High resistance to pyrethroid insecticides in the Polish pollen beetle (<Emphasis Type="Italic">Meligethes aeneus F.</Emphasis>): the role of oxidative metabolism

Pollen beetle (Meligethes aeneus F.) (PB) causes very serious problems in oilseed rape (Brassica napus var. oleifera L.) cultivations in Poland and other European countries. Pyrethroid insecticides are the most frequently used type for controlling PB in Poland. This chemical group has been used in Poland since the beginning of the 1980’s and its strong selection pressure on PB resulted in some level of resistance of this pest to many active substances. The aim of this investigation was to analyze, with the use of synergists, the main mechanisms responsible for resistance of PB to pyrethroids. The results indicate the main resistance factor in Polish PB populations to be monooxygenase enzymes.     

Summary of findings from a participant country pollen beetle questionnaire

A questionnaire was sent to all participating countries to gain some background information on rape growing and on pollen beetle ( Meligethes aeneus ). Information was sought on the use of thresholds, the availability of active substances and on the year in which resistance, if present, had been observed. A summary of the main findings of the questionnaire are presented. In total 20 countries responded and resistance in pollen beetle was reported in 12 of those countries. Information presented shows the range of active substances and doses recommended, frequency of use of insecticides on rape, and year when resistance was reported.     

Pyrethroid resistance and thiacloprid baseline susceptibility of European populations of Meligethes aeneus (Coleoptera: Nitidulidae) collected in winter oilseed rape

BACKGROUND: Pollen beetle, Meligethes aeneus F. (Coleoptera: Nitidulidae), is a major pest in European winter oilseed rape. Recently, control failures with pyrethroid insecticides commonly used to control this pest have been reported in many European countries. For resistance management purposes, the neonicotinoid insecticide thiacloprid was widely introduced as a new mode of action for pollen beetle control. RESULTS: A number of pollen beetle populations collected in Germany, France, Austria, Great Britain, Sweden, Denmark, Finland, Poland, Czech Republic and Ukraine were tested for pyrethroid resistance using lambda‐cyhalothrin‐coated glass vials (adult vial test). Most of the populations tested exhibited substantial levels of resistance to lambda‐cyhalothrin, and resistance ratios ranged from < 10 to > 2000. A similar resistance monitoring bioassay for the neonicotinoid insecticide thiacloprid was developed and validated by assessing baseline susceptibility data for 88 European pollen beetle populations. A variation of less than fivefold in response to thiacloprid was detected. The thiacloprid adult vial bioassay is based on glass vials coated with an oil‐dispersion‐based formulation of thiacloprid, resulting in a much better bioavailability compared with technical material. Analytical measurements revealed a > 56 and 28 day stability of thiacloprid and lambda‐cyhalothrin in coated glass vials at room temperature, respectively. No cross‐resistance between thiacloprid and lambda‐cyhalothrin based on log‐dose probit–mortality data was detected. CONCLUSION: Pyrethroid resistance in many European populations of M. aeneus was confirmed, whereas all populations are susceptible to thiacloprid when tested in a newly designed and validated monitoring bioassay based on glass vials coated with oil‐dispersion‐formulated thiacloprid. Based on the homogeneous results, it is concluded that thiacloprid could be an important chemical tool for pollen beetle resistance management strategies in European winter oilseed rape. Copyright © 2011 Society of Chemical Industry     

Ecological approaches to the control of pollen beetles in oilseed rape

At a time of increasing demand for rapeseed oil for biofuel and food use and as increasing areas are grown, the risk of pollen beetle resistance to pyrethroids presents a significant threat to the sustainability of the oilseed rape crop and to farm incomes. Measures are urgently required to reduce the use of insecticides against pollen beetles, to preserve activity of the limited armoury of insecticides and minimise environmental pollution. In this paper, the status of pollen beetle resistance to pyrethroid insecticides and current control methods are presented from a UK perspective. Three ecological approaches to the control of pollen beetles that are based on research into their behaviour and ecology and that of their natural enemies are highlighted: use of monitoring, trap cropping and conservation biological control. These approaches have the potential to significantly reduce insecticide use against pollen beetles by helping to identify when spray thresholds have been breached, reducing pest incidence in the crop and increasing populations of natural enemies, respectively.     

