Pest Management Science
Wiley InterScience : Pest Management Science

Evaluation of chlorfenapyr for control of the bed bug, Cimex lectularius L.
by Alvaro Romero, Michael F Potter, Kenneth F Haynes
26 Jul 2010 at 1:21am
BACKGROUND: The presence of bed bug populations resistant to pyrethroids demands the development of new control tactics, including the use of insecticides with new modes of action. Insecticides that disrupt oxidative phosphorylation in insect mitochondria can be an option. Laboratory assays were used to measure the toxicity of chlorfenapyr to susceptible strains and two strains highly resistant to pyrethroids. The effectiveness of two chlorfenapyr-based formulations was compared, and behavioral responses of bed bugs to dry residues of aerosol sprays were evaluated.RESULTS: Chlorfenapyr was effective against all bed bug strains, killing them at a similar rate, regardless of their susceptibility status to pyrethroids. Dry residues aged for 4 months were as toxic as fresh dry residues. The aerosol formulation had contact activity and caused faster mortality than a water-based formulation. Bed bugs did not avoid resting on surfaces treated with aerosol.CONCLUSION: Chlorfenapyr is an option for controlling pyrethroid-resistant bed bugs. While it does not cause quick knockdown, its long residual activity and no avoidance behavior of bed bugs to dry residues appear to make this insecticide suitable for bed bug control. A faster insecticidal effect is obtained with the aerosol formulation, suggesting greater bioavailablity of the toxicant. Copyright © 2010 Society of Chemical Industry
Biological responses to glyphosate drift from aerial application in non-glyph...
by Krishna N Reddy, Wei Ding, Robert M Zablotowicz, Steven J Thomson, Yanbo Huang, L Jason Krutz
26 Jul 2010 at 1:19am
BACKGROUND: Glyphosate drift from aerial application onto susceptible crops is inevitable, yet the biological responses to glyphosate drift in crops are not well characterized. The objectives of this research were to determine the effects of glyphosate drift from a single aerial application (18.3 m swath, 866 g AE ha-1) on corn injury, chlorophyll content, shikimate level, plant height and shoot dry weight in non-glyphosate-resistant (non-GR) corn.RESULTS: One week after application (WAA), corn was killed at 3 m from the edge of the spray swath, with injury decreasing to 18% at 35.4 m downwind. Chlorophyll content decreased from 78% at 6 m to 22% at 15.8 m, and it was unaffected beyond 25.6 m at 1 WAA. Shikimate accumulation in corn decreased from 349% at 0 m to 93% at 15.8 m, and shikimate levels were unaffected beyond 25.6 m downwind. Plant height and shoot dry weight decreased gradually with increasing distance. At a distance of 35.4 m, corn height was reduced by 14% and shoot dry weight by 10% at 3 WAA.CONCLUSIONS: Corn injury and other biological responses point to the same conclusion, that is, injury from glyphosate aerial drift is highest at the edge of the spray swath and decreases gradually with distance. The LD50 (the lethal distance that drift must travel to cause a 50% reduction in biological response) ranged from 12 to 26 m among the biological parameters when wind speed was 11.2 km h-1 and using a complement of CP-09 spray nozzles on spray aircraft. Copyright © 2010 Society of Chemical Industry
Acaricides and their residues in Spanish commercial beeswax
by Josep Serra-Bonvehí, José Orantes-Bermejo
26 Jul 2010 at 3:21am
BACKGROUND: The purpose of this work was to determine residues of acaricides in recycled Spanish beeswax.RESULTS: Chlorfenvinphos, fluvalinate, amitraz, bromopropylate, acrinathrin, flumethrin, coumaphos, chlorpyrifos, chlordimeform, endosulfan and malathion residues were determined by GC-µECD/NPD/MS detection. Owing to the extreme instability of amitraz, this analyte was transformed into the stable end-metabolite 2,4-dimethylaniline, later derivatised with heptafluorobutyric anhydride and determined by GC-µECD/MS. Recoveries from spiked samples ranged from 86 to 108%, while quantification limits varied from 0.10 to 0.30 mg kg-1 using GC-µECD/NPD, and from 12 to 85 µg kg-1 by GC-MSD. Of a total of 197 samples analysed, only eight samples (4%) were free of residues of chlorfenvinphos (0.019-10.6 mg kg-1), fluvalinate was present in 93.6% of samples analysed (0.027 -88.7 mg kg-1), while coumaphos was confirmed in only five of the 134 samples analysed at concentrations of less than 195 µg kg-1. The remaining acaricides were identified with different levels of incidence at concentrations from 12 to 231 µg kg-1.CONCLUSIONS: Residues of acaricides were found in an extensive number of beeswax samples. The contamination with chlorfenvinphos and tau-fluvalinate was very relevant, particularly as chlorfenvinphos is not legally authorised for use in beekeeping. The possible impacts of the main acaricides detected on larval and adult honey bees are discussed. Copyright © 2010 Society of Chemical Industry
An aspartate to glycine change in the carboxyl transferase domain of acetyl C...
