马尾松毛虫对马尾松和湿地松的选择与适应研究

Feeding preference of Dendrolimus punctatus Walker (Lepidoptera:Lasiocampidae) on pines Pinus massoniana and P. elliottii

用马尾松老叶、新叶,湿地松老叶、新叶,当年生马尾松新叶、湿地松新叶和当年生以20%和40%β-蒎烯处理过的马尾松新叶作食料饲养马尾松毛虫。结果表明:马尾松毛虫幼虫在第1代发生期取食马尾松老叶、马尾松新叶、湿地松老叶和湿地松新叶等4种不同质量的食料后,因其食料中10种必需氨基酸含量和挥发性物质β-蒎烯含量的不同,导致幼虫的存活率差异显著。其中,取食马尾松老叶的幼虫成活率最高(44%),依次为马尾松新叶(32.7%)、湿地松老叶(4%),而取食湿地松新叶的幼虫全部死亡。通过马尾松针叶增加外援β-蒎烯喂养马尾松毛虫实验,表明增加了外源β-蒎烯的松针饲养的马尾松毛虫幼虫与用同样松针未增加外源β-蒎烯饲养的幼虫相比,死亡率明显提高;松树中β-蒎烯含量的增加与幼虫成活率呈显著负相关。由此,我们阐明了马尾松与湿地松对马尾松毛虫的抗虫机制。

Larvae of Dendrolimus punctatus Walker （Lepidoptera： Lasiocampidae ） were fed with young needles, old needles and 6-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.