Q15TYU SYNTHESIZE YOUR KNOWLEDGE Locust... [FREE SOLUTION]

Chapter 53: Q15TYU (page 1188)

SYNTHESIZE YOUR KNOWLEDGE Locusts (grasshoppers in the family Acrididae) undergo cyclic population outbreaks, leading to massive swarms such as this one in the Canary Islands, off the west coast of Africa. Of the mechanisms of density-dependent regulation shown in Figure 53.18, choose the two that you think most apply to locust swarms, and explain why.

Short Answer

Expert verified

During recurrent population explosions, locusts (Acrididae grasshoppers) produce huge swarms because of disease (since transmission rates increase as the density of prey increases) and predation (since predators feed more as prey density increases).

Step by step solution

Locust

Locusts are a group of short-horned grasshoppers in the Acrididae family that go through a swarming phase.These insects are generally solitary, but when they get more numerous, they change their behavior and habits, becoming gregarious.

Competition for resources

Population density increases competition for resources, which lowers reproduction rates. For example, farmers use fertilizers to alleviate nutritional restrictions on crop productivity to decrease resource rivalry for wheat (Triticum aestivum) and other crops.

Swarming locust

Locusts go through two distinct 'phases' of their life cycle. When food is available, they survive in solitary form. During this phase, they act like ordinary grasshoppers, with no tendency to form swarms.

Locusts may survive for several generations in solitude. However, when a disease's transmission rate rises as a population grow denser, the disease's impact is density-dependent.

In an environment (field) where there is enough prey, a predator (locust) will thrive. The prey population shrinks as the predator consumes more prey. The size of the prey population grows as predation diminishes.