Contents - LAC Biosafety

the tunnel (e.g. Stromatium barbatum attacking a wide variety of timbers).
In timber species without heartwood, the damage is generally more extensive.
Most insect species of this group have an annual life cycle but some species
complete a generation in less than a year and some take more than a year.
For example Xylotrechus smei which attacks more than 40 timbers in India,
including Dalbergia spp., Gmelina arborea, Mangifera indica, Shorea robusta and
Tectona grandis, can complete a generation in about 2.5 months in summer but
later generations might hibernate and emerge in the second year. As the
cerambycid beetles lay eggs only when bark is present, debarked, sawn and
seasoned timber are not attacked. However, some exceptional species like
Stromatium barbatum attack debarked timber also.
The number of wood-boring cerambycid beetles in the tropics is very large.
India alone has more than 1200 species of cerambycids, although some of them
attack only slender stems, bark, cones or roots. Also, some cerambycids attack
the wood of living trees. Examples are Aristobia horridula on Dalbergia
cochinchinensis, Celosterna scabrator on Acacia nilotica, Hoplocerambx spinicornis on
Shorea robusta, and Xystrocera festiva on Falcataria moluccana, pest profiles of which
are given in Chapter 10. These insects usually continue their damage in felled
timber. Wagner et al. (1991) have listed 60 species of cerambycids which attack
various timbers in Ghana. In the survey carried out in timber depots in Kerala,
India, referred to previously, Mathew (1982) found that 18 out of 46 timber
species were attacked by cerambycid borers (Table 6.1). More than 15 species of
insects, including some unidentified species were involved. Some low density
timbers like Anacardium occidentale, Artocarpus heterophyllus, Bombax ceiba, Hevea
brasiliensis, Mangifera indica and Polyalthia fragrans suffered major damage.
Family Buprestidae
6.2 Categories of wood-destroying insects and their damage 109
This family of beetles (Fig. 6.2) range in size from 6 mm to 70 mm
in length and are usually brightly coloured, with a metallic lustre. The buprestid
larva has a characteristic appearance, with a large, flat prothorax into which the
small head is withdrawn. The larvae are usually known as flatheaded borers.
In general, buprestid borers attack sickly standing trees or recently felled trees
and continue their damage in stored logs, although some species attack dry
wood. The female beetle lays eggs on the bark and the young larvae bore
irregular galleries between the bark and sapwood, and later penetrate into the
sapwood. The galleries are usually packed with fine wood dust. Some species of
dry wood borers such as Buprestis geometrica which attack pine wood and
Chrysochroa gratiosa which attack Sterculia alata in India, penetrate deeper into the
wood and tunnel extensively, reducing it to a mass of dust with flakes of wood
left here and there (Beeson, 1941). Belionota prasina (Fig. 6.2) is a widely