by Shiv Shankhar Kaundun
20 Jul 2010 at 3:55am
BACKGROUND: The increasing use of ACCase-inhibiting herbicides has resulted in evolved resistance in key grass weeds infesting cereal cropping systems worldwide. Here, a thorough and systematic approach is proposed to elucidate the basis of resistance to three ACCase herbicides in a Lolium multiflorum Lam. (Italian rye grass) population from the United Kingdom (UK24).RESULTS: Resistance to sethoxydim and pinoxaden was always associated with a dominant D2078G (Alopecurus myosuroides Huds. equivalent) target-site mutation in UK24. Conversely, whole-plant herbicide assays on predetermined ACCase genotypes showed very high levels of resistance to diclofop-methyl for all three wild DD2078 and mutant DG2078 and GG2078 ACCase genotypes from the mixed resistant population UK24. This indicates the presence of other diclofop-methyl-specific resistance mechanism(s) yet to be determined in this population. The D2078G mutation could be detected using an unambiguous DNA-based dCAPS procedure that proved very transferable to A. myosuroides, Avena fatua L., Setaria viridis (L.) Beauv. and Phalaris minor Retz.CONCLUSION: This study provides further understanding of the molecular basis of resistance to ACCase inhibitor herbicides in a Lolium population and a widely applicable PCR-based method for monitoring the D2078G target-site resistance mutation in five major grass weed species. Copyright © 2010 Society of Chemical Industry
Cross-resistance relationships between neonicotinoids and pymetrozine in Bemi...
by Kevin Gorman, Russell Slater, James D Blande, Alison Clarke, Jodie Wren, Alan McCaffery, Ian Denholm
14 Jul 2010 at 3:56am
BACKGROUND: Although cross-resistance between compounds in the same insecticide group is a frequently observed phenomenon, cross-resistance between groups that differ in structural and functional characteristics can be extremely unpredictable. In the case of controlling the whitefly, Bemisia tabaci Gennadius, neonicotinoids and the pyridine azomethine antifeedant pymetrozine represent independent lines of discovery that should be suited for alternation to avoid prolonged selection for the same resistance mechanism. Reports of an association between responses to neonicotinoids and pymetrozine were investigated by resistance profiling of seven B. tabaci strains and complementary reciprocal selection experiments.RESULTS: All strains demonstrated a consistent correlation between responses to three neonicotinoid compounds: thiamethoxam, imidacloprid and acetamiprid. Responses to neonicotinoids for six field strains clearly correlated with responses to pymetrozine. Reciprocal selection experiments confirmed an unexpected case of intergroup cross-resistance. A seventh strain exhibited a so far unique phenotype of strong resistance to pymetrozine but full susceptibility to neonicotinoids. Selection experiments confirmed that in this strain the mechanism of pymetrozine resistance is specific and has no implications for neonicotinoids.CONCLUSION: Cross-resistance between neonicotinoids and pymetrozine in B. tabaci probably reflects the overexpression of a cytochrome-P450-dependent monooxygenase capable of metabolising both types of compound in spite of their apparent structural dissimilarity. Given the predominance of this mechanism in B. tabaci, both can contribute to resistance management but should be placed within the same treatment 'window'. Copyright © 2010 Society of Chemical Industry
Enhanced repellency of binary mixtures of Zanthoxylum piperitum pericarp stea...
