Abstract:

Entomopathogenic nematodes (EPNs) are biological combat agents living in the soil. EPNs need a guest insect throughout their lifecycles and kill their guest during their development. The biggest disadvantage of EPNs is the high cost of commercial products. Therefore, there are many studies that focus on the optimization of mass production and reduction of production costs. In the framework of a previous project, the HBH hybrid race was developed from two local isolates Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae). This hybrid race is patented due to its superior bio-ecological properties. This study aims to optimize the mass production of the hybrid HBH breed in in vitro solid culture. All laboratory trials were carried out between 2017-2018 years at the Bursa National University, Ziraat Faculty, Plant Protection Department, Nematology Laboratory. In optimization, standard environmental additives (soya lesitin and egg yellow) are selected as production parameters for temperature (24, 28 and 32°C) and environmental pH (5, 7 and 9). Optimization was evaluated by the number of hermafrodite eggs, the total number of infectious juvenil (IJ), IJ body length and IJ activity. According to the results, the best combination of production was found as agar, 28°C and pH 7, which contains soya lesite. Furthermore, the pH 9 agar has significantly reduced production efficiency. As a result, optimum values for some important in vitro solid production parameters of the HBH hybrid breed have been determined.

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Abstract:

Entomopathogenic nematodes are soil-dwelling biocontrol agents. EPNs need an insect host to complete their life cycle, and they kill their host during its development. The major disadvantage of EPNs is the high cost of commercial products. Thus, there are many studies focused on reducing production costs by optimization of mass production. In a previous project, Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) HBH hybrid strain was developed from local isolates. This hybrid strain was patented due to superior bioecological characteristics. This study aimed to optimize in vitro solid mass production of hybrid strain. All laboratory trials were performed between 2017 and 2018, in Nematology Laboratory of Bursa Uludağ University, Faculty of Agriculture, Department of Plant Protection. For optimization, additional supplementary ingredients (soy lecithin and egg yolk), temperature (24, 28 and 32°C) and medium pH (5, 7 and 9) were selected as production parameters. Optimization was evaluated based on hermaphrodite egg numbers, total infective juveniles (IJs), IJ body length and IJ virulence. Based on results, best production combination was found as agar containing soy lecithin, 28°C and pH 7. Also, agar media with pH 9 markedly reduced production yield. Consequently, optimum values for some important in vitro solid production parameters of HBH hybrid strain were determined.