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by
D. Omar |
Total Records (
3 ) for
D. Omar |
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A. Dezianian
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A. S. Sajap
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W. H. Lau
,
D. Omar
,
H. A. Kadir
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R. Mohamed
and
M. R. M. Yusoh
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Problem statement: Diamondback moth, Plutella xylostella L. (Lepidoptera, Plutellidae) is the most destructive insect pest of cruciferous plants throughout the world which become resistant to wide range of chemical pesticides. PxGV is known as an effective factor on diamondback moth larval mortality. Approach: Some morphological characteristics, viral DNA isolation and Restriction Endonuclease (REN) analysis of P. xylostella granulovirus and its effects of different concentrations on its larval host Diamondback Moth P. xylostella, were studied. Results: Taiwanian isolate confirmed due to restriction pattern and genome size of PxGV Taiwanian isolate which was compared with PxGV isolates reported earlier. PxGV originally isolated in Taiwan has capsules that are ovocylindrical with a mean size of 272.84±12 by 148.27±19 nm. The virions are 168.44±16x29.57±12 nm. Results from pathogenicity test of the granulovirus to DBM using the leaf disc method shows that first, second and third instars of P. xylostella were significantly susceptible to infection by PxGV. Older larvae were less susceptible to PxGV than younger larvae with the same virus concentration. The LC50 for second instar larvae was 1.39x106 granules mL-1. The LT50 values ranged between 3.813-6.946, 4.965-9.743 and 5.145-9.407 days for first to third instars in three different concentrations, respectively. Conclusion: Its high specificity and pathogenicity to its larval host indicate that PxGV is a good candidate as an alternative biopesticide to chemical insecticides in an Integrated Pest Management (IPM) of P. xylostella. |
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Y.L. Cheong
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A.S. Sajap
,
M.N. Hafidzi
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D. Omar
and
F. Abood
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A field study on population of bagworms was carried out in oil palm, Elaeis guineensis, plantation at Hutan Melintang, Perak, Malaysia from October 2005 to April 2006. Sampling was conducted at 14 days interval. The result suggests bagworm infestation was not correlated with amount and distribution of rainfall as being claimed by many planters. The result also shows that Pteroma pendula (Lepidoptera: Psychidae) was the most dominant bagworm species among all of the bagworms recorded. Natural enemies, predators, parasitoids and some entomopathogenic fungi, contributed to mortality of the bagworms. Larvae of Callimerus arcufur (Coleoptera: Cleridae) were the most common predator attacking the bagworms. Cosmelestes picticeps (Hemiptera: Reduviidae) was also observed attacking P. pendula. Among three species of parasitoids, Dolichodenidea metasae (Hymenoptera: Braconidae) was the most significant parasitoid of bagworm and this parasitoid commonly attacked by a hyperparasitoid, Pediobius imbrues (Hymenoptera: Braconidae). Two species of entomopathogenic fungi, Peacilomyces fumosoroseus and Metarhizium ansopliae, were isolated from fungal-infected bagworms. Even though natural enemies were affecting the bagworm populations in the field and their resultant impact in controlling the bagworm populations in the field was still far from desirable. |
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H. Sule
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R. Muhamad
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D. Omar
and
A. Hee
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The Asian citrus psyllid D. citri is regarded as one of the most important pest of citrus, because it is known to be the most efficient vector of bacterium Liberobacter asiaticum that cause citrus greening or huanglongbing. Survivorship from egg to adult emergence and fertility of D. citri on C. suhuiensis (limau madu) were studied under laboratory condition (29±1°C and 85% RH). Limau madu of height 12 cm with flush leaves were placed in a wooden cage covered with nylon mesh containing citrus plant with D. citri for egg laying. Life table was constructed base on population parameters obtained under unlimited food supply and natural enemies free environment. The result showed that highest mortality in 1st instar nymphs (40.23%) with k-value of 0.22 and mortality (25.59%) in 2nd instar nymphs with k-value of 0.13 are the key factors regulating the population size. The sex ratio (proportion of female to male) was 1:0.65. The maximum life span of female was 23.6 days and the trend of oviposition showed a peak at about the 12th day of the female life span with 3.85 mean numbers of eggs per female. The intrinsic rate of natural increase (rm) was 0.026 per female per day and daily finite rate of increase (λ) was 1.023 per female per day, with a mean generation time (T) of 26.528 days. The net reproductive rate (Ro) of the population was 2.004 and the population Doubling Time (DT) was within 26.456 days. Besides that, the life table showed that, the population of D. citri in the present study display type 3 type of survivorship with about 25.971% of the eggs successfully reached adult stage. Above findings on life table and demographic parameters of D. citri particularly its capacity for natural increase and mortality rate of the different developmental stages are necessary for development of reliable and sustainable IPM strategy for the pest. |
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