development of novel biodegradable beads of bacterial parasite pasteuria penetrans as bionematicide

Abstract

ABSTRACT newlineDEVELOPMENT OF NOVE newlineL BIODEGRADABLE BEADS OF BACTERIAL PARASITE, PASTEURIA PENETRANS newlineAS BIONEMATICIDE newlineBy newlineS.ABIRAMI newlineDegree : Doctor of Philosophy in Plant Nematology newlineChairperson : Dr. K. POORNIMA newlineProfessor and Head, newlineDepartment of Nematology, newlineTamil Nadu Agricultural University, newlineCoimbatore 641 003, newlineTamil Nadu, India. newline2019 newlineA detailed study was carried out to identify a suitable culture media for mass culturing newlineand assess the biocontrol potential of the nematode antagonistic bacterial hyperparasite, newlinePasteuria penetrans (isolate Cbe-PpM2). Accumulated degree days for P. penetrans were newlinecalculated in tomato (variety PKM 1) as host plant and root knot nematode, Meloidogyne newlineincognita as host nematode under glasshouse condition. Based on the fluctuating temperatures, newlinedegree days per day was calculated during winter (October to November, 2017) and summer newlineseason (March to April, 2018). The observations revealed that 524 and 440 degree day was newlinerequired for P. penetrans to complete its life cycle in winter and summer seasons respectively. newlineDuring winter, P. penetrans required prolonged heat units for completion of life cycle while in newlinesummer, lower heat units were sufficient to complete one generation and proceed to next newlinegeneration. Base temperature of P. penetrans depended upon the nematode survival at minimum newlinetemperature. The results showed that a base temperature of 10°C is suitable for P. penetrans newlineencumbrance on juveniles. At this base temperature, about 20 per cent of juveniles got infected. newlineThe results of life table study showed that the mortality rate of uninfected juveniles were newlinehigher at 0-6 days but death of juveniles were higher at 8,12,16,26 and 28 days in P. penetrans newlineparasitized juveniles. Life expectancy of uninfected and infected juveniles was 12.11 and 7.76 at newlinethe starting of the experiment which was gradually decreasing in infected juveniles (0.75) newlinecompared to uninfected juveniles (1.00). Survival of P. penetrans infected juveniles was lower newlinecompared to uninfected juveniles. The suit