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STEM BORER OF PLANTATION-GROWN KELAMPAYAN IN SARAWAK
Doreen H.S. Chai1*, Marfaisal Marzuki1, Het Kaliang2 and John Sabang1
SARAWAK FORESTRY Corporation 1Sarawak Forest Tree Seed Bank, Semengoh, KM 20, Jalan Puncak Borneo, 93250 Kuching, Sarawak, Malaysia
2Botanical Research Centre, Semengoh, KM 20, Jalan Puncak Borneo, 93250 Kuching, Sarawak, Malaysia
Abstract
Plantation-grown Kelampayan trees were subjected to serious attacks by stem borer. A study
was conducted to evaluate stem borer infestation intensity in Kelampayan plantations in
Sarawak. An average of 70% stem borer attacks were found in a few selected local forest
plantations. Analyses on the impact of stem borer attack on growth suggested that stem borer
attack did not affect the growth performance of Kelampayan trees. Attacks were concentrated at
the lower part of the trunk, less than 1 m from the ground level. Intensive silvicultural practice,
however, might reduce the susceptibility of stem borer attack. Biological, chemical and
silvicultural control and prevention trials are in progress.
Keywords: growth performance, intensive silvicultural practice, biological, chemical and
silvicultural control.
Introduction
Establishment of forest plantations is essential to avoid shortage of timber from the natural
forests for exportation and to avoid impact of logs as a temporarily solution. In relation to this,
Sarawak is targeting in establishing one million hectares of planted forest by the year 2020,
which requires an estimate of 30 million seedlings per annum (Anon, 2009).
Since 2003, Kelampayan has been introduced as a potential fast growing tree species suitable for
forest plantation establishment in Sarawak. To date, 18,851 hectars of Kelampayan were planted,
however, Kelampayan plantations declined from 14% in 2007 to 8% among the entire tree
species planted. Kelampayan plantations have reported that Kelampayan planted in the field in
Sarawak has low survival rate and its growth performance is not as expected. Pest problem in
the Kelampayan plantation is widespread especially for stem borers (Marzuki, 2007). Stem
borers are economically important, causing degradation of the wood quality and results in the
loss of the timber value. Nevertheless, the extent of damage relating to the wood quality,
mortality and growth performance has never been determined.
The objectives of the present study were to determine the relative importance of the borers by
evaluating their infestation intensity in Kelampayan plantations in Sarawak, and to study the
control and prevention methods in overcoming stem borer problem in the plantations.
Incidence of Stem Borer Attacks in Kelampayan Plantations and Its Extent of Damage
Inspections were made within the year 2008-2009 at four local forest plantations, selected based
on the plantation scale. Stem borers were common in many plantations, particularly in those
where the young trees had been stressed by weed competition. Our appraisals indicated that
Endoclita sp. was at that time the most widespread of the insect pests present in Kelampayan
plantations (Marzuki, 2007); therefore our studies were largely restricted to this species. Table 1
shows the prevalence of stem borer attacks in Sarawak Kelampayan plantations.
Table 1: Incidence of attacks by the Kelampayan stem borer in Kelampayan plantations in Sarawak
Stand No. of sample plot
Age (year) No. of sample tree Percentage of trees being
attacked (%)
Song 3 (60x25 m) 3-4 63 78
Kanowit I 3 (60x25 m) < 3 96 54
Kanowit II 9 (20x20 m) 1-3 109 63
Kapit I 1 (20x20 m) 2 27 81
In general, high incidences, up to an average of 70% of stem borer attack were detected within
the Kelampayan trees aged 1-4 years. Whereas the pattern of abundance of stem borer was
broadly consistent in most local forest plantations, such consistency was not found in our two
provenance trial plots. The larvae bore at the base of the tree stem, usually less than one meter
from the ground level. The borer attacks were common in those where the trees had been
stressed by grass competition or inappropriate silvicultural practices. From the observation, we
also predict that there is an invariably association between the peak of occurrence and the
difference in seasons, as well as the distribution of the sites.
