1,720,969 research outputs found
Application of powder formulation of Metarhizium anisopliae to control Oryctes rhinoceros in rotting oil palm residues under leguminous cover crops
No full textThe powder formulation of Metarhizium anisopliae was applied by spraying method onto the rotting heaps of oil palm residues under the leguminous cover crops. The M. anisopliae infected all stages of Oryctes rhinoceros. At eight months after treatment (MAT), the application of product at rates of T1, 0.2 g (2.2 x 107 spores) and T2, 0.4 g (4.4 x 107 spores) m-2 heap was significantly reduced (P0.05) with the control at all times of data recording. Although infection can occur on larvae and adults, but the percentage was low, ranging from 0% - 0.6% at five MAT and 1.7% and 2.5% at eight MAT
The use of palm kernel cake in the production of conidia and blastospores of Metarhizium anisopliae var. major for control of Oryctes rhinoceros
No full textThe yield of conidia and blastospores of Metarhizium anisopliae var. major produced on maize supplemented with palm kernel cake (PKC) was estimated. In maize supplemented with 5 g and 10 g of PKC, the fungus produced 4.3 g and 5.6 g of conidia respectively. This is significantly higher than the yield of conidia produced on maize alone, which was 2.03 g. The fungus produced submerged spores termed as blastospores, in a simple liquid medium consisting of glucose and PKC. The formation of blastospores during the fermentation process was monitored. The results showed that the young blastospores are round to ovoid, with 5.0-5.5 ?m in diameter and matured blastospores are commonly ellipsoid with dimensions ranging from 5.0-5.5 ?m x 12.5-15.5 ?m. The highest yield of the blastospores was 3.26 x 106 blastospores ml-1, produced at seven days after fermentation. The conidia and blastospores were equally effective in controlling the third instar larvae of the Oryctes rhinoceros. Sixteen days after treatment, both inocula killed 100% larvae, with infection of between 94.3% and 97.1%. The LC50 values for both inocula were almost similar, at 9.1 days for conidia and 9.5 days for blastospores. This study showed that PKC can be used as a supplement to produce conidia and blastospores of the fungus, M. anisopliae var. major, and that the blastospores are potential for the biocontrol of the rhinoceros beetle
Optimization of the polymerase chain reaction (PCR) method for the detection of Oryctes rhinoceros of virus
No full textOptimization of the polymerase chain reaction (PCR) method for the rapid detection of Oryctes rhinoceros virus (OrV) was studied. The virus DNA was extracted from the gut tissues by a robust method. Using a pair of specific primers, Primer 15a and 15b, infection was confirmed when the PCR product produced a single 945 bp DNA band. The optimized concentrations of the PCR components were at 2.0 mM MgCl2, 1.0 mM 10X PCR buffer, 0.2 mM Primer 15a and 15b, 0.5 U Taq-DNA polymerase and 0.4 mg bovine serum albumin (BSA). All tested virus DNA concentrations at 0.085, 0.170 and 0.255 ?g ?l-1 were suitable for virus detection. Addition of BSA (20 mg ml-1) at 0.4 mg in the reaction increased the PCR sensitivity. The method is capable of detecting OrV infection from DNA diluted one million times or equivalent to a virus DNA concentration as low as 2.23 pg ?l-1. The PCR detected 83.2% adult beetles from pheromone traps as being infected by OrV, 13.6% higher (P0.05) compared to the method based on gut morphological appearance. The PCR was also capable in detecting virus at an early infection stage and in dead adults with decayed tissues. Of the 307 adults that appeared to be healthy, 36.1% of them were found to be infected. As much as 61.6% of dead adults with decayed tissues (N = 428) were diagnosed to be infected by the OrV. The method can be used in further research studies relating to OrV for the management of the rhinoceros beetle
Research into the commercialization of Metarhizium anisopliae (Hyphomycetes) for biocontrol of the rhinoceros beetle, Oryctes rhinoceros (Scarabaeidae), in oil palm
No full textUsing the entomopathogenic fungus, Metarhizium anisopliae, to control the rhinoceros beetle, Oryctes rhinoceros, was first attempted in 1976. Early screening showed M. anisopliae variety major to be highly pathogenic to O. rhinoceros. Further work concentrated on using the variety to control O. rhinoceros as the pest infestation increased in oil palm plantations. Assessment of isolates from different localities found little variation in pathogenicity between them. Dipping the larvae in a spore solution of 108 spores ml-1 caused 100% mortality after 12 and 14 days. Analysis of the fungal DNA by RAPD-PCR showed a high similarity in the genetic base among isolates. Two primers can be used for fingerprinting and as a post-release monitoring tool as they were able to differentiate the isolates SE and BP from the others. An initial field study applying the fungus as spore solutions and sporulated substrates infected all stages of the pest, causing up to 84% reduction in its overall population. The effects of the fungus on the oil palm pollinating weevil and non-target organisms were studied. The fungus did not affect development of the weevil. Toxicity tests showed the fungus to be harmless to rats. Fish exposed to very high spore concentrations of 1000 mg ml-1 (eight times higher than the highest rate applied in the field) only caused 25% mortality and at 2000 mg ml-1 only 40% mortality. The larvae of the stag beetle, Aegus chelifer, were susceptible to M. anisopliae, although less so than the larvae of O. rhinoceros. At 12 days after treatment, all the tested isolates caused 33.3% - 83.3% mortality to the stag beetle larvae but killed all (100%) of the O. rhinoceros larvae. The spores of M. anisopliae were successfully mass produced using solid state fermentation. Fungal mycelia were first produced in liquid medium and then sporulated on a solid medium of maize. Harvesting was done by separating out the spores from the maize by washing in water, collecting them by vacuum filtration and drying at low temperature before finally grinding to powder. The yield of spores was 9.2-10.5 g per 200 g maize bag with a viability of > 80%. The powder formulation was tested in the field, pre-mixed with water and applied to rotting oil palm debris by spraying. M. anisopliae infected O. rhinoceros in all stages of its life cycle. Application to rotting debris reduced the O. rhinoceros population by up to 80%. The field application of M. anisopliae did not affect the populations of oil palm pollinating weevil and stag beetle
