Microalgal biopesticides in the circular economy: harnessing algae for sustainable pest management

Abstract

Environmental risks and diminishing long-term efficacy of synthetic pesticides have renewed attention toward sustainable pest control approaches. To overcome this problem, various chemical formulations and pesticides are widely used, but these practices have been harmful to human health and the environment. Therefore, the quest for safer alternatives has led to increased interest in microalgae as a potential source of biopesticides. Certain microalgal and cyanobacterial species produce bioactive metabolites that exhibit insecticidal, fungicidal, herbicidal, or nematicidal activities. The application of microalgae as biopesticides is also a significant factor in the circular economy, as they can recycle excess nutrients in the environment, thereby reducing the need for additional nutrient inputs. This review focuses on the biochemical pathways involved in the production of secondary metabolites in microalgae and the modes of action for few such metabolites thus produced, against different pests. In addition, it also focuses on formulation approaches, modes of action, their applications or usage around the globe, and relevance to sustainable and integrated pest management. Moreover, the dual application of microalgae for carbon sequestration and wastewater treatment is emphasized, along with their ability to enrich soil, which aligns with the objectives of closed-loop systems and circular agriculture. Despite the major advantages of microalgae, such as biodegradability, target specificity, and low toxicity, there are still some limitations and challenges, especially in large-scale productions and few challenges are discussed in detail.