Nayereh Hamedi

By Samira Khodayari and Nayereh Hamedi

Spider mites (family Tetranychidae) are important pests of many agricultural, medicinal and ornamental plants worldwide. They possess needle-like chelicerae which pierce plant cells, often feeding on chloroplasts on the under surface of the leaf and cause upper leaf surfaces develop whitish or yellowish stippling. Additionally spider mites produce silk webbing which covers the leaves. In this chapter we present common control methods of these mites including biological control with emphasizing on the prey preference, switching behavior and mutual interference of a biological control agent, Phytoseius plumifer (Canestrini and Fanzago). Additionally the side effects of two acaricides, abamectin and fenpyroxymate, on this predator will be discussed.

Part of the book: Insecticides

By Nayereh Hamedi

Simply estimating pesticide effects on natural enemies of pests by measuring only lethal effects, or sublethal effects on the only treated natural enemies, may underestimate the total negative effects on them. So sublethal effects on subsequent generations should be assessed to estimate the total effects of their applications. Sublethal effects of commonly used acaricides on population growth parameters, life table parameters, and predation of the predatory mites of the family phytoseiidae were investigated. For this reason, offspring of treated females were used. Gross reproductive rate (GRR), the intrinsic rate of birth (b), the intrinsic rate of death (d), mean generation time (T), survivorship (Lx), life expectancy (ex), and prey consumption were affected in comparison with control. It could be concluded that sublethal concentrations of most applied pesticides can significantly reduce population growth and life table parameters, and this should be considered in integrated pest management (IPM) programs.

Part of the book: Pesticides