Application of Paecilomyces lilacinus to suppress the Meloidogyne incognita and promote the growth of some selected vegetables

Meloidogyne incognita, also known as the root-knot nematode, is a plant-parasite that negatively impacts both the yield and quality of vegetables. The nematophagous fungus, Purpureocillium lilacinum, is widely regarded as a highly effective biocontrol agent (BCA) for M. incognita. To investigate the nematocidal efficacy of cultured P. lilacinum against eggs and second-stage juveniles of M. incognita at different application time, this investigation was carried out under invitro condition at the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh. The experiment was conducted in a complete randomized design with three replications. We used BC = blank control (Without any inoculation); MP = inoculation of M. incognita at planting (Negative control); PLP = application of P. lilacinus at planting; PLP + MP = application of P. lilacinus and inoculation of M. incognita simultaneously at planting; MPPL7DAP = inoculation of M. incognita at planting and P. lilacinus at 7 days after planting; PLPM7DAP = application of P. lilacinus at planting and M. incognita at 7 days after planting; PL7DBPMP = application of P. lilacinus at 7 days before planting and inoculation of M. incognita at planting as the treatments of the experiment. The results of the study revealed that P. lilacinum effectively reduced the survival rates of M. incognita eggs and juveniles depending on the different application time. Microscopic examination displayed that the fungi directly invaded the eggs and juveniles, demonstrating its parasitic nature against M. incognita. We also found that P. lilacinum effectively suppressed nematode populations and reduced the incidence of root galls in all the studied vegetables. Besides, P. lilacinum significantly stimulated plant growth metrics and biomass production, even in the presence of nematodes. The application of P. lilacinus at planting (PLP) or co-inoculation of P. lilacinus with M. incognita (PLP + MP) significantly controlled nematode populations and enhanced plant growth. Our study concludes that P. lilacinum is an effective biocontrol agent against RKN (M. incognita) and promotes vegetable growth.