• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 174
  • 49
  • 25
  • 13
  • 6
  • 5
  • 4
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 318
  • 310
  • 63
  • 53
  • 36
  • 29
  • 28
  • 28
  • 25
  • 25
  • 25
  • 24
  • 24
  • 23
  • 23
  • 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.
111

Minerais em méis de abelhas Apis mellífera L. produzidos na região do Pólo Cuesta, Estado de São Paulo

Ito, Erica Harue [UNESP] 24 February 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-24Bitstream added on 2014-06-13T19:18:52Z : No. of bitstreams: 1 ito_eh_me_botfmvz.pdf: 244276 bytes, checksum: 5dd109d2948cfebeebabb81a16a5238d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / Os objetivos do presente trabalho foram avaliar a presença dos minerais cálcio (Ca), cobre (Cu), enxofre (S), ferro (Fe), fósforo (P), magnésio (Mg), potássio (K) , sódio (Na) e zinco (Zn) em amostras de méis de eucalipto (Eucalyptus sp.), laranjeira (Citrus sinensis L. Osbeck) e silvestre de abelhas Apis mellifera L. da região do Pólo Cuesta, estado de São Paulo, Brasil. As análises dos minerais foram realizadas por espectrofotometria de absorção atômica e os resultados avaliados por meio da Análise de Variância (ANOVA), seguido pelo teste de Tukey-Kramer para comparação das médias (P<0,05). Houve diferenças para os minerais Ca, S, P, Mg, K e Na entre as diferentes origens botânicas. Pode-se concluir que os méis da região do Pólo Cuesta apresentam minerais essenciais ao organismo humano, sendo que o mel de eucalipto apresentou os maiores teores para a maioria dos minerais analisados / The aim of this study were to evaluate the presence of minerals calcium (Ca), copper (Cu), sulfur (S), iron (Fe), phosphorus (P) , magnesium (Mg), potassium (K), sodium (Na) and zinc (Zn) in eucalyptus (Eucalyptus sp.), orange (Citrus sinensis L. Osbeck) and wild honeys samples of Apis mellifera L. bees from Pólo Cuesta region, São Paulo state, Brazil. Analyses of minerals were carried out by atomic absorption spectrophotometry and the results evaluated by analysis of variance (ANOVA) followed by Tukey-Kramer test for comparison of means (P<0.05). There were differences for Ca, S, P, Mg, K and Na minerals between different botanical origins. It was concluded that the honey’s Pólo Cuesta region shows minerals essentials to human organism, and the eucalyptus honey had the majority minerals analysed
112

Bioindikace antropogenního zatížení prostředí chemickými polutanty (těžké kovy) s pomocí včel a jejich produktů (včelí med) / Bioindication of man effect on environmental pollution by chemical pollutants (heavy metals) with the use of bees and their products (bee honey)

KOS, Václav January 2008 (has links)
The main objective of my work was to evaluate if it is possible to use the honey bee - Apis mellifera as a bioindicator of the environmental contamination by heavy metals. Two areas were being compared. The first one was more affected by emission (The Capital city of Prague) and the second one was less hit by emission (The Highlands). During the course of three years five samples of bee honey were taken from each area. The analysis was made to show how much cadmium, lead and mercury the samples contained. In most samples higher concentration of these chemicals were dealt out in honey taken from the more polluted area. Although not all the concentrations of heavy metals in honey reflect the emission burden of the examined areas. It would be necessary to take samples from a larger number of areas in order to confirm the conclusion that bee honey is a suitable bioindicator of the environmental contamination by heavy metals.
113

Behavioural response of honeybees (Apis mellifera scutellata Lep.) to wild pollinators on sunflowers (Helianthus annuus L.)

