月中旬进行第2次补充悬挂,可有效控制苹果蠹蛾为害,成虫诱蛾量和蛀果率分别较对照下降90.8%和92.6%,成虫无明显的诱集高峰;采用迷向防治的果园,增加化学防治次数,对防治效果影响不显著(P0.05)。本研究证实苹果蠹蛾迷向防治技术有较好的防治效果,虽然防治成本相对较高,但减少了环境污染,是未来值得推广的绿色防控技术措施。     

中国及欧洲各国的苹果蠹蛾种群遗传多样性分析

为研究不同国家和地区苹果蠹蛾Cydia pomonella种群的遗传多样性,对采自我国新疆维吾尔自治区和黑龙江省,以及德国、法国和西班牙等欧洲国家的11个种群共60个苹果蠹蛾个体进行基因组重测序,有效测序样本数为56个,共获得8 455 843个群体单碱基突变（single nucleotide polymorphism,SNP）位点。利用SNP数据进行了苹果蠹蛾群体遗传进化树的构建、主成分分析以及遗传结构分析。结果显示,入侵我国黑龙江省的苹果蠹蛾与德国BD种群更为接近,我国新疆维吾尔自治区与黑龙江省苹果蠹蛾种群有一定的分化,前者种群遗传多样性更低。表明我国东北地区和西北地区的苹果蠹蛾种群具有不同的遗传多样性特征,入侵我国的苹果蠹蛾种群可能来源于欧洲。     

Spatial analysis of pheromone trap catches of codling moth (<Emphasis Type="Italic">Cydia pomonella</Emphasis>) in two heterogeneous agro-ecosystems,using geostatistical techniques

From 2000 to 2002, local distribution and dispersion patterns of the codling moth,Cydia pomonella (L.) (Lepidoptera: Tortricidae), captured in pheromone traps were investigated in two heterogeneous agro-ecosystems (A and B) of the Molise region, in central Italy. The main objectives of this study were to determine the temporal and spatial variations in distribution and abundance of codling moth inside and outside apple orchards located in these study areas, and to evaluate the importance of the presence of several host plants in relation to the observed distribution. Trap catches of male moths were clumped during almost all sampling weeks. Spatial characterizations obtained by means of geostatistical methods illustrate that the high trap capture foci were confined to the productive apple orchards for both agro-ecosystems or in small groups of apple trees, and in the case of study area B, in a zone containing pear trees, service trees and walnut trees. Occasionally moths were found in traps installed outside these zones. Furthermore, the position of high male population foci seems not to change during a single flight period. The results obtained are discussed with respect to the improvement of Integrated Pest Management programs employed in apple orchards situated in heterogeneous landscapes. http://www.phytoparasitica.org posting July 14, 2004.     

Diurnal variation of walnut tree volatiles and electrophysiological responses in Cydia pomonella (Lepidoptera: Tortricidae)

BACKGROUND: In recent years, many studies have been carried out on the behavioural and electrophysiological responses of Cydia pomonella (L.) to host volatile emissions, to find alternative attractants to the sex pheromone for pest monitoring. These studies have focused on apple and pear, and very little has been done on walnut. In the present work, the diurnal and seasonal variation in walnut volatile emissions and the electrophysiological response of C. pomonella have been studied. RESULTS: Ninety compounds were detected in walnut emissions, mainly monoterpenes and sesquiterpenes. The most abundant compound was β‐pinene, which, together with (Z)‐3‐hexenyl acetate, (E)‐β‐ocimene, limonene, germacrene D, 1,8‐cineole, sabinene, (E)‐β‐farnesene, (E)‐β‐caryophyllene, β‐myrcene and β‐phellandrene, constituted between 81.9 and 90.5% of the total chromatographic area. Differences between seasonal periods were significant for 39 compounds, and between daytimes for 14 compounds. Discernible and consistent EAD responses were detected to 11 walnut‐origin compounds, and confirmed with synthetics to seven of them. Except for alloocimene, pinocarvone and caryophyllene oxide, all these compounds are also emitted by apple. CONCLUSION: Walnut volatile emissions differ widely from apple ones, but both share many compounds that are EAD‐active in C. pomonella. However, among EAD‐active compounds there are three walnut‐specific ones, which should be further tested in behavioural assays. Copyright © 2008 Society of Chemical Industry     

