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Acta Entomologica Sinica ›› 2019, Vol. 62 ›› Issue (2): 222-232.doi: 10.16380/j.kcxb.2019.02.009

• RESEARCH PAPERS • Previous Articles     Next Articles

Bioefficacy and searching effect of entomopathogenic nematode Steinernema feltiae SF-SN treated with thiamethoxam on Bradysia odoriphaga (Diptera: Sciaridae) larvae

Bioefficacy and searching effect of entomopathogenic nematode Steinernema feltiae SF-SN treated with thiamethoxam on Bradysia odoriphaga (Diptera: Sciaridae) larvae

WU Hai-Bin1,2, GONG Qing-Tao1, CHEN Zhen-Zhen2, FAN Kun1, GONG Yi3, XU Yong-Yu2, SUN Rui-Hong1,*   

  1. (1. Shandong Institute of Pomology, Taian, Shandong 271000, China; 2. College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China; 3. Shandong Plant Protection Station, Jinan 250100, China)

  • Online:2019-02-20 Published:2019-02-28

Abstract: Aim After the entomopathogenic nematodes (EPN) are exposed to chemical pesticides, their potential bioefficacy and searching effect on insect pests might change. This study aims to investigate the bioefficacy and searching effect of entomopathogenic nematodes treated with thiamethoxam on Bradysia odoriphaga larvae. Methods The lethal and searching effects of S. feltiae SF-SN strain (Sf) treated with thiamethoxam (15 mg/L) on the 3rd instar larvae of B. odoriphaga were tested under laboratory conditions using a filter-paper culture method, and the differences in the functional responses and searching effect between the thiamethoxam-treated Sf and the untreated Sf were evaluated. Results The corrected mortality of B. odoriphaga larvae exposed to thiamethoxam-treated Sf was significantly higher than that exposed to the untreated Sf, and was increased by 2.13 times as compared with that exposed to the untreated Sf at 6 h post treatment. When the concentration of Sf was 6 400 IJs/petri dish, the functional responses for killing action of untreated and thiamethoxam-treated Sf on the 3rd instar larvae of B. odoriphaga could be described by Hollings type II and disc equation. The attack rate (a=0.5592) of thiamethoxam-treated Sf increased by 42.76%, the handling time (Th=0.0081 d) (the cumulative time taken in searching, parasitizing and killing the host) decreased by 44.90%, the consumption rate (a/Th) increased by 2.59 times, and the daily maximum lethal amount (Namax) increased by 1.81 (Hollings type II) and 1.41 (Hollings type III) times, respectively, as compared with those of the untreated Sf. The searching effect of both untreated and thiamethoxam-treated Sf decreased with increasing larval density of B. odoriphaga. When the larval density of B. odoriphaga was 40 per petri dish, the lethal effect of thiamethoxam-treated and untreated Sf increased with increasing Sf concentrations, while the searching effect first increased and then decreased. The searching parameter and mutual interference parameter of thiamethoxam-treated Sf were higher than those of the untreated Sf. Conclusion The corrected mortality of B. odoriphaga larvae and the attack rate, consumption rate, daily maximum lethal amount and searching effect of thiamethoxam-treated Sf on B. odoriphaga larvae are higher than those of the untreated Sf, while the handling time is shorter than that of the untreated Sf.

Key words: -SN')">Steinernema feltiae SF-SN, thiamethoxam, Bradysia odoriphaga, bioefficacy, searching effect