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1.
Neem, Azadirachta indica A. Juss. (Meliaceae), seed oil (NSO) added to meridic diet at concentrations as low as 0.016% reduced pupation and prevented adult eclosion of obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). At a rate of 0.0016%, NSO reduced the fitness of C. rosaceana, resulting in longer developmental times, lower adult eclosion rates, and reduced egg production compared with controls. The neem insecticide Margosan-O TM produced comparable results based on concentrations of the most biologically active constituent, azadirachtin. Pupation was completely inhibited at concentrations of 0.25% and 1.0% for larvae exposed at 5th or 6th instar, respectively; rates as low as 0.016% reduced pupal weights and adult eclosion rates. For larvae transferred to treated diet at 5th instar, physical abnormalities in the wings of adults occurred at a rate of 0.004% NSO and increased with increasing treatment rates. NSO at concentrations as high as 2.0% was not antifeedant to neonate larvae, based on 24 and 48 h choice test bioassays, when incorporated into a meridic diet.  相似文献   

2.
The impact of low levels of spinosad on the obliquebanded leafroller, Choristoneura rosaceana Harris (Lepidoptera: Tortricidae), and the koinobiont endoparasitoid, Apophua simplicipes Cresson (Hymenoptera: Ichneumonidae), was assessed when the parasitoid was in the larval stage within second‐ and fourth‐instar hosts. These are developmental stages that would be exposed to spring orchard treatments of the insecticide. Oral spinosad LC50 levels for unparasitized obliquebanded leafroller hosts were <1% of the recommended orchard treatment levels. Apophua simplicipes survival was significantly reduced within parasitized spinosad‐treated second‐ and fourth‐instar larval hosts. Both the leafroller host and parasitoid were much more susceptible (ca. 65‐fold) to spinosad when larval hosts fed on spinosad‐treated leaf material as opposed to being treated topically. When hosts were exposed to extremely low doses of spinosad, a small percentage of parasitoids was able to survive to emerge as adults. These laboratory trials predict that applications of spinosad may reduce biological control of C. rosaceana populations by ichneumonid endoparasitoids developing within treated hosts.  相似文献   

3.
Adult and sixth instar obliquebanded leafroller, Choristoneura rosaceana (Harris), exposed previously as fifth instar larvae to sub-lethal concentrations of neem, Azadirachta indica A. Juss., seed oil contained in artificial diet were more susceptible to topically applied pyrethroid, carbamate and organophosphate insecticides than C. rosaceana reared on control diets. Increased susceptibility to insecticides did not result from reduced vigour, as measured by reductions in adult or larval weights, but is instead correlated with previously demonstrated reductions in detoxication enzyme activities. The modest increases in susceptibilities, not exceeding ca. 4.5-fold, for C. rosaceana exposed to neem were achieved with subjects from a susceptible laboratory colony; a larger response could be expected for resistant field populations having elevated detoxication enzyme levels. Neem-based insecticides could be useful tools for the management of orchard pests that have developed resistance to synthetic neurotoxins. These findings also contribute to a better understanding of the numerous physiological changes that occur in larval Lepidoptera following exposure to neem extracts.  相似文献   

4.
Apple clearwing moth larvae, Synanthedon myopaeformis (Lepidoptera: Sesiidae) were found to be susceptible to infection by two entomopathogenic fungi: an indigenous fungus isolated from S. myopaeformis cadavers and identified as Metarhizium brunneum (Petch); and Beauveria bassiana isolate GHA. In laboratory bioassays, larvae exhibited dose related mortality after exposure to both the M. brunneum and Beauveria bassiana with 7 day LC50's of 2.9×105 and 3.4×105 spores/mL, respectively. Larval mortalities caused by the two isolates at 1×106 spores/mL were not significantly different and 73% of the M. brunneum-treated, and 76% of the B. bassiana-treated larvae were dead 7 days post treatment, with LT50's of 5.5 and 5.1 days, respectively.  相似文献   

