Influence of Asafoetida Extract on the Virulence of the Entomopathogenic Nematode and Its Symbiotic Bacterium in the Host .

Nematode-microbe symbiosis plays a key role in determining pathogenesis against pests. The modulation of symbiotic bacteria may affect the virulence of entomopathogenic nematodes (EPNs) and the biological management of pests. We tested the influence of asafoetida (ASF) extract on the virulence of and its symbiotic bacterium, , in A total of 100 mg of ASF killed 30% of EPNs in 48 h, while remained unaffected. The EPNs pre-treated with 100 mg of ASF influenced 's mortality by 24-91.4% during a period of 24 to 72 h. The topical application of ASF acted as a deterrent to , lowering host invasion to 70% and delaying infectivity with 30% mortality for 168 h. Interestingly, 's symbiotic bacterium, , remained unaffected by ASF. An in vitro turbidity test containing 100 mg of ASF in a medium increased the growth rate of compared to a control. A disc diffusion assay confirmed the non-susceptibility of to ASF compared to a positive control, streptomycin. Pro-phenol oxidase (PPO) and phenol oxidase (PO) upregulation showed that ASF influences immunity, while EPN/ASF showed a combined immunomodulatory effect in We report that ASF modulated the virulence of but not that of its symbiotic bacterium, , against .