Assessment of Metarhizium anisopliae (Metchnikoff) from natural forest to control tiger moth Atteva sciodoxa (Meyrick)
Eurycoma longifolia or ‘tongkat ali’ is a well-known tropical medicinal plant used widely to cure human illness. However, this plant is highly vulnerable to several insect pests, especially Atteva sciodoxa larvae. In the present study, a total of 28 E. longifolia forest and cultivation areas in P...
Saved in:
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
2017
|
Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/70939/1/FH%202017%2021%20IR.pdf |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Eurycoma longifolia or ‘tongkat ali’ is a well-known tropical medicinal plant used
widely to cure human illness. However, this plant is highly vulnerable to several insect
pests, especially Atteva sciodoxa larvae. In the present study, a total of 28 E. longifolia
forest and cultivation areas in Peninsular Malaysia were surveyed. Results of the
surveys showed that A. sciodoxa larvae infestation was major and common in E.
longifolia’s plantations, followed by scale insect, Zeuzera stem borer, animal damage,
Coptotermes sp. and spider mites. Several diseases were also observed such as algal
leaf spots, sooty mould, Sudden Death Syndrome (SDS) and Colletotrichum leaf spot.
Twenty five Metarhizium anisopliae isolates obtained from natural forest soils of
Peninsular Malaysia were identified and screened for pathogenicity against A.
sciodoxa larvae. Morphology of the fungus was studied and a phylogenetic tree of the
fungal ITS region sequences was developed. The study revealed that cultures of the
fungal isolates were flat with a yellowish mycelial mat bearing brownish to dark green
masses of conidia. Conidia were single celled, cylindrical with rounded tips and varied
in size, ranging from 5.7 ± 0.5μm × 2.5 ± 0.4 μm to 7.4 ± 1.0 μm × 3.3 ± 1.0 μm. They
were then identified as M. anisopliae var. anisopliae due to short shaped conidia.
Phylogenetic analysis found that all the isolates were closely related within species
regardless of their geographic origins. The species was also found to be closely related
with M. anisopliae var. majus supported with 99% bootstrap value. Growth rate test
showed that SDA is a media supported fastest fungus growth followed by PDA, MEA,
CMA and WA at temperatures 25oC, 28 oC and 31 oC. Screening tests revealed that all
the isolates were pathogenic against the inoculated A. sciodoxa larvae with mortality
as early as 3 days after inoculation. The highest larval mortality recorded by FRIM858,
followed by FRIM880, FRIM873, FRIM859, FRIM862, FRIM871 and the least
virulent was FRIM878. None of the larvae in the inoculated control treatment died.
Further study was conducted on isolates FRIM880, FRIM871, FRIM859 and
FRIM858 to determine the median effective conidia concentration (EC50) and median
effective time (ET50) against the pest larvae. The study revealed that FRIM589 was
the most effective and aggressive against the pest larvae. The EC50 recorded was 1.1x106 conidia ml-1 and ET50 was 2.9 days. Field trials in KESEDAR Gua Musang
and Sg. Menyala Forest Reserve show that FRIM859 significantly reduce population
of A. sciodoxa larvae with 57.0% and 63.4% larvae reduction, respectively. The study
suggests that FRIM589 was the best candidate to be developed as biological control
agent against A. sciodoxa larvae. |
---|