Chapter 2.1 Phytoseiidae

Abstract

This chapter focuses on the predator–prey relationship between phytoseiid and eriophyoid mites and, in particular, compares this relationship to other phytophagous mites, such as tetranychids. It also discusses the consequences of these relationships on the population dynamics of eriophyoid mites. When freely moving over the leaf surface, eriphyoids are extremely vulnerable to the predatory mites belonging to the Phytoseiidae. The main reason for their vulnerability is that they are much smaller and slower than the phytoseiids. In addition, eriophyoid mites are limited in their mobility as they are worm-like, have a large surface of body-substrate contact, and have only two pairs of quite short forelegs. Outrunning the agile phytoseiid mites is, therefore, a sheer impossibility. Despite their vulnerability, eriophyoid mites apparently survive readily under natural conditons. There are a number of hypotheses that are not mutually exclusive in explaining why eriophyoid mites are not eliminated by predatory mites: (1) eriophyoid mites may be nutritionally deficient, toxic, and unpalatible for predatory mites, or (2) they are not profitable relative to other prey, or (3) they may defend or escape in space by long-distance dispersal, or (4) they may hide themselves in refuges. The chapter examines these hypotheses based on the published work on the interactions between phytoseiid mites and eriophyoid mites.