A review of dipterocarps - Center for International Forestry Research

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unpublished).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