Biological control of greenhouse whiteflies (Trialeurodes vaporariorum) using indigenous Pseudomonas spp.: An eco- friendly approach

Soil deterioration and environmental degradation caused by harsh chemical pesticides have led to the search for suitable alternatives that can not only control pests but also promote plant growth. Pseudomonas spp. has been exploited immensely for its biocontrol and plant growth promotion attributes. This study isolated 5 indigenous bacterial strains from eight rhizospheric soil samples from Shimla and Sirmour districts of Himachal Pradesh and further screened them for traits such as siderophores production and hydrolytic enzyme (amylase and protease) activity. Screening data of isolates showed production of siderophores (19.56%), amylase (50%) and protease (71.73%). The strain EU- SIRCK1243 was positive for all three traits and was tested for indole-3-acetic acid (IAA) production yielding 2.03±0.30 ?g/mL (with tryptophan) and 4.23±0.17 ?g/mL (without tryptophan). It was molecularly identified as Pseudomonas aeruginosa, on the basis of 16S rRNA gene sequencing and evaluated for bioefficacy against Trialeurodes vaporariorum (greenhouse whitefly) on tomato plants over two years (2022-2023). The average adult population declined with overall percent reductions of 54.11% in 2022 and 62.04% in consecutive year 2023. In case of nymph populations the overall, reductions was 59.13% in 2022 and 62.20% in 2023. The plant growth and physiological parameters after treatment with EU- SIRCK1243 showed significant increase in shoot and root lengths, fresh, dry biomass, yield and chlorophyll content as compared to control. It is suggested that the strain EU-SIRCK1243 is a promising biocontrol agent for greenhouse whitefly and an effective plant growth promoting bacterium. In future deliberation, the better development of Pseudomonas aeruginosa bioproducts could be emphasized.