关键词: 花绒寄甲, 松褐天牛生物型, 越冬场所, 过冷却点, 耐寒性

Abstract: [Objective] In order to know the range of an excellent parasitic enemy insect, Dastarcus helophoroides, to control the cerambycid beetle, Monochamus alternatus and its population dynamic, the overwintering characteristics and the cold-hardiness are studied, providing an valuable information for applying them to control the cerambycid beetle and furthermore through control of the vector of Bursaphelenchus xylophilus to manage the pine welt disease in China. [Method] The overwintering location and height at tree trunk, aggregation ways, azimuths of natural population of D. helophoroides were surveyed by dissecting the damaged host trees by the cerambycid. At the 6 different artificially simulated overwintering locations, the overwintering survival rate, supercooling point and freezing point were determined. Furthermore, the possible suitable range of the mass-rearing D. helophoroides biotype of M. alternatus was explored on the basis of distribution area of M. alternatus. [Result] The results showed that the parasitoid overwintering positions were mainly in the bark crevice and under the trunk bark of the dead Pinus massoniana damaged by the cerambycid. Most of the parasitoid stayed in individuals and some gathered with 3-5 ones together for overwintering. The overwintering location was mainly at the 2.5-8 m height range of tree trunk, with the largest numbers at the height of 7 m. They freely selected azimuths at tree trunk for overwintering, with 58.33% individuals at south, 21.79% at east, and 9.62% at north. There was significant difference in survival rate at the 6 simulative overwintering sites. the survival rate of parasitoid groups were 68.33%±9.21%, 67.92%±8.87%, 73.33%±12.52%, 52.08%±8.87%, 52.92%±11.61% and 44.17%±12.58%, respectively under the bark, in the surface soil layer, in the trunk xylem, in the metal net partly covered tree trunk, in the metal net completely covered tree trunk, and in the cages with shout-cut wood. The supercooling points and freezing points of D. helophoroides adults in each of the above-mentioned sites were -11.40, -11.25, -11.76, -11.54, -12.75, -12.89℃ and -10.08, -9.95, -10.99, -10.39, -11.23, -12.05℃, respectively, and there were no significant differences in the supercooling points and freezing points among the sites. In comparison of the supercooling values with the mean air temperature of January in the naturally distributed areas of M. alternatus in China, it was indicated that the mass-rearing adults of D. helophoroides could successfully survive and maintain their population in most of the cerambycid pest distributed areas. [Conclusion] The present study revealed the overwintering characteristics and suitable distribution regions of artificial breeding population of D. helophoroides, indicating that they could overwinter successfully at suitable distribution region and potential dispersal region of M. alternatus. Finally, these results would provide some theoretical support for scientifically releasing D. helophoroides to control M. alternatus.

Key words: Dastarcus helophoroides, biotype of Monochamus alternatus, overwinter, supercooling point, cold-hardiness