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1.
Degree of dominance of phosphine resistance was investigated in adults of Rhyzopertha dominica F and Sitophilus oryzae L. Efficacy of the grain fumigant phosphine depends on both concentration and exposure period, which raises the possibility that dominance levels vary with exposure period. New and published data were used to test this possibility in adults of R dominica and S oryzae fumigated for periods of up to 144 h. The concentrations required for control of homozygous resistant and susceptible strains and their F1 hybrids decreased with increasing exposure period. For both species the response lines for the homozygous resistant and susceptible strains and their F1 hybrids were parallel. Therefore, neither dominance level nor resistance factor was affected by exposure period. Resistance was incompletely recessive and the level of dominance, calculated at 50% mortality level, was -0.59 for R dominica and -0.65 for S oryzae. The resistant R dominica strain was 30.9 times more resistant than the susceptible strain, compared with 8.9 times for the resistant S oryzae strain. The results suggest that developing discriminating doses for detecting heterozygote adults of either species will be difficult.  相似文献   

2.
BACKGROUND: In spite of the intensive worldwide use of phosphine against stored-product insects, its potential sublethal effects on targeted insect species is seldom recognised and may compromise the efficacy of this fumigant, particularly against phosphine-resistant insects. Therefore, the behavioural response of three populations of the lesser grain borer Rhyzopertha dominica (Coleoptera: Bostrichidae) to sublethal phosphine exposure was assessed. RESULTS: Concentration-mortality bioassays with phosphine confirmed the resistance status of the insect populations studied, with levels of phosphine resistance of 40.8-fold and 85.7-fold compared with the susceptible population. Regarding walking behaviour, determined using a digital video-tracking system, the phosphine-resistant populations were less active than the susceptible population. In addition, sublethal phosphine exposure decreased the walking activity of all three populations. CONCLUSION: Phosphine exposure decreased walking ativity. Such reduced walking activity is likely to lower the respiration rate, thereby minimising phosphine uptake. As higher phosphine resistance was also associated with reduced walking activity, phosphine-resistant populations may resist phosphine fumigation even more efficiently on account of this behavioural trait, further aiding their physiological resistance, and should be a matter of concern. Copyright © 2012 Society of Chemical Industry  相似文献   

3.
溴虫氟苯双酰胺是一种全新的双酰胺类杀虫剂,主要用于防治鳞翅目、鞘翅目、白蚁以及蚊蝇等害虫。为了明确溴虫氟苯双酰胺对小菜蛾的生物活性及解毒酶活性的影响,本研究选择氯虫苯甲酰胺为对照药剂,采用叶片药膜法测定了溴虫氟苯双酰胺对小菜蛾的生物活性,并测定了亚致死剂量(LC20、LC40)的溴虫氟苯双酰胺和氯虫苯甲酰胺对小菜蛾多功能氧化酶、谷胱甘肽S-转移酶和羧酸酯酶活性的影响。结果表明,溴虫氟苯双酰胺与氯虫苯甲酰胺对小菜蛾的生物活性相当,两者对小菜蛾的LC50分别为0.042和0.056μg/mL。与氯虫苯甲酰胺相似,亚致死剂量的溴虫氟苯双酰胺能够诱导小菜蛾体内羧酸酯酶活性升高,但溴虫氟苯双酰胺对多功能氧化酶和谷胱甘肽S-转移酶活性没有显著影响。  相似文献   

4.
BACKGROUND: The ethyl formate/carbon dioxide (CO2) formulation Vapormate? is a rapid‐acting fumigant being developed for the control of stored‐grain insects. The effects have been investigated of concentration, exposure times of 1, 3, 24 and 72 h and two grain temperatures, 15 and 25 °C, on its efficacy against mixed‐stage cultures of Sitophilus oryzae (L.) Tribolium castaneum (Herbst) and strongly phosphine‐resistant Rhyzopertha dominica (F.) strain QRD569. RESULTS: High mortalities (≥92%) of mixed‐stage cultures of all three species were obtained when grain was fumigated with the formulation (193 g m?3 ethyl formate) for 1 h. Complete control of R. dominica QRD569 and T. castaneum was achieved with 63 and 76 g m?3 ethyl formate respectively, with exposure for 24 h, whereas mean mortality of S. oryzae was 86% under the same conditions. Mortalities of S. oryzae juvenile stages were significantly lower than adults under the conditions tested, which was due to pronounced tolerance of mid‐stage pupae to the fumigant. Reducing grain temperature from 25 to 15 °C had no effect on insect mortality. CONCLUSION: Ethyl formate/CO2 formulation is highly effective against stored‐grain insects over a range of concentrations and exposure times. Efficacious fumigations were conducted in as little as 1 h, and a strongly phosphine‐resistant R. dominica strain was readily controlled with the fumigant. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd  相似文献   

