عنوان مقاله [English]
Introduction: One of the most important species of termites in the southern provinces of Iran is Microcerotermes diversus Silvestri, which is considered as subterranean termite and has the ability to attack the trees and the construction of timber. Due to the fact that Lignocellulosic material can be eaten easily by termite, this can cause great damage to buildings, so identifying resistant wooden species can help us to select suitable materials in areas where termite infestation is high. The aim of this study was to evaluate the tendency of M. diversus termite for different woods by using selective and non-selective nutritional tests in laboratory conditions.
Materials and Methods: For the collection of termites, beech wood with dimensions of 2.5 × 4 × 20 cm was buried for two months inside the soil in an abandoned palm farm, 20 km from the city of Behbahan. After that, the woods were removed from the soil and transferred to the laboratory. Then, parameters such as percentage of extract material, specific gravity, lignin and cellulose content were calculated for each wooden sample. Determination of cellulose and lignin content of woods was carried out according to the T-264cm-88 and T-222cm-88, TAPPI standard, respectively. The measurement of extractive materials was carried out in accordance with the TAPPI Regulation No: T 204om-88ISO-3131 standard to measure dry specific gravity.
The data was analyzed by Tukey's test using SPSS software version 17, and the significance test was performed at 95% level using Pearson correlation test.
Results: According to the results, the percentage of eucalyptus extractives is higher than other species and all three species have a significant difference at 95% level. All three species have a significant difference at 95% level in amount of lignin and the highest and the lowest one was related to cypress and the beech species, respectively. Also, the results showed that there is no significant difference between the three species in terms of cellulose content. The highest level of dry specific gravity is also found in beech and the least of that belongs to the cypress. All three species have a significant difference at 95% level. The results of non-selective test of wooden samples showed that the cypress samples had the least weight loss and the highest weight loss was observed in the beech samples. Eucalyptus specimens were interstitial and had a significant difference with samples cypress and beech. Comparison of weight loss percentage in wooden samples illustrated that the lowest and the highest percentage of weight loss belonged to cypress species and beech, respectively. However, there is no significant difference between eucalyptus species and two other species.
Conclusion: Selective and non-selective feeding of termites revealed that in both tests, there was a significant difference between the weight loss of cypress and beech, and the eucalyptus samples did not have a significant difference with the other two samples. Increasing the lignin decreased wood utilization for the termite. There is a significant difference between lignin content in these two species, the highest amount of lignin was obtained in cypress and the least one belongs to beech. Lignin which is composed of phenyl propane units, is known as malicious factors for pests due to the presence of aromatic groups in its structure. . The presence of extractives in eucalyptus should not be ignored in resistance to termites too. There are a wide variety of extractive materials in wooden species that affect wood properties such as the natural durability. The amount of extractives along with lignin can prevent the pest infestation. In the present study, the specific gravity among the three species was significant, and the highest and the lowest one belongs to beech and cypress, respectively. According to the results of other researchers, it was expected that the higher specific gravity would reduce the desirability for termites to consume wood, while our study demonstrated the effect of lignin and extractives are more meaningful in terms of termite deterrence.