Abstract: To explore how leaves of Ficus benjamina Linn. are damaged by rasping-sucking feeding of thrips, we studied the microstructure and the contents of amino acids and proteins in these leaves by scanning electron microscope and automatic amino acid analyzer. The results showed that after F. benjamina leaves were rasped and sucked by thrips, the microstructure of leaf surface had obvious changes, including: the wax layers cracked, the epidermal cells were injured, the function of stoma was lost and the functions and omamental value of the plant were also influenced. The foliar injuries by thrips obviously influenced the protein contents (P<0.01) in injured leaves, showing difference among different damage grades of injured leaves. Protein concentration in leaves with the 1st damage grade decreased fastest and was lower than those in leaves with other damage grades, while those in leaves with the 2nd and 3rd damage grades decreased slowly, and that in the leaves with the 4th damage grade was higher than those in undamaged leaves. There were 9 essential amino acids (EAAs) which are necessary for the development of thrips and 8 non-essential amino acids (NEAAs) in F. benjamina. In the leaves with the same damage grade, individual amino acid concentration was different for 17 amino acids and could be divided into three grades, but was relatively stable; while in the leaves with different damage grades, the concentrations of amino acids were closely related to the damage degree. The damages of leaves by thrips also resulted in the decrease of concentrations of total amino acids (TAA), EAAs and NEAAs in leaves with different damage grades, especially in the leaves with the 2nd and 3rd damage grades, but caused certain increase to the contents of three essential amino acids (arginine, methionine and lysine) and four non-essential amino acids (aspartic acid, cystine, serine and tyrosine). This research provides basic information on the changes of surface ultrastructure and the nutritional and physiological indexes of the host plant leaves damaged by thrips at the micro level. It also quantifies the functional benefit and loss of F. benjamina leaves caused by thrips.

Key words: Thrips, Ficus benjamina, rasping stress, leaf surface structure, protein content, amino acid content