We also surveyed trees at the age of 1-6 months after planting. From the surveillance, the first
emergent occurred as early as 6 months after planting. However, severe stem borer attacks did
not have a momentous contribution to the high mortality rate of Kelampayan in local forest
plantations.
Cross sections of several Kelampayan trees showing symptoms of attack were made to
determine the extent of wood damage (Figure 1). The tunnels created by the stem borer were
observed to be generally about 15-30 cm deep with diameter of around 1-2 cm. The visual
observation on the cross-section indicates that the wood could still be utilized for reconstituted
wood using technology such as finger jointing (Lai Jiew Kok, pers. comm.).
The sampling data obtained were inadequate to describe the incidence and distribution of the
stem borer attacks in Kelampayan plantations in Sarawak. Nevertheless, certain trends were
reasonably clear, giving the overall notion of the incidence.
A B
C D
E F
Figure 1: Symptoms of stem borer attack and the extent of damage. A) Symptom of stem borer with the present of
frass and sap oozing from the entry point. B) Presense of pupal exuvia indicating recent adult emergence. C & D)
Dead Kelampayan tree with its borer attack. E & F) Well-grown Kelampayan tree with multi-attack of stem borer.
Analyses of Attacks by Kelampayan Stem Borer
The analyses of attacks were based on Kanowit II Kelampayan stands. Height and diameter at
breast height (DBH) were measured for each sample tree and mean annual increment
(DBH/year) were calculated for each stand. The number of holes bored by stem borers was
recorded for each sample tree. The plot parameters and the number of sample trees are shown
in Table 2. The incidence of the attacks is summarized in Table 3 and Figure 2.
Table 2: Plot parameters and number of samples
Block No. of
sample trees
Age
(month)
Mean Height
(m)
Mean Annual Height
Increment (m)
Mean DBH
(cm)
Mean Annual
DBH Increment
(cm)
2 18 26 (2.2yr) 4.63 2.10 8.24 3.75
6 10 27 (2.3yr) 5.82 2.53 10.02 4.36
7 21 25 (2.1yr) 4.57 2.18 8.02 3.82
10 3 27 (2.3yr) 5.91 2.57 9.30 4.04
11 6 27 (2.3yr) 6.21 2.70 10.58 4.60
12 13 24 (2.0yr) 4.30 2.15 7.23 3.62
15 18 23 (1.9yr) 5.12 2.69 9.72 5.12
18 10 28 (2.3yr) 5.90 2.57 9.93 4.32
40 10 29 (2.4yr) 4.70 1.96 10.04 4.18
Table 3: Data illustrating the degree of attacks exhibited by stem borer in Kanowit II plantation, between the
visits in December 2008 and July 2009
Block No. of attacks per tree % of trees with
Past Present Past Attacks Present Attacks Attacks*
2 1.00 0.60 93.3 40.0 100.0
6 0.20 0.70 20.0 50.0 60.0
7 0.60 0.30 63.2 26.3 79.0
10 0.70 0 66.7 0 66.7
11 1.83 0.20 33.3 16.7 50.0
12 0.33 0.08 33.3 8.3 33.3
15 0.67 0.28 55.6 27.8 72.2
18 1.22 0.11 77.8 11.1 88.9
40 0.63 0 50.0 0 50.0
*Percentage of trees with at least one past and/or one present attack.
Figure 2: Percent of trees with symptom of stem borer attack between the field assessments
in December 2008 and July 2009
Attacks of stem borer were observed ranging from 33.3% to 100.0%. The density of past and
present attacks per tree ranged from 0.22-1.83 and 0-0.70, respectively. The data signifies that
multi-entry point per tree is possible (Figure 1E). Stem borer infestation seemed to be peculiar to
certain sites. There was a noticeable decrease of stem borer attacks in July 2009 comparing to
December 2008. Various factors are to be considered: the presence of slashing and clearing
maintenance in the plantation within December 2008 and July 2009 and season distinction
between December (wet season) and July (drought season).
There was no significant correlation between the density of past attacks per year and mean
annual increment (Figure 3), which implies that attack of stem borer did not affect the growth
performance of Kelampayan trees. On the other hand, there seemed to have a fair positive
correlation between the densities of past attacks and the DBH classes. We are in great interest to
comprehend whether as the plantations mature, the stem borer numbers will decline to an
insignificant level. Such information would be beneficial in planning a cost-effective pest
control and prevention regime.