Trap for the auto dissemination of metarhizium anisopliae in the management of rhinoceros beetle, oryctes rhinoceros
No full textAn inoculation trap for the auto dissemination of spores of Metarhizium anisopliae for the management of Oryctes rhinoceros in the field was designed and tested. The efficiency of the inoculation trap in capturing the adult rhinoceros beetles was found to be as good as the commercial pail type trap. The trap capture rate was 2.5 adults per trap per night (a/t/n), no different (at P>0.05) from the capture rate by the pail type trap (2.4 a/t/n). A performance test showed that 66.7% of the trapped adults that escaped from the inoculation trap were subsequently confirmed dead due to infection by the fungus. Laboratory tests also found that the infected adults had disseminated the spores to the breeding site, killing 91.7% of the larvae by fungal infection. The mortalities of the released inoculated adults were between 63% and 69%, due to infection by M. anisopliae. A field test showed that the percentage of trapped adults leaving the trap was between 85% and 95%. Both rates of spore solution (at 2 and 4 g litre-1) caused high mortality to adults within the period of 15-30 days after trapping (DAT), and complete mortality was recorded at 45 DAT. Some 75% to 90% of the dead adults were confirmed to be infected by M. anisopliae. The density of viable spores collected from the soil in the trapping region showed an increase, suggesting that the M. anisopliae had been established in the breeding sites of the beetle
Molecular approaches in the assessment of Oryctes rhinoceros virus for the control of rhinoceros beetle in oil palm plantations
No full textThe successful introduction of the Oryctes rhinoceros virus to control an outbreak of the rhinoceros beetle, O. rhinoceros on coconut in the South Pacific islands has led MPOB to embark on a project to study the potential use of the virus in oil palm plantations in Malaysia. Two DNA-based technologies, the polymerase chain reaction (PCR) and the restriction virus genome by an endonuclease enzyme, have been developed and intensively used in the project. PCR is a sensitive yet simple procedure allowing a more accurate estimation of the infection level of the O. rhinoceros virus on adult beetles and larvae. PCR diagnosis showed that the adult beetles were more commonly infected (30%-65%) as compared with larvae (0%-35%). Pre-pupae and pupae were free from the virus infection. Virus genomic analysis by an endonuclease enzyme HindIII identified four types of O. rhinoceros virus, named as type A, B, C and D. Bioassays showed that the virus type B was more pathogenic against the third instar larvae and neonates. A virus field introduction system was then established. The virus solution was produced by an in vivo method using the larvae and adult beetles. Introduction of the O. rhinoceros virus type B in an estate with palms less than one year old with
existing virus of type A resulted in a successful reduction of the adult population as well as in palm damage. The released virus established as early as three months after release (MAR) and persisted up to 15 MAR. The virus type B was then introduced in an immature area with palms more than three years old. The virus infection gradually increased and was maintained at a higher level of between 60% and 90%. The adult population was reduced, and stayed at a low level for a certain period of time before slowly increasing again to reach a second peak. The virus infection had a weak negative correlation with the adult population. A slow reduction in the proportion of males was observed, possibly due to slow virus transmission, as the adult population had probably already adapted to the virus infection. Genomic analysis showed that the virus type B was detected only at four MAR. Factors ensuring the success of virus transmission in the population were elaborated upon. Further research to fully utilise the O. rhinoceros virus to ensure maximum control of the rhinoceros beetle was also discussed
Pathogenicity of granule formulations of Metarhizium anispoliae against the larvae of the oil palm rhinoceros beetle , Oryctes rhinoceros (L.)
No full textGranule formulations consisting of mycelia and spores of Metarhizium anisopliae var. major as the active ingredient were produced and tested against the larvae of Oryctes rhinoceros. The effect of the medium pH on the production of mycelia was investigated, and the granule compositions were optimized. The fungus produced higher yields of mycelial pellets (0.58 g) at pH=8 as compared to pH=5, 6 or 7. Granules prepared from mycelia with the growing medium (G+MM) improved fungal growth (100%) and sporulation (87.2%) as compared to granules prepared from the mycelia alone (G+M) (growth and sporulation, 62.4% and 47.6%, respectively). The amounts of ingredients, such as kaolin and rice bran used in making the granules, were then optimized. The weight of granules increased as the amount of kaolin and rice bran increased, but granule quality was reduced. The highest quality granules (with growth 98.5%, sporulation 88.6% and dry weight 1249 g) were prepared with 925 g kaolin and 400 g rice bran. The pathogenicity of the G+MM granules was tested against the third instar larvae of O. rhinoceros. The test showed that at 20 days after treatment (DAT), treatment with rates of 1.0 g and 2.0 g granules/box caused 90% mortality, which was as high as with the treatment using pure spore solutions (96%). The G+MM granules produced more spores and more quickly than granules made from spores (G+Sp). Both types of granules produced 0.42-6.60 x 106 spores/granule. Results of the bioassay indicated that application of G+MM and G+Sp at rates of 3 g, 6 g and 9 g killed 100% the third instar larvae as early as at 18 DAT. Infection level increased as the application rate increased. G+MM and G+Sp applied at 9 g/box caused the highest infection of 93.3% in the larvae. The potential use of the granule formulation to control O. rhinoceros in the field was also discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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