At present a locust plague is destroying huge swathes of crops as they swarm across East Africa, but what are they, where did they come from, and why are they so destructive? There are around 7000 species of grasshoppers, and of these roughly 20 species are capable of transforming into ‘locusts’ capable of swarming.
While normally dull brown, with small muscles and ‘solitarious’, when given the right conditions these grasshoppers transform into what is called a ‘gregarious’ phenotype. This transformation results in a change of colour to bright yellow and black, and development of larger muscles to aid migration as the insects start to swarm together. It is thought the change is initiated by heavy rains that cause the grasshoppers to lay vast numbers of eggs, and when they hatch, they become more gregarious and have to migrate to search for new sources of food.
Once they begin migrating, they may travel 90 miles in a day, an enormous distance. Their new body phenotype of bigger muscles helps with this migration, but these bigger bodies need to be fueled, and the locusts actively search out carbohydrates. It is this physiological need for food rich in carbohydrates that causes the swarm to decimate the grain crops people rely on for sustenance. Their ability to so quickly adapt to changes in their environment, increase the population size with each generation and ability to travel huge distances in search for food that makes them such a formidable pest. Hopefully the population can be brought under control swiftly.
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