Abstract:

To explore the feasibility of controlling Monochamus alternatus by using entomopathogenic nematodes Steinernema carpocapsae ALL and Heterorhabditis sp. WG, the natural state conditions of M. alternatus were simulated in laboratory, and control effect with the two entomopathogenic nematodes on the larvae of Japanese pine sawyer were determined. The TDM(time-dose-mortality) model of control function of the two nematodes against M. alternatus was established and tested. The results showed that under the doses of 30 000, 40 000, 50 000 and 60 000 mL^-1 for seven days, 41.11%, 51.11%, 53.33% and 82.22% individuals of M. alternatus at the 3rd instars were killed by S.carpocapsae ALL respectively; and 35.56%, 51.11%, 51.11% and 74.44% individuals were killed by H. sp. WG, respectively. The start time of killing M. alternatus at the 3rd instars by H. sp. WG was earlier than that by S.carpocapsae ALL. The peak of daily mean mortality of M. alternatus at the 3rd instars was between the 1st day to 3rd day. The LC₅₀ values of S.carpocapsae ALL between the 1st day and 7th day were calculated by the TDM model and they were 52 888 176, 147 128.61, 25 953.95, 17 915.36, 14 964.30, 12 968.78 and 11 663.99 mL^-1, respectively; and the LC₅₀ values of H. sp. WG of the 1st day to 7th day were 326 212.05, 29 566.51, 14 474.38, 13 934.78, 12 234.89, 10 531.74 and 9 543.33 mL^-1, respectively, and under the doses of 40 000, 50 000 and 60 000 mL^-1, the LT₅₀ of S.carpocapsae ALL was 6.70, 4.97, and 3.98 days, respectively; and under the doses of 50 000 and 60 000 mL^-1, the LT₅₀ of WG was 5.39 and 4.06 days, respectively. It is concluded that the two of nematodes species have a high control effect on the larvae of M. alternatus, which provides a basis for field control of M. alternatus.

Key words: entomopathogenic nematodes, Steinernema carpocapsae, Heterorhabditis sp., Monochamus alternatus, control effect, biological control