B2 B6 B7 B10 B11 B12 B15 B18 B40
Figure 3: Relationship between density of past attacks per year by Endoclita sp. and (LEFT) mean annual height
increment ; (RIGHT) mean annual DBH increment
Figure 4: Difference in density of past attacks by Endoclita sp. among 5 cm DBH classes
DBH Class
No
. o
f p
ast
atta
cks/
tree
Pest Susceptibility of Kelampayan under Intensive Management Practices and Its
Implications for control of stem borer
From our survey, most of the Kelampayan plantations in Sarawak do not practice intensive
silvicultural management. It is perhaps not surprising that Kelampayan survival rate is
considerably low as the trees were left to nature after planting and only a minimal care was
taken. According to Stone and Clarke (1998), plantation management requires a holistic multi-
disciplinary approach rather than focusing on a single specific stress such as pest attack.
Focusing on stresses such as weed competition and nutrient deficiencies that are easier to
manage may reduce the potential impact of other stresses such insect attack and weather on
plantation performance (Norris, 1988; Browning 1998).
A recent visit to successful Kelampayan plantation and trial plots in Sabah suggested that
intensive management practice is necessary in maximizing productivity. From the records,
circle weeding, blanket slashing and manuring were conducted quarterly for three years after
planting. Stem borer control were carried out intensively after three years of planting until
harvesting.
Stem Borer Control and Prevention Trials
A few trials were currently carried out in the aim to reduce the susceptibility of pest attacks in
Kelampayan plantations.
Biological control
The weaver ant (Oecophylla smaragdina) has been a promising biological control agent on
mahogany shoot borer (Lim et. Al., 2007). Kelampayan is not listed as host plant for weaver ant
to date and yet considering on possibilities of using weaver ant to reduce stem borer problem in
kelampayan planted forest in Sarawak, a collaborative research work has been initiated.
Surveillance on weaver ants nesting habit and host plants has been conducted since 2008 in few
planted forest and natural forest in Sarawak. More study on conserving and augmenting
existing and relocated colonies are to be initiated. Basically the feeding habits of weaver ant
have yet to be investigated in depth for the prevalence and success of relocated colonies.
Chemical control
A few trial plots were installed to test the effectiveness of insecticides in Kelampayan plantation.
Approximately 10 g of systemic insecticide (carbofuran 3%) was applied into the ground in a
crescent shape on the upper slope of each tree. Monitoring of pest attack and tree growth will be
done every month for up to 6-12 months periods to test the efficacy of the pesticide. In
conjunction with this, we also study the insect pest life cycle as pesticides are generally only
used as required and often only at a specific time in their life cycle.
Silvicultural control
A trial site designed to measure benefits of weed control in a 6-month old Kelampayan
plantation was used to test whether young trees benefiting from such silvicultural practices
were more resilient to stress from stem borer damage. Our data obtained in the past 4-months
of monthly circle weeding treatment was insufficient for us to come into any conclusion yet.
However, we expect that, with the knowledge on the seasonal outbreak of this pest, weed
control and other silvicultural practices will accelerate the growth of the trees, therefore
shortening the period of maximum susceptibility to attack.
Conclusion
Surveys of Kelampayan stem borer during the past two years, and current studies in Kanowit II
Kelampayan plantation, permit certain generalizations concerning the incidence of stem borer
attack in Sarawak to be made.
The evidence presented in this paper suggests that Endoclita sp. is rarely the cause of significant
loss of growth increment or high mortality rate of Kelampayan. The use of silvicultural
practices known to promote tree vigour which also reduce the susceptibility of attack is to be
considered. Together with the knowledge in site characteristics and associated tree growth,
these practices can be tailored to improve cost efficiency and to maximize productivity.
Acknowledgements
Empenit Empawi and Lily Encharang assisted in surveillance and trials. We also thank the
commercial plantation agencies, and others who were involved to make this study successful.
References
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