5.
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.  相似文献   

6.
BACKGROUND: Methyl bromide is being phased out for use on stored commodities, as it is listed as an ozone‐depleting substance, and phosphine is the fumigant widely used on grains. However, phosphine resistance occurs worldwide, and phosphine fumigation requires a long exposure period and temperatures of > 15 °C. There is an urgent requirement for the development of a fumigant that kills insects quickly and for phosphine resistance management. This paper reports on a new fumigant formulation of 95% ethyl formate plus 5% methyl isothiocyanate as an alternative fumigant for stored grains. RESULTS: The formulation is stable for at least 4 months of storage at 45 °C. A laboratory bioassay with the formulation showed that it controlled all stages of Sitophilus oryzae (L.), Sitophilus granarius (L.), Tribolium castaneum (Herbst), Rhyzopertha dominica (F.), Trogoderma variabile Ballion and Callosobruchus maculatus (Fabricius) in infested wheat, barley, oats and peas at 80 mg L?1 for 5 days, and in canola at both 40 mg L?1 for 5 days and 80 mg L?1 for 2 days at 25 ± 2 °C. After an 8–14 day holding period, residues of ethyl formate and methyl isothiocyanate in wheat, barley, peas and canola were below the experimental permit levels of 1.0 and 0.1 mg kg?1. However, fumigated oats needed an 18 day holding period. CONCLUSIONS: The findings suggest that the ethyl formate plus methyl isothiocyanate formulation has potential as a fumigant for the control of stored‐grain insect pests in various commodities. Copyright © 2011 Society of Chemical Industry  相似文献   

7.
Resistance to fumigants has been frequently reported in insect pests of stored products and is one of the obstacles in controlling these pests. The authors studied phosphine resistance and its physiological basis in adult insects of 12 populations of Tribolium castaneum (Herbst) (Tenebrionidae), ten populations of Rhyzopertha dominica (F.) (Bostrichidae) and eight populations of Oryzaephilus surinamensis L. (Silvanidae) from Brazil, and the possible existence of fitness costs associated with phosphine resistance in the absence of this fumigant. The bioassays for the detection of phosphine resistance followed the FAO standard method. The production of carbon dioxide and the instantaneous rate of population increase (r(i)) of each population of each species were correlated with their resistance ratios at the LC(50). The resistance ratio at LC(50) in T. castaneum ranged from 1.0- to 186.2-fold, in R. dominica from 2.0- to 71.0-fold and in O. surinamensis from 1.9- to 32.2-fold. Ten populations of T. castaneum, nine populations of R. dominica and seven populations of O. surinamensis were resistant to phosphine. In all three species there was significant association (P < 0.05) between respiration rate and phosphine resistance. The populations with lower carbon dioxide production showed a higher resistance ratio, suggesting that the lower respiration rate is the physiological basis of phosphine resistance by reducing the fumigant uptake in the resistant insects. Conversely, populations with higher r(i) showed lower resistance ratios, which could indicate a lower rate of reproduction of the resistant populations compared with susceptible populations. Thus, management strategies based on the interruption of phosphine fumigation may result in reestablishment of susceptibility, and shows good potential for more effective management of phosphine-resistant populations.  相似文献   

8.
Phosphine gas has been used world-wide for more than four decades as an ideal fumigant for disinfestation of stored grains and other commodities. Its use as a safe fumigant of stored products has become even more important with recent restrictions on the production of the only alternative, methyl bromide. Widespread resistance to phosphine has emerged in several species of stored-product insects in many countries, which in some instances may have caused control failures. Chemically, phosphine is a strong reducing agent and biological redox systems, especially the components of the mitochondrial electron transport chain, are probably the site of its action in insects. The oxidation of phosphine could produce reactive phosphorylating species and interactions of phosphine with biological redox systems have been reported to cause generation of highly reactive oxyradicals. This appears to be the basis of phosphine toxicity to insects, which differs from that of respiratory inhibitors such as hydrogen cyanide. Phosphine-resistant strains of several species of stored-product insects have been reported to absorb very small amounts of the compound compared to their susceptible counterparts. This reduced uptake in resistant insects appears to result from respiratory exclusion of phosphine. The overall mechanism of resistance also involves a detoxification process. Despite the likely involvement of oxyradicals in the insecticidal action of phosphine, the level of anti-oxidant enzymes in resistant insects is apparently not higher than that in their susceptible counterparts. The reduced uptake of the compound might be due either to the presence of a phosphine insensitive target site or to a membrane-based efflux system that excludes phosphine gas in resistant insects. Studies have indicated the oxygen uptake in mitochondrial preparations from susceptible and resistant insects to be equally sensitive to inhibition by phosphine in vitro. The nature of the phosphine-exclusion system in resistant insects has not been fully elucidated. The possibilities of controlling resistant insects with phosphine and prospects for developing new alternative fumigants are also discussed. © 1997 SCI.  相似文献   

