Studies on searching capacity of the larvae of three predators of the citrus red mite

Abstract does not appear. First page follows.

The citrus red mite, Paratetranychus citri (McGregor), probably native to China, was originally recorded from orange in Florida in 1885. It now occurs in all states in which citrus is grown, with the possible exception of Arizona. There are no known parasites of this pest, but it is attacked by a number of predaceous insects and mites. A comprehensive account of the life histories and habits of the citrus red mite and its natural enemies in California has been given by (Quayle (1912)).4

Three predators of the citrus red mite commonly found in California are the red mite destroyer, Stetborus picipes Casey; the green lacewing, Chrysopa californica Coquillett; and the dusty wing, Conwentzia hageni Banks. The laboratory studies reported here were undertaken to gain a better understanding of various interesting factors which determine the searching capacity of the larval stages of these predaceous species.

Procedure

Experiments were carried on in a basement room at the University of California Citrus Experiment Station, Riverside. This room was maintained at a constant temperature of 80° ± 2° F, and at a relative humidity of 50 ± 2 per cent. Illumination was entirely artificial.

The Experimental Universes

The prey and each species of predator were tested separately in four types of experimental universe: Type-I, characterized by conditions of uniform light and topography; Type-II, varied light and uniform topography; Type-III, uniform light and varied topography; and Type-IV, varied light and topography. The predators were then tested in each environment with prey present in its preferred locations, and again with the prey present in its least-preferred locations.