Studies On The Ecology Of Massicus Raddei (coleoptera: Cerambycidae) And Its Biological Control

The oak longhorn beetle, Massicus raddei (Blessig) (Coleoptera: Cerambycidae) is an important insect pest outbreak recently in the northeast of China. To explore the non-pubic hazard way to control this pest, we studied the integrated management techniques of M. raddei mainly by biological control. The distribution pattern of M. raddei, the behaviors and the activity rhythm of adults were studied by observation in the field and tested in lab. And studies also were conducted by using a new parasitoid Sclerodermus pupariae Yang et Yao to control the young larvae of the pest, and using another parasitoid Dastarcus helophoroides (Fairmaire) to control the old larvae and pupa. In addition, other parasitoids of the longhorn beetle larvae were investigated in field at its difference stages. Finally, a systematic strategy for controlling the M. raddei which mainly depending on biocontrol was constructed.1. The distribution pattern of M. raddei was studied. The larvae mainly lived in oak trunk below 4m and the pupae were 1-4m whose trunk was dried partly, while the larvae mainly distributed below 6m and the pupae were on the 3-7m trunk whose crowns dried. The relationship between the number of larvae and thickness of bark was positive correlation, also between the amount of longhorn beetles and trunk diameter. In the year after the eggs hatched and before June of next year, the larvae located in phloem, and larvae begun to bore in xylem in June, the peak periods of larvae bored to xylem were July and August, most of them entered into xylem in September. The key description factors were slope position, DBH and crown density which affected the infestation degree of M. raddei.2. The behavior and the activity rhythm of adults were studied. The M. raddei adult feed with juice excreted from the oak bark wound. A whole mating behavior of adult included six stages, including finding, recognizing and chasing-climbing, consoling and tentative inserting-inserting and insemination-inserting and protecting after insemination-inserting intermission-protecting after mating and leaving. The M. raddei female laid eggs in the bark crack. The peak period of feeding, mating, ovipositing, creeping and flying behaviors of M. raddei adult were 18:00-20:00, 17:00-22:00, 19:00-22:00, 19:00-22:00 and 19:00- 21:00 respectively.3. Using a parasitoid Sclerodermus pupariae Yang et Yao to control the young larvae of the pest was studied. Parasitism rates of S. pupariae to M. raddei young larvae increased with the increase of parasitoid density, and the maximum could be up to 60% in the lab. And the periods to control M. raddei larvae using S. pupariae were in the year after the eggs hatched and before August of next year. The super-cooling point of the field parasitoid was -26.2℃, so it could be over-wintered in most years in the northeast of China. In addition, the female wasps have excellent learning ability.4. Using another parasitoid Dastarcus helophoroides (Fairmaire) to control the old larvae and pupa was studied. Parasitism rates of D. helophoroides to M. raddei old larvae could reach 80% in lab and 30% in the field. And the best time to control M. raddei larvae using D. helophoroides was form the past second half year and the first half year of the adult. The distribution pattern of M. raddei larvae and D. helophoroides adults were aggregation, and the parasitoid followed the host obviously.5. Other parasitoids of the longhorn beetle were investigated. Zaommoencyrtus myopsi Yang was a new species described which parasitized M. raddei larvae. Two new species of braconid Doryctes raddeii Yang sp.nov. and Iphiaulax massicusi Yang sp.nov were also found to attack the longhorn beetle larvae. In addition, three predatory enemies were found in field, one was click beetle, other two were checked beetles.6. Alternate hosts of S. pupariae and D. helophoroides in oaks forest were studied. The results showed that there were many other longhorn beetles in oaks forest, such as Moechotypa diphysis, Mesosa myops, etc. And the life histories of these longhorn beetles were not tidiness. So there were many larvae in May to September. After that, both of two parasitoids could parasitize this longhorn beetle larvae. M. diphysis or M. myops would be the excellent alternate hosts of these two parasitoids in oak forest.