| Phytoseiid mites were found in higher numbers on leaves within the canopy of grapefruit trees than on outer leaves. No differences in phytoseiid abundance were found among leaf samples collected at different hours throughout the day between 0600–2200 h. Mite abundance on grapefruit trees was compared among young-leaves, healthy-mature leaves, and mined-leaves by Phyllocnistis citrella Stainton. Predacious phytoseiids and stigmaeids and Eotetranychus sexmaculatus (Riley) were significantly more abundant on mined leaves than on young or healthy-mature leaves in weekly samples taken between February and April from an unsprayed orchard. Eutetranychus banksi (McGregor), and Phyllocoptruta oleivora (Ashmead) did not differ in abundance among the three types of leaves.; Development and reproduction of Iphiseiodes quadripilis (Banks) was evaluated on diets of Malephora crocea Jacquin and Quercus sp pollens and, E. banksi, Panonychus citri (McGregor), and P. oleivora at 28° ± 1°C, 14:10 (L:D) daylength and 45%-RH. Iphiseiodes quadripilis completed its life cycle and oviposited viable eggs on exclusive diets of M. crocea, Quercus sp. pollens or E. banksi or P. citri eggs and motiles. Panonychus citri stages were acceptable as prey to I. quadripilis but survival of larvae to adulthood was significantly lower than on Quercus sp. pollen. Iphiseiodes quadripilis larvae provided water, or P. oleivora alone, developed to protonymphs and then died. Starved I. quadripilis nymphs and adult females preyed on Aculops pelekassi (Keifer), but not on P. oleivora. Iphiseiodes quadripilis was significantly more abundant on grapefruit leaves than on orange leaves in adjacent citrus orchards at four sites in central Florida. This disparity was consistent whether samples were taken from border or interior trees. Total numbers of phytoseiids were not significantly different between citrus species in most cases. Eutetranychus banksi was significantly more abundant on orange than on grapefruit, suggesting that biological control by I. quadripilis was better on grapefruit trees. Iphiseiodes quadripilis preferred grapefruit leaves over orange leaves in olfactometer experiments and in contact choice tests using leaf discs of the two citrus species.; Cryptothelea gloverii (Packard) (Lepidoptera) was identified as a predator of both P. oleivora and P. citri, although it also feeds on fruit and leaves of citrus. In the laboratory, C. gloverii preferred to feed on oranges russeted by P. oleivora than on fruit without russeting. Feltiella sp. and a Lestodiplosis sp. two undescribed Cecidomyiidae were highly specialized predators feeding on P. oleivora eggs, nymphs, and adults. |
