In order to examine the effect of emamectin benzoate to Frankliniella occidentalis

the toxicity of this insecticide to the adult and 2nd instar of F. occidentalis were studied  by dip method in this paper. In addition

  the content of soluble protein

soluble sugar and lipid in F. occidentalis were also tested after these insects were exposed to medial lethal doses of emamectin benzoate for the following exposure times: 2

4

6

and 8 h. Furthermore the utilization rate of the energy source in F. occidentalis was calculated after the insects were exposed to emamectin benzoate until dead at the medial lethal doses. The results showed that emamectin benzoate had different toxicity to the adult and 2nd instar of F. occidentalis

and the medial lethal doses were 1.11 and 0.62 mg/L

respectively. With the extension of exposure time at medial lethal doses of emamectin benzoate

there was significant a increase or decrease on the content of soluble protein

soluble sugar and lipid in F. occidentalis adult

but no significant variation on their content in F. occidentalis nymph. When the F. occidentalis was dead under the medial lethal doses exposure

there was significant difference in the utilization rate of the three kinds of energy sources in F. occidentalis

the utilization was soluble sugar（74.12%）> soluble protein（58.10%）> lipid（42.13%）in adult

significantly higher than that in nymph at any kind of the three energy sources

and the utilization was soluble sugar（64.01%）> soluble protein（48.12%）> lipid（36.48%）in nymph. According to the results

we could conclude that the different variation and utilization of energy source between F. occidentalis adult and nymph under the exposure of emamectin benzoate

may have some relationship to their different tolerance to this insecticide.