by Tran Trung Hieu, Soon-Il Kim, Hyung Wook Kwon, Young-Joon Ahn
13 Jul 2010 at 12:30am
BACKGROUND: The repellency to stable fly, Stomoxys calcitrans (L.), of Zanthoxylum piperitum (L.) DC pericarp steam distillate (ZP-SD), Zanthoxylum armatum DC seed oil (ZA-SO) and their constituents alone or in combination with Calophyllum inophyllum L. nut oil (CI-NO), as well as six aerosol formulations containing ZP-SD or ZP-SO and CI-NO, was compared with that of a synthetic repellent, DEET, using an exposed human hand bioassay.RESULTS: At 0.20 mg cm-2, ZP-SD treatments resulted in 91 and 68% repellency following 30 and 60 min exposure respectively, while DEET gave 100 and 84% repellency. ZA-SO was less effective than ZP-SD. At 0.2 mg cm-2, the most active constituents, cuminaldehyde, cuminyl alcohol, limonene and methyl cinnamate, gave 82, 74, 74 and 64% repellency at 30 min respectively, but DEET gave 100 and 87% repellency at 30 and 60 min. An increase in effectiveness and duration of repellency was produced by binary mixtures of ZP-SD, ZA-SO or bioactive constituents (each 0.01 mg cm-2) and CI-NO (0.99 mg cm-2). The repellency of aerosols containing 2.5% ZP-SD or 2.5% ZA-SO and 2.5% CI-NO was comparable with that of 5% DEET aerosol.CONCLUSION: Mixtures formulated from ZP-SD, ZA-SO or bioactive constituents and CI-NO could be useful as potential repellents for the control of stable fly populations in light of global efforts to reduce the level of highly toxic synthetic repellents. Copyright © 2010 Society of Chemical Industry
Multifunctionalised benzoxazinones in the systems Oryza sativa-Echinochloa cr...
by Francisco A Macías, Nuria Chinchilla, Elena Arroyo, Rosa M Varela, José MG Molinillo, David Marín
13 Jul 2010 at 12:29am
BACKGROUND: Fifteen novel derivatives of D-DIBOA, including aromatic ring modifications and the addition of side chains in positions C-2 and N-4, had previously been synthesised and their phytotoxicity on standard target species (STS) evaluated. This strategy combined steric, electronic, solubility and lipophilicity requirements to achieve the maximum phytotoxic activity. An evaluation of the bioactivity of these compounds on the systems Oryza sativa-Echinochloa crus-galli and Triticum aestivum-Avena fatua is reported here.RESULTS: All compounds showed inhibition profiles on the two species Echinochloa crus-galli (L.) Beauv. and Avena fatua L. The most marked effects were caused by 6F-4Pr-D-DIBOA, 6F-4Val-D-DIBOA, 6Cl-4Pr-D-DIBOA and 6Cl-4Val-D-DIBOA. The IC50 values for the systems Echinochloa crus-galli-Oryza sativa and Avena fatua-Triticum aestivum for all compounds were compared. The compound that showed the greatest selectivity for the system Echinochloa crus-galli-Oryza sativa was 8Cl-4Pr-D-DIBOA, which was 15 times more selective than the commercial herbicide propanil (Cotanil-35). With regard to the system Avena fatua-Triticum aestivum, the compounds that showed the highest selectivities were 8Cl-4Val-D-DIBOA and 6F-4Pr-D-DIBOA. The results obtained for 6F-4Pr-D-DIBOA are of great interest because of the high phytotoxicity to Avena fatua (IC50 = 6 µM, r2 = 0.9616).CONCLUSION: The in vitro phytotoxicity profiles and selectivities shown by the compounds described here make them candidates for higher-level studies. 8Cl-4Pr-D-DIBOA for the system Echinochloa crus-galli-Oryza sativa and 6F-4Pr-D-DIBOA for Avena fatua-Triticum aestivum were the most interesting compounds. Copyright © 2010 Society of Chemical Industry
Risk assessment for honey bees and pesticides - recent developments and 'new ...
