No description available.

Vita. / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1979 C54 / Master of Science

No description available.

Les maladies transmises par les moustiques représentent une menace permanente en santé publique. La principale mesure pour protéger les populations contre les piqûres infectieuses repose actuellement sur l’utilisation d’insecticides, mais celle-ci est menacée par la propagation des mécanismes de résistance au sein des populations de moustiques. Dans ce contexte, les répulsifs représentent un outil de choix pour réduire à la fois les nuisances provoquées par les moustiques et le risque d’infection. Parmi eux, le DEET (N, N-diéthyl-3-méthylbenzamide) a prouvé une efficacité remarquable aussi bien lors d’expérimentations en laboratoire que sur le terrain. Malgré cela, les répulsifs ont toujours été utilisés de manière empirique, et leur mode d’action reste très mal connu. Le but de ce projet de thèse a été : i) de participer à l’évaluation du potentiel d’intégration du répulsif DEET dans la lutte antivectorielle, ii) de mesurer l’impact de paramètres physiologiques du moustique d’intérêt épidémiologique tels que l’expérience, l’âge et l’infection sur l’efficacité des méthodes de lutte, répulsifs et insecticides pyréthrinoïdes et iii) de quantifier l’impact des répulsifs et insecticides sur les traits d’histoire de vie des moustiques. Les expériences ont été réalisées sur Anopheles gambiae et Aedes albopictus, respectivement vecteurs de l’agent du paludisme et d’arbovirus tels que le virus de la dengue. Nos résultats ont permis de démontrer que l’état physiologique du moustique influe sur l’efficacité des méthodes de lutte ; premièrement, les moustiques porteurs de la mutation kdr ayant obtenu un repas de sang en contact avec de la perméthrine ne sont plus irrités par ce composé lors d’une seconde exposition, dans les conditions testées et à une dose recommandée pour l’imprégnation de moustiquaires. Au contraire, un repas de sang obtenu en présence DEET n’a pas affecté l’efficacité de ce composé à inhiber un repas de sang à l’exposition suivante. Ensuite, le DEET s’est montré plus efficace chez les moustiques âgés que chez les moustiques jeunes, et les résultats sont similaires chez les deux espèces et indépendants du statut de résistance aux insecticides. D’autre part, l’efficacité de la deltaméthrine et du DEET ne sont pas modifiés lorsque les moustiques sont infectés par le parasite Plasmodium falciparum. Cependant, une augmentation de la mortalité a été observée chez les femelles anophèles infectées au stade sporozoites lors de certaines expérimentations, indépendamment du traitement chimique de la moustiquaire, et suggère un coût de l’infection « réplicat-dépendant ». Enfin, le DEET génère un impact au long terme sur la fécondité et la fertilité des moustiques, effets qui ne sont pas observés dans notre protocole pour la perméthrine. Ces résultats donnent donc des pistes pour redéfinir les priorités dans les programmes de lutte, afin de cibler en premier lieu les moustiques les plus à même de transmettre des pathogènes. Ils soulignent également la nécessité de considérer à la fois l’état physiologique du moustique et l’impact sur le long terme des insecticides et répulsifs lors de l’évaluation des outils de lutte. / Mosquito-borne diseases are a permanent public health threat. The main way to protect populations against infectious bites relies on the use of insecticides, but their efficacy is threatened by the spread of resistance mechanisms among vector populations. In this context, repellents are a promising tool for reducing both mosquito nuisance and infection risk. Among them, DEET (N, N-diéthyl-3-méthylbenzamide) has proven great efficacy both in laboratory and field experiments. Despite this, repellents, are still used from an empirical way and their mode of action remains poorly understood. The aim of the present project was to: i) participate to the evaluation of the potential of integration of the DEET repellent in mosquito control, ii) measure the impact of mosquito physiological parameters of epidemiological relevance such as experience, age and infection, on the efficacy of repellents and insecticides, and iii) quantify the impact of repellents and insecticides on mosquito life-history traits. Experiments were performed on Anopheles gambiae and Aedes albopictus, vectors of the malaria parasite and of arboviruses such as dengue, respectively. Our results allowed to demonstrate that mosquito physiological state influences the efficacy of control tools; first, after successfully obtaining a blood meal in contact with permethrin, mosquitoes carrying kdr mutation are no longer inhibited by this compound at the subsequent exposure, at the recommended dose for net impregnation and under our experimental design. On the contrary, a first blood meal obtained in presence of DEET does not affect its efficacy at the following exposure. Then, DEET appeared to be more efficient against old mosquitoes that against younger ones, and results are consistent in the two species, independently of the insecticide resistance status. Besides, efficacy of DEET and deltamethrin is not modified when mosquitoes are infected with Plasmodium falciparum. However, an increased mortality was observed in anopheles when infected with transmissible stages (i.e. sporozoites), independently of chemical exposure, which suggest a cost of infection and seems to be “replicate-dependent”. Finally, DEET produces a long-term impact on mosquito fecundity and fertility, which is not observed with permethrin under our protocol. These results give insights to redefine the priorities in mosquito control programs, in order to specifically targeting mosquitoes that are the most susceptible to transmit pathogens. These observations also underline the need for considering both mosquito physiological state and the long-term impact of repellents and insecticides during the evaluation of control tools.