Shenkute, Awraris Getachew 10 November 2010 (has links)
Pollination is an essential ecosystem service, increasing reproductive success of many crops, which can be provided by managed pollinators, wild bees (including honeybees) and other insect pollinators. However, the pollination services and the economic value of wild pollinators are often underestimated. Better understanding of the factors that influence honeybee foraging behaviour and pollination efficiency can contribute to the improvement of management practices that aim to enhance crop pollination and ecosystem services. The objectives of this study were to investigate the importance of managed honeybees and wild honeybees to sunflower pollination as well as to evaluate the response of honeybees to different levels of floral rewards and to behavioural interactions with wild flower visitors. The study was conducted in 16 commercial sunflower farms and one experimental farm of South Africa during the 2009 sunflower flowering season. The results showed that insects, particularly honeybees, were efficient pollinators, improving sunflower production in all self-fertile sunflower cultivars used in this study. Furthermore, wild honeybee colonies were found to be as efficient as managed honeybee colonies in sunflower pollination near to natural habitat. Both sunflower yield and the abundance of pollinators decreased with distance from natural habitat, suggesting that sunflower yield is directly correlated with the abundance of pollinators. The amount of nectar present in the florets of sunflower significantly affected pollinator behaviour, influencing honeybee visitation length and foraging rate which prefer to exploit floral rewards from the same source if they find the higher amount per foraging trip, possibly having a negative impact on cross-pollination. Moreover, the concentration of nectar collected from honeybees was significantly lower than the nectar concentration from florets, suggesting that honeybees diluted highly concentrated sunflower nectar with their saliva to their optimum concentration level. Interspecific exploitative competition between honeybees and wild pollinators (wild bees, butterflies and moths) significantly increased the movement of honeybees among sunflower heads, which enhances cross-pollination. Furthermore, behavioural interactions influenced the length of foraging time spent by individual honeybees per sunflower head. Butterflies were the most influential in enhancing honeybee foraging movement, followed by wild bees and then moths. The importance of a given flower visitor species to honeybee movement is likely related to the size of the visitor, as the bigger size of butterflies and movement of their wings increases the chance of disturbing a neighbouring honeybee. Conservation of natural habitat is important to maintain the diversity of flower visitors which indirectly contribute to crop production by enhancing honeybee foraging activity and consequent direct pollination service. Furthermore, the pollination effectiveness of wild pollinators, density of wild honeybees surrounding sunflower fields and effects of human activities on pollination disruption are suggested as topics for future research. / Dissertation (MScAgric)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted
114

Regulation of protein and carbohydrate intake in caged honeybees Apis mellifera scutellata : assessment based on consumption and various performance measures

Altaye, Solomon Zewdu 12 November 2010 (has links)
When provided with the opportunity to select their diet, most insect herbivores regulate their nutrient intake. However, in a nutritionally heterogeneous environment and with changing demands for growth, development and reproduction, obtaining the required amount and balance of nutrients is a challenge. This is especially true for social insects where the workers bring food into the colony to be shared by nestmates. The ability of insects to self-select their diet is an important trait related to fitness. In this study we investigated whether and how caged worker honeybees meet their nutritional requirements in response to the nutritional composition of the food they find. Using the ‘geometric framework’ we looked at the behavioural and physiological mechanisms used by caged worker honeybees in balancing their diet when provided with different pairs of complementary imbalanced foods. First, we investigated whether caged worker honeybees maintain their intake target by providing them with pairs of complementary imbalanced foods with varying protein to carbohydrate (P:C) ratios. Diets were formulated using different protein sources: casein, royal jelly and Feed-Bee®. Honeybees self-selected or balanced their diet by switching between the complementary foods in accordance with the composition of the food and the type of protein that they encountered. Honeybees selected average P:C ratios of 1:12, 1:14 and 1:11 on casein, royal jelly and Feed-Bee® diets respectively. The level of self-selection was confirmed using two performance measures: survival and ovarian activation. Both survival and ovarian activation differed depending on the type of protein source used. Second, we investigated if honeybees regulated their growth target, which is the amount of nutrients incorporated into growth and storage tissue, by measuring physiological parameters in honeybees confined on imbalanced complementary food combinations having different P:C ratios. Feed-Bee® was used as a protein source. The physiological parameters measured were head fresh mass, hypopharyngeal gland (HPG) development, and protein concentration in the haemolymph. The bees fed on different diet combinations with different P:C ratios maintained each of the performance measures to the same level, which supports the ability of worker honeybees to self-select their diet. The measured physiological parameters were compared with other studies to asses the appropriateness Feed-Bee® diet as a protein source for the bees. In the absence of brood the intake target is directly related to the physiological requirements of the worker bees. The behavior of these individual adult bees gives an insight in to the complex system; similar responses may be seen in nurse bees in the colony condition to obtain protein, carbohydrate and other nutrient requirements from stored pollen and nectar in the hive, either for their own nutritional requirements or for other colony members, especially larvae. / Dissertation (MScAgric)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted
115

Improvement and use of laboratory methods for toxicological assessments on eusocial bees / Plasticidade cerebral e comportamental e danos múltiplos de pesticidas em abelhas eussociais

