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INFLUENCE OF CORN PLANT DENSITY ON POPULATION ESTIMATES AND POPULATION DYNAMICS OF THE WESTERN (DIABROTICA VIRGIFERA VIRGIFERA, LECONTE) AND NORTHERN (D. LONGICORNIS BARBERI, SMITH AND LAWRENCE) CORN ROOTWORM (COLEOPTERA: CHRYSOMELIDAE) (NEBRASKA)
Abstract
The influence of corn plant population, time of day, and growth stage on several factors of adult western (WCR) (Diabrotica virgifera virgifera, Leconte) and northern (NCR) (D. longicornis barberi, Smith and Lawrence) corn rootworms was studied in eastern Nebraska during 1981 and 1982. Plant population did not influence sex ratio, species composition, or oviposition. The beetle counting methods (whole plant and ear zone) estimated different WCR beetle densities (sig. p = 0.05) across plant populations in 2 of 4 growth stages. There were no significant differences in NCR counts across plant population. The beetle counts for both species were significantly (p = 0.05) correlated (WCR, r = 0.70 - 0.77; NCR, r = 0.45 - 0.52) with the actual beetle population. However, there were higher correlations (WCR, r = 0.78 - 0.86; NCR, r = 0.56 - 0.57) between beetle counts and actual beetle populations, if the counts were corrected for plant population. Day degrees required to complete the pre-oviposition period in the field were similar both years. Across all plant growth stages, ear zone and whole plant WCR beetle (both sexes) and female counts, if corrected for plant population, were significantly (p = 0.05) correlated (r > 0.87) with final egg populations. The corrected NCR ear zone beetle and female counts, but not whole plant counts, were also significantly (p = 0.05) correlated (r > 0.75) with final egg numbers. Analysis within growth stages indicated that the corrected WCR ear zone and whole plant counts in the milk stage were also significantly (p = 0.05) correlated (r > 0.79) with final egg populations. The NCR counts, corrected for plant population, taken in both the silk and milk stage were significantly (p = 0.05) correlated (r > 0.80) with final egg numbers. A WCR oviposition model developed from the data was accurate in predicting egg populations in the field. Approximately 14% more eggs were predicted by the model.
Subject Area
Entomology
Recommended Citation
WEISS, MICHAEL JOHN, "INFLUENCE OF CORN PLANT DENSITY ON POPULATION ESTIMATES AND POPULATION DYNAMICS OF THE WESTERN (DIABROTICA VIRGIFERA VIRGIFERA, LECONTE) AND NORTHERN (D. LONGICORNIS BARBERI, SMITH AND LAWRENCE) CORN ROOTWORM (COLEOPTERA: CHRYSOMELIDAE) (NEBRASKA)" (1983). ETD collection for University of Nebraska-Lincoln. AAI8314914.
https://digitalcommons.unl.edu/dissertations/AAI8314914