ORCID Profile
0009-0006-4099-9375
Current Organisation
Department of Agriculture and Fisheries
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Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 07-2013
Publisher: Oxford University Press (OUP)
Date: 22-11-2018
DOI: 10.1093/JEE/TOX284
Abstract: Phosphine is the most widely used fumigant for stored grain insect pests, and resistance to phosphine has evolved in several species worldwide. This study was designed to determine the presence of phosphine resistance in 34 populations of Rhyzopertha dominica (F.) collected from the United States and Canada. Adult R. dominica were s led and subjected to a discriminatory dose toxicity assay of exposure to 20 ppm of phosphine for 20 h of exposure to distinguish a susceptible R. dominica adult by death from a resistant beetle that survives the treatment. All but two of the 34 geographic populations surveyed had some beetles that were resistant to phosphine, and the frequency of resistance varied from 97% in a population from Parlier, California to 0% in beetles from both Carnduff, Saskatchewan and Starbuck, Manitoba. Probit analyses of dose-mortality bioassays with beetles from a laboratory-susceptible strain and those from five of the populations s led were used to calculate resistance ratio factors (RRs) based on the ratio of LC50 (estimate for the concentration to kill 50% of a test group) in the s led population to the LC50 for the susceptible strain. The highest RR for the five resistant populations was nearly 596-fold in beetles from Belle Glade, Florida, whereas the lowest RR in that group was 9-fold in Wamego, Kansas. This study revealed that phosphine resistance in R. dominica is common across North America and some populations have levels of resistance that may pose challenges for continued use of phosphine for their management.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 20-01-2021
DOI: 10.1186/S12864-020-07354-8
Abstract: The lesser grain borer, Rhyzopertha dominica is a serious pest of stored grains. Fumigation and contact insecticides play a major role in managing this pest globally. While insects are developing genetic resistance to chemicals, hormonal analogues such as s-methoprene play a key role in reducing general pest pressure as well as managing pest populations that are resistant to fumigants and neurotoxic contact insecticides. However, resistance to s-methoprene has been reported in R. dominica with some reports showing a remarkable high resistance, questioning the use of this compound and other related analogues in grain protection. The current study attempts to identify possible molecular mechanisms that contribute in resistance to s-methoprene in R. dominica. Transcriptome analysis of resistant and susceptible strains of this pest species identified a set of differentially expressed genes related to cytochrome P450s, indicating their potential role in resistance to s-methoprene. Laboratory bioassays were performed with s-methoprene treated wheat grains in presence and absence of piperonyl butoxide (PBO), a cytochrome P450 inhibitor. The results indicate that PBO, when applied alone, at least at the concentration tested here, had no effect on R. dominica adult emergence, but has a clear synergistic effect to s-methoprene. The number of produced progeny decreased in presence of the inhibitor, especially in the resistant strain . In addition, we also identified CYP complement (CYPome) of R. dominica , annotated and analysed phylogenetically, to understand the evolutionary relationships with other species. The information generated in current study suggest that PBO can effectively be used to break resistance to s-methoprene in R. dominica .
Publisher: Elsevier BV
Date: 12-2022
Publisher: Portico
Date: 2015
DOI: 10.2212/SPR.2015.1.3
Publisher: Elsevier BV
Date: 03-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 09-11-2012
Abstract: Worldwide populations of pest insects—such as the lesser grain borer, Rhyzopertha dominica , and the rust-red flour beetle, Tribolium castaneum —have become highly resistant to the fumigant phosphine, providing a potential threat to global food security. The nematode, Caenorhabditis elegans is vulnerable to phosphine, but phosphine-resistant strains are known. Schlipalius et al. (p. 807 ) show that mutations in the delta-1-pyrroline-5-carboxylate dehydrogenase and dihydrolipoamide dehydrogenase ( dld-1 ) genes both give rise to phosphine resistance in C. elegans . Phosphine resistance mutants in R. dominica , and T. castaneum also map to the dld-1 gene, which codes for a core metabolic enzyme. These mutants are, however, hypersensitive to arsenic, mimics of which might thus synergize with phosphine.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Wiley
Date: 13-04-2021
DOI: 10.1002/PS.6373
Abstract: The rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) is a cosmopolitan pest of stored cereal grains and other commodities globally. Infestations caused by S. oryzae makes grains unsuitable for consumption, processing, and export. Deltamethrin, a synthetic pyrethroid insecticide, is widely used in major grain storages in India as a prophylactic treatment to control this pest. However, recurrent use of this insecticide had led to genetic resistance in S. oryzae , questioning its ongoing use at the current recommended concentration. Dose response analysis of resistant (Delta‐R) and susceptible (Lab‐S) strains of S. oryzae collected from grain storages across southern India, revealed that Delta‐R was 134‐fold more resistant than the Lab‐S at median lethal concentration (LC 50 ). A concentration of 180 ppm over 48 h effectively discriminated 16 resistant field populations from Lab‐S with per cent resistance ranging from 8.72% to 75.86%. Exposing all the resistant populations to 1000 ppm over 48 h identified 12 populations with strongly resistant in iduals and confirmed the existence of two distinct resistance phenotypes, ‘weak’ and ‘strong’ in S. oryzae . Furthermore, sequence analysis of the voltage‐gated sodium channel ( vgsc ) gene in Delta‐R identified a single target site mutation, T929I conferring resistance in S. oryzae . CAPS (Cleaved Amplified Polymorphic Sequence) marker analysis of this allele confirmed that frequency of resistance is high (up to 0.96) supporting the results of phenotypic analysis. Both phenotype and molecular marker analyses clearly demonstrated that deltamethrin at 180 and 1000 ppm can be used to discriminate weakly and strongly resistant populations in S. oryzae , respectively. Resistance diagnostics based on the mutation, T929I, supports our phenotypic data and indicates that resistance to deltamethrin in S. oryzae is prevalent in southern parts of India, stressing the need to identify a synergist or suitable alternatives. © 2021 Society of Chemical Industry.
