关键词: 栗山天牛, 花绒寄甲, 生物防治

Abstract:

Dastarcus helophoroides is an important parasitoid of the oak longhorn beetle Massicus raddei and mainly parasitizes the middle and old age larvae and pupa of the cerambycid. In order to control M. raddei by the parasitoid, we investigated the parasitization rate to the pest by releasing D. helophoroides adults and eggs. The results showed that the parasitoid preferred to parasitize mid-old instars larvae and pupa of the pest. The parasitization rate was able to reach 88.15% in a month with two D. helophoroides adults released per one pest in the lab., and reach 90% with 100 D. helophoroides eggs released per one pest in the lab. The results in the field were similar, and the parasitization rate could reach 88.80% after releasing adults and 93.10% after releasing eggs. The average number of second generation adults of D. helophoroides, which consumed up longhorn beetle after parasitizing, was 30 per host in the lab. and 13.34 times of the released number. The second generation adult number in the field was 28 per host, and 17.62 times of the released number. Parasitization, regardless by one or several parasitoids, would cause the pest, longhorn beetle, death in few days. After releasing D. helophoroides in the field, the parasitization rate of parasitoid was most when the pests were at developmental stages of mid-old instars larvae and pupa, however when the pests were 1-3 instars, the parasitization rate was zero. The number of D. helophoroides was sustainable even though the pests were at 1-3 instars because the parasitoid has long lifespan and could find alternative hosts. The parasitization rate ascended again when the mid-old instars larvae and pupa were available, the parasitoid’s number would increase too. The results showed that D. helophoroides could continually parasitize the M. raddei after its release.

Key words: Massicus raddei, Dastarcus helophoroides, biocontrol