ABSTRACT
This chapter demonstrates the great variety of host plant effects on insects, specifically spider mites and their natural enemies. It considers the effects of plant chemistry, plant morphology, and endophytic microorganisms. Fertilization of host plants can strongly influence growth rates, and reproduction rates, of insects in culture. Some insects are attracted to their host plants by allelochemicals that are elucidated by the plants. One of the most important aspects of host plant relations in oligophagous or monophagous insects is their coincidence in the course of the year. The effect of light intensity on leaf morphology is a common phenomenon and must be considered while choosing the climatic conditions under which the host plants are grown, especially in breeding programs concerning plant resistance to pests. Fungi occurring occasionally in host plants may alter the biology of the insects which thrive on them.