Publisher: Springer Berlin Heidelberg
Date: 2018
Publisher: Springer Berlin Heidelberg
Date: 2018
Publisher: Elsevier BV
Date: 05-2021
Publisher: Springer Science and Business Media LLC
Date: 23-05-2015
Publisher: Elsevier BV
Date: 2005
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 05-12-2015
DOI: 10.1002/PS.3940
Abstract: Our aim was to ascertain the potential of sulfuryl fluoride (SF) as an alternative fumigant to manage phosphine-resistant pests. We tested the susceptibility of all life stages of red flour beetle, Tribolium castaneum (Herbst), to SF and assessed the presence of cross-resistance to this fumigant in phosphine-resistant strains of this species. Analysis of dose-response data indicated that the egg was the stage most tolerant to SF under a 48 h exposure period. At LC50 , eggs were 29 times more tolerant than other immature stages and adults, and required a relatively high concentration of 48.2 mg L(-1) for complete mortality. No significant differences in tolerance to SF were observed among the three larval instars, pupae and adults, and all of these stages were controlled at a low concentration of 1.32 mg L(-1) . Phosphine-resistant strains did not show cross-resistance to SF. Our research concluded that the current maximum registered rate of SF, 1500 gh m(-3) , is adequate to control all the post-embryonic life stages of T. castaneum over a 48 h fumigation period, but it will fail to achieve complete mortality of eggs, indicating the risk of some survival of eggs under this short exposure period. As there is no cross-resistance to SF in phosphine-resistant insects, it will play a key role in managing phosphine resistance in stored-grain insect pests.
Publisher: Elsevier BV
Date: 03-2015
Publisher: Wiley
Date: 11-12-2019
DOI: 10.1002/PS.5688
Abstract: Rhyzopertha dominica is a serious pest of stored grains and many populations have resistance to the fumigant phosphine. Some populations contain beetles with a 'strong resistance' phenotype. Recent work found the LC A dose-mortality assay estimated that phosphine fumigation over 48 h using 730-870 ppm at 25° C would control adults of both strongly resistant R. dominica populations. Fumigations with mixed life stage cultures found 200 ppm killed all susceptible and weak-resistant beetles in 2 days, but the strong-resistant Minneapolis and Belle Glade strains had substantial survivors at 200 ppm. Furthermore, the Belle Glade strain had beetles that survived 1000 ppm in 2-day fumigations. The strong-resistant Belle Glade strain needed nearly 10 days at over 400 ppm to have acceptable levels of control. This study recommends protocols to manage strongly resistant R. dominica populations provided that a minimum phosphine concentration of 400 ppm be maintained at 25° C or higher for up to 10 days. © 2019 Society of Chemical Industry.
Publisher: Wiley
Date: 06-11-2006
DOI: 10.1002/PS.1313
Abstract: The combined efficacy of spinosad and chlorpyrifos-methyl was determined against four storage psocid pests belonging to genus Liposcelis. This research was undertaken because of the increasing importance of these psocids in stored grain and the problem of finding grain protectants to control resistant strains. Firstly, mortality and reproduction were determined for adults exposed to wheat freshly treated with either spinosad (0.5 and 1 mg kg(-1)) or chlorpyrifos-methyl (2.5, 5 and 10 mg kg(-1)) or combinations of spinosad and chlorpyrifos-methyl at 30 degrees C and 70% RH. There were significant effects of application rate of spinosad and chlorpyrifos-methyl, both in idually and in combination, on adult mortality and progeny reduction of all four psocids. Liposcelis bostrychophila Badonnel and L. decolor (Pearman) responded similarly, with incomplete control of adults and progeny at both doses of spinosad but complete control in all chlorpyrifos-methyl and combined treatments. In L. entomophila (Enderlein) and L. paeta Pearman, however, complete control of adults and progeny was only achieved in the combined treatments, with the exception of spinosad 0.5 mg kg(-1) plus chlorpyrifos-methyl 2.5 mg kg(-1) against L. entomophila. Next, combinations of spinosad (0.5 and 1 mg kg(-1)) and chlorpyrifos-methyl (2.5, 5 and 10 mg kg(-1)) in bioassays after 0, 1.5 and 3 months storage of treated wheat were evaluated. The best treatment was 1 mg kg(-1) of spinosad plus 10 mg kg(-1) of chlorpyrifos-methyl, providing up to 3 months of protection against infestations of all four Liposcelis spp. on wheat.
Publisher: Elsevier BV
Date: 10-2010
Publisher: Springer Science and Business Media LLC
Date: 08-04-2015
DOI: 10.1038/HDY.2015.24
Publisher: Oxford University Press (OUP)
Date: 25-03-2017
DOI: 10.1093/JEE/TOX091
Abstract: The red flour beetle, Tribolium castaneum (Herbst), is a common stored-product pest found worldwide. Phosphine, hydrogen phosphide (PH3), is the most commonly used fumigant for stored grains, for which genetically based resistance has been recorded for several pest species. This study assessed phosphine resistance in 25 T. castaneum populations from across the United States and Canada using a discriminating dose bioassay. Dose-mortality assays were conducted with adults from seven of these populations to categorize weak and strong resistance phenotypes. Phosphine resistance was detected in 12 out of the 25 populations, and the frequency of resistance within populations varied from 2% in Victoria, TX, to 100% in Red Level, AL. Two resistant populations from Kansas that had been s led three years earlier were found to have similar resistance frequencies in the current study. None of the four Canadian populations had any detectable resistance among the insects tested. Resistance ratio calculations from LC50 value in resistant populations relative to the LC50 for the laboratory susceptible strain allowed resistance phenotypes to be assigned as either weak resistance, at 5- to 26-fold resistance relative to susceptible, or strong resistance at 95- to 127-fold relative to susceptible. This study suggests that proper resistance assessment techniques can help to determine occurrence of phosphine resistance in populations of T. castaneum and can further characterize the strength of resistance present. These data can be used to support resistance management programs that consider either cessation or modification of phosphine fumigation to control T. castaneum.
