Author
I. E. Ssemaganda1 , P. Mugabi1 , S. B.Tumwebaze2
ABSTRACT
Termites are one of the major wood destroying agents in the tropics and with the increasing rate of deforestation, there is a need to protect wood from biodegradation in order to extend its service life. In this study the incidence and severity of termite attack on Eucalyptus grandis sapwood treated with CCA, used engine oil and neem extract were investigated. Sixty samples (20 × 20 × 300mm) were prepared from the sapwood at mid-height of the tree of E. grandis and air seasoned for two weeks then treated with the preservatives. An area of 20m by 20m in a pine plantation and 15 plots of 1m by 1m were selected at random. Four samples, one from each treatment, were placed at the corners of the selected plots.
Inspection and evaluation of stakes was made by visual assessments after every 30 days for any sign of termite attack for a period of 8 months. The specimens were removed from the ground, damage assessed and returned to the ground. After 4 weeks all the untreated wood samples had been attacked, neem extract treated wood samples were attacked after 17 weeks and used engine oil treated samples after 30 weeks. None of the CCA treated wood samples were attacked by the end of study period. Chi square analysis showed a high association between treatment and incidence as well as between treatment and severity. It was recommended that further research be carried out on neem extract using different concentrations.
Keywords: Eucalyptus grandis, preservatives, termite attack, Uganda
INTRODUCTION
Bowyer et al. (2003) indicated that wood products in use throughout the world are subject to infestation by insects. The same authors further noted that of the insects, termites have by far the greatest economic importance. Termites destroy wood by feeding on its components, thereby reducing its structural ability and appearance. Cellulose being the principal food of termites, wood and wood products such as paper, fabrics and wood structures are avidly consumed, and hence, a constant effort is directed towards their control (Peralta et al. 2004).
Eucalyptus grandis is one of the widely used construction tree species in Uganda. It is used for electricity poles, fence posts and roof trusses. However, in a survey carried out in Tororo district in Uganda, Nyeko and Olubayo (2005) reported that eucalyptus species are highly susceptible to termites. Some of the strategies to protect wood from termite attack include using naturally resistant tree species and applying toxic chemicals to wood. The common preservatives used in Uganda to protect wood against biodegrading agents are creosote, used engine oil and Chromated Copper Arsenate (CCA). Over the past few decades, there has been a substantial global quest to develop eco-friendly wood preservatives which do not cause any ill effect on the health of mammals (Venmalar and Nagaveni 2005). The search for effective bio-control methods for wood preservation is continuing but one that could be useful is the natural insect growth regulator, azadirachtin (AZA). This botanical compound can be effective yet it is biodegradable and rapidly metabolizes in the environment (Weathersbee and Tang 2002). AZA can be extracted from the seeds of Azadirachta indica i.e. the neem tree. According to Venmalar and Nagaveni (2005) neem possesses a number of toxic constituents exhibiting high toxicity against wood destroying microbes. However, the effectiveness of chemicals to control biological attack on wood depends upon the wood, the chemical used and the pests that are present and environmental conditions following treatment (Johnson, 2000). As Walker (1993) noted, the use of a single, universal wood preservative treatment does not provide optimal economy since the spectrum of hazards to which timber is exposed is wide both in type and severity. This spectrum of hazards includes attack by fungi, insects and marine borers, any of which can result in degradation at varying rates depending on the immediate environment. The objectives of the study were to determine (i) the incidence and (ii) severity of termite attack on E. grandis sapwood samples treated with CCA, used engine oil and neem extract.
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http://www.scielo.cl/pdf/maderas/v13n2/art01.pdf
I. E. Ssemaganda1 , P. Mugabi1 , S. B.Tumwebaze2
ABSTRACT
Termites are one of the major wood destroying agents in the tropics and with the increasing rate of deforestation, there is a need to protect wood from biodegradation in order to extend its service life. In this study the incidence and severity of termite attack on Eucalyptus grandis sapwood treated with CCA, used engine oil and neem extract were investigated. Sixty samples (20 × 20 × 300mm) were prepared from the sapwood at mid-height of the tree of E. grandis and air seasoned for two weeks then treated with the preservatives. An area of 20m by 20m in a pine plantation and 15 plots of 1m by 1m were selected at random. Four samples, one from each treatment, were placed at the corners of the selected plots.