5.
Virulent entomopathogenic fungal strains against Cydia pomonella (Lepidoptera: Tortricidae) were isolated and identified in the Western Cape Province of South Africa. Thirty-nine isolates belonging to six species were obtained using the insect bait method. Generally, Metarhizium robertsii (Ascomycota: Hypocreales) was the most frequently encountered species representing 51% of the total number of isolates collected from the soil samples. This is the first report of M. robertsii from southern Africa. Mortality data from an immersion bioassay indicated that the 39 fungal isolates were pathogenic against fifth instar larvae of C. pomonella inducing 47–85% insect mortalities. Two M. robertsii strains, MTL151 and GW461, induced 85% larval mortality and were selected for further evaluations. The exposure of freshly laid eggs to wax papers that were pre-treated with fungal spores ranging from 103 to 108 spores ml?1 of MTL151 and GW461 resulted in a significant reduction of egg hatchabilities, from 95 to 66% and 93 to 71%, respectively as spore concentration increased. First instar larval neonates were exposed to apples that were pre-sprayed topically with varied conidia suspensions (103?108 spores ml?1). The mean percentage of participating apples with larvae in their cores/flesh significantly reduced from 53 to 10% (MTL151) and 76 to 10% (GW461) of 10 apples, and a concurrent decrease in the incidence of apple fruit rot was observed as conidia concentration increased. Up to 90% of apples treated with 1 × 108 spores ml?1 had no larvae present in their cores and this result compared favourably with the commercial pesticide Fruitfly®, containing the active ingredient cypermethrin (20 g/l) used at a recommended dose of 0.25 ml/250 ml of water.  相似文献   

6.
Abstract Feeding experiments using three strains of entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea were conducted with newly moulted 3rd–5th instar Ocinara varians Walker larvae in the laboratory. The mortality of larvae immersed individually in spore suspension (1 × 107 spores/mL) of all the strains was ≥ 80% except 5th instar larvae treated with M. anisopliae which transformed into pupae, but did not result in adult emergence. The growth (total body mass), consumption, relative consumption rate and relative growth rate, were reduced at all three larval stages, while developmental time was extended in infected larvae with concurrent significant increase in approximate digestibility in infected larvae. Conversion of digested food (ECD) and ingested food (ECI) values declined in infected larvae as compared to the healthy larvae (control). The 5th instar larvae treated with M. anisopliae showed higher ECD and ECI values than control. Based on mortality and growth inhibition it can be suggested that all the studied fungal strains have a high potential for biocontrol and could be developed into biocontrol agents against O. varians.  相似文献   

7.
The main objective of this study was to assess the susceptibility of the black cutworm (Agrotis ipsilon) to the biopesticide spinosad and to a commercial formulation (GHA strain) of the entomopathogenic fungus, Beauveria bassiana. Secondly, we quantified the effects of sublethal doses of spinosad on a number of A. ipsilon fitness parameters, and interactions resulting from simultaneous applications of sub-lethal doses of spinosad and B. bassiana. Under laboratory conditions, A. ipsilon third instar larvae were highly susceptible to spinosad, with an estimated LC50 of 50 ppm. The entomopathogenic fungus, B. bassiana had a lower efficacy with an estimated LC50 of 7×107 spores mL?1. Topical applications of 5, 7.5 and 10 ppm of spinosad on third instar larvae reduced larval size and increased time to pupation and to emergence. However, pupal and adult weights were not significantly different between treated and control individuals. Additivity was observed from most spinosad–B. bassiana combinations tested, thus indicating compatibility between products. We concluded that spinosad is a promising tool for controlling black cutworm larvae alone or in combination with other products.  相似文献   

8.
Low impact alternatives to synthetic insecticides for the control of apple sawfly (Hoplocampa testudinea Klug) are scarce encumbering pest management in organic apple orchards. We investigated the soil persistence and field efficacy of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (BotaniGard) against apple sawfly under common organic orchard practices. We also assessed the efficacy of B. bassiana GHA and Metarhizium brunneum Petch (indigenous strain) against sawfly in the laboratory. Larvae treated with either fungus in the laboratory died faster than control larvae and displayed 49.4%–68.4% mycosis. In the field, B. bassiana density remained high in the week after application, during larval descent to the soil. Fungal density decreased to 25% at 49 d after application and to 0.4% after 55 weeks. Molecular markers revealed that the majority of fungal isolates recovered comprised the applied B. bassiana strain GHA. Larvae pupating in soil cages in the orchard for 49 d displayed 17% mycosis. The high efficacy under laboratory conditions was not seen in the field. B. bassiana application resulted in densities above the upper natural background level during the growing season, but reversion to background levels occurred within a year. It remains to be investigated whether this has a detrimental effect on nontarget organisms. Additional work is needed to bridge the knowledge gap between laboratory and field efficacy in orchards.  相似文献   

9.
The pathogenicity of Beauveria bassiana on Cerambyx welensii is first reported. Three native fungal isolates from Badajoz (Spain) were bioassayed on neonates using cork oak disks and LC50s were 1.16–1.76 × 105 and 0.30–0.61 × 105 spores/ml on the 7th and 14th day post-inoculation. The fungus is potentially a biocontrol agent of C. welensii.  相似文献   