9.
The effect of phosphine at exposure periods of 24, 48 and 120 h on hatching and mortality of 0- to 1-day-old eggs of susceptible (TN6) and resistant (FC10) strains of Rhyzopertha dominica of field origin was investigated. The fumigant affected hatching in both the strains. In a 48-h exposure at 27 (+/- 2) degrees C, the LD99 doses for the eggs of TN6 and FC10 were 0.56 and 3.25 mg litre-1, respectively. Significant reduction in hatching was observed in treated batches with progressive increase of phosphine dose in the first 2-3 days. On subsequent days the numbers hatching were often similar to those in controls, and sometimes exceeded control hatch, especially following a 5-day exposure. A critical change in the order of susceptibility of egg and adult stages of the two strains was noticed. In 48-h exposures, eggs of the susceptible strain were more tolerant than their adults, whilst the reverse was true in the resistant strain.  相似文献   

10.
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 samples 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 sample 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 samples were compared with reference susceptible, weak-resistance and strong-resistance strains from Australia in parallel assays. All Brazilian population samples showed resistance to phosphine: five were diagnosed with weak resistance and 14 with strong resistance. Five samples showed levels of resistance similar to the reference strong-resistance strain. A representative highly resistant sample 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 sample were generally similar to those of the reference strong-resistance strain. For example, 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 samples, 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.  相似文献   

11.
Ethyl formate is being evaluated as a fumigant for stored grain as it is a potential alternative to the ozone-depleting fumigant methyl bromide and to phosphine, which is under pressure owing to the development of strong resistance in stored grain insects. However, use of ethyl formate faces significant challenges, such as poor penetration through grain, significant losses to grain sorption, high concentrations of fumigant required to control insects, and flammability risks, which have limited its further development. In this study it was found that the combination of carbon dioxide (5-20%) with ethyl formate significantly enhanced efficacy of the fumigant against external living stages of the rice weevil, Sitophilus oryzae (L.), the lesser grain borer, Rhyzopertha dominica F., and the flour beetle, Tribolium castaneum (Herbst). Dynamic application of ethyl formate and carbon dioxide mixture (100 mg litre-1 ethyl formate, 20% CO2) pumped through a model silo containing wheat (50 kg) for one gas exchange was also investigated. A flow rate of 6 litres min-1 gave a relatively even distribution of fumigant throughout the grain column and similar mortality levels among cultures of S. oryzae and T. castaneum placed at three positions, the top, middle and bottom of the column. Mortality of 99.8% of mixed stage cultures of T. castaneum and 95.1% of S. oryzae was achieved in 3 h exposures to 111 and 185 mg ethyl formate h litre-1 respectively applied by the dynamic method. It is concluded that the combination of carbon dioxide with ethyl formate and dynamic application enhances distribution and efficacy of the fumigant against stored grain insects.  相似文献   

12.
The effects of exposure period and phosphine concentration on mortality of susceptible and resistant Sitophilus oryzae (L) were investigated. Although S oryzae is one of the world's most serious pests of stored grain there are few data on the practical significance of phosphine resistance in this species. The strains investigated were an Australian susceptible strain, a homozygous resistant strain exhibiting a level of resistance common in Australia and an unselected field strain from China with a much stronger resistance. Fumigations were carried out at 25 degrees C on adults and mixed-age cultures. For adults of all three strains and mixed-age cultures of the susceptible and resistant Australian strains, the relationship between concentration and time could be described by equations of the form Cnt = k. In all cases n < 1, indicating that time was a more important variable than concentration. In all fumigations of adults the resistant strains were harder to kill than the susceptible strain. However, in fumigations of mixed-age cultures, which contained the tolerant pupal stage, the difference between susceptible and resistant strains was more pronounced at lower concentrations than higher concentrations. For example, at 0.02 mg litre-1 the estimated LT99.9 for mixed-age cultures of the Australian resistant strain (27 days) is 3.4 times that of the susceptible strain (8 days), but at 1 mg litre-1 there is no difference between the two strains (4 days). Limited data on the Chinese resistant strain supported this finding. Twenty-three days exposure at 0.02 mg litre-1 had no effect on mixed-age cultures of this strain, but there were no survivors after 5 days exposure to 1 mg litre-1.  相似文献   

13.

