Predation, oviposition and longevity of the predacious mite, Agistemus exsertus Gonzalez at different prey densities of Tetranychus urticae Koch (Acari: Stigmaeidae, Tetranychidae)

Abstract

The relation between some biological aspects of the predatory mite, Agistemus exsertus Gonzalez and nymph densities of Tetranychus urticae Koch was studied in the laboratory. Predation and oviposition of A. exsertus showed Holling's Type II functional and numerical responses to changes in prey density. The total predation by A. exsertus females initially averaged 79.42 nymphs/female at 2 prey nymphs/day, significantly increased to a maximum average of 208.92 nymphs/female at 10 nymphs/day and gradually decreased to 90.92 nymphs/female at 30 prey items/day. Similarly, the predator significantly deposited total averages of 14.75, 76.42 and 34.33 eggs/female at 2, 10 and 30 nymph densities/day, respectively. The preoviposition and oviposition periods as well as longevity of A. exsertus significantly shortened with increasing prey densities.

Keywords:

• Agistemus exsertus
• Tetranychus urticae
• predation
• oviposition
• longevity