Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 169-186).

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Three criteria, development, flight, and oviposition, were used to compare a laboratory-adapted and wild-type colony of Trichoolusia ni. The laboratory-adapted colony was further examined to determine the effect of larval crowding and starvation on the above criteria. The laboratory-adapted colony displayed a shorter development time and higher immature mortality than the wild-type colony. Differences in flight activity between and within the colonies were observed. Wild-type mated females were the most active group of tested moths. The oviposition rate of the laboratory-adapted colony was higher than the wild-type colony. Innate differences in parent populations and selective pressures during the rearing of the laboratory-adapted colony may explain differences between the colonies. Larval crowding resulted in prolonged development time, lower pupal weight, increased larval mortality, and increased adult longevity. Starvation during the larval stage produced similar changes. Flight activity declined with the degree of larval crowding and starvation. Larval crowding and starvation also resulted in a decline in adult fecundity and mating frequency. It is postulated that stress to the larvae resulted in a decline in energy sources to be used in the adult stage, producing docile adults. / M.S.

Possible effects of steady low strength magnetic fields on insects were studied using the cabbage looper moth, Trichoplusia ni (Hubner). In the first tests, adult loopers were used to determine their locational preference in response to areas of stronger or weaker magnetic field ranging from slightly above the geomagnetic field strength to a strength of 120 gauss. In a second series of tests, looper eggs were continuously exposed to steady magnetic fields of various strengths ranging from 10 to 1850 gauss. In a third series of tests t individual adult loopers were exposed to a steady 500 gauss field for five minutes. Oxygen consumption was monitored to indicate the level of moth activity before, during, and after this exposure. Results of the tests conducted revealed no effect of low magnetic fields on moth locational preference, egg hatchability, or activity level. / Master of Science

The roles of ocelli and octopamine in regulating the onset, intensity, and duration of cabbage looper moth flight activity were examined. This was achieved by studying the flight activity of control, sham, and anocellate moths with and without octopamine treatment. Sham and anocellate moths were produced by cauterization in last-instar larvae, of ocellar primordial cells for anocellate moths, and of non-involved cells for sham moths. Flight activity of moths was monitored by a computerized actograph under normal light (LD) conditions, under advanced-sunset, and under constant dark (DD) conditions to determine the effect of ocelli on flight activity. The role of octopamine was investigated by treating the three groups of moths topically with octopamine dissolved in dimethyl sulfoxide (DMSO) and with DMSO alone, and comparing flight activity before and after treatment. Results support a combined role for ocelli and the compound eyes in determining flight initiation times, and a role for ocelli in determining flight intensity. These roles were more pronounced in males than in females. It was found that the cauterization operation itself decreases flight activity in sham moths. No evidence was found that supports the existence of an octopamine effect on flight activity in any of the groups of moths when octopamine is topically applied. / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.93-105).

The structure of the cabbage looper ocellus was examined by light and electron microscopy. Rhabdoms were found in the distal region of the retinula cells. These were formed by the apposition of microvillar borders of adjacent cells, thus, an interrupted network of rhabdoms was found to exist in cross section. No convergence of first order neurons to second order neurons was found anywhere above the protocerebrum as is typical of insect photoreceptors in general. No synapses were found to exist anywhere above the brain. It is hypothesized that the cabbage looper ocellus plays a major role in determining the light intensity at which crepuscular flight is initiated. This hypothesis was tested in the following manner. Laboratory reared moths were divided into five groups each with a different or no treatment. These were: 1. Compound eyes and ocelli occluded. 2. Compound eyes occluded. 3. Ocelli occluded. 4. Controls. 5. Controls sham treated. All groups were placed in transparent flight chambers and submitted to a simulated sunset. Test results were compared using the Duncan Multi-Range Test and Standard errors. The results indicate that the cabbage looper ocellus plays a role in determining the light intensity at which crepuscular flight is initiated. / Master of Science

Effects of electrostatic fields on insects were studied using cabbage loopers, Trichoplusia ni (Hubner) and houseflies, Musca domestica L. Two series of tests were conducted; one to determine the electrostatic field effect on the locational preference and the other to determine the field effect on wingbeat. Among the field gradients examined (250, 500, 750, 1000, 1250, 1500 v/crn), those with 750 v/cm and up had significant influence on the locational preference of houseflies at the five percent significance level. With a choice between two regions, having no field and with field at an e.f.i. of 750 v/cm, houseflies preferred to be in the field. For gradients above 750 v/cm the houseflies preferred the region with no field. Electrostatic fields with gradients 500, 750, 1000, 1250, and 1500 v/cm had significant effect on the wingbeat frequency of male cabbage loopers and no effect on females. The change in wingbeat among males was found to increase linearly with increasing e.f.i. Removal of part or full antenna did not effect the response of loopers to electrostatic fields. / Master of Science

Respondents of the 1986 Broccoli Growers Survey grew an average of 6.2 acres of broccoli in Fall 1986; popular varieties were Green Valiant (87.5% of respondents), Packman and Emperor (62.5%). Less than 5% of tobacco land was converted to broccoli production by 62.5% of the growers. Before heading, 2.4 insecticidal sprays were applied for worms at $20.51/acre. During heading, 2.4 insecticidal sprays were applied for worms at $19.40/acre. Under normal growing conditions, a nine-day mean of 8.4 and a 15-day mean of 12.1 cabbage looper larvae/plant did not significantly reduce yield in the Spring and Fall respectively. However, means of 7.4 and 11.1 cabbage looper larvae/plant reduced yield (head weight) under drought conditions. Harvest date was not affected by the above cabbage looper levels. In Fall 1986, a reduction in yield occurred when plants had 50% or more defoliation and harvest date was significantly delayed at 100% defoliation. In the drought stressed Spring 1987 planting, a stimulation in yield occurred at 25% defoliation and 75% defoliation was needed to significantly reduce yield, but there was no difference in harvest date. The imported cabbageworm was the most abundant pest of broccoli in Montgomery Co., VA. Based on counts of all immature stages of the insects for three seasons, Packman and Southern Comet varieties were less preferred compared to Green Defender. Laboratory studies indicated that imported cabbageworm larvae developed faster to the fifth instar on Packman broccoli than those reared on Green Defender, Southern Comet or Emperor. Difference in amount consumed between varieties was not detected. Pupae reared on Southern Comet weighed significantly more than those reared on Packman. / M.S.