Publisher: Springer Science and Business Media LLC
Date: 03-01-2021
Publisher: Wiley
Date: 09-09-2011
Publisher: Wiley
Date: 29-12-2017
DOI: 10.1002/PS.4468
Abstract: Susceptibility to phosphine (PH Characterisation of susceptibility and resistance to phosphine in eggs and adults showed that C. ferrugineus was the most tolerant as well as resistant species. Mortality responses of eggs and adults to SF at 25 °C revealed T. castaneum to be the most tolerant species followed by S. oryzae, C. ferrugineus and R. dominica. A high dose range of SF, 50.8-62.2 mg L Our research concludes that phosphine resistance does not confer cross-resistance to SF in grain insect pests irrespective of the variation in levels of tolerance to SF itself or resistance to phosphine in their egg and adult stages. While our study confirms that SF has potential as a 'phosphine resistance breaker', the observed higher tolerance in eggs stresses the importance of developing SF fumigation protocols with longer exposure periods. © 2016 Society of Chemical Industry.
Publisher: Wiley
Date: 10-11-2010
DOI: 10.1002/PS.1873
Abstract: Piperonyl butoxide (PB)-synergised natural pyrethrins (pyrethrin:PB ratio 1:4) were evaluated both as a grain protectant and a disinfestant against four Liposcelidid psocids: Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman. These are key storage pests in Australia that are difficult to control with the registered grain protectants and are increasingly being reported as pests of stored products in other countries. Firstly, mortality and reproduction of adults were determined in wheat freshly treated at 0.0, 0.75, 1.5, 3 and 6 mg kg(-1) of pyrethrins + PB (1:4) at 30 +/- 1 degrees C and 70 +/- 2% RH. Next, wheat treated at 0.0, 1.5, 3 and 6 mg kg(-1) of pyrethrins + PB (1:4) was stored at 30 +/- 1 degrees C and 70 +/- 2% RH and mortality and reproduction of psocids were assessed after 0, 1.5, 3 and 4.5 months of storage. Finally, the potential of synergised pyrethrins as a disinfestant was assessed by establishing time to endpoint mortality for adult psocids exposed to wheat treated at 3 and 6 mg kg(-1) of synergised pyrethrins after 0, 3, 6, 9 and 12 h of exposure. Synergised pyrethrins at 6 mg kg(-1) provided 3 months of protection against all four Liposcelis spp., and at this rate complete adult mortality of these psocids can be achieved within 6 h of exposure. Piperonyl butoxide-synergised pyrethrins have excellent potential both as a grain protectant and as a disinfestant against Liposcelidid psocids.
Publisher: Oxford University Press (OUP)
Date: 26-04-2019
DOI: 10.1093/JEE/TOZ085
Abstract: A key component in the management of resistance to fumigant phosphine in stored products pests is their early detection and implementation of control strategies. Currently, resistance testing involves exposing adults to a specific discriminating concentration over a fixed time period (20–48 h). Although it is widely adopted, this test takes significant time for assay preparation (up to 4 wk) as well as diagnosis (1–2 wk). To address these lacunae, we have established a ‘quick knockdown test’ using a key grain insect pest, rice weevil, Sitophilus oryzae (L.). Susceptible, weakly and strongly phosphine-resistant reference strains were exposed to a threshold concentration of phosphine over short exposure periods (min to h). The time to knockdown (KT) responses to phosphine were characterized at 2 (1,440 ppm) and 5 mg/liter (3,600 ppm). The time to 99.9% KT (KT99.9) at 2 mg/liter was 12.52 min for the susceptible adults, compared with 167.9 and 1,510 min in the case of weakly and strongly resistant phenotypes, respectively. As anticipated, increasing the concentration of phosphine to 5 mg/liter halved the KT99.9 (81.57 min) to separate weakly and strongly resistant populations than it was required at 2 mg/liter. We validated the KT99.9 value for the 5 mg/liter against field-derived populations of S. oryzae. The results were aligned with the existing Food and Agriculture Organization approach, confirming that the proposed ‘quick test’ is a reliable tool to rapidly diagnose resistance in this species.
Publisher: Oxford University Press (OUP)
Date: 24-04-2020
DOI: 10.1093/JEE/TOAA081
Abstract: Strong resistance to phosphine (PH3) in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Laemophloeidae: Coleoptera) poses a serious risk to stored-grain biosecurity. Resistant populations hold risk of surviving in PH3 fumigation, particularly in storage structure that limits achieving very high concentrations of PH3, demanding the need for alternative fumigation strategies. Cofumigation with PH3 and carbon dioxide (CO2) is one alternative approach that has the potential to be used widely. CO2 fumigation of adults of strongly PH3-resistant reference strain of C. ferrugineus, for 48 h, showed that the effective concentration (LC50) of CO2 was 30.99%. This 30% level of CO2 in combination with PH3 decreased the LC50 of PH3 from 6.7 mg/liter to 0.84 mg/liter, an eightfold increase in PH3 efficacy relative to PH3 fumigation in normal air. The LC99.9 decreased from 16.2 mg/liter to 5.8 mg/liter, a 2.8-fold increase in PH3 efficacy. Comparison of mortality response data of PH3 alone and the PH3 + CO2 mixture confirmed that CO2 enhances the toxicity of PH3 synergistically in addition to exerting its own toxicity. These results were validated against three independently field-derived strains of strongly resistant C. ferrugineus that confirmed that observed enhancement in toxicity with the PH3 + CO2 mixture was consistent, irrespective of differences in resistance phenotypes and inherent tolerance levels. Results of the current study provide further opportunities to develop new commercially viable strategy to control strongly PH3-resistant C. ferrugineus.