Tomé, Hudson Vaner Ventura 23 February 2015 (has links)
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-25T08:40:33Z No. of bitstreams: 1 texto completo.pdf: 7983251 bytes, checksum: 5f6d6830b746d01b9e45183b84281ef3 (MD5) / Made available in DSpace on 2015-11-25T08:40:33Z (GMT). No. of bitstreams: 1 texto completo.pdf: 7983251 bytes, checksum: 5f6d6830b746d01b9e45183b84281ef3 (MD5) Previous issue date: 2015-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A importância das abelhas para a polinização é inquestionável. Apesar disso, populações desses organismos têm sofrido consideráveis reduções no mundo por diversos fatores que incluem o uso de pesticidas. Abelhas eussociais geralmente vivem em ninhos, onde parte do desenvolvimento pós-embrionário ocorre em favos fechados, constituindo empecilho para o estudo do desenvolvimento. Portanto, para se estudar o efeito de pesticidas nesses organismos sem interferência de fatores ambientais é necessário a criação em condições controladas em laboratório, sendo que em condições naturais parte da exposição a pesticidas ocorre via alimentação larval. Nesse sentido, o aprimoramento de métodos de criação pode contribuir para o entendimento de como pesticidas afetam processos morfofisiológicos e moleculares nas abelhas mediante exposição das larvas a esses compostos. A presente tese objetivou desenvolver e/ou melhorar técnicas de criação de abelhas in vitro e realizar testes toxicológicos para avaliar a plasticidade cerebral e comportamental em abelhas sem ferrão. Além disso, desordens ocasionadas por pesticidas em abelhas sem ferrão e abelhas melíferas também foram estudadas. De maneira geral, os resultados obtidos na presente tese permitiram concluir que: 1) a criação de abelha sem ferrão M. quadrifasciata em laboratório retarda o desenvolvimento de algumas regiões cerebrais em relação às abelhas mantidas em condições naturais; 2) o inseticida sintético imidaclopride e o bioinseticida spinosade são altamente tóxicos a abelha sem ferrão M. quadrifasciata e também promovem efeitos subletais em operárias dessa espécie; 3) é possível reduzir consideravelmente a mortalidade de Apis mellifera criadas in vitro mediante o uso de procedimentos descritos de forma inédita no presente estudo e 4) todos os pesticidas causaram mortalidade e efeitos subletais (reduções no peso corporal, alterações na atividade de genes associados a destoxificação, distúrbios no desenvolvimento e estruturas das antenas) em abelhas melíferas em virtude da exposição de concentrações realistas de campo durante a fase larval. / The importance of bees for pollination is unquestionable. Nevertheless, populations of these organisms have suffered considerable reductions in the world by several factors including the use of pesticides. Eusocial bees usually live in nests, where part of the post-embryonic development occurs in closed combs, what makes difficult the study of bee development. Therefore, to study the impact of these pesticides without interference from environmental factors, the rearing of these organisms under controlled conditions in laboratory is necessary whereas part of pesticide exposure occurs via larval feeding in natural conditions. In this sense, the improvement of rearing methods can contribute to the understanding of how pesticides affect morphophysiological and molecular processes in bees by exposure of larvae to these compounds. This work aimed to develop and/or improve in vitro bee rearing techniques and perform toxicological tests to assess brain and behavioral plasticity in stingless bees. In addition, disorders caused by pesticides in stingless bees and honeybees were also studied. In general, it can be concluded that: 1) the rearing of stingless M. quadrifasciata laboratory de reased de elop e t of so e ees’ rai regio s compared with bees kept in natural conditions; 2) the synthetic insecticide imidacloprid and bio-insecticide spinosad are highly toxic to stingless M. quadrifasciata and also promote sublethal effects on workers of this species; 3) the mortality of Apis mellifera reared in vitro can be greatly reduced by using procedures described in the present study and 4) all pesticides tested caused mortality and sublethal effects (reductions in body weight, changes in gene activity associated with detoxification, developmental disorders and structures of the antennas) in honey bees after exposure during the larval stage to realistic field pesticide concentrations.
116

