A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
A review of dipterocarps - Center for International Forestry Research
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Pests and Diseases <strong>of</strong> Dipterocarpaceae 117<br />
in growth by attacking the young shoots and twigs <strong>of</strong><br />
Dryobalanops aromatica saplings over 1 m tall (Anon.<br />
in Tho and Norhara 1983).<br />
Shoot and root borers were recorded on various<br />
dipterocarp species (Beeson 1941, Chatterjee and Thapa<br />
1970, Daljeet-Singh 1975, 1977, Sen-Sarma and Thakur<br />
1986, Shamsuddin 1991, Smits et al. 1991). Shoot<br />
boring does not generally cause mortality (although it<br />
was recorded as the major factor <strong>of</strong> die-back <strong>of</strong> Shorea<br />
teysmanniana seedlings (Shamsuddin 1991) but rather<br />
induces the <strong>for</strong>mation <strong>of</strong> multiple leaders after<br />
destroying the main shoot (Daljeet-Singh 1975, 1977,<br />
Smits et al. 1991). There<strong>for</strong>e, shoot boring insects are a<br />
problem <strong>for</strong> re<strong>for</strong>estation programmes. Planting trials<br />
with Shorea ovalis, S. leprosula, S. acuminata and S.<br />
parvifolia were conducted in Malaysia, where 50% <strong>of</strong><br />
S. acuminata and 7.3-16.5% <strong>of</strong> the other Shorea<br />
seedlings were attacked by shoot borers (Daljeet-Singh<br />
1975).<br />
Insect borers and nematodes can destroy roots. The<br />
lepidopteran root borer Pammene theristhis<br />
(Eucosmidae) has emerged as the most serious pest <strong>of</strong><br />
the seedlings and young shoots <strong>of</strong> Shorea robusta (sal)<br />
in all areas where it is grown in India. It probably plays a<br />
prominent role in the regeneration-failure in sal. It has<br />
been closely associated with the dying-<strong>of</strong>f <strong>of</strong> new sal<br />
regeneration in the submontane belt <strong>of</strong> Uttar Pradesh<br />
(Beeson 1941; Chatterjee and Thapa 1970). The borer<br />
has more than three generations a year: the first generation<br />
lays eggs on the seeds on which the larvae feed; the<br />
second one bores into young growing shoots <strong>of</strong> coppice<br />
or regeneration <strong>of</strong> sal up to sapling stage with the<br />
resultant die-back <strong>of</strong> leaders; and the third generation<br />
attacks and kills the young seedlings by hollowing the<br />
tap root and a part <strong>of</strong> the stem (Beeson 1941, Sen-Sarma<br />
and Thakur 1986). Nematodes were recorded feeding on<br />
rootlets <strong>of</strong> Hopea foxworthyi and Shorea robusta<br />
(Catibog 1977, Mathur and Balwant Singh 1961a).<br />
Wild pigs (Sus scr<strong>of</strong>a) can completely destroy<br />
seedling regeneration (Becker 1985, Elouard<br />
unpublished). Rodents can be significant as pests <strong>of</strong><br />
germinating seeds and the cotyledons <strong>of</strong> young seedlings<br />
(Wyatt-Smith 1958) and deer browsing was partly<br />
responsible <strong>for</strong> mortality <strong>of</strong> Shorea robusta seedlings<br />
and saplings in India (Davis 1948).<br />
Trees<br />
Tree pests were recorded in Malaysia, Thailand,<br />
Indonesia, India, Pakistan and Burma. Most <strong>of</strong> them are<br />
insects belonging to Coleoptera and Lepidoptera, causing<br />
defoliation and leaf damage, wood boring and root<br />
sucking.<br />
The extent <strong>of</strong> the damage and the economic losses<br />
due to defoliation, essentially caused by insects, has<br />
seldom been estimated. Over 130 species <strong>of</strong> insects<br />
cause leaf damage, mostly belonging to the families<br />
Geometridae, Lymantriidae, Noctuidae, Pyralidae,<br />
Tortricidae (Stebbing 1914, Beeson 1941, Bhasin and<br />
Roonwal 1954, Ghullam Ullah 1954, Mathur and Balwant<br />
Singh 1959, 1960a, b, 1961a, b, Anderson 1961,<br />
Torquebiau 1984, Pratap-Singh and Thapa 1988, Messer<br />
et al. 1992).<br />
Defoliators in India, Pakistan, Malaysia, Indonesia,<br />
Thailand and Philippines, at times cause important<br />
damage, e.g. Shorea robusta trees in Assam, India were<br />
entirely stripped <strong>of</strong> all green leaves over a very large<br />
area by species <strong>of</strong> caterpillars <strong>of</strong> the genus Lymantria<br />
(Stebbing 1914). Defoliation can lead the trees to an<br />
extremely weak state which makes them attractive and<br />
highly receptive to a lethal infestation from borers such<br />
as Hoplocerambyx spinicornis (Pratap-Singh and Thapa<br />
1988). Successive defoliations can kill trees, e.g.<br />
Lymantria mathura on Shorea robusta in Assam and<br />
north India (Beeson 1941). Following defoliation, the<br />
physiology <strong>of</strong> the tree is affected by the loss <strong>of</strong><br />
photosynthetic activity: Shorea javanica trees, tapped<br />
<strong>for</strong> resin in Sumatra, Indonesia, stopped their resin<br />
production (Torquebiau 1984). The attack by insects in<br />
Shorea robusta <strong>for</strong>ests <strong>of</strong> Bangladesh appeared to be<br />
minor (Ghullam Ullah 1954). According to the author,<br />
this may be due to the presence <strong>of</strong> large colonies <strong>of</strong> the<br />
brown ant, Oecophylla smaragdina, known to destroy<br />
all kinds <strong>of</strong> caterpillars (except the hairy species) and to<br />
drive away beetles and bugs, thus preventing oviposition<br />
in the latter case. Ghullam Ullah noted all the Shorea<br />
robusta defoliating larvae are hairy caterpillars which<br />
are not destroyed by ants.<br />
The borer-fauna <strong>of</strong> Dipterocarpaceae is very<br />
extensive, and has been mostly recorded in India.<br />
According to Beeson (1941), only one species, the<br />
heartwood borer Hoplocerambyx spinicornis<br />
(Cerambycidae), is capable <strong>of</strong> killing healthy trees. The<br />
other borers, or secondary borers, attack sickly trees,<br />
possibly hastening death by a year or two.<br />
Hoplocerambyx spinicornis is widely distributed in<br />
Asia (Burma, Bhutan, India, Indo-China, Indonesia,<br />
Malaysia, Nepal, Papua New Guinea, Pakistan,