Publisher: Elsevier BV
Date: 2002
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.PESTBP.2015.09.008
Abstract: Inheritance of resistance to phosphine fumigant was investigated in three field-collected strains of rusty grain beetle, Cryptolestes ferrugineus, Susceptible (S-strain), Weakly Resistant (Weak-R) and Strongly Resistant (Strong-R). The strains were purified for susceptibility, weak resistance and strong resistance to phosphine, respectively, to ensure homozygosity of resistance genotype. Crosses were established between S-strain×Weak-R, S-strain×Strong-R and Weak-R×Strong-R, and the dose mortality responses to phosphine of these strains and their F1, F2 and F1-backcross progeny were obtained. The fumigations were undertaken at 25°C and 55% RH for 72h. Weak-R and Strong-R showed resistance factors of 6.3× and 505× compared with S-strain at the LC50. Both weak and strong resistances were expressed as incompletely recessive with degrees of dominance of -0.48 and -0.43 at the LC50, respectively. Responses of F2 and F1-backcross progeny indicated the existence of one major gene in Weak-R, and at least two major genes in Strong-R, one of which was allelic with the major factor in Weak-R. Phenotypic variance analyses also estimated that the number of independently segregating genes conferring weak resistance was 1 (nE=0.89) whereas there were two genes controlling strong resistance (nE=1.2). The second gene, unique to Strong-R, interacted synergistically with the first gene to confer a very high level of resistance (~80×). Neither of the two major resistance genes was sex linked. Despite the similarity of the genetics of resistance to that previously observed in other pest species, a significant proportion (~15 to 30%) of F1 in iduals survived at phosphine concentrations higher than predicted. Thus it is likely that additional dominant heritable factors, present in some in iduals in the population, also influenced the resistance phenotype. Our results will help in understanding the process of selection for phosphine resistance in the field which will inform resistance management strategies. In addition, this information will provide a basis for the identification of the resistance genes.
Publisher: Oxford University Press (OUP)
Date: 28-02-2018
DOI: 10.1534/GENETICS.118.300688
Abstract: Next-generation sequencing methods enable identification of the genetic basis of traits in species that have no prior genomic information available. The combination of next-generation sequencing, variant analysis, and linkage is a powerful way of identifying candidate genes for a trait of interest. Here, we used a comparative transcriptomics [RNA sequencing (RNAseq)] and genetic linkage analysis approach to identify the rph1 gene. rph1 variants are responsible for resistance to the fumigant phosphine (PH3) that is used to control insect pests of stored grain. In each of the four major species of pest insect of grain we have investigated, there are two major resistance genes, rph1 and rph2, which interact synergistically to produce strongly phosphine-resistant insects. Using RNAseq and genetic linkage analyses, we identified candidate resistance (rph1) genes in phosphine-resistant strains of three species: Rhyzopertha dominica (129 candidates), Sitophilus oryzae (206 candidates), and Cryptolestes ferrugineus (645 candidates). We then compared these candidate genes to 17 candidate resistance genes previously mapped in Tribolium castaneum and found only one orthologous gene, a cytochrome b5 fatty acid desaturase (Cyt-b5-r), to be associated with the rph1 locus in all four species. This gene had either missense amino acid substitutions and/or insertion/deletions/frameshift variants in each of 18 phosphine-resistant strains that were not observed in the susceptible strains of the four species. We propose a model of phosphine action and resistance in which phosphine induces lipid peroxidation through reactive oxygen species generated by dihydrolipoamide dehydrogenase, whereas disruption of Cyt-b5-r in resistant insects decreases the polyunsaturated fatty acid content of membranes, thereby limiting the potential for lipid peroxidation.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Annual Reviews
Date: 07-01-2014
DOI: 10.1146/ANNUREV-ENTO-011613-161947
Abstract: Previously regarded as minor nuisance pests, psocids belonging to the genus Liposcelis now pose a major problem for the effective protection of stored products worldwide. Here we examine the apparent biological and operational reasons behind this phenomenon and why conventional pest management seems to be failing. We investigate what is known about the biology, behavior, and population dynamics of major pest species to ascertain their strengths, and perhaps find weaknesses, as a basis for a rational pest management strategy. We outline the contribution of molecular techniques to clarifying species identification and understanding genetic ersity. We discuss progress in s ling and trapping and our comprehension of spatial distribution of these pests as a foundation for developing management strategies. The effectiveness of various chemical treatments and the availability and potential of nonchemical control methods are critically examined. Finally, we identify research gaps and suggest future directions for research.