Control of Colorado beetle (Leptinotarsa decemlineata) in Poland1

Leptinotarsa decemlineata (Colorado beetle) was found in Poland for the first time in 1945 and a great invasion of this pest took place in 1950. It now plays a very important role in Polish plant protection, mainly because the acreage of potato in Poland amounts to about 1.8 million ha. The pest is controlled by repeated insecticide applications to a yearly total of 2 million ha, which is the highest amount of insecticides used in Poland. Research has been carried out in Poland on the following subjects: biology and ecology of Colorado beetle, influence of pest appearance and control on the biocenosis of fields, methods of control, biochemical factors influencing the life cycle, forecasts and warning of appearance, artificial diet, resistance of potato cultivars and reaction of leaf blades of potato to the eggs of Colorado beetle. Research is also carried out on chemical control, modernization of pesticide recommendations and resistance of Colorado beetle to pesticides. The influence of biotic and abiotic factors on the reduction of Colorado beetle numbers has been studied. With a view to possible biological control, predatory bugs (Perillus bioculatus and Podisus maculiventris) were introduced into Poland in 1959 and 1979. Research is also conducted on entomopathogenic fungi, parasitic nematodes, protozoans, spiroplasms and Bacillus thuringiensis.     

Untersuchungen zum gezielten Einsatz von Insektiziden gegen den Rapsglanzkäfer (<Emphasis Type="Italic">Meligethes aeneus</Emphasis>) in der landwirtschaftlichen Praxis des Landes Brandenburg im Zeitraum von 2006 bis 2014

Before 2006, agents of class II pyrethroids were used to control rape pests including the rape pollen beetle mainly. Thus, the selection of pyrethroids-resistant pollen beetle populations was encouraged. The aim of our study was to identify ways to combat these populations. Therefore, data of 465 real on-farm insecticide applications from nine years since 2006 were analyzed with regard to their effects on the pollen beetle and own experiments were carried out to test the efficacy of approved insecticides and control strategies. The analysis showed that the highest efficiencies were obtained with agents of the group of organophosphates and with the active substances indoxacarb and pymetrozine. Beyond that, the data examined revealed that the efficiency of thiacloprid (an insecticide of the class of neonicotinoids) has remained relatively constant throughout the observation period. In contrast, the increase in pyrethroid-resistant pollen beetle populations reflects the further decrease in efficacy of class II pyrethroids in the period 2011–2014.In summary, it should be noted that currently available insecticides achieve a maximal abatement level of 80–85?%. Therefore, an economic damage cannot be prevented on rapeseed locations with a very strong pollen beetle infestation even if multiple use of insecticides happens.To prevent further escalation of the resistance problem, another aspect should be given greater attention in the future. 55?% of the insecticide applications in the practice dataset where carried out before the control threshold (BRW) for weakly developed oilseed rape crops was achieved; often in the stage of micro-bud (BBCH 51). In compliance with the currently suggested higher control threshold, only 15?% of the insecticide applications would have been necessary. Thus, a reduction of the number of insecticide applications could be achieved by considering the higher thresholds. This would significantly reduce the selection pressure. Therefore, plant protection advice should mediate between exploiting the control thresholds and using the most appropriate insecticide.     

Different methods of monitoring susceptibility of oilseed rape beetles to insecticides

The resistance of oilseed rape pollen beetles to lambda-cyhalothrin has increased in Germany over the period 2002 to 2007. Oilseed rape pollen beetles are very good at dispersing, therefore field results should always be compared with those of laboratory experiments. The response of oilseed rape pollen beetles to active substances may not be the same as that to formulated products. Bioassays in which beetles are exposed to insecticides on either complete inflorescences or flower buds give different results. It is evident that samples of the genus Meligethes collected in the field can include several different species. Monitoring for insecticide resistance should be done using only the true oilseed rape pollen beetle.     

Target-site resistance to pyrethroids in European populations of pollen beetle, Meligethes aeneus F.

Pollen beetle, Meligethes aeneus F. (Coleoptera: Nitidulidae) is a major univoltine pest of oilseed rape in many European countries. Winter oilseed rape is cultivated on several million hectares in Europe and the continuous use of pyrethroid insecticides to control pollen beetle populations has resulted in high selection pressure and subsequent development of resistance. Resistance to pyrethroid insecticides in this pest is now widespread and the levels of resistance are often sufficient to result in field control failures at recommended application rates. Recently, metabolic resistance mediated by cytochrome P450 monooxygenases was implicated in the resistance of several pollen beetle populations from different European regions. Here, we have also investigated the possible occurrence of a target-site mechanism caused by modification of the pollen beetle para-type voltage-gated sodium channel gene. We detected a single nucleotide change that results in an amino acid substitution (L1014F) within the domain IIS6 region of the channel protein. The L1014F mutation, often termed kdr, has been found in several other insect pests and is known to confer moderate levels of resistance to pyrethroids. We developed a pyrosequencing-based diagnostic assay that can detect the L1014F mutation in individual beetles and tested more than 350 populations collected between 2006 and 2010 in 13 European countries. In the majority of populations tested the mutation was absent, and only samples from two countries, Denmark and Sweden, contained pollen beetles heterozygous or homozygous for the L1014F mutation. The mutation was first detected in a sample from Denmark collected in 2007 after reports of field failure using tau-fluvalinate, and has since been detected in 7 out of 11 samples from Denmark and 25 of 33 samples from Sweden. No super-kdr mutations (e.g. M918T) known to cause resistance to pyrethroids were detected. The implications of these results for resistance management strategies of pollen beetle populations in oilseed rape crops are discussed.     

