Abstract: The pea leafminer, Liriomyza huidobrensis (Blanchard), is a polyphagous insect pest on vegetables and ornamental plants. In order to investigate the interaction between this pest and its host plants, we assayed the contents of soluble sugars, soluble proteins, tannins, flavones and chlorophyll in cucumber leaves infested by the 1st to 3rd larvae of L. huidobrensis with different damage levels using anthrone colorimetric method, Coomassie brilliant blue staining, phosphor-molybdenum acid-phosphor-tungstenic acid colorimetry, Soxhlet extraction and acetone spectrophotometry, respectively. The results showed that the contents of soluble sugars, soluble proteins and chlorophyll in cucumber leaves decreased while those of tannins and flavones increased with the increase of damage by the larvae. The largest decrease amplitudes of the former three were 62%, 35% and 40%, respectively, and the highest increase amplitudes of the latter two were 26% and 53%, respectively. The influences of the larval infestation on the above compounds were systemic. The results suggest that the larval damage caused the decrease of nutrient contents and phytosynthesis of host plants while the increase of secondary metabolite contents, and therefore induced the resistance to herbivores. This study may provide a useful reference to further research on the interactive mechanisms between the leafminer and its host plants.

Key words: Liriomyza huidobrensis, cucumber, plant-insect interaction, soluble sugar, soluble protein, tannin, flavone, chlorophyll