Publisher: Wiley
Date: 10-11-2015
DOI: 10.1002/PS.3926
Abstract: The emergence of high levels of resistance in Cryptolestes ferrugineus (Stephens) in recent years threatens the sustainability of phosphine, a key fumigant used worldwide to disinfest stored grain. We aimed at developing robust fumigation protocols that could be used in a range of practical situations to control this resistant pest. Values of the lethal time to kill 99.9% (LT99 .9 , in days) of mixed-age populations, containing all life stages, of a susceptible and a strongly resistant C. ferrugineus population were established at three phosphine concentrations (1.0, 1.5 and 2.0 mg L(-1) ) and three temperatures (25, 30 and 35 °C). Multiple linear regression analysis revealed that phosphine concentration and temperature both contributed significantly to the LT99 .9 of a population (P < 0.003, R2 = 0.92), with concentration being the dominant variable, accounting for 75.9% of the variation. Across all concentrations, LT99.9 of the strongly resistant C. ferrugineus population was longest at the lowest temperature and shortest at the highest temperature. For ex le, 1.0 mg L(-1) of phosphine is required for 20, 15 and 15 days, 1.5 mg L(-1) for 12, 11 and 9 days and 2.0 mg L(-1) for 10, 7 and 6 days at 25, 30 and 35 °C, respectively, to achieve 99.9% mortality of the strongly resistant C. ferrugineus population. We also observed that phosphine concentration is inversely proportional to fumigation period in regard to the population extinction of this pest. The fumigation protocols developed in this study will be used in recommending changes to the currently registered rates of phosphine in Australia towards management of strongly resistant C. ferrugineus populations, and can be repeated in any country where this type of resistance appears.
Publisher: Public Library of Science (PLoS)
Date: 20-02-2012
Publisher: Springer Science and Business Media LLC
Date: 10-05-2017
Publisher: Elsevier BV
Date: 10-2001
DOI: 10.1016/S0022-474X(00)00029-1
Abstract: An improved method of mass culturing liposcelid psocids is described that enables the production of large numbers of insects with minimal equipment and handling. The key factor was the provision of refuge by the addition of black chart papers (five pieces, each 10x2cm) inside the culture jars. A culture medium comprising whole wheat (14% moisture content), kibbled wheat, wholemeal wheat flour and brewer's yeast in the proportion of 10:10:10:0.1 (v/v) was tested on Liposcelis bostrychophila, L. entomophila and L. paeta. When reared on this medium with initial colonies of 10 adults, there was a 12-fold increase in L. bostrychophila, 5-fold increase in L. entomophila and an 8-fold increase in L. paeta populations over a 4-week period. The method enables quick and simple extraction and handling of insects. This rearing method produced significantly (P<0.05) larger population numbers when compared with a range of published and unpublished methods.
Publisher: Oxford University Press (OUP)
Date: 04-2003
DOI: 10.1093/JEE/96.2.525
Abstract: The efficacy of bifenthrin (0.5 mg/kg) + piperonyl butoxide (7 mg/kg) + chlorpyrifosmethyl (10 mg/kg) against beetle and psocid pests of sorghum was evaluated in silo-scale trials in southeast Queensland, Australia. The pyrethroid bifenthrin was evaluated as a potential new protectant in combination with the organophosphate chlorpyrifos-methyl, which is already registered for control of several insect pests of stored cereals. Sorghum (approximately 200 metric tons) was treated after both the 1999 and 2000 harvests and s led at intervals to assess treatment efficacy and residue decline during up to 7 mo of storage. Generally, test strains of the beetles Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L), and Cryptolestes ferrugineus (Stephens) were prevented from producing live progeny for up to 7 mo. The treatment failed against one strain of R. dominica known to be resistant to bioresmethrin and organophosphates. Two malathion-resistant strains of O. surinamensis were marginally controlled with 94-100% fewer adult progeny produced. For psocids, no strains of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), or Liposcelis paeta Pearman produced live progeny, although the control of a field strain of Liposcelis entomophila (Enderlein) was generally poor. Results show that this treatment should protect sorghum for at least 7 mo against most prevalent strains of grain insect in eastern Australia, although control may be limited in areas in which L. entomophila or pyrethroid-resistant R. dominica are present.
Publisher: MDPI AG
Date: 16-05-2019
Abstract: Resistance to the fumigant phosphine in Tribolium castaneum occurs worldwide. This study evaluated tests based on adult knockdown time, the time for a beetle to become immobile, when exposed to a high concentration of phosphine. We recorded knockdown times of beetles that remained completely still for 30 s when exposed to 3000 ppm of phosphine in a large, gas-tight glass tube. Beetles were used from 12 populations, of which six were ‘susceptible’ to phosphine, three were ‘weakly resistant’, and three were ‘strongly resistant’. Knockdown times were determined for single beetles, as well as for groups of ten beetles for which the time to knockdown for either five beetles (KT50) or ten beetles (KT100) were recorded. Similar knockdown times occurred across susceptible and resistant populations. However, the KT100 tests generated conservative times for diagnosing strong vs. weak resistance. The strong resistant populations were all over 100 min with KT100, compared to 60 min or less for susceptible and weak resistant populations. Special tests on single beetles revealed higher knockdown times in insects that were deliberately disturbed compared to those without any disturbances. Work reported here suggests a knockdown test conducted on beetles in a matter of minutes or hours could help classify phosphine resistance status prior to decisions on phosphine fumigation.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Wiley
Date: 11-10-2002
DOI: 10.1002/PS.602
Abstract: Numerous strains of the psocid pest, Liposcelis decolor (Pearman) were collected from farms and central storages and interbred to form three representative strains from three major grain-growing states of Australia: Queensland, South Australia and New South Wales. These were tested against the grain protectants and structural treatments currently registered for use in Australia. Recently, L decolor has become an important pest of stored grain in Australia, particularly in the eastern and southern parts. There is no published information available on management of this pest and the current pest-management strategy, based predominantly on phosphine fumigation, has failed to control infestations of this pest in numerous grain storages in Australia. Alternative methods of control such as use of contact insecticides were explored in the present work to supplement phosphine fumigation to manage this new pest. From eight grain protectants tested as admixtures, only chlorpyrifos-methyl, bioresmethrin plus piperonyl butoxide, and fenitrothion were found to provide long term (3-9 months) protection against all three strains of L decolor. Chlorpyrifos-methyl gave the best protection, providing a minimum of 7.5 to a maximum of 9 months protection, depending on the strains tested. Three structural treatments, azamethiphos, azamethiphos plus carbaryl and permethrin provided long-term control (8-9 months) of all three strains of L decolor on galvanised steel surfaces, with permethrin delivering 9 months protection against all strains. However, all of these treatments failed to provide long-term control of any strains on concrete surfaces. We conclude that chlorpyrifos-methyl as a grain admixture can be incorporated into fumigation strategies to optimise the control of L decolor infestations. Structural treatments, such as permethrin can be used to support a fumigation strategy in storages made of galvanised steel.
