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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.
861

Evolution of Parasitism in the Lycaenidae (Lepidoptera)

Kaliszewska, Zofia 04 December 2015 (has links)
Of the four most diverse insect orders, the Lepidoptera contain remarkably few predatory and/or parasitic taxa, and while species with carnivorous life histories have evolved independently numerous times in moths and butterflies, this has rarely led to diversification. As a rule, aphytophagous taxa seem prone to extinction. In this dissertation, I explore the ecological and evolutionary consequences of entomophagy in the butterfly family Lycaenidae using several approaches: natural history observation, phylogenetics, population genetics and stable isotope chemistry. A striking exception to the lack of radiation and persistence in aphytophagous lineages is the lycaenid subfamily Miletinae, which with 13 genera and 190 species is among the largest and most diverse groups of aphytophagous Lepidoptera. Most miletines eat Hemiptera, although some consume ant brood or are fed by trophallaxis from their host ant. I inferred the higher-level phylogeny of this group using data from one mitochondrial and six nuclear genes sampled from representatives of all genera and nearly half the described species. Biogeographic analyses indicate that Miletinae likely diverged from an African ancestor near the start of the Eocene, and four lineages dispersed between Africa and Asia. Phylogenetic constraint in prey selection is apparent at two levels: related miletine species are more likely to feed on related Hemiptera and are also more likely to associate with closely related ants species, either directly by eating the ants, or indirectly by eating hemipteran prey attended by those ants. I then examined the influence of diet on the population structure of lycaenid butterflies, and more specifically, I investigated whether particular feeding habits are correlated with traits that might make species vulnerable to extinction. To do this, I compared the phylogeography and population genetics of two endemic lycaenid species of roughly similar age from southern Africa: Chrysoritis chrysaor, whose caterpillars are strictly herbivorous, and Thestor protumnus, whose cuckoo-like caterpillars survive by soliciting regurgitations from their host ants. I sampled both species from populations throughout their entire known ranges, and found that in contrast to C. chrysaor, T. protumnus has exceedingly small effective population sizes and individuals disperse poorly. With its aphytophagous life history, T. protumnus exhibits a high degree of host dependence and specialization. Although these results are correlative and based on only a single comparison, it seems likely that small population sizes and extreme ecological specialization make populations of T. protumnus more susceptible to disturbance and prone to extinction. Having focused in detail on the population biology of just one species, I then analysed the evolution of Thestor as a whole. This genus is exceptional because all of its 27 described species are thought to be entomophagous, and all are thought to be predators or parasites of a single species of ant, Anoplolepis custodiens. Using representatives sampled from all known species and populations of Thestor as well as 15 outgroup species, I inferred the phylogeny of the genus in two ways: first by using characters from mitochondrial and nuclear genes, and second by analyzing genome-wide SNPs generated for each species using double digest RADseq. I also sequenced the ants associated with each of these taxa using ddRADseq. This investigtion showed that all 24 of the species in the Western Cape utilize Anoplolepis custodiens, while T. protumnusand T. dryburghi (the two species that are found in the north-western part of South Africa) use a closely related, but different species of Anoplolepis, and T. basutus (the species found in the eastern part of South Africa) utilizes yet a third species. Thus factors driving diversity in the genus Thestor may have initially involved ant associations and/or geographic isolation, but other forces are likely to be responsible for generating and maintaining the more recent diversity in the group. Flight time may have separated the “black” and “yellow” groups of Thestor: the black group fly predominantly in the summer months, while the yellow group fly predominantly in the spring. And while species spread across the genus fly in the spring and summer months, only members of the yellow group fly during the winter and fall months. Despite these broad scale differences, species in the genus Thestor show little evidence of niche partitioning, especially those in the Western Cape, and represent an extreme example of the coexistence of 24 species apparently utilizing a single food resource. While working on the previous three projects, I was surprised by the number of species of South African Lycaenidae with incomplete life histories despite decades of work by avid lepidopterists in the region. For example, in the genus Thestor, although all 27 species are assumed to be aphytophagous, partial life histories have been described for only four species. In part the paucity of data is due to the difficult terrain occupied by these butterflies, and the fact that those whose caterpillars associate with ants often spend significant portions of their lives hidden in ant nests in crevices of rock that are intractable for excavation and observation. To deepen our understanding of South African lycaenid life histories, I used nitrogen and carbon stable isotopic methods to survey a large number of species and their potential food sources. With these methods, I confirmed some known or suspected life histories and showed that in any one area, a species can have a highly variable diet. I also discovered that some of the nitrogen stable isotope values are much higher than expected for land animals, implying longer than average food chains and/or extreme environmental conditions. Together, these studies shed light on how carnivorous life histories affect the evolution of lycaenid butterflies, and help to explain why entomophagous lineages appear to be an evolutionary “dead end” in contrast to their herbivorous counterparts. / Biology, Organismic and Evolutionary
862