BACKGROUND

The fumigant phosphine is used all over the world for disinfestation of stored grains and commodities. Adults of 23 different populations of Tribolium castaneum from 10 different countries were evaluated for phosphine resistance using a modification of the Detia Degesch Phosphine Tolerance Test Kit (DDPTTK). Adults were exposed to 3000 ppm and recorded for 5–270 min for their mobility.

RESULTS

Among the tested populations, high levels of phosphine resistance were recorded in populations from Brazil, Serbia, and Spain. No survivals were recorded after 7 days post exposure for eight of 23 in a tested population.

CONCLUSIONS

Our work revealed four scenarios: 1, quick knockdown–low (or no) recovery; 2, Slow knockdown–high recovery; 3, Quick knockdown–high recovery; and 4, Slow knockdown–low recovery. Our data indicate that post exposure period is critical for the evaluation and characterization of phosphine resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

14.
BACKGROUND: Most fumigants are adsorbed by grain at differing rates depending on the fumigant or grain type. Sorption can reduce the concentrations of fumigation doses to sublethal levels before grain has been disinfested. A model to predict fumigant losses due to sorption in industrial scenarios is needed. RESULTS: This work reviews the kinetics of grain fumigant sorption and develops a new alternative model based upon key factors established from the literature and batch experimental results. The novel model accounts for linear mass transfer within the grain, irreversible 'binding' and linear partitioning of the fumigant to the grain. Model coefficients were estimated by minimizing the sum of squared residuals between model predictions and experimental data. The model was compared with other options including diffusion into spheres, and results for methyl bromide and phosphine are provided. CONCLUSION: The model describes the transient changes of fumigant concentrations in both the intergranular air and grain. It provides the capacity to predict fumigant concentrations throughout grain stacks for a wide range of scenarios of industrial importance.  相似文献   

15.
Field efficacy of five insecticides to a greenhouse strain ofFrankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) of known resistance status was studied. In a greenhouse trial, the mortality of aF. occidentalis strain (Uncali) which exhibited resistance only against cypermethrin in laboratory assays, reached 56%, 68%, 82%, 94% and 99%, 24 h after application of abamectin, cypermethrin, endosulfan, malathion and methomyl, respectively. In the laboratory, for larval mortality equal to that achieved in the field, much lower doses — half of the field dose of cypermethrin and endosulfan, and one-third and one-sixth of malathion and methomyl, respectively, were required in topical application. Because of differences between laboratory and field responses ofF. occidentalis to insecticides, a sound resistance evaluation program to determine field efficacy of insecticides is needed. Resistance increased 28.0- and 139.3-fold at LC50 in theF. occidentalis strain subjected to 27 and 44 cycles of cypermethrin selection, respectively. A slight cross-resistance of two- to threefold was found with endosulfan, malathion and methomyl and no cross-resistance was observed with abamectin. http://www.phytoparasitica.org posting August 4, 2008.  相似文献   

16.
Woodchips from several pine species, infested with the pine wood nematode, Bursaphelenchus xylophilus , were treated in transit using phosphine fumigant. Using aluminum phosphide tablets producing 4 g m−3 phosphine, the percentage of infested samples was reduced from 79 to 6% during the voyage from the USA to Sweden. Temperatures in the periphery of the cargo were lower than in the center, and the fumigation was less effective in the periphery. Phosphine concentration had declined to nearly zero before arrival of the chips in Sweden and posed no safety threat to workers or the ship's crew.  相似文献   

