Efficacy of the Plant Growth Promoting Rhizobacterium and Lufenuron for Reducing Insect-associated Yield Losses in Cauliflower

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Insect attacks on plants are a severe problem in the agricultural sector. The damages caused by insects have an adverse impact on plant growth which leads to slow economic growth, particularly in countries dependent on agriculture. Plant growth-promoting rhizobacteria (PGPR) are widely utilized in agriculture because they offer a viable alternative to pesticides and artificial fertilizers. The growth and life cycle of insects/pests is inhibited by the insect growth regulators (IGRs), which belong to third-generation insecticides. Lufenuron is an IGR having a broad-spectrum insecticidal activity. Lufenuron inhibits insect growth by reducing chitin synthesis. A field experiment was carried out at Ayyub Agricultural Research Institute, Faisalabad, to evaluate the effect of MUR-4 (a potential PGRP) and lufenuron on cauliflower under insect attack. Cauliflower (Naran F1) seedlings were grown with and without a potential PGPR (MUR-4) using a randomized complete block design (RCBD). Attacks of cutworms, diamondback moths, armyworms and aphids were recorded periodically. Lufenuron was applied as a foliar spray, to inoculated as well as non-inoculated plants, upon insect attack. A foliar spray of lufenuron exerted a positive effect and reduced the insect attack. Plant biochemical analysis manifested the higher activities of phenolics and proline (secondary metabolites) in MUR-4 PGPR inoculated plants. Increased levels of malondialdehyde (MDA) and H2O2 indicated oxidative stress in plants. Peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) enzymes play a very important role in defence against insect-induced biotic stress. MUR-4 PGPR inoculation enhanced the activity of the mentioned enzymes i.e. POD, CAT and SOD. We concluded that lufenuron spray can positively assist farmers in insect control strategies. Furthermore, MUR-4 PGPR inoculation improved the plant defence system against insect herbivory.