by Helen M Thompson
13 Jul 2010 at 12:34am
In 2008, major areas of discussion at the ICPBR Bee Protection Group meeting were the development of a honey bee risk assessment scheme for systemic pesticides and revision of the test guidelines for semi-field and field studies. The risk assessment scheme for systemic pesticides is based on analysis of conditions for exposure of bees to residues. These are based on a stepwise approach, starting with simple calculations based on existing data in dossiers and progressing to higher-tier semi-field and field studies (the guidelines for these have been modified in line with this). The proposed scheme has been tested with data packages of high- and low-risk PPPs. A future area of interest for the group may be the risks posed by guttation fluid containing systemic pesticides. A recent paper on 'Translocation of neonicotinoid insecticides from coated seeds to seedling guttation drops: a novel way of intoxication for bees' has focused significant interest on the possible risks posed by the presence of residues of systemic pesticides in guttation fluid to water-collecting honey bees. The occurrence of guttation and the presence of pesticide residues in the fluid are discussed, together with remaining questions that will need to be addressed in answering whether such a route of exposure may pose a risk to honey bees. © Crown copyright 2010. Reproduced with permission of Her Majesty's Stationery Office. Published by JohnWiley & Sons, Ltd.
Evaluation of the toxicity of 17 essential oils against Choristoneura rosacea...
by Cristina M Machial, Ikkei Shikano, Michael Smirle, Roderick Bradbury, Murray B Isman
13 Jul 2010 at 12:32am
BACKGROUND: The obliquebanded leafroller, Choristoneura rosaceana Harris, and the cabbage looper, Trichoplusia ni Hübner, are serious fruit and vegetable pests requiring multiple insecticide applications per year. To reduce non-target exposure to hazardous insecticides and to curb resistance development, alternative controls are required. Accordingly, a selection of 17 essential oils was screened against both lepidopteran pests, and the influence of azinphos-methyl resistance on essential oil toxicity to C. rosaceana was studied.RESULTS: Of the 17 essential oils screened, patchouli oil (Pogostemon cablin Benth.) and thyme oil (Thymus vulgaris L.) were selected for further testing against C. rosaceana, whereas patchouli oil, garlic oil (Allium sativum L.) and lemongrass oil (Cymopogon nardus L.) were selected for further testing against T. ni. LC50 and LD50 values confirmed that patchouli oil was the most toxic to C. rosaceana larvae, with LC50 = 2.8 µL mL-1 and LD50 = 8.0 µg insect-1. Garlic oil was the most toxic oil to T. ni larvae with LC50 = 3.3 µL mL-1 and LD50 = 22.7 µg insect-1, followed by patchouli oil and lemongrass oil. Azinphos-methyl-resistant leafrollers were 1.5-fold more tolerant to patchouli oil and 2.0-fold more tolerant to thyme oil.CONCLUSIONS: Based on these results, patchouli oil and other essential oils have sufficient efficacy to be considered as components of an essential oil-based insecticide that targets these lepidopteran pests. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd
Field evaluation of systemic imidacloprid for the management of avocado thrip...