10.
Maize is a major staple food for over 300 million people in sub‐Saharan Africa. Sustainable productivity of this primary crop has been recently threatened by Fall armyworm (FAW), Spodoptera frugiperda invasion. Due to lack of environmentally safe management strategies, immediate responses by growers and governments to tackle FAW are based on rampant use of pesticides. Looking for efficient biopesticides, twenty entomopathogenic fungal isolates (14 Metarhizium anisopliae and 6 Beauveria bassiana) were screened for their efficacy against eggs and second instar larvae of FAW. A single discriminating concentration of 1 × 108 conidia ml?1 and four replicates per treatment were used in all experiments. Isolates were assessed for their ability to cause mortality of FAW second instar larvae, eggs and the neonate larvae that emerged from treated eggs. Among the isolates tested, only B. bassiana ICIPE 676 caused moderate mortality of 30% to second instar larvae. Metarhizium anisopliae ICIPE 78, ICIPE 40 and ICIPE 20 caused egg mortalities of 87.0%, 83.0% and 79.5%, respectively, and M. anisopliae ICIPE 41 and ICIPE 7 outperformed all the others by causing 96.5% and 93.7% mortality to the neonate larvae, respectively. The cumulated mortality of eggs and neonates was highest with M. anisopliae ICIPE 41 (97.5%), followed by M. anisopliae ICIPE 7, 655, 40, 20 and 78 with total mortality of 96.0%, 95.0%, 93.5%, 93.0% and 92.0%, respectively. These isolates with high cumulated mortality (≥92%), especially ICIPE 78 and 7, which are already commercialized for spider mites and ticks control respectively, would be good candidates for development as biopesticides for management of FAW in Africa if further evidence of their efficacy is obtained in the field.  相似文献   

11.
Three isolates of Beauveria bassiana were evaluated under laboratory conditions for pathogenicity against the European corn borer, Ostrinia nubilalis. Dose-mortality regressions and nonparametric statistical analyses revealed significant differences in pathogenicity between isolates and across O. nubilalis instars. First instars were found to be the most susceptible of the five larval stages. Little difference was noted for instars 2, 3, and 5 within any of the three B. bassiana isolates. Fourth instar larvae were found to be the most tolerant in all cases.  相似文献   

12.
Two strains of Pseudomonas fluorescens were found contaminating a biopesticide used in a previous study against Varroa destructor infestations in honey bee hives. In that study, the biopesticide, a formulation of a fungal pathogen of arthropods, Beauveria bassiana, failed to have any negative impact on the mite infestation despite successful results in previous studies using uncontaminated batches of the same biopesticide. The objective of the present research was to determine whether the bacteria may have interfered with the infectivity and/or virulence of B. bassiana in a simplified system; positive results in that system would then provide a rationale for further work under more complex conditions. Galleria mellonella late instar larvae treated topically with both a bacterial suspension of 6.8 to 7.0×107 cfu/ml and a fungal suspension of 2.5×107 or 2.5×108 B. bassiana conidia/ml showed, in the case of one of the bacterial strains, significantly increased survivorship compared to larvae treated with just the B. bassiana suspension. When larvae were immersed in a bacterial suspension prior to application of B. bassiana suspension using a spray tower, a significant positive effect of the same P. fluorescens strain on larval survivorship was observed at 2.5×108 conidia/ml. Neither the bacterial suspensions alone nor blank control solutions had any effect on larval survivorship. These results show that an interaction between the bacteria and the pathogen may explain some of the results from the prior field trial.  相似文献   

13.
The effects of Beauveria bassiana strain GHA, applied as BotaniGard ES, on newly colonised and well-established populations of emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae) were evaluated in the field using foliar and trunk sprays in Michigan in 2004–2005. Results from field trials at a newly colonised white ash site showed a 41% reduction in A. planipennis population in fungal-treated trees compared with that of untreated controls. In addition, fungal infection was also found in 20% of the larval population within 14 days of incubation under laboratory conditions. At a site with a well-established Agrilus planipennis population in green ash trees, larval density was reduced by 47% for trees treated with the fungus compared with that of the controls; 21% of larvae from the current generation were found infected after 14 days of laboratory incubation. Fungal-treated green ash trees also produced fewer adults emerging in the next generation, with a 63% reduction in adult density observed in treated trees compared to that of controls. As a result, fungal-treated trees sustained 42% less crown dieback than did controls. A. planipennis larval density was negatively correlated with trunk height above the ground, and positively correlated with log diameter. Results of laboratory leaf bioassays on A. planipennis adults showed that fungal conidia persisted well under field conditions, with mortality of 78–100% at 7 – days post – exposure for leaves collected between 2 and 264 h after application. Potential strategies for using B. bassiana strain GHA for managing A. planipennis are discussed.  相似文献   

