The encyclopedia of insects and their diversity discusses the variety of insects at all levels, from genetic variants of the same classification to an array of species, genres, families and higher classification standards; it also mentions various ecosystems and physical conditions that insects rely on for their survival. Insect population refers to all insects that belong to the same species and reside in the same geographic area. A community meanwhile is the collection of several insect species living in a particular geographic area. This encyclopedia introduces insects as the biological foundation for all terrestrial ecologies. They circulate nutrients, pollinate plants, scatter seeds, preserve soil structure and fertility, manage populations of other living things, and provide the main food source for other organisms. Most insect pests in agriculture largely are non-native species, typically without their natural biotic control agents, and they have been introduced into new ecosystems. The encyclopedia remarks that insects have developed unique characteristics in the animal kingdom, which benefit specialists in biomechanics and bioengineering who use their adaptations to create modern inventions. Ever since humans began to cultivate the soil, insects have been complementing their labor by helping in pollination and other such biological processes. The encyclopedia emphasizes that the ecological and economic significance of insects in natural pollination of agricultural crops can't be underestimated, since it enhances their overall quality and quantity.