This work begins with chemotaxis studies involving Salmonella typhimurium. Known chemical attractants (ribose, aspartic acid, etc.) and repellents (nickel chloride, sodium acetate, etc.) were tested to direct bacteria swimming patterns. It was found that high concentrations of both attractant and repellent, approximately 10% chemical in deionized (DI) water, yielded better separation results than lower concentrations, such as 1% and .1% chemical in DI water. Utilizing these attractants or repellents appropriately can allow live bacteria to be directed in a desired manner in a microfluidic device, while dead bacteria, which yield no response, can be separated into a waste reservoir. Another important aspect of bacteria separation is preconcentration, or the process of concentrating bacteria in a usable amount of liquid for further analysis in a microfluidic device. This study introduces a method of capturing Salmonella typhimurium through the use of magnetic nanoparticles (MNPs) without functionalizing them with antibody or amine coatings. Based on the work by Deng et al., MNPs were prepared in various ways to alter their diameter and surface characteristics to achieve optimal bacteria capture efficiency. A capture efficiency of approximately 94% has been achieved by altering chemical quantities in the MNP fabrication process. A macro-scale flow cell prototype was designed and characterized in order to ‘clean’ large volumes of buffer and separate the bacteria-MNP aggregates through the use of a magnetic field. Finally, intervention of bacteria is a significant topic in food safety applications. This study utilizes Fe (III) to inhibit bacteria growth. This chemical was used in the presence of Salmonella, E. coli, Staphylococcus, and Pseudomonas. Further experiments were conducted with raw chicken and lettuce contaminated with Salmonella typhimurium. Using as little as .005M Fe III in DI water, up to 5 orders of magnitude reduction in bacteria growth was seen on test plates as compared to control plates.

Orientador: Carlos Fernando Salgueirosa de Andrade / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-05T10:07:55Z (GMT). No. of bitstreams: 1 Cabrini_Isaias_M.pdf: 1094913 bytes, checksum: 29b708cf734298b93b1507f9c318b1ed (MD5) Previous issue date: 2005 / Resumo: Já é bem conhecida há várias décadas a transmissão de diversas doenças para o homem e outros animais, por fêmeas de mosquitos (Diptera: Culicidae). Devido a isso, inúmeros estudos laboratoriais, utilizando sistemas fechados, têm sido realizados para se conhecer melhor o comportamento dos mosquitos. Esses sistemas consistem em olfatômetros, túneis de vento, câmaras-teste, entre outros, e podem ser utilizados para avaliar, por exemplo, produtos para a proteção pessoal, como os repelentes e telas de proteção, obtendo-se dados sobre a eficácia em impedir que as fêmeas de mosquitos consigam picar um hospedeiro. O presente trabalho teve como objetivo desenvolver inicialmente um sistema de câmara-teste, a partir de um sistema já descrito em literatura científica, para estudos com mosquitos Aedes spp. O sistema foi feito em isopor, sendo composto de uma caixa grande conectada a um tubo, que por sua vez foi dividido em duas seções. Ao todo, o sistema ficou então constituído por três seções. Na parte distal do tubo foram liberadas fêmeas de Aedes aegypti ou Ae. albopictus que eram atraídas para os estímulos de uma mão humana e uma fonte de luz, disposta na caixa, na outra extremidade. Primeiro foi avaliado nessa câmara-teste a repetitividade do padrão de comportamento de atração, verificando-se que proporção dos mosquitos seria atraída para a outra extremidade. / Abstract: The transmission of some diseases to humans and others animals by mosquitoes (Diptera: Culicidae) is knew. Due to this fact many studies have been done in the laboratory in order to better understand the mosquito behavior. Examples of some studies are those with olfactometers, wind tunnels and test-chambers, among others. Such approaches can also be in order to evaluate products for personal protection such as repellents and bednets, gathering data on their efficacy in avoiding female bites. The aim of the present work was to develop a test-chamber based on a system already described to study Aedes spp. mosquitoes. The system was constructed with polystyrene, consisting of a cage connected to a tube, which was divided in three sections. At the distal end of the tube Aedes aegypti or Ae. albopictus females were released, to be attracted to the stimulus of a human hand and a light source placed at the box in the opposite side. This system was developed in order to assess the host behavior testing a attraction of the stimulus for females, evidenced by their attraction to the other end of the tube. The developed test-chamber proved to be feasible to be use, since 94% Ae. albopictus and 95% of Ae. aegypti females were attracted to the section where the attractive were placed. Sonic frequencies devices, the so-called electronic repellents for insects, spiders and rats have been sold for many years. / Mestrado / Mestre em Parasitologia

