In vitro evaluations to determine the effect of Bacillus firmus strains on the motility of Meloidogyne incognita second-stage juveniles

Abstract

Eco-friendly control strategies, such as biological agents containing Bacillus firmus, are known to adversely impact the biology of Meloidogyne incognita and other nematode pests that damage agricultural crops. The efficacy of two isolated strains as well as one reference strain was evaluated for their effect on M. incognita second-stage juvenile (J2) motility. All three B. firmus strains successfully reduced J2 motility, with the reference strain being superior. Non-cultured cell-free products of the isolated strains inhibited J2 motility only between 3 and 7 % compared to the tap-water controls, respectively, and compared to up to 42 % by their cultured, cell-free water filtrate counterparts. The latter range was also recorded for the 100 % cultured, cell-free suspension concentration of the reference strain. The efficacy of cell suspensions of the two isolated strains were low (7-19 %) compared to the 100 % achieved by the reference strain. Although secondary compounds of the two isolated B. firmus strains may contribute towards disrupting the movement and host finding abilities of J2, they had no pronounced effects on J2 motility inhibition