by Frank J Byrne, Eduardo C Humeres, Anthony A Urena, Mark S Hoddle, Joseph G Morse
9 Jul 2010 at 12:00am
BACKGROUND: The efficacy of systemic applications of imidacloprid for the management of avocado thrips and avocado lace bug was determined in field trials. Following insecticide treatment by chemigation, leaves of appropriate age for each insect were sampled over a 6 month period and used for bioassays. Imidacloprid residues were measured by ELISA in leaves used for bioassays to determine concentrations of insecticide that were toxic to both pests.RESULTS: The uptake of imidacloprid into treated trees was extremely slow, peaking in the current year's leaf flush at only 8 ng cm-2 leaf tissue after 15 weeks. Avocado thrips mortality in bioassays with young flush leaves, the preferred feeding substrate for this insect, was minimal, indicating that imidacloprid concentrations were below threshold levels needed for effective control. Residues present in older leaves, which are preferred by the avocado lace bug, were higher than in young flush leaves, and provided good control of this pest. Probit analysis of bioassay data showed that the avocado lace bug (LC50 = 6.1 ng imidacloprid cm-2 leaf tissue) was more susceptible to imidacloprid than the avocado thrips (LC50 = 73 ng imidacloprid cm-2 leaf tissue).CONCLUSIONS: In spite of the slow uptake of imidacloprid into avocado trees, the levels of imidacloprid would be sufficient to control avocado lace bug infestations. In contrast, the slow uptake would be problematic for avocado thrips control because inadequate levels of insecticide accumulate in new flush foliage and would allow avocado thrips populations to build to levels that would subsequently damage developing avocado fruit. Copyright © 2010 Society of Chemical Industry
Degradation and adsorption of terbuthylazine and chlorpyrifos in biobed biomi...
by Konstantina Kravvariti, Nikolaos G Tsiropoulos, Dimitrios G Karpouzas
8 Jul 2010 at 11:59pm
BACKGROUND: Biobeds have been well studied in northern Europe, whereas little is known regarding their use in southern Europe. The degradation and adsorption of terbuthylazine (TA) and chlorpyrifos (CP) were studied in three different biomixtures composed of composted cotton crop residues, soil and straw in various proportions, and also in sterilised and non-sterilised soil.RESULTS: Compost biomixtures degraded the less hydrophobic TA at a faster rate than soil, while the opposite was evident for the more hydrophobic CP. These results were attributed to the rapid abiotic hydrolysis of CP in the alkaline soil (pH 8.5) compared with the lower pH of the compost (6.6), but also to the increasing adsorption (Kd = 746 mL g-1) and reduced bioavailability of CP in the biomixtures compared with soil (Kd = 17 mL g-1), as verified by the adsorption studies.CONCLUSIONS: Compost had a dual but contrasting effect on degradation that depended on the chemical nature of the pesticide studied: a positive effect towards TA owing to increasing biodegradation and a negative effect towards CP owing to increasing adsorption. Overall, composted cotton crop residues could be potentially used in local biobed systems in Greece, as they promoted the degradation of hydrophilic pesticides and the adsorption of hydrophobic pesticides. Copyright © 2010 Society of Chemical Industry
Mosquito repellents: a review of chemical structure diversity and olfaction
by Gretchen Paluch, Lyric Bartholomay, Joel Coats
8 Jul 2010 at 11:59pm
Research on mosquito chemical repellents continues to advance, along with knowledge of mosquito olfaction and behavior, mosquito-host interactions and chemical structure. New tools and technologies have revealed information about insect olfactory mechanisms and processing, providing a more complex approach for the interpretation of how chemical repellents influence host-seeking and feeding behavior. Even with these advances, there is still a large amount of information contained in the early works on insect repellents. Many of the standard test methods and chemicals that are still used for evaluating active repellents were developed in the 1940s. These studies contain valuable references to the activity of different structural classes of chemicals, and serve as a guide to optimization of select compounds for insect repellency effects. Copyright © 2010 Society of Chemical Industry
The development of integrated pest management for the control of mushroom sci...
