Virulence of Steinernema ceratophorum against different pest insects and their potential for in vivo and in vitro culture

Abstract

Entomopathogenic nematodes (EPN) are biological control agents used to control different insect pests. Indigenous EPN resources are important for the successful control of endemic pests. A native EPN isolate collected in Yunnan, China that showed high virulence against Spodoptera litura was identified and studied for virulence and production potential. The EPN isolate was identified as Steinernema ceratophorum and showed high virulence against different larval stages of Spodoptera exigua, Ostrinia nubilalis, Helicoverpa armigera, and the 2nd instar larvae of Spodoptera frugiperda when applied at 50 IJ/larva under in vitro conditions. In vivo culture of the S. ceratophorum isolate showed that Galleria mellonella larvae were the most suitable host compared to Tenebrio molitor and S. litura. The highest yield in in vivo culture was 1.15 × 10 5 IJ/larva when cultured in G. mellonella with inoculum concentration of 50 IJ/larva at 25°C. For in vitro solid culture, the highest yield for S. ceratophorum was 2.09 × 10 6 IJ/g when cultured at optimal temperature of 25°C. Nematodes from the in vivo and in vitro culture, both retained their virulence against the G. mellonella larvae. The S. ceratophorum showed high potential to be mass produced, which will enable the commercial use of this EPN isolate. This is the first attempt to mass culture the S. ceratophorum species. The study explores the usage of S. ceratophorum and provides basis for the commercialization of the EPN species.

Virulence of Entomopathogenic Nematodes and their Symbiotic Bacteria against Insect Pests, with Special Reference to Agrotis ipsilon (Lepidoptera: Noctuidae): A Comprehensive Review.

“…and Heterorhabditis sp. as promising biocontrol agents against the bean pod borer Maruca vitrata (Crambidae) causing 100% mortality within 48 h.The beet armyworm Spodoptera exigua (Noctuidae) larvae were sensitive to S. ceratophorum, with mortality rates of 100% for the 2 nd and 3 rd instar after treatment for 48 h. For the 4 th and 5 th instars, although mortality did not reach 100% after treatment for 48 h when the EPN was applied at lower concentrations of 25 and 50 IJ/larva, mortality reached 100% after treated for 72 h (Yan et al, 2021). Kumar et al (2022) evaluated the infectivity of EPN S. asiaticum against the diamondback moth Plutellaxylostella(Plutellidae) as a foliar spray on cabbage plants in screen house with single, two or three applications.…”

Susceptibility of Different Developmental Stages of the Tobacco Cutworm, Spodoptera litura (Fabricius) to Entomopathogenic Nematode, Steinernema abbasi PN-1

“…Pupation occurs in the soil close to the plant base [4]. The larvae of S. litura older than the third instar exhibit a strong tolerance to a wide range of chemical pesticides [5]. Chemical pesticide usage in excess leads to major environmental and resistant issues.…”