INTRODUCTION

Bamboo is an important forest resource in many countries of Asia. Over 1 200 bamboo species, belonging to 75 genera, are reported to occur in the world. As overexploitation rapidly depletes bamboo along with other forest resources, bamboo cultivation has received increasing attention in many countries and from various international organizations for ecological, economic and social reasons. In Asia, the major bamboo-growing area in the world, bamboo industry is closely related to people---- daily lives and has an important role in national economies.

Bamboos are subject to injury by various kinds of herbivorous insects. They feed on foliage, bore holes on shoots, culm and finished products, or suck sap from the tissues of different plant organs. Attack by these insects reduces plant vigour and the productivity of bamboo stands.

Insect pests on bamboos have generally received little attention in Asian countries. In natural bamboo stands with reasonable biodiversity and stable population, insect attacks are not considered serious because various natural enemies of these insects play a useful role in the control of their populations. In addition, although some pest insects, especially the shoot borers, keep relatively high population levels and sometimes break out in natural stands, the damage caused tends to be ignored because such stands often are of low economic value. However, human intervention can have profound effects on the ecological balance and the population dynamics of insects in bamboo forest ecosystems, as in the case of some silvicultural measures for increasing the productivity of bamboos which also favour the survival and growth or herbivorous insects. For example, the establishment of large-scale pure bamboo plantations will improve breeding conditions of insect pests, and the use of chemical insecticides will weaken the role of natural predators of these insects.

More than 800 insect species have been recorded on bamboos in Asian countries, but the threat these pose to the bamboo industry has been recognized only in a few countries. In China, where about 400 species of bamboos are grown in an area exceeding three million hectares, 683 insect species have been reported as attacking bamboos (Chang Yuzhen 1986; Xu Tiansen et al. 1993). About 60 of them break out regularly or occasionally, infesting from tens to thousands of bamboo stands in each case and causing considerable economic losses to the Chinese bamboo industry.

Although nearly 180 insect species are reported to be associated with bamboos in India (Beeson 1941; Bhasin et al. 1958; Chatterjee and Sebastian 1964; Singh and Bhandari 1988; Mathew and Nair 1990; Mathew and Varma 1990; Roonwal 1977; Singh 1990; Thakur 1988a,b; Tewari 1992), the pest status of many species is not known.

Of the approximately 80 pest insect species recorded on bamboos in Japan, the most common and important pests would probably be the bamboo leaf rollers (Nakahara and Kobayashi 1963) and the shoot-boring noctuids which sometimes attacks over 50% of the new shoots (Kaneko 1959).  

Very limited information on bamboo insect problems is available from other Asian countries. There are a few references reporting shoot borers and sap-suckers in Thailand (Choldumrongkul 1994) and Nepal (Stapleton 1985) and leaf rollers in Korea (Kim and Lee 1986). Dayan (1990) reported the results of survey on pests and diseases of bamboo in the Philippines, noting three insect pests.

Insects that cause damage to felled culm and finished products are probably the most common and serious pests for the Asian bamboo industry. Over 50 such insect species have been reported, and maximum damage is caused by ghoon borers (Dinoderus spp.) found in most Asian countries. The damages usually result in the loss of large amounts of raw materials or in the destruction of finished bamboo products.

The International Network for Bamboo and Rattan (INBAR) has been well aware of the possibility of insect pest problems becoming more significant when bamboos are cultivated intensively to meet the growing demand. Consequently, it made the decision to fund a project that would review the insect pests on bamboos in Asia, a project jointly undertaken by the CAF Research Institute of Subtropical Forestry, China, and the Kerala Forest Research Institute, India. This publication Insect Pests of Bamboos in Asia is a result of the project.

The main objective of this manual ----prepared after extensive literature collection, review and field visits ----is to provide  a comprehensive account of existing knowledge on insect pests of bamboos in Asia, so as to form a knowledge base for combating the pests. Insect pests described in the text are grouped according to their feeding habits and the parts of bamboo plants they affect, except in the case of pests that attack felled culms and finished products which are grouped together. Details on hosts, distribution, biology and control measures of important pests are provided, so that they can be identified and appropriate control methods can be selected. Basic approaches of integrated management of bamboo insect pests, the major constraints faced and the research areas to be strengthened in the future are also discussed.

One word of caution. While describing the biologies of various insect pests, the authors have used time-specific statements such as "Adults emerge in July and remain in tunnels till the following June"or "Eggs are laid in August, and larvae emerge in September", etc. Although such information is important in understanding the biology of the insects, they may not apply equally to all Asian countries because of seasonal variations that exist from country to country.