Absence of Consistent Diel Rhythmicity in Mated Honey Bee Queen Behavior

Johnson, Jennifer N., Hardgrave, Emily, Gill, Curtis, Moore, Darrell 01 July 2010 (has links)
Relatively little is known about the temporal control of behavior of honey bee queens under natural conditions. To determine if mated honey bee queens possess diel rhythmicity in behavior, we observed them in glass-sided observation hives, employing two focal studies involving continuous observations of individual queens as well as a scan-sampling study of multiple queens. In all cases, all behaviors were observed at all times of the day and night. In four of the five queens examined in focal studies, there were no consistent occurrences of diel periodicity for any of the individual behaviors. A more encompassing measure for periodicity, in which the behaviors were characterized as active (walking, inspecting, egg-laying, begging for food, feeding, and grooming self) or inactive (standing), also failed to reveal consistent diel rhythmicity. Furthermore, there were no consistent diel differences in the number of workers in the queen's retinue. Behavioral arrhythmicity persisted across seasons and despite daily changes in both light and temperature levels. Both day and night levels of behavioral activity were correlated with daytime, but not with nighttime, ambient temperatures. The behavior of the one exceptional queen was not consistent: diurnal activity patterns were present during two 24-h observation sessions but arrhythmicity during another. Based on the behavior observed by all but one of the queens examined in this work, the arrhythmic behavior by the mated honey bee queen inside the colony appears to be similar to that exhibited by worker bees before they approach the age of onset of foraging behavior.
117

Polinización y polinizadores de colza y especies espontáneas de Brassicaceae : su incidencia en la producción

Marinozzi, Luciano Alberto 17 November 2023 (has links)
Entre todas las especies de brasicáceas, la de mayor importancia es Brassica napus L. (colza), que se destaca por su elevada participación en la producción mundial de aceites comestibles. Muchas especies de brasicáceas, cultivadas y silvestres, no sólo tienen importancia en la alimentación humana, sino que han sido mencionadas como fuentes de polen y néctar. Es decir, que el solo hecho de formar parte de la comunidad vegetal aumenta las posibilidades de alimento para un gran número de polinizadores y visitantes florales. La presencia de visitantes florales de brasicáceas en el centro-sur de la Provincia de Buenos Aires (República Argentina) fue evaluada en parcelas de colza y en parches de brasicáceas espontáneas ubicados en la localidad de Tres Arroyos, en la Chacra Experimental Integrada Barrow (-38.319305, - 60.239380). Para realizar los muestreos se utilizaron redes entomológicas, trampas de agua de colores y el método de observación directa. Además, con el objetivo de determinar el efecto de los polinizadores sobre el rendimiento y sus componentes, en las parcelas de colza se colocaron jaulas excluidoras de polinizadores. Otra parte del trabajo se realizó en dependencias del Departamento de Agronomía de la Universidad Nacional del Sur con el fin de evaluar la germinabilidad in vitro del polen expuesto a condiciones ambientales de la colmena. Para esto, se seleccionaron colmenas de Apis mellifera L. y se colocaron en su interior muestras de polen de colza que se obtuvieron de plantas cultivadas en macetas de 10 litros. En la zona de estudio se comprobó que numerosas especies de insectos, de diversas familias y órdenes, visitaron el cultivo de colza al igual que los parches de especies espontáneas. Todas las especies capturadas se encontraron tanto en el cultivo como en las malezas aledañas. Esto indica que los polinizadores utilizan ambos recursos. Las zonas con vegetación espontánea aledañas a las parcelas de colza presentaron una floración más extensa, brindando recursos a los visitantes florales antes, durante y después de la floración del cultivo. Los resultados de este trabajo muestran que la visita de insectos polinizadores en el cultivo de colza mejora la producción de semilla y esto se traduce en un mayor rendimiento, que es, en definitiva, el objetivo de todo productor. También se demostró que el aumento de rendimiento de semilla tuvo implicancia directa sobre la producción de aceite por hectárea, dado que la visita de los polinizadores mejoró la cantidad de semilla y no generó variaciones significativas en el tenor de materia grasa. Por otro lado, se demostró que las condiciones ambientales dentro de la colmena de Apis mellifera son adversas para la germinabilidad de los granos de polen de colza, independientemente de las condiciones ambientales externas. Las zonas de cría son las de mayor temperatura y en 24 h no se registraron granos de polen con capacidad de germinar. A partir de las 48 h la capacidad de germinabilidad del polen disminuyó significativamente y el bajo porcentaje que germinó presentó tubos completamente atrofiados. Aunque el polen que se ubicó alejado de las zonas de cría mantuvo más tiempo su capacidad de germinar, sólo lo hizo por menos de 72 h. Los resultados de este trabajo respaldan una reducción sustancial del tiempo de carencia que exigen las empresas semilleras y abren la posibilidad de que se utilice una misma colmena en dos servicios de polinización consecutivos sin riesgo de contaminación por polen no deseado. / Among all the species of brassicas, the most important one is Brassica napus L. (rapeseed), which stands out for its significant contribution to the global production of edible oils. Many species of brassicas, both cultivated and wild, are not only important for human consumption but have also been mentioned as sources of pollen and nectar. In other words, simply being part of the plant community increases the food possibilities for a large number of pollinators and floral visitors. The presence of brassica floral visitors in the central-southern region of Buenos Aires Province (Argentina) was evaluated in rapeseed plots and patches of spontaneous brassica plants located in Tres Arroyos, at the Chacra Experimental Integrada Barrow (- 38.319305, -60.239380). Entomological nets, colored water traps, and direct observation methods were used for sampling. Additionally, exclusion cages were placed in the rapeseed plots to determine the effect of pollinators on yield and its components. Another part of the study was conducted at the Department of Agronomy, Universidad Nacional del Sur, to assess the in vitro germinability of pollen exposed to hive environmental conditions. Honey bee (Apis mellifera L.) colonies were selected, and samples of rapeseed pollen obtained from plants cultivated in 10-liter pots were placed inside the hives. The study in the area confirmed that numerous insect species from different families and orders visited both the rapeseed crop and the patches of spontaneous species. All captured species were found in both the crop and the surrounding weeds, indicating that pollinators utilize both resources. The areas with spontaneous vegetation adjacent to the rapeseed plots exhibited more extensive flowering, providing resources for floral visitors before, during, and after the crop's flowering period. The results of this study demonstrate that the visitation of pollinating insects in the rapeseed crop improves seed production, ultimately resulting in higher yields, which is the goal of every farmer. It was also shown that the increased seed yield directly impacted oil production per hectare, as pollinator visitation improved seed quantity without generating significant variations in fat content. On the other hand, it was demonstrated that the environmental conditions within the Apis mellifera hive are unfavorable for the germinability of rapeseed pollen grains, regardless of external environmental conditions. The brood areas have the highest temperatures, and within 24 hours, no pollen grains capable of germinating were recorded. From 48 hours onward, the germination capacity of the pollen significantly decreased, and the low percentage that did germinate exhibited completely atrophied tubes. Although pollen placed away from the brood areas maintained its germination capacity for a longer period, it did so for less than 72 hours. The results of this study support a substantial reduction in the required waiting time demanded by seed companies and open up the possibility of using the same hive for two consecutive pollination services without the risk of contamination by undesired pollen.
118

