Acaricidal effects of two native isolates of entomo-pathogenic bacteria Photorhabdus luminescens (Thomas & Poinar) against spider mite, Tetranychus truncatus Ehara (Acari: Tetranychidae)

ABSTRACT

Two local isolates of P. luminescens (NCBI GenBank Accession numbers ON627692, and ON627695) were evaluated for their bio-efficacy against the spider mite Tetranychus truncatus in the laboratory. Different concentrations (10⁴ to 10⁸ CS/CFS mL⁻¹) of cell suspension (CS) and cell-free supernatant (CFS) of the bacterial isolates obtained by centrifugation (4000 rpm for 20 min) were topically applied on eggs and adults of spider mites. The observations on ovicidal as well as adulticidal activity of bacterial isolates were recorded at 24, 48, and 72 h intervals. The bacterial isolates showed significant ovicidal and adulticidal properties for both CS and CFS after 72 h of treatment application. The isolate CNT1 recorded 84.00 and 58.67% mortality of eggs and 100 and 97.33% mortality of adults, respectively, for CS and CFS, at 10⁸ mL⁻¹ concentration. At the same concentration, the isolate ODA showed 44.00 and 84.00% mortality of eggs and 98.67 and 100% mortality of adults, respectively, for CS and CFS. The study identified two bacterial isolates of P. luminescens with appreciable acaricidal properties that can be exploited as a potential biocontrol agent against spider mite pests of crops.

KEYWORDS:

• Bio efficacy
• Tetranychus truncatus
• Heterorhabditis indica
• Photorhabdus luminescens
• cell suspension
• cell-free supernatant

Acknowledgments

The authors are thankful to the All-India Network Project on Agricultural Acarology, ICAR, and Kerala Agricultural University (KAU) for providing the necessary funds.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Author contributions

All authors contributed to the study’s conception and design. Material preparation, data collection, and analysis were performed by Athira G. Menon. The first draft of the manuscript was written by Athira G. Menon and Haseena Bhaskar and all authors suggested corrections in the manuscript. All authors read and approved the final manuscript.

Additional information

Funding

This work was supported by the Kerala Agricultural University [100000].