Abstract:

The detecting results of the basic nutrient materials, the chemical substance content of phenolic type, etc.and the wood fibre morphology of 4 Casuarina species with different insect-resistant performances were reported, the relation between the chemical and morphological factors of Casuarina spp. and the harm of Anoplophora chinensis was analysed and the insect-resistant mechanism of Casuarina spp.was studied.The distribution difference of basic nutrient material content in the Casuarina barks was not notable whereas that in their xylems was obvious, i.e. their content reduced with their insect-resistant performance enhancement, which caused the wood internal environmental difference of different strains of Casuarina and formed the living environmental difference of A. chinensis, the bole-boring injurious insect.The soluble total carbohydrate content in the highly sensitive Strain C₂₃(2.80%) was obviously higher than that in the highly resistant Strain C₄₄(0.62%) and was 4.52 times as high as the latter.The free amino-acid content in the C₂₃(1.857g) was 1.94 times as high as that in the C₄₄(0.955g).Meanwhile by adopting the glucose solution and the clear water(for a contrast)respectively to soak Casuarina segments and imitating the burrows with the segments to inoculate A. chinensis larvae for a feeding experiment, it was also tested and verified that the enhancement of the glucose content was advantageous to the enhancement of the larva living rate, which illustrated that the chemical nutrient material content in the xylems was closely realted to the larval growth and development.The phenolic compound (such as catechol or caffeic acid) content in the highly resistant Strain C₄₄ was obviously higher than that in the other strains.The average wood fibre length of the C₄₄ was 0.77mm, its average fibre width was 12.07μm and its ratio of length to width was 63.6.Its wood fibre was the thickest and strongest in that of all the strains, which illustrated that its fibre tenacity was the strongest and its bending strength was the highest to cause A. chinensis to nibble difficultly and also illustrated that its wood fibre status tallied with its performance of both insect resistance and wind resistance.

Key words: Casuarina, Basic nutrient material, Phenolic compound, Wood fibre, Insect resistance