Evaluation of a Novel Strain from Egyptian Soil for Biological Control of in Greenhouse Cucumber Plantations.

BACKGROUND

Infestation in greenhouse cucumber with the two-spotted spider mite ( Koch) commonly causes severe damage to crop quality and quantity and increases crop production costs.

OBJECTIVE

This study was conducted to investigate the efficacy of high-abamectinproducing isolates of against -infested cucumber and to assess their impact on biochemical stress markers in these vegetables.

METHODS

In this study, 72 non-antagonistic were isolated from rhizospheric soil samples collected from eight different locations in Egypt and screened for their ability to produce the secondary metabolite, abamectin.

RESULTS

The screening process identified two potent abamectin-producing isolates, EW8 and T2, which produced 42.7 and 29.6 μg/L abamectin, respectively, as confirmed by LC-MS/MS analysis. According to DNA sequence analysis of the 16S rRNA gene, these two isolates belong to the species . The acaricidal activity of either culture suspensions of strains WE8 and T2, or their extracts containing abamectin, against the mobile stages and egg hatchability of was evaluated in the laboratory and the greenhouse. Data on the mortality among the examined female mites and the reduction in their number of eggs point out a potential acaricidal activity of the examined strains of and their extracts containing abamectin against . Furthermore, the extracts containing abamectin from these two strains induced oxidative stress in the infested cucumber plants by , as indicated by increased levels of malondialdehyde (MDA). However, the levels of MDA in -infested cucumber plants varied depending on the strain and the specific abamectin crude extract used.

CONCLUSION

strains T2 or WE8, or their crude extract could be applied in greenhouse cucumber plantations to combat red mite infestation.