Floral resources as ecological tools to enhance natural enemies for pest management in rice ecosystem

Conservation biological control in rice ecosystems can be promoted through habitat management by providing natural enemies with various resources, such as nectar, pollen, physical refugia, alternative prey and hosts. Laboratory and field studies were conducted to identify the most attractive flowering plants to natural enemies in paddy fields and to evaluate their efficacy in pest management. Olfactometric studies revealed that flowers of marigold, cowpea and sesame attracted major predators in paddy fields, such as Micraspis discolor, Ophionea nigrofasciata and Cyrtorhinus lividipennis and parasitoids Trichogramma chilonis and T. japonicum. Habitat management with flowering plants, around the paddy bunds, significantly increased the abundance and diversity of key natural enemies, followed by a reduction in pest population. A higher population of natural enemies viz., coccinellids, ground beetles, rove beetles, mirid bugs, damselflies and spiders were recorded in plot with flowering plants. This plot recorded the highest yield of 529.73 g m-2, while the lowest was in the control plot, with a yield of 263.46 g m-2. The cost-benefit ratio of paddy cultivation showed the highest benefit-cost ratio (BCR) in the plot with flowering plants (2.16), followed by conventional (1.96) and farmers' practice (1.83). The lowest BC ratio of 0.95 was recorded in the control. The study highlighted the role of flowering plants in enhancing the natural enemy population in paddy fields and the augmentation of biocontrol services.