Population growth and factors affecting the seasonal abundance of Monellia caryella (Fitch) and Monelliopsis pecanis Bissell in central Texas /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Highest aphid densities in unmanaged populations of the yellow pecan aphid complex occurred in the middle of July in 1987, 1988, and 1989. Densities of about 120 adults/ per 10 leaves were the highest observed in the control area. Insecticide treated areas showed multipeaks. Population densities of adults were usually not different among the 4 cardinal directions of canopies, significantly greater number of adult M. caryella occurred in the lower level (1-3 m) as compared to the higher level (3-6 m) of the tree canopy. Adult aphid densities on 'Success' (100-200/10 leaves) were higher than on 'Stuart' (50-100/ 10 leaves). Mixed populations of adult M. caryella and M. pecanis coexisted well in sleeve cages and reached a fairly high density (100-200: 200-300/ 10 leaves, respectively), with M. caryella increasing in density early, followed by M. pecanis (25 vs. 90 days after inoculation). Reinoculation of 20 M. caryella and M. pecanis at the 1st, 15th, and 45th day after initial infestation declined to zero in a young Cherokee pecan orchard, and populations were not able to build up again. Five consecutive reinoculations of 20 M. caryella at the 65th day after the first inoculation and about 25 days after the initial population declined to zero in Adriance Orchard, resulted in populations eventually building up again. Cross virulence experiments indicated the M. caryella density on 'Success' foliage (233 adult aphid/ 10 leaves) was significantly greater than that on 'Stuart' (132 adult aphid/ 10 leaves). Observations in the field on individual aphids indicated that about 29 percent of adult M. caryella stayed on the same leaflet less than one day; 55 percent for up to 5 days, and the remainder stayed 6-13 days. About 50 percent of the nymphal M. caryella stayed on leaflets 2 days or less, and the remainder stayed 3-9 days. About 63 percent of adult M. pecanis stayed on the same leaflets less than one day, and most departing before 3 days had elaped. Spiders from 9 families, approximately 13 genera, 18 species, and 5 unidentified species, and insects representing 6 orders, 9 families and about 21 species were noted feeding on or parasitizing aphids. Spiders and lacewings were by far the most abundant aphid predators observed during these studies and provided sufficient numbers for additional analyses. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Entomology." |
| Physical Description: | xv, 181 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |