KFRI Research Report No. 260 a STUDY of WOOD BORING
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KFRI Research Report No. 260 A STUDY OF WOOD BORING BEETLES IN THE KERALA PART OF NILGIRI BIOSPHERE RESERVE George Mathew Kerala Forest Research Institute Peechi – 680 653 June 2004 KFRI Research Report No. 260 A STUDY OF WOOD BORING BEETLES IN THE KERALA PART OF NILGIRI BIOSPHERE RESERVE (Final Report of the Project KFRI/317/'99 sponsored by the Ministry of Environment and Forests, Government of India, New Delhi) George Mathew Entomology Forest Protection Programme Division Kerala Forest Research Institute Peechi – 680 653 June 2004 Contents Abstract i 1. General Introduction 1 1.1. Biosphere Reserves and Biodiversity Conservation 1 1.1.i. The Nilgiri Biosphere Reserve 2 1.1.ii. Zones of Nilgiri Biosphere Reserve 6 1.2. Timber beetles 6 1.2.i. Primary borers 8 1.2.ii. Secondary borers 11 1.2.iii. Scavengers 12 1.2.iv. Predatory beetles 13 2. Materials and Methods 15 2.1. Study area: Kerala part of Nilgiri Biosphere Reserve 15 2.2. Sampling of insects 18 3. Results 19 3.1. Predisposing factors leading to borer infestation 19 3.2. Incidence pattern of wood borers in the study area 20 3.3. Relative susceptibility of various timber species to borer infestation 24 3.4. Timber beetle fauna of the Kerala part of Nilgiri Biosphere Reserve 25 4. Discussion 43 4.1. Faunal elements 43 4.2. Host specificity 43 4.3. Intensity and nature of infestation 44 4.4. Significance of timber beetles recorded from the Kerala part of Nilgiri Biosphere Reserve 45 5. Conclusions 47 6. Acknowledgements 49 7. References 50 Appendix I List of timber beetles collected from the Kerala part of Nilgiri Biosphere Reserve Appendix II Summary of borer infestation to different tree species in the study area Appendix III Observations on tree mortality due to reasons other than borer attack in Nilambur Biosphere Division Appendix IV Observations on tree mortality due to reasons other than borer attack in Palghat Biosphere Division Appendix V Observations on tree mortality due to reasons other than borer attack in Wynad Biosphere Division Plates 1-V1 Abstract In the survey on the timber beetles in the Kerala part of Nilgiri Biosphere Reserve, 57 species of beetles belonging to 8 families were recorded. Maximum number of insects was recorded from Silent Valley (24 spp.) followed by New Amarambalam (17 spp.) and Wynad (11 spp.). Of the various groups recorded, Platypodidae and Scolytidae contained maximum number of species, which mostly preferred fresh logs or unhealthy standing trees. In the case of older logs, infestation by the secondary borers like Bostrychidae, Passalidae and Blattidae (woodroaches) have been noticed in addition to termites and scavengers like millipedes, earthworms and wood louse. With regard to the various factors leading to borer infestation, wind, damage by wild animals, mechanical injury to trees due to lopping of branches for fodder and firewood, were the most important. Tectona grandis, Kydia calycina and Terminalia alata were highly susceptible to damage by wild animals, especially the elephants. Wind damage was noticed with large trees having dense crown such as Mesua ferrea, Dysoxylum beddomei, Myristica malabarica and Palaquium ellipticum. With regard to relative susceptibility to borer attack, Palaquium ellipticum, Dysoxylum beddomei, Cullenia exarillata, Bischofia javanica, Cinnamomum spp., Myristica dactyloides and Mesua ferrea among evergreen species and Schleichera oleosa and Macaranga peltata among deciduous species were the most susceptible. The faunal elements showed high degree of endemism and also contained species having affinities with Australasian, African and Malaysian forms. Most of the beetles recorded on various evergreen tree species such as the cerambycids Chloridolum alemene Thoms. (attacking Palaquium ellipticum) and Xylotrechus subscutellatus Chev. (attacking Callicarpa tomentose); the scolytid Diamerus curvipes Wlk. (attacking Myristica malabarica); the platypodid Crossotarsus minax Wlk. (attacking Palaquium ellipticum); the curculionid Trachodes sp. nr. acutangulus Hell. (attacking Myristica malabarica); the brenthid Cyphagogus westwoodi Parry (attacking Bischofia javanica) and the passalid Leptaulax dentatus Fb. were mostly restricted to the evergreen forests. Because of their role in the decomposition of dead wood, these beetles have more ecological significance. Since they are restricted to evergreen forest habitats, their chances of assuming pest status in other timber species outside their habitat are rather limited. 1. INTRODUCTION The term ‘Biosphere’ refers to that zone of earth where life exists. It includes three strata viz., the lithosphere, hydrosphere and atmosphere. The lithosphere, which varies in thickness from 15-40 kms, forms the outer crust of earth. The outer most layer of this crust is rocky in nature and it disintegrates to form the soil. Atmosphere is the layer of air surrounding the earth and extending to a height of 600 kms. The hydrosphere includes all the water bodies. 1. 1. Biosphere Reserves and Biodiversity Conservation All biodiversity that we find on earth are the products of several million years of evolution. Creation and extinction are two phases of life. The interaction of living organisms among themselves and with the environment has led to an increase in biodiversity over the years. In addition to this, there are also various evolutionary pathways, which produce a vast array of species and ecosystems. On the contrary, various catastrophes like drastic changes in climate brought about by continental drift, massive volcanic eruptions or asteroid impacts have caused mass extinction of life on various parts of the globe. Equally or even more important is the change brought about by human interference. Ever since the appearance of man on the earth's surface, there has been considerable disturbance to natural ecosystems due to exploitation of the natural resources, for both short term and long term requirements. With industrialization and stress on productivity, the pressure on biosphere has increased tremendously leading to pollution of air and water. One third of world’s forests, major part of fresh water lakes, rivers, seas and most of the grass lands have been either destroyed or altered affecting all life existing in these habitats. Loss of biodiversity has tremendous implications on the survival of mankind in this universe. Therefore, it has long been felt that man should mend his ways to bring a halt to this degradation. It was with this concern 1 abundant water availability because of the rivers Krishna, Godavari, Cauvery and their tributaries Bhima, Thungabhadra, Kabani and Bhavani. The plateaus and the adjoining hills of Wynad, Mysore, Sigur and Talaimalai with elevation ranging from 700 to 1000m form the boundaries of this Reserve in the north. In the south are the plateau and the hills of Attappadi, Siruvani and Bolampatti with altitudes ranging from 150m to 1800m. In the west are the slopes of Nilambur, New Amarambalam and Silent Valley, which descend to 250 m in Calicut plains. In the east are the mountains of Nilgiris, which slopes down to 250m in the Coimbatore plains. The wildlife sanctuaries of Wynad, Nagarhole, Bandipur, Mudumalai and the Silent Valley National Park belong to this Reserve. 1.1.1. a. Forests types An array of habitats and vegetation types ranging from dry scrub jungle, dry and moist deciduous forests, semi evergreen, evergreen and wet evergreen forests, sholas, grass lands and swamps are found in this area. The most important forest types are described below. Tropical wet evergreen forests The wet evergreen forests, which are dense and multi storied, occur along the western slopes up to an altitude of 1500m where the annual rainfall is over 2000mm. This type of forests, having large trees attaining over 50m in height is characteristically found in Silent Valley and in parts of New Amarambalam and Attapadi areas of Kerala State. Dipterocarpus indicus, Mesua ferrea, Palaquim ellipticum, Artocarpus hirsuta, Bischofia javanica, Garcinia indica, Hopea parviflora, Hopea wightiana, Pterospermum reticulatum, Syzygium gardneri, Diospyros spp. and Cinnamomumum zeylanicum are the dominant trees. Association of Dipterocarpus – Mesua - Palaquim is very prominent. Lichens, mosses, epiphytes and climbers are fairly common. Due to the closed canopy, the ground is usually devoid of grasses. 3 Tropical montane evergreen shola-grassland In the Nilgiri Biosphere Reserve, sholas are found along the upper Nilgiris plateau and on the higher reaches of Siruvani hills in Tamil Nadu State above an altitude of 1800m. Shola vegetation is very specialised on account of typical temperate conditions. Trees are stunted and are usually restricted to the valleys and the slopes are covered with grasses. The important tree species in the sholas are Cinnamomumum wightii, Elaeocarpus spp., Gordonia obtusa, Meliosoma spp., Liqustrum roxburghi, Litsea spp., Symplocos sp. and Syzygium arnottianum. The ground flora consists of Rubiaceae and Acanthaceae of which Strobilanthus spp. are quite abundant. The grasslands contain species from the genera Cymbopogon, Themeda, Ergrostis and Tripogon. Tropical semi evergreen forests This type of forests, which is a transition between the evergreen and the moist deciduous types, is found along the lower reaches of western slopes and below the montane shola vegetation along the northern and eastern slopes. It contains several elements of the evergreen forests like Vitex altissima, Persea macrantha, Holigarna arnottiana and moist deciduous species