Recent locust swarms, especially the 2019-2020 East Africa outbreak, caused severe crop destruction across multiple countries. Traditional pesticide use harms the environment and food security. New research offers eco-friendly methods targeting locust swarming behaviour through pheromone manipulation.
Locust Swarming and Its Impact
Locusts shift from solitary to gregarious phases, forming large swarms that devastate crops quickly. These swarms can travel over 150 km daily and consume vast amounts of vegetation. The 2019-2020 outbreak was the worst in 25 years, triggered by favourable weather conditions. Controlling these swarms is critical for food security worldwide.
Pheromones and Gregarious Behaviour
Locusts release a chemical called 4-vinylanisole (4VA) after feeding. This pheromone attracts other locusts, causing aggregation and swarming. The process involves rubbing hind legs, which triggers serotonin release, reinforcing group behaviour. About this chemical signalling is key to disrupting swarms.
Biochemical Pathway of 4VA Production
Phenylalanine in plants triggers enzymes 4VPMT1 and 4VPMT2 in locusts to convert a precursor (4VP) into 4VA. Genetic deactivation of the 4VPMT1 gene stops this conversion, preventing swarming. This discovery identifies enzymes as targets for controlling locust behaviour.
Small Molecule Inhibitors to Block Swarming
Researchers found 4-nitrophenol (4NP) can bind to 4VPMT enzymes, blocking 4VA synthesis. This prevents locusts from aggregating. Although effective, 4NP is toxic and environmentally persistent, limiting its direct use. The study suggests further search for safer inhibitors.
Alternative Eco-Friendly Approaches
RNA interference (RNAi) technology could silence 4VPMT genes, stopping enzyme production without toxic chemicals. Combining small molecule inhibitors with biopesticides and genetically modified locusts may offer sustainable control. Strategies include attracting locusts with synthetic pheromones to traps and monitoring populations via pheromone signatures.
Challenges and Future Directions
Current pesticide use remains widespread despite environmental harm. Safer, scalable methods need development and testing. The complexity of locust biology requires multi-pronged approaches integrating molecular biology, ecology, and pest management. International cooperation is essential to manage cross-border infestations.
Historical and Societal Context
Locust control has ancient roots, from noise and smoke to chemical insecticides. Modern science now targets behaviour at the molecular level. Effective control protects millions dependent on agriculture in vulnerable regions. Sustainable solutions align with global environmental and food security goals.
Questions for UPSC:
- Critically discuss the environmental and socio-economic impacts of locust swarms on agrarian communities in South Asia and Africa.
- Examine the role of pheromones in insect behaviour. How can this knowledge be applied to develop eco-friendly pest control methods?
- Analyse the potential benefits and risks of using RNA interference (RNAi) technology in pest management. Point out the challenges in its field application.
- Estimate the impact of climate change on the frequency and intensity of locust outbreaks. How should international policies adapt to address these challenges?