Follicle cell calmodulin: transcript accumulation in vitellogenic follicles of Blattella germanica is regulated by juvenile hormone

Iyengar, Anand R 01 January 1995 (has links)
Calmodulin (CaM) is a major intracellular calcium receptor. There is abundant calmodulin (CaM) in the oocytes and eggs of B. germanica during vitellogenesis and early embryogenesis. The accumulation of CaM in oocytes may be for immediate use in the oocytes and/or in preparation for later stages of their development. Previous investigation from this laboratory suggested that maternal follicle cells are the most likely source of this CaM. Tissue culture labeling with $\sp{35}$S methionine showed a 13-fold higher rate of synthesis of CaM in the follicle cells than in oocyte preparations (Zhang & Kunkel, 1994). The high rate of biosynthesis of CaM in the follicle cells, and the absence of extracellular CaM in transit in the hemolymph suggested that CaM is made in the follicle cells and transferred to the oocytes. In order to obtain more information about the site of CaM synthesis I isolated total RNA from different tissues that could potentially contribute to the high amounts of follicular CaM and measured the amounts of CaM transcripts during development. I show that isolated whole follicles accumulate more transcripts for CaM than the fat body. The steady state levels of CaM transcripts increases 150 fold during the 4 day developmental period under study. This is in addition to a 32 fold increase in total follicle RNA during the period. Steady state levels of CaM transcripts in whole follicles also show a pattern of increase disproportionate to the increase in volume of the whole follicle. In comparison steady state levels of actin transcripts increase 35 fold during the same developmental period. At 96 hr post feeding, in a given amount of total RNA, follicle cell total RNA contains 3 times more CaM transcripts than whole follicle total RNA, and 70 times more CaM transcripts than the fat body tissue. The oocyte total RNA collected from material expelled from the whole follicle contains less than 10% of the amount of CaM transcripts available in the follicle cells. The fat body tissue preparation shows little developmental increase in steady state levels of CaM transcripts despite a 4 fold increase in total RNA. In my investigation into the control of the accumulation of this transcript I found that deprivation of JH, by head ligation, not only causes atresia of the follicles, but also reduces CaM transcript accumulation. Reconstituting JH titer by injection allows a selected population of follicles to develop to full size and also reinstates steady state CaM transcript levels above that of unligated controls. The results of my study makes the CaM gene a potentially important target for the study of JH action in follicle cells during oogenesis.
863

The roles of midgut hormone and allatotropin in the adult black blow fly, Phormia regina Meigen (Diptera: Calliphoridae)