by Afsheen Shamshad
1 Jul 2010 at 5:36am
Mushrooms are susceptible to a range of diseases and pests that can cause serious crop loss. Effective pest and pathogen control is a very important factor for the maintenance of efficient production of cultivated mushrooms. Integrated pest management in mushrooms is reliant upon four main principals/elements: sanitation, exclusion, monitoring and pest control. Bradysia ocellaris (Comstock) and Lycoriella ingenua (Dufour) (Diptera: Sciaridae) are major pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. These pests cause losses in yield through larval damage of the compost, mycelium and sporophores, and affect the structural features of the compost itself. Adult flies of these species also act as vectors for the introduction of mites and fungal diseases in cultivated mushrooms. Copyright © 2010 Society of Chemical Industry
Homology modelling of Drosophila cytochrome P450 enzymes associated with inse...
by Robert T Jones, Saskia E Bakker, Deborah Stone, Sally N Shuttleworth, Sam Boundy, Caroline McCart, Phillip J Daborn, Richard H ffrench-Constant, Jean MH van den Elsen
25 Jun 2010 at 2:32am
BACKGROUND: Overexpression of the cytochrome P450 gene Cyp6g1 confers resistance against DDT and a broad range of other insecticides in Drosophila melanogaster Meig. In the absence of crystal structures of CYP6G1 or complexes with its substrates, structural studies rely on homology modelling and ligand docking to understand P450-substrate interactions.RESULTS: Homology models are presented for CYP6G1, a P450 associated with resistance to DDT and neonicotinoids, and two other enzymes associated with insecticide resistance in D. melanogaster, CYP12D1 and CYP6A2. The models are based on a template of the X-ray structure of the phylogenetically related human CYP3A4, which is known for its broad substrate specificity. The model of CYP6G1 has a much smaller active site cavity than the template. The cavity is also 'V'-shaped and is lined with hydrophobic residues, showing high shape and chemical complementarity with the molecular characteristics of DDT. Comparison of the DDT-CYP6G1 complex and a non-resistant CYP6A2 homology model implies that tight-fit recognition of this insecticide is important in CYP6G1. The active site can accommodate differently shaped substrates ranging from imidacloprid to malathion but not the pyrethroids permethrin and cyfluthrin.CONCLUSION: The CYP6G1, CYP12D1 and CYP6A2 homology models can provide a structural insight into insecticide resistance in flies overexpressing P450 enzymes with broad substrate specificities. Copyright © 2010 Society of Chemical Industry
Thrips (Thysanoptera: Thripidae) mitigation in seedling cotton using strip ti...
by Michael D Toews, R Scott Tubbs, Dylan Q Wann, Dana Sullivan
25 Jun 2010 at 2:31am
BACKGROUND: Thrips are the most consistent insect pests of seedling cotton in the southeastern United States, where symptoms can range from leaf curling to stand loss. In a 2 year study, thrips adults and immatures were sampled at 14, 21 and 28 days after planting on cotton planted with a thiamethoxam seed treatment in concert with crimson clover, wheat or rye winter cover crops and conventional or strip tillage to investigate potential differences in thrips infestations.RESULTS: Densities of adult thrips, primarily Frankliniella fusca (Hinds), peaked on the first sampling date, whereas immature densities peaked on the second sampling date. Regardless of winter cover crop, plots that received strip tillage experienced significantly fewer thrips at each sampling interval. In addition, assessment of percentage ground cover 42 days after planting showed that there was more than twice as much ground cover in the strip-tilled plots compared with conventionally tilled plots. Correlation analyses showed that increased ground cover was inversely related to thrips densities that occurred on all three sampling dates in 2008 and the final sampling date in 2009.CONCLUSIONS: Growers who utilize strip tillage and a winter cover crop can utilize seed treatments for mitigation of early-season thrips infestation. Copyright © 2010 Society of Chemical Industry

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