17.
The susceptibilitity of newly hatched larvae of laboratory-adapted and field-collected populations of the Southwestern corn borer, Diatraea grandiosella (Dyar) (Lepidoptera: Crambidae), to a Bacillus thuringiensis protein (Cry1Ab) was examined using a larval feeding bioassay. D grandiosella populations were collected from five states: Missouri, Kansas, Texas, Tennessee and Kentucky. Using larval mortality as the end-point of the bioassay, the magnitude of differences in the susceptibility of the laboratory-adapted and the field-collected populations to Cry1Ab protein varied from one to 46 times depending on the time of observation and the standard of comparison (LC50 or LC95). However, significant differences in susceptibility to Cry1Ab protein among these populations were not detected when the comparisons were based on growth inhibition (EC50 or EC95); the magnitude of differences was less than fourfold. Either using larval mortality or larval growth inhibition, the results indicated that the field-collected populations of D grandiosella were susceptible to Cry1Ac, and differences in susceptibility may reflect natural variation among populations. The bioassay using larval growth inhibition offers advantages over that using larval mortality, including giving more accurate representation of the toxicological effects of the toxin.  相似文献   

18.
The silverleaf whiteflyBemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) [also known as strain B of the sweetpotato whiteflyB. tabaci (Gennadius)] is a major pest of tomatoes due to both feeding damage and transmission of plant viruses. Certain wild species ofLycopersicon have demonstrated high levels of resistance to the pest. Greenhouse studies were undertaken to quantify the effects on whitefly behavior and mortality of individual, resistant plants selected from three accessions ofL. pennellii (Corr.) D’Arcy (LA 1340, LA 1674 and LA 2560), five accessions ofL. hirsutum f.typicum Humb. & Bonpl. (LA 386, LA 1353, LA 1777, PI 127826 and PI 127827) and one accession ofL. hirsutum f.glabratum C.H. Mull. (PI 126449). In no-choice experiments, fewer adults settled on leaflets of the wild species and deposited 75–100% fewer eggs compared to the cultivated tomato,L. esculentum Mill. Adult mortality ranged from 77–100% on wild accessions but was only 1% onL. esculentum. Most dead adults were trapped in glandular trichome exudates. The effects of these resistant accessions onB. argentifolii were mechanically transferable by appressing the trichome exudates onto the leaves of the susceptible tomato, indicating an association between the factors mediating the resistance and the glandular trichomes. Laboratory studies evaluated the repellent, fumigant and residual toxic effects of representative constituents of trichome exudates onB. argentifolii adults by using selected concentrations and probit analyses. RC50 values (estimated concentration to repel 50% of the adults) and LC50 values for fumigant and residual toxicity indicated that 2-tridecanone had low levels of repellent and residual toxicity activity; that 2-undecanone had high levels of repellent and fumigant activity; and that ginger oil (composed, in part, of sesquiterpene hydrocarbons) had high levels of repellent and residual toxicity activity. These studies suggest that multi-factor resistance exists in wild tomato germplasm. By combining genetically the observed chemical constituents of resistance into a single germplasm, the resulting resistance may be more difficult forB. argentifolii to overcome. http://www.phytoparasitica.org  相似文献   

19.
Abstract: The susceptibility of eggs, pupae and adults of Tribolium castaneum (Herbst) and adults of Rhyzopertha dominica (F.), (both phosphine-resistant strains) to phosphine at fixed concentration-time (ct) products, with either constant or increasing or decreasing concentrations was studied at 25 (± 1)°C. At lower ct products, falling concentrations of phosphine generally caused reduced insect mortality in all the three exposure periods in the range 12 to 72 h. However, in R. dominica, both increasing and decreasing concentrations were less effective than constant concentrations. At higher ct products, no significant change in the mortality response was observed in either species after exposure to constant or changing concentrations. The findings indicate the need to maintain sufficiently high concentrations of phosphine until the end of the fumigation period.  相似文献   

20.
The variation in tolerance to diflubenzuron [1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea] was examined in fourth instar larvae of seven strains of Aedes aegypti, some of which were resistant to DDT and permethrin. The difference between the least and the most tolerant to diflubenzuron was approximately two-fold. There was no correlation with resistance to the other insecticides. A DDT-resistant strain (T8) was selected 10 times (during 12 generations) with diflubenzuron. The LC50 to diflubenzuron had increased 3.3 times by the S8 generation but there was no further increase in later generations despite further selection. Associated with this increase, a marked decrease in resistance to DDT was observed but no change in permethrin tolerance. A genetically enriched strain (Hotchpotch) was synthesised from 35 strains of different geographic origin and crossed to the selected T8 strain before subsequent generations were selected five times with diflubenzuron. This procedure resulted in an 8 to 12-fold increase in the LC50 value over that for unselected T8, accompanied by a decrease in the slope of the log dose against probit mortality line.  相似文献   

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