Factors affecting the presence of Typhlodromusspp. (Acarina: Phytoseiidae) in the calyx cavities of apple fruits and implications for integrated pest management
Predatory mites of the family Phytoseiidae include several species of importance as biological control agents of phytophagous mites in various crops including apples. We report on the post-harvest presence of the motiles of two species, Typhlodromus occidentalis and Typhlodromus pyri, in the calyx cavities of apple fruits of three cultivars. The mean numbers of motiles per fruit were as high as 6.10. The phytoseiid densities were lowest in cv. Bonza and tended to be greater in samples taken in late autumn, particularly in cv. Red Delicious. No significant effect (p > 0.05) was observed for different insecticide treatments. Phytoseiids remained present within fruits of cv. Granny Smith left on the orchard floor in winter. Together with an observed reduction in the numbers of T. occidentalis in the early spring, this suggests that fruits constitute an overwintering refuge. The findings are discussed in relation to the implications for biological control, in particular the minimization of the removal of natural enemies from orchards.
Life History and Behavior of the Predatory Mite Typhlodromus occidentalis in Utah
Many phytoseiid mites are predators of orchard spider mites. Of the species in northern Utah, Typhlodromus occidentalis (Nesbitt) is most abundant in apple orchards. Several other phytoseiid mites are found on apple trees in Utah, the most frequently encountered are Amblyseius fallacis (Garman) and T. mcgregori Chant. T. occidentalis was studied, using Tetranychus urticae Koch as prey. Adult females were found during the winter and early spring under the matted cover crop and tree bark. Laboratory and field observations suggested that there were at least 10 generations a season. The stages of development were egg, larva, protonymph, deutonymph, and adult; with partial quiescence between instars. The male of Typhlodromus occidentalis passed through a distinct deutonymph stage, as did the female. The average developmental time from egg to adult was 6.3 days at 75°F. The females mated once; the males several times. When ample numbers of tetranychid mites were present, they fed only as predators. In the absence of prey, the phytoseiids occasionally fed on pollen and apple foliage. Immature forms could not complete their development without spider mites as food. Adults would not lay eggs without feeding on mites, although they could survive for several weeks. They did not become cannibalistic, even when starved.
Comparison between Two Chemicals for Reducing Scale Formation in Reverse Osmosis Systems
In this present research was transacted with the calcium carbonate scale inhibition on the membrane surface of the reverse osmosis desalination system. Influence of changing feed solution flow rate (10-25)l/h, pH of the feed solution (6-10) on the recovery ,penetrate flow rate and total dissolved solid in (RO) system by using solution of calcium carbonate as feed solution was investigated, furthermore the effect of adding two types of scale inhibitor ,zinc chloride and polyamino polyether methylene phosphonate with difference concentration (2-8)mg/l for zinc chloride and (8-15) mg/l for polyamino polyether methylene phosphonate was calculated. The results showed that the permeate rate increases as the feed flow rate augmentation ,while it reducing with time, the total dissolved solids decreases as the feed flow rate increases while it increases with time and recovery rate decreases as the feed flow rate increases and it also decreases with time. It was concluded that the permeate rate decreases as the feed solution pH value increases and it cause high scale forming thus decrease the permeate TDS.By adding the scale inhibitor, it was found that the permeate rate and recovery rates increases as the concentration of inhibitor increases while the total dissolved solids decreases in the permeate with increasing the concentration of both inhibitors .It was discovered that Polyamino polyether methylene phosphonate more sturdy than zinc chloride as scale inhibitor for reverse osmosis desalination system in all concentrations was studied in this article.