Bacillus amyloliquefaciens AG1 biosurfactant: putative receptor diversity and histopathological effects on Tuta absoluta midgut.
The use of biosurfactant in pest management has received much attention for the control of plant pathogens, but few studies reported their insecticidal activity. The present study describes the insecticidal activity of biosurfactant extracted from Bacillus amyloliquefaciens strain AG1. This strain produces a lipopeptide biosurfactant exhibiting an LC50 of about 180 ng/cm2 against Tuta absoluta larvae. Accordingly, the histopathologic effect of this biosurfactant on T. absoluta larvae showed serious damages of the midgut tissues including rupture and disintegration of epithelial layer and cellular vacuolization. By PCR, we showed that this biosurfactant could be formed by several lipopeptides and polyketides including iturin, fengycin, surfactin, bacyllomicin, bacillaene, macrolactin and difficidin. Binding experiment revealed that it recognized five putative receptors located in the BBMV of T. absoluta with sizes of 68, 63, 44, 30 and 19 kDa. Therefore, biosurfactant AG1 hold potential for use as an environmentally friendly agent to control the tomato leaf miner.