Tu, Meng-Ping 01 January 2000 (has links)
Nutrition greatly affects the reproductive success in many insects. Also, previous studies have shown this nutrition-reproduction connection is mediated via endocrine control. In Phormia regina, a proteinaceous meal is essential for egg maturation. Recent discovery of a midgut hormone, from liver-fed P. regina, established a link between feeding and endocrine function which leads to oogenesis. This midgut hormone is the first such insect gut hormone governing oogenesis. Whether or not this hormone is released into the hemolymph, however, is not determined. To demonstrate the existence of the midgut hormone in the hemolymph, hemolymph was partially purified and its oogenesis-stimulating effect tested. A gonadotropic effect was observed in the hemolymph extracts prepared from 5 and 6h post-liver-fed females. The midgut hormone appears to circulate in the hemolymph to reach its target, presumably the brain neurosecretory cells. Injection of partially purified midgut hormone caused a significant volume increase and changes in the distribution of stainable materials of the type-A brain median neurosecretory cells (MNCs). It is conceivable that these cellular changes reflect the synthesis/release of neurohormones by the type-A MNCs. Thus, results suggested that midgut hormone is hemolymph-borne and has a cerebrotropic function. The possible role of the brain after being stimulated by midgut hormone was investigated. In vitro studies showed that the brain releases, at 8h after a protein meal, a factor(s) with a strong allatotropic effect (i.e., causing the corpus allatum (CA) to produce 6.9 times more juvenile hormones (JHs) than the control CA). The characteristics of this allatotropic factor(s) were estimated with different experiments. First, Manduca sexta allatotropin (Mas-AT)-immunopositive substances were observed in the lateral neurosecretory cells (LNCs) and the neurosecretory cells located between the pars intercerebralis and oesophagus foramen. Second, synthetic Mas-AT stimulated JH biosynthesis by the fly's CA (2.64-fold activation when stimulated with 20 pmol per test). Third, when brain-released factor(s) was neutralized with anti-Mas-AT antiserum both in vivo and in vitro, the CA still synthesized a considerable quantity of JH. This result suggested that there may be additional non-Mas-AT allatotropic agent in P. regina.
864

Cuterebra (Diptera: Cuterebridae) of Utah and the Neighboring States

Graham, Charles L. 01 May 1962 (has links)
Cuterebra are robust flies, which in flight resemble large black bees. Little is known about the bionomics of most of the species included in this genus. Nearly all members of this group parasitize rodents and lagomorphs. Some species have a wide host range, others seem to be specific or semi-specific to a single host. Accidental parasitism of animals other than specific host animals does occur. In such cases the larvae or the host usually die before the larvae can mature. There is a wide variation in the effect of of the parasite on its host. If the parasite is found in a natural host, the ability of the host to tolerate the parasite is much greater. In chipmunks one to three parasites have no apparent effect but with four to nine parasites in one animal, there is a loss of weight and a decrease in activity. Occasionally death results from parasitism by Cuterebra. A valid key to the species of this genus does not exist. It is the purpose of this paper to establish a valid key for the described species of Cuterebra found in Utah and the neighboring states and to furnish descriptions of these species, which in conjunction with the key will aid the reader in identification of Cuterebra specimens. Whenever possible the host or hosts associated with each species will be listed. Within the genus Cuterebra there are several species complexes. As used here, complexes are supposedly intraspecific groups which have several major characteristics in common but differ on a few minor points. Only more detailed studies on the members of these complexes will indicate the extent of intraspecific variation and the delimitation of a true species.
865

The effect of simulated climate change on overwintering physiology in solitary bees and the impacts of floral and landscape resources on nesting

Varvaro, Megan Frances, Varvaro 12 December 2018 (has links)
No description available.
866

Some insect and vertebrates recovered from the coprolites of prehistoric Indians of Southwestern Tamaulipas, Mexico.

Marsh, David C. January 1965 (has links)
No description available.
867

Studies on the micro-arthropod fauna of two Quebec woodland humus forms.

Marshall, Valin G. January 1965 (has links)
No description available.
868

Biology and dynamics of the birch leaf miner, Fenusa Pusilla (Lepeletier) Hymenoptera: Tenthredinidae), on blue birch, Betula Caerulea Grandis Blanchard, in Quebec.

Cheng, Hsien-Hua. January 1965 (has links)
No description available.
869

Investigating the diversity and small mammal host ecology of Borrelia burgdorferi in Ohio

Bai, Ningzhu 06 September 2022 (has links)
No description available.
870

A taxonomic study of the adult mosquitoes of Utah county with notes on the biology and distribution of the more common species 1946-1947

Hopla, Cluff E. 01 May 1947 (has links)
In Utah County, information has been lacking concerning the taxonomy and distribution of mosquitoes. With the knowledge of this condition, it is felt that information can be presented which will be of value both to the scienoe of Entomology and the area concerned.

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