Publisher: Public Library of Science (PLoS)
Date: 26-03-2012
Publisher: Wiley
Date: 16-07-2012
DOI: 10.1002/PS.3360
Abstract: The recent development of very high resistance to phosphine in rusty grain beetle, Cryptolestes ferrugineus (Stephens), seriously threatens stored-grain biosecurity. The aim was to characterise this resistance, to develop a rapid bioassay for its diagnosis to support pest management and to document the distribution of resistance in Australia in 2007-2011. Bioassays of purified laboratory reference strains and field-collected s les revealed three phenotypes: susceptible, weakly resistant and strongly resistant. With resistance factors of > 1000 × , resistance to phosphine expressed by the strong resistance phenotype was higher than reported for any stored-product insect species. The new time-to-knockdown assay rapidly and accurately diagnosed each resistance phenotype within 6 h. Although less frequent in western Australia, weak resistance was detected throughout all grain production regions. Strong resistance occurred predominantly in central storages in eastern Australia. Resistance to phosphine in the rusty grain beetle is expressed through two identifiable phenotypes: weak and strong. Strong resistance requires urgent changes to current fumigation dosages. The development of a rapid assay for diagnosis of resistance enables the provision of same-day advice to expedite resistance management decisions.
Publisher: Wiley
Date: 24-11-2005
DOI: 10.1002/PS.1141
Abstract: A laboratory study was undertaken to determine the persistence and efficacy of spinosad against Rhyzopertha dominica (F.) in wheat stored for 9 months at 30 degrees C and 55 and 70% relative humidity. The aim was to investigate the potential of spinosad for protecting wheat from R. dominica during long-term storage in warm climates. Wheat was treated with spinosad at 0.1, 0.5 and 1 mg kg(-1) grain and s led after 0, 1.5, 3, 4.5, 6, 7.5 and 9 months of storage for bioassays and residue analyses. Residues were estimated to have declined by 30% during 9 months of storage at 30 degrees C and there was no effect of relative humidity. Spinosad applied at 0.5 or 1 mg kg(-1) was completely effective for 9 months, with 100% adult mortality after 14 days of exposure and no live F1 adults produced. Adult mortality was <100% in some s les of wheat treated with 0.1 mg kg(-1) of spinosad, and live progeny were produced in all s les treated at this level. The results show that spinosad is likely to be an effective grain protectant against R. dominica in wheat stored in warm climates.
Publisher: Oxford University Press (OUP)
Date: 17-09-2018
DOI: 10.1093/JEE/TOY269
Abstract: Resistance to phosphine (PH3) in key insect pests of stored grain is increasing, with a requirement for maintaining a dose as high as 1 mg l-1 for 14 d for effective fumigation, which is difficult to achieve under most commercial storage conditions. There is no suitable replacement for PH3, as most of the available alternatives suffer from specific weaknesses, creating an urgent need to increase the efficacy of this fumigant. One such possibility is co-fumigation of PH3 with another fumigant, sulfuryl fluoride (SO2F2-SF), with the goal of decreasing the time required for a successful fumigation. In this study, adult of two PH3-resistant strains in each of four key grain insect pests, Rhyzopertha dominica, (F.) (Coleoptera: Bostrichidae) Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), Sitophilus oryzae (L.) (Coleoptera: Curculionidae), and Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) were fumigated with PH3 and SF in idually as well as in combinations at 25°C over 48 h. Mortality responses in each species were subjected to probit analysis to determine the LC50 and LC99.9 of PH3, SF, and PH3 + SF. Co-fumigation of PH3 with SF resulted in a 50% reduction of the PH3 concentration required to achieve 99.9% mortality in two pest species. For ex le, the PH3 + SF mixture, reduced the amount of PH3 required from 14.2-14.5 to 5.6-6.36 mg l-1 and from 2.71-5.03 to 0.93-1.2 mg l-1, respectively, for C. ferrugineus and S. oryzae. The overall mortality response to the PH3 + SF mixture followed an "additive model" suggesting that mutual enhancement in toxicity can be achieved with this mixture specifically to control PH3-resistant insects.
Publisher: Wiley
Date: 02-11-2018
DOI: 10.1002/PS.5221
Abstract: Next-generation sequencing can enable genetic surveys of large numbers of in iduals. We developed a genotyping-by-sequencing assay for detecting strong phosphine resistance alleles in the dihydrolipoamide dehydrogenase (dld) gene of Rhyzopertha dominica populations. The assay can estimate the distribution and frequency of resistance variants in thousands of in idual insects in a single run. We analysed 1435 in idual insects collected over a 1-year period from 59 grain-storage sites including farms (n = 29) and central storages (n = 30) across eastern Australia. Resistance alleles were detected in 49% of s les, 38% of farms and 60% of central storages. Although multiple alleles were detected, only two resistance variants (P49S and K142E) were widespread and each appeared to have a distinct but overlapping geographical distribution. The type of structure in which the grain is stored had a strong effect on resistance allele frequency. We observed higher frequencies of resistance alleles in bunker storages at central sites compared with other storage types. This contributed to the higher frequencies of resistance alleles in bulk-handling facilities relative to farms. The discovery of a storage structure that predisposes insects to resistance highlights the utility of our high-throughput assay system for improvement of phosphine resistance management practices. © 2018 Society of Chemical Industry.
