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Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 38-39.

The efficiency of the carabid beetle, Bembidion lampros (Herbst) as a predator of the eggs of Hylemya brassicae (Bouché) and the effects of the insecticides Dipel, methomyl and chlorfenvinphos on the beetle were studied by introducing some B. lampros into experimental plots of Brussels sprouts and restricting their movements by surrounding the plots with polythene barriers. More eggs were laid in the first than in the second generation of the cabbage root fly. There was progressive decrease in the number of root fly eggs and the number of B. lampros as the plants matured. During the first generation the untreated control had significantly more eggs than the other treatments. Egg predation by B. lampros resulted in a 45% reduction. In plots containing B. lampros and treated with methomyl, Dipel or chlorfenvinphos, the numbers of eggs were reduced by 35, 44 and 66% respectively. Laboratory toxicity studies showed that methomyl at 1 g/ litre produced 100% mortality of B. lampros one day after treatment. When the rate was reduced to 1/2, 1/4 and 1/8, the mortality of B. lampros dropped to 70, 40 and 20% respectively. Dipel [Bacillus thurinqiensis Berliner (16000 IU/mg)] at 1 g/litre and 5 g/litre and chlorfenvinphos at 10 ppm and 40 ppm; produced no mortality three days after treatment. Foliar application of methomyl for aphid control in the field significantly reduced the B. lampros population. There was no significant effect on B. lampros when Dipel was applied as a foliar spray to control lepidopterous larvae. Chlorfenvinphos granules applied once early in the season as a subsurface treatment prevented damage by cabbage maggot and was not toxic to B. lampros. Cabbage maggot damage was not severe enough to cause significant reduction in yield at harvest but examination of roots showed that untreated plots had significantly more maggot damage than other treatments. The damage index ranged from 2.5 for untreated plants to 0.0 in plants from plots treated with chlorfenvinphos and containing B. lampros. Although differences were not significant, the numbers of overwintering root fly puparia were highest in untreated plots. Significantly more empty puparia, indicating second generation fly emergence, were also found in the untreated plots. Besides B. lampros, other carabids removed from the experimental plots included: Harpalus affinis Schr., Amara spp., Calathus fuscipes Goeze, Pterostichus melanarius 111. and other Bembidion spp., in decreasing order of abundance. B. lampros alone does not give complete protection against root maggot, especially if fly oviposition is very heavy during the first generation when the beetle is most effective. But the beetle will go a long way to suppress part of the population. The use of non-selective insecticides for control of pests of Brassica may lead to reduction of B. lampros populations and a consequent increase in cabbage maggot attack. / Land and Food Systems, Faculty of / Graduate

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Speciation is the process by which life diversifies into discrete forms, and understanding its underlying mechanisms remains a primary focus for biologists. Increasingly, empirical studies are helping explain the role of ecology in generating biodiversity. Adaptive radiations are often propelled by selective fitness tradeoffs experienced by individuals that invade new habitats, resulting in reproductive isolation from ancestral conspecifics and potentially cladogenesis. Host specialist insects are among the most speciose organisms known and serve as highly useful models for studying adaptive radiations. We are just beginning to understand the pace and degree with which these insects diversify. The apple maggot, Rhagoletis pomonella, is a well-studied insect whose eastern and southern populations are models for ecological speciation. Recently (40–65 ya), the fly has invaded the Pacific Northwestern United States through human-transported apples infested with larvae. There, populations of R. pomonella have rapidly colonized two novel hawthorn hosts whose fruiting times bracket apple’s (early-season native Crataegus douglasii and introduced C. monogyna, which fruits late in the season). The recent introduction might initiate host shifts, providing opportunities to examine the pace and mechanistic means with which host races (an evolutionary stage preceding speciation) become established. Here, I demonstrate that host-associated populations at a site in southwest Washington are partially allochronically isolated from one another, and life cycles temporally match with natal host fruit ripening times in sympatry. If spatially widespread, these temporal barriers could result in reproductive isolation and possibly cladogenesis. Implications of these findings reach beyond academic import, as R. pomonella is expanding not only its host range, but its geographic range is encroaching upon central Washington, the site of a multi-billion dollar per year apple-growing industry.

There is very low tolerance for blueberry maggot (Rhagoletis mendax Curran) in blueberries making it a serious pest in eastern North America. Control is focused on eliminating flies with insecticides before oviposition in fruit. Organic mulches may improve highbush blueberry production, but their effects on this pest are largely unknown. The research in this thesis evaluated compost and pine needle mulches on blueberry maggot (mature maggots, pupae, emerging flies) and predatory beetles that may consume these stages. Mulches affected fly emergence and maggot pupation. Fly emergence was reduced by 80-100% and delayed ~8 days from pupae covered with 20 cm of pine needles compared to 1 cm of soil. Emergence from 20 cm of compost was lower in wet conditions, and 5 cm of mulch did not limit emergence in the field. Pupation at increased depth reduced emergence because flies did not eclose or, if eclosed, were unable to crawl to the surface. The delay was likely due to lower temperatures at depth. No flies emerged from 1 cm in pine needles in the field probably due to high temperatures. In the laboratory, maggots pupated more deeply in pine needles than other substrates, but ~30% did not pupate in dry pine needles. Saturated soil caused ~50% of maggots to pupate on the surface. Mulching altered beetle diversity and activity/density and affected beetle predation on maggots and pupae. Compost plots in a highbush blueberry field attracted predatory carabids and staphylinids, although some staphylinids were frequent in pine needles and phytophagous carabids preferred unweeded compost plots. Attraction to compost, particularly for Pterostichus melanarius (Illiger), was due primarily to higher prey densities - earthworms and millipedes - than other treatments. This beetle consumed some maggots or pupae in soil or compost, but predation rates decreased when alternative prey was abundant. Blueberry bushes in weedy compost plots attracted many flies, but infestation rates were higher in composted bushes only in the year mulch was applied. Overall, thick mulching with pine needles contributes most significantly to blueberry maggot management. Future research should explore integration of mulch with other tactics for R. mendax control.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Abstracted in Dissertation abstracts, v. 17 (1957) no. 11, p. 2359-2360. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-72).