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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

OVIPOSITIONAL BEHAVIOR OF THE 12-SPOTTED LADY BEETLE, <i>COLEOMEGILLA MACULATA</i>: CHOICES AMONG PLANT SPECIES AND POTENTIAL FACTORS INFLUENCING THOSE CHOICES

Griffin, Marisa Lynn 01 January 2000 (has links)
Coleomegilla maculata is a beneficial coccinellid commonly found in sweet cornfields in Kentucky. Previous work on C. maculata has shown an ovipositional preferencefor the weed Acalypha ostryaefolia, compared to three selected weed species and corn. Also, predation of C. maculata egg clusters on A. ostryaefolia was less compared toclusters on corn and the presence of A. ostryaefolia led to higher densities of C. maculata larvae on corn. I determined C. maculata ovipositional preference among weed species in fieldtests using nine common weeds. I also examined ovipositional preference using just A.ostryaefolia and Abutilon theophrasti. I assessed the roles of potential prey densities,plant structures, and weed attractiveness to adult C. maculata. Finally, I examineddiurnal and nocturnal predation of C. maculata eggs on corn, A. ostryaefolia, A.theophrasti, and Amaranthus hybridus. Significant ovipositional preference was always observed for A. theophrasti. C. maculata egg clusters on A. theophrasti and A.ostryaefolia were preyed upon less frequently than clusters on A. hybridus and corn.
2

Patterns of reproductive allocation in aphidophagous lady beetles and their response to various levels of resource availability

Vargas Orozco, German Andres January 1900 (has links)
Doctor of Philosophy / Department of Entomology / J.P. Michaud / James R. Nechols / The manner in which organisms allocate reproductive resources for reproduction is a central question with respect to life history theory. The main objectives of this research were to i) examine lifetime patterns of reproductive allocation in the lady beetles Coleomegilla maculata (DeGeer) and Hippodamia convergens (Guérin-Menéville) (Coleoptera: Coccinellidae) while manipulating environmental conditions that affect female body size (i.e., larval food supply), ii) to study the interaction between factors underlying female body size and the resources available during reproduction, and iii) to explore the maternal effects of female size and age on the development and survival of progeny. When different size classes of females were produced and adult females were maintained with unlimited food, there were no differences in egg size across female size in C. maculata, but egg size increased over time in all females. In H. convergens, only larger females increased egg size over time, and they laid larger eggs, on average, than did small females. Maternal body size was positively correlated with the number of eggs laid per day in both species. When three size classes of females were subjected to a fluctuating food supply as adults, female size was again positively correlated with egg and daily fecundity. Whereas both species varied daily fecundity in response to adult food supply, egg size was unaffected and demonstrated a fixed pattern of change with female age and species-specific effects of maternal body size. To observe maternal effects in H. convergens, three female size classes were again produced and progeny were reared from three different periods of each female‟s reproductive life. Offspring from later oviposition days and larger females developed faster and achieved larger adult size than those reared from earlier oviposition days. Egg size showed inconsistent correlations with developmental parameters and adult progeny size, so other, more cryptic, maternal signals were inferred to signal phenotype development in progeny. A fixed program of producing faster-developing offspring that mature to larger sizes late in the oviposition cycle is adaptive for exploiting ephemeral aphid blooms that exhibit predictable dynamics of declining prey abundance and increasing competition. In the case of H. convergens, resource limitation during development constrained not only body size, fecundity and egg size, but also maternal ability to manipulate progeny phenotypes.

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