Inspection and evaluation of stakes was made by visual assessments after every 30 days for any sign of termite attack for a period of 8 months. The specimens were removed from the ground, damage assessed and returned to the ground. After 4 weeks all the untreated wood samples had been attacked, neem extract treated wood samples were attacked after 17 weeks and used engine oil treated samples after 30 weeks. None of the CCA treated wood samples were attacked by the end of study period. Chi square analysis showed a high association between treatment and incidence as well as between treatment and severity. It was recommended that further research be carried out on neem extract using different concentrations.
Keywords: Eucalyptus grandis, preservatives, termite attack, Uganda
INTRODUCTION
Bowyer et al. (2003) indicated that wood products in use throughout the world are subject to infestation by insects. The same authors further noted that of the insects, termites have by far the greatest economic importance. Termites destroy wood by feeding on its components, thereby reducing its structural ability and appearance. Cellulose being the principal food of termites, wood and wood products such as paper, fabrics and wood structures are avidly consumed, and hence, a constant effort is directed towards their control (Peralta et al. 2004).
Eucalyptus grandis is one of the widely used construction tree species in Uganda. It is used for electricity poles, fence posts and roof trusses. However, in a survey carried out in Tororo district in Uganda, Nyeko and Olubayo (2005) reported that eucalyptus species are highly susceptible to termites. Some of the strategies to protect wood from termite attack include using naturally resistant tree species and applying toxic chemicals to wood. The common preservatives used in Uganda to protect wood against biodegrading agents are creosote, used engine oil and Chromated Copper Arsenate (CCA). Over the past few decades, there has been a substantial global quest to develop eco-friendly wood preservatives which do not cause any ill effect on the health of mammals (Venmalar and Nagaveni 2005). The search for effective bio-control methods for wood preservation is continuing but one that could be useful is the natural insect growth regulator, azadirachtin (AZA). This botanical compound can be effective yet it is biodegradable and rapidly metabolizes in the environment (Weathersbee and Tang 2002). AZA can be extracted from the seeds of Azadirachta indica i.e. the neem tree. According to Venmalar and Nagaveni (2005) neem possesses a number of toxic constituents exhibiting high toxicity against wood destroying microbes. However, the effectiveness of chemicals to control biological attack on wood depends upon the wood, the chemical used and the pests that are present and environmental conditions following treatment (Johnson, 2000). As Walker (1993) noted, the use of a single, universal wood preservative treatment does not provide optimal economy since the spectrum of hazards to which timber is exposed is wide both in type and severity. This spectrum of hazards includes attack by fungi, insects and marine borers, any of which can result in degradation at varying rates depending on the immediate environment. The objectives of the study were to determine (i) the incidence and (ii) severity of termite attack on E. grandis sapwood samples treated with CCA, used engine oil and neem extract.
MATERIALS AND METHODS
Timber
One Eucalyptus grandis tree of DBH 25cm was felled from a wood lot in Masaka district, central Uganda. The tree was crosscut into three portions of 4m each representing the butt, middle and top parts. The middle portion was further cross cut into two billets of 2m each which were used to produce eight 20×50×2000mm boards from the sapwood. Each board was then ripped into two 20× 20× 2000mm scantlings (Fig. 1). Sixty samples of 20× 20 × 300mm were then prepared from the scantlings (Fig. 1) and air seasoned for two weeks to approximately 20% moisture content and then treated with the preservatives.
Timber
One Eucalyptus grandis tree of DBH 25cm was felled from a wood lot in Masaka district, central Uganda. The tree was crosscut into three portions of 4m each representing the butt, middle and top parts. The middle portion was further cross cut into two billets of 2m each which were used to produce eight 20×50×2000mm boards from the sapwood. Each board was then ripped into two 20× 20× 2000mm scantlings (Fig. 1). Sixty samples of 20× 20 × 300mm were then prepared from the scantlings (Fig. 1) and air seasoned for two weeks to approximately 20% moisture content and then treated with the preservatives.
http://www.scielo.cl/pdf/maderas/v13n2/art01.pdf
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