From introduction: In South Africa the native ladybird beetle Exochomus flaviventris Mader feeds on the introduced cochineal insect Dactylopius opuntiae (Cockerell) (Pettey, 1943, 1946, 1948; Geyer, 1947 a, b; Pettey and Marais, 1950). It has also been reported to feed on Dactylopius austrinus Lindley (Geyer, 1947 a; Pettey, 1948), but this appears to occur rarely in the field (H.G. Zimmermann and H.G. Robertson pers. camm. ; Appendix 1 ). This thesis attempts to determine why E. flaviventris feeds on D. opuntiae in the field but not on D. austrinus.

Call number: LD2668 .T4 1966 H169 / Master of Science

No description available.

No description available.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1991. / Includes bibliographical references (leaves 199-203). / Microfiche. / xi, 203 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

Thesis (M.S.)--Virginia Polytechnic Institute and State University. / Vita. Abstract. Includes bibliographical references (leaves 66-72). Also available via the Internet.

The colour vision of adult citrus psylla, Trioza erytreae, was investigated in the laboratory using the behavioural parameters: alightment and walking. Light green flushing leaves (under which the nymphs develop) were significantly preferred, visually, to dark green mature leaves for alightment. Diffuse reflectance spectroscopy showed (when expressed in the parameters of human colour vision) that flush has a very slightly longer dominant wavelength, and roughly double the reflectance and purity. Alightrnent frequency correlated almost equally well with "purity" (as noted by Moericke, 1952 et seq., in "yellow-sensitive" aphids) as with the aphidological colour parameter "long/short ratio" developed by Kennedy et al. (1961). Elucidation of the mechanism underlying the citrus psylla's alightment colour preference was initially attempted with a printed spectrum and several paint series of measured spectral characteristics. It was clear that T.erytreae belongs to the "yellow-sensitive" group of Homoptera, but it was impossible to distinguish which pararneter(s) of colour the psyllids were responding to. Phototactic (walking) response to the individual parameters of colour was therefore measured using a monochromator. The phototactic action spectrum (against wavelength) was tri-modal, with peaks in the yellow-green (YG), blue (B), and ultra= violet (UV). Rate of phototaxis was not influenced by bandwidth (roughly equivalent to purity), but was proportional to intensity (roughly equivalent to reflectance). To investigate the influence of the above three wavelength regions on alightment, use was made of a very simple flight chamber incorporating a target of coloured light. Yellow-green and UV light both independently stimulated alightment . Their effect was additive. Different thresholds indicated distinct YG and UV receptor systems. Blue light alone did not stimulate alightment, and was strongly alightment-inhibitory in combination both with YG and with UV light. On the basis of the above physiological/behavioural findings, a new alightment formula was drawn up for describing the hamopteran's apparent manner of alightment determining integration of surface reflectance. The flush preference and alightment distributions on the series of artificial surfaces were found to correlate slightly more accurately, on average, as well as more consistently, with the new formula than with previously-available colour parameters. These findings are placed in perspective to the literature, and their possible economic relevance is discussed.

The scurfy scales in the genus Chionaspis comprise a unique taxon among the armored scale insect genera in North America. The taxonomic reviews of the species belonging to the genus by Cooley (1899) and Ferris (1937, 1942) are far outdated. The present research is a comprehensive review of all the species in this genus in North America, with special emphasis on polymorphism associated with feeding sites which has been discovered in some species. Seventeen species have been redescribed and illustrated in detail, each with a discussion of their morphological affinities and relationships. Their host habits and zoogeography are summarized. The five species having typical bark and leaf forms, as well as intermediate forms, are discussed in more detail. A separate chapter deals with polymorphism, including a historical literature review of the subject. A hypothesis is given on the modes of transfer from the bark form to the leaf form and vice versa, that results in different morphs in first or second generations. Two keys were prepared: one for the genera related to Chionaspis and another for the determination of the species of this genus in North America. The three species that have been recently redescribed, C. americana and C. kosztarabi and C. nyssae are also discussed, and the most important morphological characters and the plates prepared by the original authors for each of these three species are given in order to better utilize the key to the species in North America. As a direct result of this research, two new species have been discovered: Chionaspis gilli Liu and Kosztarab, and C. hamoni Liu and Kosztarab. In addition new morphs were found for C. platani and C. wistariae. This thesis also includes many new distribution and host records for several species. The phylogenetic relationship of all the species in this study has been discussed, and as a result of the Ward's Minimum Variance Cluster Analysis (1985 version, SAS), a dendrogram has been provided based on 23 numerical characters. / Master of Science

Three distinct plant viruses, transmitted by the tobacco whitefly Bemisia tabaci Genn., were associated with diseased food or fiber crops grown in the southwestern deserts of Arizona. The cotton leaf crumple virus (CLCV), thought to affect only cotton Gossypium (L.) spp., is now known to infect other malvaceous plants and members of the Convolvulaceae and Leguminosae. Results of an experimental host range study suggest that potential virus-vector reservoirs may exist in cotton growing regions which include both weeds and cultivated plants. Geminivirus-like (GVL) particles of ∼18 x 30 nm were isolated for the first time from CLCV-infected bean, Phaseolus vulgaris (L.), 'Red Kidney', a plant which was a better purification host than cotton. Studies of CLCV-vector relationships indicated that the acquisition- and inoculation-access times, latent period and length of retention by whitefly vectors were similar to those of the original isolate reported in California in 1954. When growth chamber temperatures of 26, 32, and 37C were used in virus-vector studies, optimal acquisition and transmission occurred at 32C while temperatures of 37C were lethal to whitefly adults. Two additional virus-like agents were isolated from single and mixed infections of lettuce or melons, respectively. The virus-like agent from lettuce infected primarily members of the Chenopodiaceae, Compositae and Cucurbitaceae, and was whitefly but not mechanically transmissible. Long flexuous closterovirus-like rods of ∼10 x 1400-2000 nm were visualized in extracts prepared from plants inoculated with the lettuce isolate. The isolate was similar to the lettuce infectious yellow virus (LIYV) based upon host range, transmission characteristics and unique particle morphology. Both long flexuous rods like those associated with the lettuce isolate and GVL particles of 18 x 30 nm were associated with diseased melons. The host range of the GVL agent was confined to the Cucurbitaceae and Leguminosae and the agent was separated from the mixed infection by mechanical transmission to a non-LIYV host. The GVL-agent was distinct from previously described cucurbit viruses including the squash leaf curl virus, based upon host range and transmission characteristics and was tentatively designated as the watermelon curly mottle virus (WCMV).