Row crop environments provide an all-you-can-eat buffet and pesticide exposure to foraging honey bees

Silliman, Mary Rachel 03 June 2021 (has links)
The western honey bee, Apis mellifera, provide invaluable economic and ecological services while simultaneously facing stressors that may compromise their health. For example, agricultural landscapes, such as a row crop system, are necessary for our food production, but they may cause poor nutrition in bees from a lack of available nectar and pollen. Row crops are largely wind or self-pollinated, and while previous studies have focused on the impact of bees to row crops, fewer studies have examined the reciprocal relationship of the row crops on honey bees. Here we investigated the foraging dynamics of honey bees in a row crop environment. We decoded, mapped, and analyzed 3460 waggle dances, which communicate the location of where bees collected food, for two full foraging seasons (April – October, 2018-2019), and concurrently collected pollen from returning foragers. We found that bees foraged mostly locally (< 2 km) throughout the season. The shortest communicated median distances (0.48 and 0.32 km), indicating abundant food availability, occurred in July in both years, which was when our row crops were in full bloom. We determined, by plotting and analyzing the communicated locations, that most mid-summer foraging was in row crops, with at least 40% of honey bee recruitment dances indicating either cotton or soybean fields. Bees also largely foraged for nectar when visiting row crop fields, only returning to the hive with Glycine spp. pollen, and foraging on nearby trees and weeds for pollen. Foragers were exposed to thirty-five different pesticides throughout the foraging season, based on pesticide residues in collected pollen. Overall, row crop fields are contributing a surprising majority of mid-summer forage to honey bee hives and suggests that similar agricultural landscapes may also provide abundant, mid-summer forage opportunities for honey bees, however, at the risk of pesticide exposure. / Master of Science in Life Sciences / Declines in the number of honey bee hives have been observed in the United States and western Europe throughout the last century, driven by environmental stressors such as poor nutrition caused by anthropogenic landscape change and pesticide exposure. Agricultural landscapes, for example, contain monocultures and often necessitate pesticide use, which may be detrimental to bee health. Because of these effects, it is necessary to understand how honey bees forage in these systems and what potential health risks they face. We investigated honey bees foraging dynamics in a row crop environment, observing honey bee waggle dance recruitment behavior and gathering forager-collected pollen to better understand when, where, and what honey bees forage on throughout the season (April – October). We found that bees largely foraged near the hive throughout the season, indicating that sufficient resources were available, particularly in July when crops were in full bloom. During full bloom bees considerably foraged in cotton and soybean fields. We found that bees collected minimal row crop pollen, apart from soybean pollen, largely foraging on trees and flowering weeds for pollen. Through pollen foraging bees were exposed to thirty-five pesticides, ranging in toxicity and mode of action. Overall, honey bees foraging in a row crop system foraged substantially in row crop fields during the mid-summer. Row crops systems may be able to provide abundant forage during the mid-summer, but could come at the risk of exposure to pesticides.
119

