Abstract: Larvae of Dendrolimus punctatus Walker (Lepidoptera：Lasiocampidae) were fed with young needles, old needles and β-pinene-treated (20% and 40% in concentration) young needles of masson pine (Pinus massoniana) and slash pine (P. elliottii) respectively in the laboratory. The survival rates of the larvae among these needle groups were observed. The masson pine old needle group had the highest survival rate (44％), followed by the masson pine young needle group (32.67％) and the slash pine old needle group (4％), while all larvae feeding on slash pine young needles died. The analysis of the amino acid content and β-pinene showed the content of amino acid was highest but the content of β-pinene was lowest in masson pine old needles. In contrast, the content of amino acid was lowest but the content of β-pinene was highest in slash pine young needles. Also, the mortality rate of the larvae feeding on the β-pinene-treated needles was higher than that of the control. We speculated that the high content of β-pinene and the low content of amino acid could lead to high mortality of D. punctatus larvae feeding on slash pine needles. The content level of β-pinene should be considered as a standard for the resistance ability to D. punctatus, which prefers to feed on masson pine but not slash pine in the wild.

Key words: Dendrolimus punctatus, Pinus massoniana, Pinus elliottii, host preference, amino acid, β-pinene, survival rate, mortality