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 *
[email protected]
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
Song Kanowit I Kanowit II Kapit I
3 (60x25 m) 3 (60x25 m) 9 (20x20 m) 1 (20x20 m)
3-4 <3 1-3 2
63 96 109 27
Percentage of trees being attacked (%) 78 54 63 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)
2 6 7 10 11 12 15 18 40
18 10 21 3 6 13 18 10 10
26 (2.2yr) 27 (2.3yr) 25 (2.1yr) 27 (2.3yr) 27 (2.3yr) 24 (2.0yr) 23 (1.9yr) 28 (2.3yr) 29 (2.4yr)
4.63 5.82 4.57 5.91 6.21 4.30 5.12 5.90 4.70
2.10 2.53 2.18 2.57 2.70 2.15 2.69 2.57 1.96
8.24 10.02 8.02 9.30 10.58 7.23 9.72 9.93 10.04
Mean Annual DBH Increment (cm) 3.75 4.36 3.82 4.04 4.60 3.62 5.12 4.32 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 2 6 7 10 11 12 15 18 40
No. of attacks per tree Past Present 1.00 0.60 0.20 0.70 0.60 0.30 0.70 0 1.83 0.20 0.33 0.08 0.67 0.28 1.22 0.11 0.63 0
Past Attacks 93.3 20.0 63.2 66.7 33.3 33.3 55.6 77.8 50.0
*Percentage of trees with at least one past and/or one present attack.
% of trees with Present Attacks 40.0 50.0 26.3 0 16.7 8.3 27.8 11.1 0
Attacks* 100.0 60.0 79.0 66.7 50.0 33.3 72.2 88.9 50.0
B2
B6
B7
B10
B11
B12
B15
B18
B40
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.
No. of past attacks/tree
Figure 3: Relationship between density of past attacks per year by Endoclita sp. and (LEFT) mean annual height increment ; (RIGHT) mean annual DBH increment
DBH Class Figure 4: Difference in density of past attacks by Endoclita sp. among 5 cm DBH classes
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 multidisciplinary 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 Anon. 2009. Seminar to boost forest plantation activities. Sarawak Timber Association Review 188 : 2 Browning, J.A. 1998. One phytopathologist’s growth through IPM to holistic plant health: The key to approaching genetic yield potential. Annual Review of Phytopathology 36: 1-24 Lim, G.T., Kirton, L.G., Ariffin, S., Salom, S. M., Kok, L.T. and Pfeiffer, D.G. 2007. Partnering the weaver ant to control the mahogany shoot borer in peninsular Malaysia. Applied Forest Science Research Seminar 2007. Catalysing Planted Forest Development and Biodiversity Conservation. Wisma STA, Kuching, Sarawak. 1-2 November 2007
Marzuki, M. 2007. Endoclita aroura Tindale: Stem Borer of Kelampayan Species. Applied Forest Science Research Seminar 2007. Catalysing Planted Forest Development and Biodiversity Conservation. Wisma STA, Kuching, Sarawak. 1-2 November 2007 Norris, D.M. 1988. Sensitivity of insect-damaged plants to environmental stresses. In: Heinrichs, E.A. (ed.). Plant Stress-Insect Interactions. John Wiley and Sons, New York Stone, C. and Clarke, A.R. 1998. A phytocentric approach towards future pest management in Australia eucalypt plantations – an alternative to classical IPM. In: Zalucki, M.P., Drew, R.A.I. and White, G.G. (eds). Pest Management – Future Challenges. Proceedings of Sixth Australasia Applied Entomological Research Conference. Brisbane, Australia, 29 September – 2 October 1998. Pp. 144-152
