Evaluation of the effects of infection by different entomopathogenic nematodes and thiamethoxam on Bradysia odoriphaga
Author of the article:WU Hai-Bin1, 3** LING Fei2 GONG Qing-Tao1 FU Li1 XU Yong-Yu3*** SUN Rui-Hong1***
Author's Workplace：1.Shandong Institute of Pomology, Tai’an 271000, China; 2. Shandong Rizhao International Ocean City Investment CO. LTD, Rizhao 276800, China; 3. College of Plant Protection, Shandong Agricultural University, Tai’an 271018, China
Key Words：entomopathogens nematodes, thiamethoxam, Bradysia odoriphaga, combination
Abstract： [Objectives] To increase the effectiveness of controlling Bradysia odoriphaga with entomopathogenic nematodes, and to screen pesticides as synergists for entomopathogenenic nematodes.[Methods] The survival rate and infectivity of six entomopathogenic nematodes (Steinernema carpocapsaeNC116, S. carpocapsae All, S. longicaudum X-7, S. feltiae SF-SN, Heterorhabditis bacteriophora H06 and H. indica LN2) were tested after dipping them in a commonly used pesticide (25% water dispersible granules of thiamethoxam). The effects of treatment with six nematodes and low concentrations of thiamethoxam (12 mg·L-1) on 3rd instar larvae were determined. Interactions between three kinds of nematodes (S. feltiae SF-SN,H. indica LN2 and S. carpocapsae All), and low concentrations of thiamethoxam (30 mg·L-1), were evaluated under various temperature and humidity conditions and further tested under greenhouse conditions.[Results] The recommended concentration of thiamethoxam (100 mg·L-1) had no effect on nematode survival. Mortality of B. odoriphaga treated with a combination of six nematodes and a low concentration thiamethoxam (12 mg·L-1) was higher after 3 d than that of larvae that had been treated with thiamethoxam and any one nematode. Mortality of B. odoriphaga treated with S. feltiae SF-SN+ thiamethoxam, H. indica LN2+ thiamethoxam and S. carpocapsae All+ thiamethoxam was higher at 20-25℃, 25-30℃, and 25-30℃, respectively, than at other temperatures. The optimum substrate moisture level for these treatments was 10%-18%. The results of greenhouse trials show that a combination treatment (S. feltiae SF-SN+ thiamethoxam) achieved > 93 % better control than treatment with thiamethoxam (100 mg×a.i./L) alone after 7 d. [Conclusion] The S. feltiae SF-SN+ thiamethoxam combination appears an effective way of controlling B. odoriphaga.