Abstract:

Based on the results of observations and analyses for successive three years ,the relationships between Apriona swainsoni and its host trees were reported in this paper. The results were as follows:(1) According to the feeding and oviposting behaviour ,the survival time of the adult and the inoculating egg situation on different trees , the host trees reported in other papers could be divided into four types—highly sensitive tree (Sophora japonica); lowly sensitive tree (including Dalbergia hupehana,Caesalpinia decapetala);resistant tree (Robinia pseudoacacia)and immune tree (Salix matsudana). (2) Phenotic compound content in S.matudana (3.03～9.73 mg·(100g)^-1)was much higher than that in other host trees,which may be the reason why A swainsoni refused to eat, ovipsit and bore on this tree .The higher content of amino acid with the most types and higher C/N ratio was notable characteristic of nutrient material in S.japonica. Maybe this nutrient characteristic offers many attractions for A swainsoni. On the contrary, perhaps the lowest C/N ratio of R.pseudoacacia results in slight harm to it .The wood of D.hupehana with 0.837 mm in average fibre length,18.90 μm in average fibre width and 50.96 in the ratio of length to width,indicated that its tenacity and bending strength were the highest in that of all experiment host trees. In addition, the C/N ratio in the wood of this tree was also lower (0.36).These factors might make it difficult for the larvae to nibble and live on it .C.decapetala has thin and smooth trunk bark ,so it is hard for the adult to oviposit on this type of tree.

Key words: Host trees, Apriona swainsoni Hope, Insect resistance, Wood fibre, Internal chemical substance