Insecticide-resistant pollen beetles (Meligethes aeneus F) found in Danish oilseed rape (Brassica napus L) fields

The pollen beetle is the most important pest in Danish oilseed rape fields. In 2001, we screened a broad range of pollen beetle populations for pyrethroid and dimethoate resistance. A standard dip-test was used to test insecticide resistance in 18 populations collected from oilseed winter and spring rape fields. The beetles were treated with four different insecticides: the pyrethroids tau-fluvalinate, lambda-cyhalothrin and esfenvalerate, and the organophosphate dimethoate. The results show that up to 99% of the pollen beetles survived Danish standard doses of pyrethroids and up to 36% of the beetles survived standard doses of dimethoate.     

Resistance and cross-resistance to imidacloprid and thiamethoxam in the Colorado potato beetle Leptinotarsa decemlineata

One of the major challenges in managing the Colorado potato beetle, Leptinotarsa decemlineata (Say) is its remarkable ability to develop resistance to virtually every insecticide that has ever been used against it. Resistance is particularly common throughout northeastern USA as far north as Maine. The first instances of resistance to imidacloprid have already been reported from several locations in New York, Delaware and southern Maine. Rotating insecticides with different modes of action may delay insecticide resistance, but successful implementation of this technique depends on a good understanding of resistance and cross-resistance patterns in populations of target pests. LC(50) values were measured for imidacloprid and thiamethoxam in Colorado potato beetle populations from a variety of locations in the USA and Canada using diet incorporation bioassays. The field performance of imidacloprid, thiamethoxam and clothianidin against imidacloprid-resistant beetles on a commercial potato farm in southern Maine was also evaluated. Correlation between LC(50) values for imidacloprid and thiamethoxam was highly significant, even when populations previously exposed to thiamethoxam were excluded from the analysis. There was no statistically detectable difference in the LC(50) values between populations exposed to both insecticides and to imidacloprid alone. Applications of neonicotinoid insecticides at planting delayed build-up of imidacloprid-resistant beetle populations on field plots by 1-2 weeks but failed to provide adequate crop protection. Consistently with bioassay results, there was also substantial cross-resistance among the three tested neonicotinoid insecticides. Results of the present study support the recommendation to avoid rotating imidacloprid with thiamethoxam as a part of a resistance management plan.     

Problems of resistance development in arthropod pests of agricultural crops in Russia

This paper presents the results of long‐term monitoring of insecticide resistance in populations of agricultural pests in Russia. Over the last 45 years, resistance developments were recorded for 36 arthropod pest species in 11 agricultural crops and pastures in relation to nearly all commonly used plant protection products. Development of group, cross and multiple resistance has been revealed in populations of many economically important pests. Toxicological and phenotypical (for Colorado potato beetle) methods have been devised to monitor the development of pesticide resistance. Based on experience over the last century, systems aimed at preventing the development of pest resistance to insecticides and acaricides are elaborated. These systems are based on resistance monitoring and using plant protection measures which minimize the toxic pressure on agroecosystems.     

Möglichkeiten der gezielten Bekämpfung von Pyrethroid-resistenten Rapsglanzkäferpopulationen – Ergebnisse von Ringversuchen mehrerer Bundesländer

