Vermiwash allows reduced application rates of acaricide azocyclotin for the control of two spotted spider mite, Tetranychus urticae Koch, on bean plant (Phaseolus vulgaris L.)

•Vermiwash controlled T. urticae and reduced application of azocyclotin up to 50%.•Vermiwash as a biofertilizer can also have an inhibitory effect against T. urticae.•It was known that T. urticae was also susceptible to odour of vermiwash.•Inhibitory effect of vermiwash was not due to microorganisms existed in vermiwash.

The two-spotted spider mite, Tetranychus urticae Koch, is a cosmopolitan mite. It reproduces very rapidly and can also develop resistance to chemicals easily. Vermiwash is the watery extract of vermicomposts, extracted in the presence of rich population of earthworms, with plant growth promoting effects. The study was carried out to determine the efficacy of vermiwash and its combination with acaricide azocyclotin compared to the acaricide alone for control of T. urticae on bean plant under the laboratory and greenhouse conditions. Combinations of vermiwash and the acaricide obviously reduced the population density of T. urticae on bean plant. When the 50% of recommended rate of the acaricide and vermiwash were used, percentage of mortality (100%) of T. urticae was statistically comparable to those with the full rate of acaricide (1 g l−1) without vermiwash. It may be suggested that combination of vermiwash with the acaricide can be a promising candidate for biological control of T. urticae on the bean plant reducing the application of the chemical pesticide up to 50%.

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