EFFECT OF WIND-BORNE POLLENS ON THE POPULATION-DYNAMICS OF AMBLYSEIUS-HIBISCI [ACARINA, PHYTOSEIIDAE]

Populations of Amblyseius hibisci (Chant), an important predator of citrus red mite, Panonychus citri (McGregor) exhibited varying responses to field applications of cat-tail, Typha latifolia L., pollen in San Joaquin Valley citrus groves. Predator densities increased to significantly higher levels after pollen treatments during the fall months, and to a limited extent after late winter treatments, but not after early spring treatments. The amount of response appeared to be inversely related to the levels of natural foods present during the various seasons. Results of the wind-borne pollen monitoring studies indicated that population growth in A. hibisci was correlated with the seasonal pattern of pollen fallout. Population growth was slowest in years when pollen catches were low during the late winter and early spring, and fastest in years when peak pollen catches occurred in late winter or early spring. Population growth in A. hibisci did not appear to be markedly responsive to P. citri populations although suppression of prey densities was indicated in ca. 50% of the cases. In laboratory tests, A. hibisci reproduced through 3 generations on 11 of 23 pollens tested. © 1979 Le François.