14.
An indigenous betabaculovirus (PapyGV) of the Pandemis leafroller, Pandemis pyrusana (Kearfott), was studied in the laboratory and greenhouse to determine how the virus affected leafroller mortality and foliar damage. Probability of mortality increased with virus concentration as observed after 7 and 10 days of feeding on virus treated diet in neonates and second instar larvae. LC50 estimates for neonates at 7 and 10 days was 2743 and 389 occlusion bodies (OBs)/mm2. For second instars, LC50 was 139,487 and 813 OBs/mm2 at 7 and 10 days. There was no biologically significant mortality response to increasing virus concentrations by fourth instar larvae; however, when fourth instar larvae were infected with virus on diet and then fed apple leaves, the leaf area consumed declined up to 50% with higher virus concentrations. In a greenhouse study, neonate larvae that fed on seedlings treated with water showed >90% survival and 80% pupation rate of larvae after being transferred to diet. In contrast, larvae that fed on apple seedlings sprayed with 3×106 OBs/ml showed poor survival when transferred to diet after acquiring the virus and failed to reach the pupal stage. This virus shows promise for population regulation and can produce reduction in feeding damage.  相似文献   

15.
The potato psyllid, Bactericera cockerelli (?ulc), is a pest of potato, tomato, and some other solanaceous vegetables and has also been incriminated in the transmission of a bacterial pathogen, Candidatus Liberibacter solanacearum, resulting in a serious disease known as ‘zebra chip’. Although there are several reports of fungal pathogens in psyllids, there are none from B. cockerelli, nor have any fungi been evaluated against it. Five isolates of fungi, one Beauveria bassiana, two Metarhizium anisopliae and two Isaria fumosorosea, were bioassayed against B. cockerelli on potato leaves under ideal conditions for the fungi. All applications were made with a Potter spray tower. With the exception of concentration-effect studies, all other applications were made using 107 conidia/mL in a 2-mL aqueous suspension. All isolates except B. bassiana, produced 95–99% mortality, corrected for control mortality, in adults 2–3 days after application of conidia and 91–99% in nymphs 4 days after application. The corrected mortalities for adults and nymphs treated with B. bassiana were 53 and 78%, respectively, 4 days after application. I. fumosorosea Pfr 97 produced 95% corrected mortality in both first and late third instar nymphs. M. anisopliae (F 52) produced 96% corrected mortality in first and third instar nymphs. Pfr 97 and F 52 were evaluated for insecticidal activity against third instar B. cockerelli using 105, 106, and 107 conidia per mL. Mortality produced by I. fumosorosea Pfr 97 ranged from 83 to 97% and that of M. anisopliae F 52 was 88 to 95% at these concentrations.  相似文献   

16.
Four fungicides used for controlling foliar diseases of potato (Solanum tuberosum) were evaluated under field and laboratory conditions for their effects on the infectivity and sporulation of Beauveria bassiana when used as a control for the Colorado potato beetle, Leptinotarsa decemlineata (CPB). We investigated the direct effects of fungicides on B. bassiana-induced CPB mortality and the effect of time between fungicide and B. bassiana application. Effects of fungicide on conidial survival in the soil and on foliage were examined in the field. Significantly more larval mortality was observed when larvae were sprayed with B. bassiana than with the water control. Fungicide had no significant effect on larval mortality in the field. In the laboratory, survival of larvae was significantly lower among larvae fed fungicide-treated foliage. B. bassiana-induced mortality in the laboratory was observed only when larvae were fed foliage treated with copper hydroxide or water. Larvae fed mancozeb- or chlorothalonil-treated foliage experienced high mortality regardless of B. bassiana treatment. While there was no significant effect of fungicide on B. bassiana sporulation on cadavers in the field, a pattern emerged that indicated higher proportions of cadavers producing conidia in plots sprayed with water or copper hydroxide than in plots sprayed with chlorothalonil or mancozeb. Survival of B. bassiana conidia in the soil and on foliage was significantly greater in plots treated with copper hydroxide or water than in plots treated with mancozeb or chlorothalonil. Fungicides such as copper hydroxide may be less deleterious to the fungus than mancozeb and chlorothalonil.  相似文献   