From 2006 to 2008, tests for regulating pyrethroid-resistant pollen beetle populations using new insecticidal agents were conducted in the states of Brandenburg, Saxony, Saxony-Anhalt and Thuringia. Reason for this test series were high yield losses in winter rape in some states in 2006. These losses were the result of unilateral licensing procedures focussing on class??II pyrethroids. Organophosphates, like chlorpyrifos-ethyl and chlorpyrifos-methyl, as well as class??I pyrethroids like etofenprox and bifenthrin were examined during the tests concerning their efficiency towards Meligethes aeneus. As a comparative agent, neonicotinoid based on thiacloprid was used. Mixtures of class??II pyrethroids with piperonylbutoxid were not admitted by the producers in 2008 despite good insecticidal effects due to economic reasons. Therefore, in 2008, insecticides with different mode of action agents were tested for pollen beetle control. Investigations at five different locations showed that pymetrozin (Plenum 50 WG) and indoxacarb (STEWARD) were identical in their efficiency as thiacloprid (Biscaya) against pyrethroid-resistant pollen beetle. Metaflumizone (Alverde), a semicarbazone, is not eligible for controlling M.??aeneus populations in both investigated formulations. In order to avoid further selection of neonicotinoid-resistent pollen beetle populations, the admittance of other insecticidal agents in the coming years is necessary. For that purpose, organophosphates and insecticides based indoxacarb and pymetrozin would be good alternatives.     

Cytochrome P450 mediated pyrethroid resistance in European populations of Meligethes aeneus (Coleoptera: Nitidulidae)

Pollen beetle, Meligethes aeneus (Coleoptera: Nitidulidae) is a major pest on several million hectares in European winter oilseed rape cultivation. Synthetic pyrethroids have been successfully used for many years to keep them under economic damage thresholds. Recently wide-spread resistance development to pyrethroids in pollen beetle populations was described in many European countries, including Germany, France, Poland, Denmark and others. Resistance monitoring is conducted by incubating beetles for 24 h in glass vials coated with different concentrations of lambda-cyhalothrin. Using such an assay format we were able to show cross-resistance to other pyrethroids, such as deltamethrin, cypermethrin, and to a somewhat lower extent bifenthrin, etofenprox and tau-fluvalinate. Here we also investigated in more detail in 27 different populations the biochemical mechanism of pyrethroid resistance. Synergism experiments revealed a high synergistic potential for piperonyl butoxide in vivo, whereas other compounds such as S,S,S-tributylphosphorotrithioate and diethylmaleimide failed to suppress pyrethroid resistance. Incubating microsomal fractions of pollen beetle with deltamethrin and subsequent LC–MS/MS analysis revealed 4-OH-deltamethrin as the major metabolite. Metabolite formation in vitro and pyrethroid resistance in vivo is correlated and inhibition trials with piperonyl butoxide, tebuconazole and aminobenzotriazole suggest the involvement of cytochrome P450′s. Furthermore we were able to show cross-resistance to tau-fluvalinate which is supported by the competitive inhibition of 4-OH-deltamethrin formation by increasing concentrations of tau-fluvalinate in microsomal hydroxylation assays. Although we provided clear experimental evidence for an oxidative mechanism of resistance in numerous populations, other mechanisms might be involved based on the data discussed.     

Occurrence of insecticide resistant pollen beetles (Meligethes aeneus F.) in Danish oilseed rape (Brassica napus L.) crops

The pollen beetle is the most important pest in Danish oilseed rape crops and it is essential that farmers are able to control this pest, especially in years when the economic damage threshold will be exceeded. About seven years ago, Danish oilseed rape growers began reporting that the pyrethroids seemed to be losing effectiveness towards pollen beetles. In 2001 18 populations collected from winter and spring oilseed rape fields were tested and very high level of insecticide resistance was found. In 2003 100 populations of pollen beetles were tested, using a FAO dip-test, for resistance to fenitrothion, lambda-cyhalothrin and tau-fluvalinate. It can be concluded that many Danish populations of pollen beetles are resistant to the pyrethroid lambda-cyhalothrin and to a lesser extent to the pyrethroid tau-fluvalinate. No resistance to the organophosphate fenitrothion was found.     

Patterns of bark beetle occurrence in Norway spruce stands of national parks in Tatra Mts. in Poland and Slovakia

This paper presents the results of a research project concerning bark beetle populations in Norway spruce stands managed under a nature protection regime in national parks in Tatra Mountains in Poland and Slovakia. The preliminary data on bark beetle occurrence and related selected stand characteristics are presented. The dynamics of a bark beetle outbreak that occurred from 1994–97 in the stands localized on both sides of the state border and in various nature protection regimes is analyzed retrospectively. The data concerning the tree/stand characteristics, i.e. DBH and increment of trees are discussed in relation to its potential role in the mechanism for the spread of bark beetle populations. The patterns of the spatial distribution of trees attacked during the research period (1999–2001) are described.     

