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The Population Dynamics and Sampling Plan of the Corn Borer Ostrinia furncalis (Guenee) (Pyralidae: Lepidoptera).
Dissertation Abstract:
The life cycle, population dynamics and sampling plan of the corn borer were investigated in this study.
The insect was found to have five instars instead of six as previously reported. Insects were reared on corn plants on the field had longer life cycles with corresponding bigger size of individuals and higher fecundity than those reared in artificial diet, bush sitao and cornstalk in the laboratory. The second, third, and fourth leaves were significantly preferred for oviposition by the moths. The biology of the first generation corresponded with the vegetative growth and whorl stage of the corn plant and and the biology of the second generation, with the pollen shedding of the tassel and ear formation.
Distribution of the egg masses of the corn borer was found to fit the Poisson series at 15 to 27 and 39 to 48 days after planting. Underdispersion and overdispersion of the eggmasses were observed at 30 to 33 and 36 days after planting, respectively. Larval distribution was found to fit the negative binomial series, meaning that the sistribution was contagious and the population was randomly clumped or aggregated.
Change in the age distribution of the corn borer become evident as the corn plant approached maturity. Increasing, stable, and decreasing populations were observed over time. There were remarkable changes in population density with changes in growth of the corn plant. Natality rates were higher than mortality rates. Parasites, predators, the host plant and climatic variables exerted regulatory and disturbing effects on population density. The integration of such changes in the population of O. furnacalis within its natural system is necessary to understand its role as a key pest of corn.
A sampling plan, which allows sampling with the least variation ad cost foe live eggs and larvae of O. furnacalis, was developed an optimum sufficient when sampling for eggs and larvae, respectively. The number of plants per sampling for a 10% standard error of the mean density was 1408 and 420 for the eggs and larvae, respectively.