Biology ofAmblyseius citrifolius(Denmark and Muma) (Acarina—Phytoseiidae)

Abstract

Descriptions of the morphological changes within each stage, of the molting and hatching processes and of the quiescent states of Amblyseius citrifolius (Denmark &; Muma) were given. The larva emerged, posterior first, from the narrow end of the egg. Hatching took ca. 8 min. The duration of the ecdysis (ca. 20 to 30 min) was approximately the same for all the stages. Quiescent states were characterized by the extended, apposed palpi, by the protruded gnathosoma, by the pale, shiny coloration of the body and by a typical response to a contact stimulus. Duration of the quiescent state ranged from ca. 9.7 to 11.3 hours. Continuous observations of behavior indicated that more than 80 percent of the time in the postembryonic stages was spent resting. Number of prey (eggs and larvae) consumed by each individual in the larval, protonymphal, and deutonymphal stages were 6.3, 17.2, and 12.0, respectively. Protonymphs averaged 3.2 minutes feeding on each prey; deutonymphs, 4.7 minutes; and larvae, 8.0 minutes. At a given temperature, different relative humidities did not seem to affect the duration of the egg stage. The eclosion rates of A. citrifolius were shown in relation to saturation deficit at 16, 20, 24, 28, and 32° C. Development from egg to adult was completed in 19.7, 7.7, 5.0, and 3.6 days at 15, 20, 25, and 30 °C, respectively. Egg, larval, protonymphal and deutonymphal stages required 27.3, 10.7, 14.1, and 15.8 degree days, respectively, to be completed. Preoviposition, oviposition, and postoviposition periods and longevity were observed at 15, 20, 25, and 30 °C. Fecundity averaged 31.3, 40.9, 49.7, and 41.3 eggs per female at 15, 20, 25, and 30 °C, respectively. Average daily egg production at 15, 20, 25, and 30 °C was .75, 1.25, 2.11, and 2.51 eggs, respectively, per female. Pollens of Pyrus kawakamii, Malephora crocea (Jacq.), and avocado, a combination of Tetranychus pacificus McGregor (eggs + larvae) plus M. crocea pollen, and T. pacificus (all stages) were the best food for oviposition and survival of A. citrifolius. Tetranychus pacificus (eggs + larvae) also was one of the best for survivorship of the predator.