Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 51-60).

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 80-84).

Studies of the life history and habits of Diabrotica longicornis (Say), a new pest of corn in Quebec, were undertaken in the field and in the laboratory. Seasonal activity and habits were established by monitoring life stages in the field during the years 1979, 1980 and 1981. The threshold temperature for development of NCR eggs was estimated at 9.7(DEGREES)C. The mean thermal constant for first hatching in the laboratory was 326 degree days above 9.7(DEGREES)C. Eclosion occurred in the field when average soil temperature conditions at the 5 - 10 cm depth reached 331 - 334 degree days. / Pupation occurred in the soil from late June to early July. Adults emerged from mid-July to August, and oviposition occurred during the same period. Oviposition preferences of NCR beetles were studied in relation to local soil types, soil moisture, and soil surface conditions, both in the laboratory and in the field under free choice conditions. In both cases, a clear preference was shown for moist, cracked, clay soil. / The behaviour of adults held under controlled environmental conditions (12L:12D diel light cycle, 23 (+OR-) 2(DEGREES)C temperature, 60 - 80 per cent RH) was investigated, and emergence, locomotor activity and sexual behaviour were recorded. The duration of larval stages reared in the laboratory on natural diets were compared with those for field-collected larvae. Natural enemies and mortality factors for the species were investigated in the field. A simple method for rearing NCR in the laboratory was developed.

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Horizontal distribution of Diabrotica longicornis (Say) eggs around plants was random in three Quebec cornfields. Vertically, 72% and 24% eggs occurred in the surface 10 cm soil before and after fall plowing, respectively. A 5 x 10 cm x 15 cm (deep) sampling unit was appropriate for estimating egg populations before plowing. Thereafter, 20 cm depth was needed. Larvae and pupae were concentrated around the root system and a soil quadrat 20 x 20 cm x 10 cm (deep) was an easily reproducible sampling unit. Direct counting on corn plants in early morning was the most efficient method for adult sampling. Sample sizes for all stages were calculated for different precision levels. Spatial distribution of eggs and larval field populations were contagious, and a stratified random sampling is appropriate for density estimation. Spatial distribution of adults changed with corn phenology. Average mortality of overwintering eggs was 66% and of spring larvae 89%. The field population density of beetles did not change significantly during 1979-82.

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