Entomology
Permanent URI for this communityhttp://hdl.handle.net/1903/11813
Browse
3 results
Search Results
Item INTEGRATED MANAGEMENT OF THE BOXWOOD LEAFMINER(1999) d'Eustachio, Gabriel John; Raupp, Michael J.; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Landscape managers need durable, effective, and safe methods for controlling key pests of valued plants in both landscape and nursery settings. The boxwood leafminer (Monarthropalpus flavus, Diptera: Cecidomyiidae) is a serious pest of boxwoods. Boxwoods (Buxus sp.) are a key plant in suburban Maryland landscapes. They are the second most common woody ornamental plant in these settings. In a recent study almost 43% of boxwoods surveyed required treatment for leafminer infestation. Boxwood leafminers also pose a serious problem in historical gardens, such as Longwood Gardens, PA, Dumbarton Oaks and the US National Arboretum in Washington, DC. At the present time, there is a lack of a comprehensive, environmentally sound, management program for the boxwood leafminer. The first step toward an effective management strategy is a better understanding of the boxwood leafminer's life cycle. Over the summers of 1994-1995, leafminer populations were surveyed and life cycles documented and correlated with growing degree days. The first growing degree day developmental chart for boxwood leafminer was developed. Various pesticides were tested in 1995. Different chemicals and application times were evaluated for control of both adults and larvae. At present it appears that application of a translaminar pesticide such as Avid or Merit at adult emergence (growing degree day 352) provides the best control. Resistant cultivars appear to be the most durable, simplest method to control the leafminer. Some cultivars.are highly resistant to boxwood leafminer attack while others are highly susceptible. The third goal of my project was to identify resistant cultivars. This was accomplished by first observing natural variation in leafminer populations in the field. Next I caged ovipositing adults on terminal branches of various cultivars of boxwood, and measured survival of larvae. All cultivars received heavy oviposition with equal frequency, although survival rates were very different. Finally, I tested the hypothesis that leafminers could discriminate among resistant and susceptible cultivars. To test this emerging adults were caged with different cultivars of boxwood and allowed to select plants for oviposition. Plants were then analyzed to determine acceptance of various host plants. I found that although survival on different cultivars can vary dramatically, leafminers were unable to distinguish between suitable and unsuitable host plants.Item Characterization of Female Specific Salivary Gland Glycoproteins of Anopheles Gambiae and their Interaction with Plasmodium Berghei Sporozoites(1999) Bartels-Andrews, Lucy; Sina, Barbara; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)This study investigated the female specific salivary gland glycoproteins of Anopheles gambiae mosquitoes and their possible role in malaria sporozoite invasion of the salivary glands. Male and female Anopheles gambiae salivary gland proteins were analyzed by western blot with various lectins to identify glycoproteins that are specific to the female salivary glands. At least, 14 female glycoproteins were detected by specific lectins in the female glands but not in the male glands and were designated as female specific. The different morphological regions of the female salivary glands showed distinct lectin binding characteristics with the distal lateral and the median regions displaying the most glycoproteins. The lectins that identified the most female specific glycoproteins were tested in a transplantation assay to determine their effect on Plasmodium berghei sporozoite invasion of the salivary glands. The transplantation procedure was similar to that reported by Rosenberg (1985) with some improvements which resulted in 90-95% mosquito survival after the transplant procedure. Up to 3% of the total sporozoites that invaded the salivary glands were found in the transplanted glands. The results of our analyses showed that the lectins soybean agglutinin (SBA) and wheat germ agglutinin (WGA) significantly reduced sporozoite invasion while the lectins Concanavalin agglutinin (Con A) and Dolichos biflorus agglutinin (DBA) had no effect on sporozoite invasion. The pattern of distribution of glycoconjugates on the female salivary glands showed that Con A bound uniformly and moderately to the whole gland while SBA and WGA bound intensely to the distal ends of the median and lateral lobes of the salivary glands. The binding pattern of SBA and WGA corresponds to the regions of the female glands where sporozoites enter the glands. These results suggest that malaria sporozoites interact with specific carbohydrate molecules on the salivary glands for invasion. To characterize salivary gland surface glycoproteins that may be involved in sporozoite invasion, salivary gland surface proteins were labeled by the biotinylation reagent sulfosuccinimidyl 6-biotinamido hexanoate, followed by lectin affinity chromatography. 7 of the labeled surface glycoproteins detected by sporozoite blocking lectins (SBA and WGA) had molecular weights corresponding to female specific glycoproteins. These female specific salivary gland surface glycoproteins are of potential interest in studying sporozoite interaction with salivary gland glycoconjugates. To determine that malaria sporozoites capable of invading mosquito salivary glands interact with carbohydrate molecules, hemagglutination and carbohydrate binding assays were conducted using sporozoites isolated from infected mosquito midguts. The results obtained suggest that interaction of sporozoites with mosquito salivary gland glycoconjugates may be mediated by sporozoite proteins other than the circumsporozoite protein, the major protein covering the surface of sporozoites.Item Biosystematics and the evolution of gall formation in hackberry psyllids Pachypsylla (Insecta: Homoptera: Psylloidea: Psyllidae)(1995) Yang, Man-Miao; Mitter, Charles; Miller, Douglass R.; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)This dissertation is a study of the phylogeny and evolutionary biology of gall formation in psyllids of the subfamily Spondyliaspidinae, with particular focus on North American hackberry gallers in the genus Pachypsylla. Species in this genus produce a variety of gall types on the leaves, petioles, buds and twigs of their hosts, four species of Celtis subgen. Euceltis (Ulmaceae). The homogeneity of adult morphology in Pachypsylla, contrasted to the great variation in gall morphology and phenology, has led to much difficulty in delimiting species. Chapter I investigates species limits as related to gall type and host specificity in Pachypsylla. Strong differences in allozymes, morphology and life history confirm that leaf, petiole, bud and twig gallers belong to different species or species groups. Different leaf gall morphs probably also represent different species, as evidenced by significant allozyme frequency differences among sympatric pairs of gall morphs, consistent frequency difference between co-occurring morphs across localities, and discrete differences in gall type between progenies of individual females. Differences in allozymes, female phenology, adult and nymphal coloration, as well as laboratory rearings and field manipulations, show that side cell individuals within two nipple gall types represent an inquiline sibling species (Chapter II). Chapter III is an analysis of phylogenetic relationships within Pachypsylla, based on allozyme, morphological, life history and chromosome characters. Galler populations attacking the same plant tissue form monophyletic groups. The leaf galler morphs are little diverged, and phylogenetic relationships among them are unclear. Populations of inquilines from two different gall types appear closely related; the inquiline appears to be derived from a gall-forming ancestor. Phylogenetic relationships among gallers on different plant parts are consistent with an evolutionary sequence of gall position from leaf to petiole to bud to twig. Chapter IV is a morphological study of phylogenetic relationships within Spondyliaspidinae. The tribe Pachypsyllini, including Pachypsylla and two related Celtis feeders, is monophyletic. The tree favors the hypothesis of Burckhardt over that of White and Hodkinson. The distribution of lerp and gall formation is shown to be non-random within Spondyliaspidinae.