Foraging of coptotermes curvignathus (Insecta: Isoptera: Rhinotermitidae) and pattern of damage in oil palm on peat in Bintulu Sarawak
Coptotermes curvignathus is a major pest in oil palm plantation planted on peat. The control of the pest was unsatisfactory due to its lifestyle that made the observation on its foraging behaviour difficult. The objectives of this study were to verify the identity of the pest, to determine the tu...
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| Format: | Thesis |
| Language: | English |
| Published: |
2012
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/78048/1/FSPM%202012%202%20%20ir.pdf |
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| Summary: | Coptotermes curvignathus is a major pest in oil palm plantation planted on peat. The
control of the pest was unsatisfactory due to its lifestyle that made the observation
on its foraging behaviour difficult. The objectives of this study were to verify the
identity of the pest, to determine the tunnelling activity of C. curvignathus towards
presence and absence of food source in the laboratory, to detect the presence and
absence of C. curvignathus surrounding an infested palm and lastly to investigate
the damage pattern and infestation in oil palm. Tunnelling arena with and without
food was prepared to compare the distribution of tunnel length and frequency of
tunnel initiation in all direction to see whether any directional feeding occurred.
Field study using underground baiting station with rubber wood arranged in all
direction was set up surrounding an infested palm to detect the presence or absence of C. curvignathus. Infested oil palms were dissected to see the interior damage
caused by C. curvignathus, while survey of the infestation rate was carried out to
determine its pattern of infestation. Morphological and molecular studies have
verified the termite species as C. curvignathus with 99-100% similarity between 2-
403 bp from the reference samples. The initial tunnelling activity of C. curvignathus
was random but food oriented. This was due to insignificant distribution of
tunnelling activity and tunnel initiation in no food arena but presence of food
induced higher tunnelling activity and higher amount of tunnel initiated. Higher
tunnel length was found (234.53 mm) in food present arena compared to no food
arena (156.00 mm). The distribution of tunnelling activity in food present arena was
not uniform as North sector (335.68 mm) possessed significant higher tunnel length
than East (176.55 mm), Southwest (212.76 mm), West (185.24 mm) and Northwest
(187.15 mm) respectively. Although the distribution of tunnel initiation was random,
it was more likely for C. curvignathus to search in North sector as indicated in the
present study. The significant difference of tunnel distribution in certain sector was
also due to the search behaviour of the termite whenever food source was
encountered. Coptotermes curvignathus tend to branch if the primary tunnel
managed to encounter food source while long primary tunnel was excavated if no
food were discovered. This observation was supported by significant differences in
length of exploratory tunnels (1420. 8 mm) compared to secondary tunnels (351.8
mm) in food present arena. In the food absent arena, primary tunnels significantly
dominated with tunnel length of 700.7 mm compared to secondary tunnels (280.6
mm). Coptotermes curvignathus was also observed not visiting all available food
sources in the arena and thus, skewed the tunnel distribution in certain sector. Field
study revealed that C. curvignathus was scattered surrounding an infested palm. It was a dominant termite species in peat as no other termite species was found within
a baiting station occupied by C. curvignathus. Similarly to the laboratory
observation, not all baiting station was found infested at any one time during the
assessment period. Coptotermes curvignathus damaged the oil palm by excavation
and eventually chambers were formed inside the trunk. Thin laminae structures were
found within these chambers. Each structure had different thickness (0.98-2.27 mm)
and shapes (cell height 3.54-8.92 mm, cell width 6.54-16.82 mm). This constructed
structure was believed to be its endoecie where alates and nymphs were found.
However the availability of thin laminae structure was random among the infested
palm. The infestation incidences of oil palm were found to fluctuate throughout the
year. Total infestation incidence ranged from 0.02 to 0.11%. Among the infested
palms, about 11.7-23.9% had damage through spear region infestation. There was
no evidence of basal infestation during the assessment period. The pattern of
infestation was not influenced by monthly rainfall since no significant relationship
was established. Regular chemical control managed to keep infestation low but the
infestation persisted throughout the years in the surveyed plantations. |
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