Factors affecting the field performance of an attracticide against the codling moth Cydia pomonella

Factors affecting the efficacy of an attracticide strategy for the control of the codling moth Cydia pomonella L (Lepidoptera: Tortricidae) were investigated using laboratory and field experiments. The sex-pheromone-based insect-control strategy utilises 100-microliters droplets of a sticky, paste-like formulation containing 1 mg g-1 (E,E)-8,10-dodecadien-1-ol (codlemone) as an attractant for male moths and 40 mg g-1 cyfluthrin, a contact insecticide, applied to branches in the upper parts of the tree crown. The longevity of the treatment under field conditions was assessed in the laboratory by biological testing of variously aged samples of the attracticide formulation which had been applied to the bark of apple trees growing in commercial orchards. Electroantennogram responses of male moth antennae were used to compare codlemone release from the attracticide after different lengths of environmental exposure. Changes in insecticidal efficacy of the same samples were assessed with reference to the speed of knockdown (KT50) and the mortalities after 48 h among populations of male moths confined in cages containing samples of fresh and field-aged formulations. Gradual declines in both the amount of pheromone released and insecticidal activity were observed over the 10-week period of the experiments. Various factors associated with the behaviour of codling moths in the field which might influence the attracticide strategy were also investigated. Although the vertical position of attracticide sources within apple trees had a strong influence on their attractiveness, their horizontal position had none. Results of field trials showed that efficacy of the attracticide depends on the population density of the pest. Under the conditions of the current study a density of three or more sources per tree (= 4500 sources per ha) was required to attain satisfactory levels of codling moth control.     

苹果蠹蛾在中国的适生性分析

苹果蠹蛾是严重危害全球水果生产的一种重要害虫。本研究根据中国760个气象站点的气象数据和苹果蠹蛾生物学数据,综合运用CLMEX模型和ArcGIS分析相结合的方法,对苹果蠹蛾在中国的适生性进行分析。分析结果表明:苹果蠹蛾在我国的适生区域较为广泛。中高度适生区主要包括黑龙江、内蒙古、山西、宁夏、甘肃,吉林、北京、陕西、新疆、西藏的大部分地区,辽宁西部、河北西部和北部、青海北部、云南北部、四川西部、贵州西部及山东沿海地区。     

Azinphos-methyl and carbaryl resistance in adults of the codling moth (Cydia pomonella (L.), Lepidoptera: Tortricidae) from Northeastern Spain

The resistance of Cydia pomonella (L.) to organophosphates is widespread throughout the pome fruit growing areas. The lethal effects of two insecticides inhibitors of the acetylcholine esterase, azinphos-methyl and carbaryl, were evaluated in adults of five and four field populations of the codling moth, respectively. The lethal concentrations (LC₅₀ and LC₉₀) of these insecticides were determined in a susceptible strain from Spain (S_Spain). Topical bioassays using the approximate LC₉₀ values (3000 mg (a.i.)/L of carbaryl and 2000 mg (a.i.)/L of azinphos-methyl) that were obtained in S_Spain were tested as diagnostic concentrations. The enzymatic activities of mixed-function oxidases (MFO), glutathione S-transferases (GST) and esterases (EST) were measured to investigate their potential role in the detoxification of these insecticides.Carbaryl and azinphos-methyl caused ?53% and ?39% corrected mortality, respectively, in field populations, although the diagnostic concentrations applied were twofold and fourfold higher than the maximum concentration registered in Spain, respectively. The activities of MFO and GST were 7.3- to 16.1-fold higher and 2.5- to 3.7-fold higher in all the field populations compared to those in S_Spain, respectively.