17.
We tested the combined effect of the fungus Beauveria bassiana and the microsporidium Nosema pyrausta on the European corn borer larvae, Ostrinia nubilalis, in the laboratory. The first instar of O. nubilalis larvae was the most sensitive to the B. bassiana infection followed by the fifth, second, third, and fourth instar (LC50s were 4.91, 6.67, 7.13, 9.15, and 6.51 × 105 conidia/ml for the first to fifth instars, respectively). Mortality of each instar increases positively with concentration of conidia. When B. bassiana and N. pyrausta were used in combination, mortality increased significantly in all instars. Relative to the B. bassiana treatment alone, the B. bassiana + N. pyrausta treatment decreased the LC50s by 42.16%, 37.63%, 21.60%, 27.11%, and 33.95% for the first to fifth instars, respectively. The combined effects of the two pathogens were mostly additive. However, at the two highest concentrations the pathogens interacted synergistically in the first and second instar. Individuals that survived the B. bassiana and B. bassiana + N. pyrausta treatments and developed into adults had significantly shorter lifespans and females oviposited fewer eggs than non-exposed insects. The effects on the longevity and the egg production were most pronounced at high concentration of B. bassiana conidia.  相似文献   

18.
The larvae of the pine processionary moth (PPM), Thaumetopoea pityocampa, feed on the needles of pine and cedar. The urticating hairs of older instars pose a threat to human and animal health. Strains of the entomopathogenic fungi, Metarhizium brunneum (V275, ARSEF 4556) and Beauveria bassiana (KTU-24), were assayed against first to fourth instar T. pityocampa using doses ranging from 1?×?105 to 1?×?108 conidia mL?1. The three strains differed slightly in their virulence but caused 100% mortality of all instars at the highest dose. The newly emerged or first instar larvae were extremely susceptible with 100% mortality being achieved 2–4 days post inoculation with V275 at all but the lowest dose. The fourth instar larvae appeared to be less susceptible than earlier instars. There was good horizontal transmission of conidia from treated to un-inoculated larvae. However, mortality was higher in third and fourth instars and where the ratio of inoculated versus untreated larvae was high. This we presume is due to spores being more readily trapped by the urticating hairs found on third and older instar larvae. Injection of the nests offers a simple and environmentally friendly way of controlling the pest with reduced risk to operators.  相似文献   

19.
This study examined the effects of strain Beauveria bassiana (LPSC 1067) on nymphal development time, fecundity and adult survival in Dichroplus maculipennis and Ronderosia bergi under laboratory conditions. It was observed that infection with 1×103 conidia/ml altered nymphal development time, fecundity and adult survival in both species. Mortality of D. maculipennis during third through the last instar (sixth) was significantly higher among treated nymphs (66±3.8%) than in controls (15±1.7%). Similarly, mortality in R. bergi during third through the last instar (fifth) was higher in treated nymphs (71±2.8%) than in controls (19±1.5%). Nymphal development times of both infected D. maculipennis and R. bergi were longer than controls. On the other hand, among survivors of both the species, control adults lived longer than infected adults. Finally, control grasshoppers of both species were much more successful reproductively than infected grasshoppers.  相似文献   

20.
The strawberry bud weevil, Anthonomus signatus (Say) (Coleoptera: Curculionidae) is a serious pest of strawberry crops in Canada. The results of previous laboratory screening and bioassay experiments showed that A. signatus adults were susceptible to several isolates of Beauveria bassiana (Balsmo) Vuillemin. Based on these results, the INRS-IP and INRS-CFL isolates were selected for field trails. Using a randomized block design with four replicates, three applications of the INRS-IP and INRS-CFL isolates were applied at a rate of 1×1013 conidia/ha at 7-day intervals. The multiple applications of B. bassiana triggered a significant reduction of A. signatus adult populations in strawberries. Twenty-four days after the first application, a significant difference was observed between the mean numbers of surviving adults in all B. bassiana-treated plots compared to control plots. During the field experiment, the persistence of insecticidal activity and the viability of B. bassiana conidia were also monitored. Results showed the presence of viable and infective conidia on strawberry foliage up to 6 days after each application. Moreover, the multiple applications of B. bassiana at a rate of 1×1013 conidia/ha resulted in a significant reduction of damaged strawberry fruits compared with control plots, where fruit loss was caused by A. signatus feeding and egg laying.  相似文献   

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