Efficacy of microbial biopesticides to manage Pieris brassicae (Linnaeus) and Plutella xylostella (Linnaeus) in cauliflower

Cauliflower is an essential vegetable crop globally, providing essential nutrition and income for millions of people. However, it is highly susceptible to various pests, resulting in a significant reduction in both quality and yield. The conventional solution to control these pests has been the use of chemical pesticides, but their usage has resulted in severe negative effects on the environment, human health, and non-target organisms. Therefore, it is crucial to explore alternative methods, such as biological control with microbials, to manage cauliflower pests sustainably. The study aimed to assess the effectiveness of different microbial agents for controlling Pieris brassicae and Plutella xylostella on cauliflower over two rabi seasons of 2020–2021 and 2021–2022. The microbial agents evaluated were Beauveria bassiana 1.0% WP at 1.50 and 1.75 kg/acre, Bacillus thuringiensis var kurstaki 0.5% WP at 600 g and 800 g/acre, Metarhizium anisopliae 1.0% WP at 1.50 and 1.75 kg/acre, and Spinosad 2.5 SC at 240 ml/acre. The results showed that B. thuringiensis var kurstaki 0.5% WP (800 and 600 g/acre) was the most effective treatment against P. brassicae and P. xylostella on cauliflower, followed by B. bassiana 1.0% WP (1.75 g/acre). These two treatments significantly reduced the population of the target pests on cauliflower crops compared to untreated control. Additionally, treatments with B. bassiana and M. anisopliae recorded the highest populations of natural enemies, including coccinellid beetles, spiders, syrphids, and Cotesia glomerate cocoon on cauliflower. Regarding yield, spinosad 2.5 SC was found to be at par with B. thuringiensis var kurstaki 0.5% WP (800 and 600 g/acre) during rabi seasons of 2020–2021 and 2021–2022. The study suggests that B. thuringiensis var kurstaki 0.5% WP (800 and 600 g/acre) can be a suitable alternative to chemical pesticides, against P. brassicae and P. xylostella on cauliflower.