Publisher: Wiley
Date: 11-05-2006
DOI: 10.1002/PS.1220
Abstract: The effectiveness of the neonicotinoid insecticide imidacloprid was evaluated against four psocid pests of stored grain. This research was undertaken because of the growing importance of psocids in stored grain and the need to identify methods for their control. The mortality and reproduction of adults of Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman in wheat treated with imidacloprid were determined. There were five application rates (0.5, 1, 2, 5 and 10 mg AI kg(-1) grain) and an untreated control. There were significant effects of application rate on both adult mortality and reproduction for all four species, but the effect of imidacloprid was sometimes more pronounced on reproduction. Imidacloprid was most effective against L. bostrychophila, with 100% adult mortality after 7 d at 5 mg AI kg(-1), 14 d at 2 mg AI kg(-1) and 28 d at 0.5 and 1 mg AI kg(-1). No live progeny were produced at 2 mg AI kg(-1). For L. decolor, there was 100% adult mortality after 28 d at 10 mg AI kg(-1) and no live progeny were produced at 2 mg AI kg(-1). For L. entomophila, there was 100% adult mortality after 14 d at 10 mg AI kg(-1) and 28 d at 2 and 5 mg AI kg(-1). No live progeny were produced at 10 mg AI kg(-1). At 10 mg AI kg(-1) there was 100% mortality of L. paeta adults after 28 d exposure and no live progeny developed. Because reproduction at some application rates occurred only in the first 14 d of exposure, it is concluded that the application rate leading to population extinction was 1 mg AI kg(-1) for L. bostrychophila, 2 mg AI kg(-1) for L. decolor and L. entomophila and 5 mg AI kg(-1) for L. paeta. This study shows that imidacloprid has potential as a grain protectant to control all four Liposcelis species in stored grain.
Publisher: Oxford University Press (OUP)
Date: 10-1998
Publisher: Wiley
Date: 21-02-2007
DOI: 10.1002/PS.1344
Abstract: As failure to control Rhyzopertha dominica (F.) with phosphine is a common problem in the grain-growing regions of Brazil, a study was undertaken to investigate the frequency, distribution and strength of phosphine resistance in R. dominica in Brazil. Nineteen s les of R. dominica were collected between 1991 and 2003 from central storages where phosphine fumigation had failed to control this species. Insects were cultured without selection until testing in 2005. Each s le was tested for resistance to phosphine on the basis of the response of adults to discriminating concentrations of phosphine (20 and 48 h exposures) and full dose-response assays (48 h exposure). Responses of the Brazilian R. dominica s les were compared with reference susceptible, weak-resistance and strong-resistance strains from Australia in parallel assays. All Brazilian population s les showed resistance to phosphine: five were diagnosed with weak resistance and 14 with strong resistance. Five s les showed levels of resistance similar to the reference strong-resistance strain. A representative highly resistant s le was characterised by exposing mixed-age cultures to a range of constant concentrations of phosphine for various exposure periods. Time to population extinction (TPE) and time to 99.9% suppression of population (LT(99.9)) values of this s le were generally similar to those of the reference strong-resistance strain. For ex le, at 0.1, 0.5 and 1.0 mg L(-1), LT(99.9) values for BR33 and the reference strong-resistance strain were respectively 21, 6.4 and 3.7 days and 17, 6.2 and 3.8 days. With both strains, doubling phosphine concentrations to 2 mg L(-1) resulted in increased LT(99.9) and TPE. High level and frequency of resistance in all population s les, some of which had been cultured without selection for up to 12 years, suggest little or no fitness deficit associated with phosphine resistance. The present research indicates that widespread phosphine resistance may be developing in Brazil. Fumigation practices should be monitored and resistance management plans implemented to alleviate further resistance development.
Publisher: Wiley
Date: 17-04-2008
DOI: 10.1002/PS.1586
Abstract: The psocid Liposcelis bostrychophila Badonnel, is a widespread, significant pest of stored commodities, has developed strong resistance to phosphine, the major grain disinfestant. The aim was to develop effective fumigation protocols to control this resistant pest. Time to population extinction of all life stages (TPE) in days was evaluated at a series of phosphine concentrations and temperatures at two relative humidities. Regression analysis showed that temperature, concentration and relative humidity all contributed significantly to describing TPE (P<0.001, R(2)=0.95), with temperature being the dominant variable, accounting for 74.4% of the variation. Irrespective of phosphine concentration, TPE was longer at lower temperatures and high humidity (70% RH) and shorter at higher temperatures and low humidity (55% RH). At any concentration of phosphine, a combination of higher temperature and lower humidity provides the shortest fumigation period to control resistant L. bostrychophila. For ex le, 19 and 11 days of fumigation are required at 15 degrees C and 70% RH at 0.1 and 1.0 mg L(-1) of phosphine respectively, whereas only 4 and 2 days are required at 35 degrees C and 55% RH for the same respective concentrations. The developed fumigation protocols will provide industry with flexibility in application of phosphine.
