What is considered one of the five causes of insect outbreaks?

The overuse of the same insecticide leading to resistance is a recognized cause of insect outbreaks. When specific insecticides are applied repeatedly, certain insect populations may develop resistance to the chemical properties of the pesticide. This means that the insects that survive the treatments are those with genetic traits that protect them from the effects of the insecticide. As a result, these resistant insects can reproduce and pass on their resistance traits to their offspring, leading to a population that can thrive despite the use of the insecticide. This resistance can ultimately result in greater insect populations, as pest control becomes less effective and the initial populations can grow unchecked.

In contrast, an unusually cold autumn and winter typically reduces insect populations by killing off unable insects and eggs, while a boom in insect-eating birds can likewise decrease pest populations by providing natural control. The introduction of resistant plant varieties may limit the effectiveness of certain pests but does not inherently contribute to an outbreak on its own; rather, it represents a strategy to manage pest populations.