The small hive beetle (Aethina tumida) is an invasive pest from sub-Saharan Africa that has posed increasing threats to European honey bee (Apis mellifera) colonies in the United States over the past two decades. While control has been attempted, consistently effective management strategies still not been developed. This study sought to explore novel experimental methods to better understand and use A. tumida biology to target this pest. One aspect of A. tumida biology that has emerged as potential basis for improved control is olfactory manipulation, which could be used to disrupt beetles as they seek out A. mellifera colonies. Through olfactometry and electroantennography, key volatiles in A. tumida attraction and repulsion were tested and sensitivity of A. tumida to several attractants and repellents was quantified on behavioral and physiological levels. An additional source of attractive volatiles is the A. tumida fungal symbiont Kodamaea ohmeri, which ferments larval waste and is present throughout the A. tumida lifecycle, both externally and in the GI tract. This study explored the development of feeding and soil bioassays to test the effects of several insecticides on A. tumida larvae. Feeding and injection bioassays were also used to deliver a fungicide with the goal of repressing K. ohmeri, which was expected to detrimentally impact A. tumida health. The results of this work enhance our current knowledge or A. tumida biology and provide a useful basis for development of safe and selective management A. tumida management options for the future. / Doctor of Philosophy / The small hive beetle is an invasive European honey bee pest that poses a significant threat to apiaries in the United States. These beetles feed on hive products and brood, pollute the hive with fermenting waste, and, in severe infestations, cause colonies to abandon their hives. This project investigated previously unexplored control options that take small hive beetle biology into account. Small hive beetles have an exceptional sense of smell compared to other beetles, and this ability helps them to locate honey bee hives. Therefore, behavioral responses to attractants and repellants were tested through olfactometry, in which beetles were given a choice to travel toward or away from specific odors or odor blends. Responses to these odors on a physiological level were also quantified through electrical recordings of beetle antennae. Small hive beetles are also known to have a yeast-like symbiont, which is present throughout the small hive beetle lifecycle, both externally and internally. Feeding bioassasy for small hive beetle larvae, along with soil bioassays for the delivery of insecticides were also developed and used to test several compounds against small hive beetle larvae. Feeding bioassays were also used to deliver a fungicide to larval and adult beetles with the goal of repressing internal fungal activity The results of these studies help expand the knowledge of small hive beetle olfaction and provide a background for the development of novel control options to effectively manage this destructive pest.

Thesis (M.Sc. (Plant Production)) -- University of Limpopo, 2014 / In most cases the discipline plant protection is restricted to the protection of propagules, the plants and their produce in storage, while excluding the protection of processed (cooked) food from contaminants. Generally, the German cockroach (Blattella germanica L.) is a serious contaminant of processed food and had recently been viewed as a pest worthy of control in plant protection when viewing the entire value chain of agricultural commodities. Due to the nature of the pest, it is quite difficult to control using registered agrochemicals on the market. An entrepreneur in the rural areas of Limpopo Province developed bait for cockroach control, which was code named Mohlolo during efficacy trials. The use of baiting in cockroach management is currently the sought after approach in the world where cockroaches are problematic. Bait has the advantage over liquid or dust formulations because baiting requires shorter service, has shown increased efficacy, and has reduced environmental contamination. The objectives of this study were to determine whether the effect of MIB would be age related in the suppression of populations of B. germanica under laboratory conditions, and also to investigate whether MIB would reduce populations of B. germanica in residential areas. Five concurrent B. germanica age-related experiments were run in a complete randomized design. 1-d, 2-d, 3-d, 4-d, 5-d old nymphs and adult German cockroach experiments were conducted at Limpopo Agro-Food Technology Station (LATS) laboratory, (53’21,41” S/29 23o 44’19,95”E) hosted at the University of Limpopo. Each age group consisted of 10 nymphs and was put in 250 cm3 container that contained xv Mohlolo insecticide bait (MIB). One gram (1 g) of Mohlolo insecticide bait and moistened cotton wick were put at the bottom centre of the 250 cm3 containers containing nymphs based according to their respective ages. Residential experiments were conducted at UL student apartments. Two Bait containers were then placed in the kitchen, lodge, bathroom and bedroom. In the kitchen MIB containers were put behind the cooking stove and refrigerator, in the lodge the bait was placed next to the study table (because most study tables are also used during the eating time). In the bathroom the baits were put next to toilet seat and lastly in the bedroom, the bait was placed next to study table. According to the results, 100% mortality of 1-, 2-, 3-, 4-, 5-days nymphs and adult B. germanica was obtained after 7th, 2nd 3rd 3rd and 4th day, whereas LT50 values ranged from half a day to one and half (1.5) day. The study also demonstrated that B. germanica populations had high LT50 and LT100 values in residential areas compared to LT50 and LT100 values obtained in the laboratory experiments. This is probably due to the fact that residential areas that have low levels of sanitation availed the cockroaches with an opportunity to choose from many foods hence, it reduced the probability for cockroaches to feed on Mohlolo insecticide bait in the respective apartments. Results of this study showed that, Mohlolo bait toxicity and effectiveness as a control agent can reduce infestation of cockroaches in all developmental stages when applied at small quantity. Providing results of this study would provide information on resistance and tolerance of B. germanica nymphs and adult population against MIB in the xvi laboratory and residential areas. It would also provide biological information on the efficacy of MIB against the German cockroaches.

Graduation date: 1996