Publisher: Portico
Date: 2011
DOI: 10.2212/SPR.2011.3.8
Publisher: Wiley
Date: 03-04-2013
DOI: 10.1002/PS.3514
Abstract: The lesser grain borer, Rhyzopertha dominica (F.), is a highly destructive pest of stored grain that is strongly resistant to the fumigant phosphine (PH3 ). Phosphine resistance is due to genetic variants at the rph2 locus that alter the function of the dihydrolipoamide dehydrogenase (DLD) gene. This discovery now enables direct detection of resistance variants at the rph2 locus in field populations. A genotype assay was developed for direct detection of changes in distribution and frequency of a phosphine resistance allele in field populations of R. dominica. Beetles were collected from ten farms in south-east Queensland in 2006 and res led in 2011. Resistance allele frequency increased in the period from 2006 to 2011 on organic farms with no history of phosphine use, implying that migration of phosphine-resistant R. dominica had occurred from nearby storages. Increasing resistance allele frequencies on organic farms suggest local movement of beetles and dispersal of insects from areas where phosphine has been used. This research also highlighted for the first time the utility of a genetic DNA marker in accurate and rapid determination of the distribution of phosphine-resistant insects in the grain value chain. Extending this research over larger landscapes would help in identifying resistance problems and enable timely pest management decisions.
Publisher: Annual Reviews
Date: 07-01-2020
DOI: 10.1146/ANNUREV-ENTO-011019-025047
Abstract: Development of resistance in major grain insect pest species to the key fumigant phosphine (hydrogen phosphide) across the globe has put the viability and sustainability of phosphine in jeopardy. The resistance problem has been aggravated over the past two decades, due mostly to the lack of suitable alternatives matching the major attributes of phosphine, including its low price, ease of application, proven effectiveness against a broad pest spectrum, compatibility with most storage conditions, and international acceptance as a residue-free treatment. In this review, we critically analyze the published literature in the area of phosphine resistance with special emphasis on the methods available for detection of resistance, the genetic basis of resistance development, key management strategies, and research gaps that need to be addressed.
Publisher: Oxford University Press (OUP)
Date: 14-03-2020
DOI: 10.1093/JEE/TOAA033
Abstract: Resistance in pest insects to the grain fumigant phosphine (PH3) poses a threat to trade and food security. The possible pleiotropic effects of PH3 resistance on development and reproduction were investigated in the red flour beetle, Tribolium castaneum (Herbst), by introgressing two genes known to be major contributors to strong resistance (tc_rph1 and tc_rph2) into a susceptible background. The tc_rph2 allele was the G135S variant, whereas the identity of tc_rph1 allele was unknown but could have been one of the three known variants (L119W, V123F, or S349G). The introgressed resistant strain was 288× more resistant than the susceptible strain, based on mortality after a 20 h fumigation with PH3. Molecular screening confirmed that the introgressed strain was homozygous for the resistance genes, but was otherwise indistinguishable from the susceptible strain based on screening with 12 neutral DNA markers. We found no differences of consequence in developmental time between the susceptible and introgressed resistant strains. Similarly, the number of F1 adults produced by these strains was more or less equal, as was the weight of in idual F1 adults. The conclusions remained the same regardless of whether the experiments were conducted on a flour-based medium or wheat. Thus, we found no evidence that being fully strongly PH3 resistant (i.e., homozygous for tc_rph1 and tc_rph2) has major consequences in terms of development or reproduction in T. castaneum.
Publisher: Elsevier BV
Date: 05-2015
Publisher: Wiley
Date: 30-07-2003
DOI: 10.1002/PS.753
Abstract: Phosphine-induced delay in development of eggs was investigated as a mechanism of resistance to this fumigant in Liposcelis bostrychophila Badonnel. One-day-old eggs of a susceptible and a strongly resistant strain of L bostrychophila were exposed to a range of phosphine concentrations for 6days at 30 (+/- 1) degrees C and 70 (+/- 2)% RH. Delay in mean hatching period occurred in both susceptible and resistant eggs, although it was more pronounced in the latter. A maximum delay of 2.65 days was recorded for eggs of the susceptible strain at 0.01 mg litre(-1) (the highest concentration at which eggs survived) and 13.39 days for the resistant strain at 1 mg litre(-1) (the highest concentration tested). Delay in egg development time was positively correlated with increasing phosphine concentration. Our results reveal that the most successful strategy to control resistant L bostrychophila is to apply relatively low concentrations of phosphine for extended exposure times (eg 0.05 mg litre(-1) for 16 days) that allow all eggs to hatch to the much less tolerant nymph stage.
Publisher: Elsevier BV
Date: 2003
Publisher: Wiley
Date: 25-05-2021
DOI: 10.1002/PS.6424
Abstract: Managing resistance to phosphine (PH 3 ) in rusty grain beetle, Cryptolestes ferrugineus , is challenging, as strongly resistant insects of this species require very high concentrations over lengthy exposure periods ( days). Recently, approaches that enhance the efficacy of PH 3 have gained momentum to control this pest, especially co‐fumigations. In this study, efficacy of co‐fumigating PH 3 with another commercially available fumigant, sulfuryl fluoride (SF), has been evaluated against adults and eggs of two PH 3 ‐resistant strains of C. ferrugineus . Concentrations of the mixture, representing lower than current application rates of both fumigants, were tested towards its field use. Co‐fumigation of PH 3 with SF was achieved in two patterns: over a continuous exposure period of 168 h simultaneously and sequentially over two periods of 78 h, in which insects were exposed to SF first followed by PH 3 with 12 h aeration in‐between. Results of simultaneous fumigations identified two effective co‐fumigation rates, SF 185 + PH 3 168 g hm −3 and SF 370 + PH 3 84 g hm −3 that yielded complete control of adults and eggs. These two rates also were equally effective when they were applied sequentially and produced consistent results. Irrespective of application methods, concentrations of both PH 3 and SF failed in idually in achieving complete mortality of either adults or eggs or both. Our results confirmed that a co‐fumigation strategy involving half the current standard rate of PH 3 (84 g hm −3 ) with one‐fourth of the current maximal registered rate of SF (370 g hm −3 ) can provide effective control of strongly PH 3 ‐resistant C. ferrugineus .
No related grants have been discovered for Manoj Nayak.