An ecological study of Pteroma Pendula (Iepidoptera: Psychidae) in oil palm plantations with emphasis on the predatory activities of Oecophylla Smaragdina (hymenoptera: Formicidae) on the bagworm / Exelis Moise Pierre
A study entitled “An ecological study of Pteroma pendula (Lepidoptera: Psychidae) in oil palm plantations with emphasis on the predatory activities of Oecophylla smaragdina (Hymenoptera: Formicidae) on the bagworm was conducted at the MPOB Research Plantation at Teluk Intan, Perak, Malaysia from...
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| Format: | Thesis |
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2013
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| Online Access: | http://studentsrepo.um.edu.my/4817/ http://studentsrepo.um.edu.my/4817/1/PDF_FILE.pdf http://studentsrepo.um.edu.my/4817/2/PDF_FILE.pdf |
| Summary: | A study entitled “An ecological study of Pteroma pendula (Lepidoptera: Psychidae) in
oil palm plantations with emphasis on the predatory activities of Oecophylla smaragdina
(Hymenoptera: Formicidae) on the bagworm was conducted at the MPOB Research
Plantation at Teluk Intan, Perak, Malaysia from 11.11.2010 to 31.01.2013. The main
objectives of the study was to assess the infestation of P. pendula and investigate a
correlation between pest density fluctuations with abiotic factors in the study area and to
elucidate O. smaragdina occupancy pattern and its predatory behaviours towards P.
pendula as well as assessing the productivity of palm trees occupied and not occupied by
the weaver ants.
Results of the survey showed that there was an infestation of the bagworm with peak
outbreak from October to November 2010 which coincides with the ending of the dry
season (Pearson correlation coefficient r = 0.474, p <0.05).
O. smaragdina shows a high preference for tall trees where 92% of sampled palms were
occupied with a Preference Index (Pi) of 1.84 but avoid short palms where none were
occupied (Pi =0). Forty percent of the occupied palms harbours nests of various types
ranging from 1-13 nest per palm with an average of 3.98 ±1.74 and uniquely the number
was always odd. The weaver ants exhibited a bimodal foraging circadian cycle with two
peaks: midday (12:00 h-15:00 h) and around dusk (17:30 h-18:30 h).
O. smaragdina showed a moderate positive correlation of foraging activity with increase
in air temperature (r=0.874, p < 0.001). However it is negatively correlated to relative
humidity (r = - 0.921, p < 0.001). The attack tactic deployed by O. smaragdina towards
the bagworm larva can be simplified into four main stages: Foraging and detection of
prey; physical attack & securing of prey; piercing and releasing of formic acid and
finally the lifting of paralyzed prey followed by transporting it to the nest. O. smaragdina
shows no aggressive behavior towards Elaeidobius kamerunicus, the principal pollinators
for oil palm.
O. smaragdina had a high preference for pupae (Pi = 1.73) over larvae (Pi = 0.13) when
the former was in abundance within the cut-off period of 90 minutes (U = 0; P < 0.01). A
log-rank test demonstrated a statistically significant difference in survival ability between
pupae and larvae (for equivalence death rates X2 = 3.42, d.f =1; P = 0.06).
The degree of infestation by the bagworm was significantly different between the
occupied and unoccupied palms (X2 = 406.30, d.f = 4, p < 0.001). Among the tall
occupied palms, none were infested to Level 3 and 4 with 84% not infected at all (Level
“0”). But 40% of the tall unoccupied palms were infested to Level 3 and 25% to Level 4.
For the short unoccupied palms 31% were infested to Level 2 and 28% to Level 3 with
only 2.2% showed no evidence of infestation. The degree of foliar injury is significantly
less severe for the occupied palms (X2= 439.2), d.f = 4, p < 0.001). There is positive
correlation between the level of infestation and the degree of foliar injury (rs= 0.952; d.f
= 48; P < 0.01) in occupied palms and unoccupied palms (rs= 0.848; d.f = 48; P < 0.01).
The productivity of DFB/FFB is significantly higher for the occupied palms (z ≥ 4.16, p
< 0.0003) compare to shorter unoccupied palms. Similarly, the difference between tall
occupied and tall unoccupied palms was highly significant at P < 0.002 (U=1). Based on
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the finding of this study, O. smaragdina holds a promising potential as biological control
agent for the bagworm pests particularly against the increasing concern for sustainable
oil palm industries. |
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