Patterns of bark beetle occurrence in Norway spruce stands of national parks in Tatra Mts. in Poland and Slovakia

This paper presents the results of a research project concerning bark beetle populations in Norway spruce stands managed under a nature protection regime in national parks in Tatra Mountains in Poland and Slovakia. The preliminary data on bark beetle occurrence and related selected stand characteristics are presented. The dynamics of a bark beetle outbreak that occurred from 1994–97 in the stands localized on both sides of the state border and in various nature protection regimes is analyzed retrospectively. The data concerning the tree/stand characteristics, i.e. DBH and increment of trees are discussed in relation to its potential role in the mechanism for the spread of bark beetle populations. The patterns of the spatial distribution of trees attacked during the research period (1999–2001) are described.     

Comparison of dose responses and resistance ratios in four populations of the rice stem borer, Chilo suppressalis (Lepidoptera: Pyralidae), to 20 insecticides

BACKGROUND: Chemical control is a major strategy for suppressing the rice stem borer, Chilo suppressalis (Walker). Owing to their high toxicity and increasing resistance development in the target insect, many insecticides will be phased out entirely in 2007 in China. Alternatives with relatively low toxicity are urgently needed to replace traditional chemicals for rice stem borer control. In this study, the authors examined four field populations of C. suppressalis for their toxicological responses to more than 20 insecticides, including a few low-toxicity organophosphates and many novel pesticides. Interpopulation resistance levels to 12 conventional insecticides were also compared. RESULTS: Based on LD(50) values, the rice stem borer was most sensitive to avermectins and fipronil (LD(50) < 1 ng larva(-1)). The stem borers exhibited the least sensitivity to endosulfan (LD(50) > 100 ng larva(-1)) and monosultap (LD(50) > 1000 ng larva(-1)). Insect growth regulators and chitin synthase inhibitors showed great efficacy against C. suppressalis, especially against populations that had developed resistance to conventional insecticides. Four field populations showed variable tolerance levels to many insecticides. LYG05 was the most susceptible population, only with a low level of resistance to monosultap (RR = 6.6). NC05 and GL05 populations exhibited intermediate tolerance levels with RR values up to 20.4 and 52.8 respectively. RA05 was the most resistant population to many insecticides, with resistance ratios up to 76.2. CONCLUSION: The results from this study provide valuable information for selection and adoption of new alternative insecticides and for resistance management of the rice stem borer.     

新烟碱类杀虫剂抗药性研究进展

新烟碱类杀虫剂是一类新开发的杀虫剂。研究表明，害虫野外种群对其敏感性差弄较大，现已有多种害虫对吡虫啉和啶虫脒产生了抗性。初步研究显示，马铃薯叶甲对吡虫啉抗性以不完全隐性的常染色体遗传；抗性似不稳定，交互抗性谱随虫种而变化，抗性形成可能与多功能氧化酶和酯酶有关。合理轮用和高剂量杀死策略是治理其抗性的有效措施。     

The effect of a piperonyl butoxide/tau-fluvalinate mixture on pollen beetle (Meligethes aeneus) and honey bees (Apis mellifera)

BACKGROUND: Previous work has characterised pyrethroid resistance in pollen beetle (Meligethes aeneus F.) as principally an oxidative mechanism. Piperonyl butoxide (PBO) can synergise this resistance in the field, but its effects on the honey bee are thought to be unacceptable. RESULTS: A field trial in Poland was conducted to show that a mixture of PBO and tau‐fluvalinate at the registered rate gave increased and longer‐lasting control of resistant pollen beetle. Four days after spraying with tau‐fluvalinate, only 20% of pollen beetles were controlled, compared with 70% if the tau‐fluvalinate/PBO mixture was used. No detriment to honey bee health was observed using the same mixture. CONCLUSIONS: PBO, if used in conjunction with a pyrethroid of relatively low bee toxicity, can successfully overcome pyrethroid resistance in pollen beetle without incurring an increased loss of honey bees, even if they are present at the time of spraying. Copyright © 2012 Society of Chemical Industry     

Pollen beetle in the UK; the start of a resistance problem?

In 2003, the first report of poor control of pollen beetle Meligethes aeneus at a site in South East England in the UK was investigated but resistance to pyrethroid insecticides was not confirmed in subsequent laboratory testing. Bioassays of 26 UK samples of M. aeneus collected in 2004 with the pyrethroid lambda-cyhalothrin showed little or no divergence from the response expected of a fully susceptible strain. In 2006 samples of pollen beetle from the UK were sent to Germany, and again these were shown to be fully susceptible. In 2007 using test kits supplied by Udo Heimbach, BBA, 19 samples of pollen beetle were tested, again from across the UK. Results indicated that a small number of individuals were fully resistant, surviving the highest dose of lambda-cyhalothrin tested (0.375 microg/L) after 5-h exposure at 4 sites, and after 24-h exposure at 2 of these sites.