Respiration rates and Factors which Influence the levels of Carbohydrates and Lipids in Honey Bee Eggs (<I>Apis mellifera </I>Linnaeus)

Mackasmiel, Lucas Aloyse Mugah 21 May 1999 (has links)
Respiration rates and changes in the amount of nutrients in queen-laid and worker-laid eggs of the honey bee, <I>Apis mellifera</I> L., were determined for the 3 days of embryonic development. Respiration was quantified by measuring the amount of CO₂ produced during 13 hr of artificial incubation at four temperature treatments: 28°C, 31°C, 34°C, 36°C (± 0.5°C). The amounts of lipids and carbohydrates were also quantified in the eggs of queens and laying workers on day 1, 2 and 3 using high performance thin layer chromatography. The mean respiration rate for fertilized and unfertilized eggs from queens was 0.1 ± 0.0 µL CO₂/hr/egg, the same as the mean respiration rate obtained for unfertilized eggs from laying workers. The results of carbohydrate analysis showed a total of 2.4 ± 0.6 µg/egg total sugars in the fertilized eggs of queens, an equivalent of 8.3% on a dry weight basis, while unfertilized eggs contained a total of 1.4 ± 0.4 µg/egg total sugars, equivalent of 6.3% on a dry weight basis. Total lipids, excluding fatty acids, were 10.7 ± 6.1 µg/egg (37.4%) for fertilized eggs and 8.4 ± 1.3 µg/egg (40.8%) for unfertilized eggs. The respiration rate at 34°C was 0.17 ± 0.01 µL CO<sub>2</sub>/hr/egg on day 1, the same as day 1 at 36°C. Day 2 respiration rates were 0.13 ± 0.04 µL CO₂/hr/egg and 0.15 ± 0.01 µL CO₂/hr/egg, respectively. On day three, 0.22 ± 0.01 µL CO₂/hr/egg was recorded at 34°C and 0.24 0.01 µL CO₂/hr/egg at 36°C. At low temperatures of 28°C and 31°C, a respiration rate of 0.12 ± 0.01 µL CO₂/hr/egg was recorded on day 1, for eggs held at both temperatures. Day 2 results were 0.07 ± 0.01 µL CO₂/hr/egg at 28°C and 0.11 ± 0.01 µL CO₂/hr/egg at 31°C, while 0.07 ± 0.01 and 0.12 ± 0.01 µL CO₂/hr/egg, respectively, were measured on day 3. Mortality results, as indicated by pre-emergence embryos, showed that 75% developed at 34°C compared to 37.5% at 36°C. Low temperatures of 28°C had 12.5% developing to pre-emergence stage while 50% developed at 31°C. Respiratory results showed significant differences (p=0.05) between the different days of incubation and temperature treatments, respectively. No significant difference was observed between the fertilized eggs and unfertilized eggs from queens at the same temperature treatment. The comparison of unfertilized eggs from queens and those from laying workers also showed no significant difference. The regression (R²=0.65) was significant (P=0.05) when CO₂ output on all the days and temperature treatments were compared. The amount of nutrients in the eggs of queens and those of laying workers, were significantly different (P=0.05) depending on egg type and age. No significant difference was observed between the colonies headed by queens or those of laying workers. Although the queen-laid eggs showed a relatively higher mean value for carbohydrates than worker-laid eggs, the reverse was the case for lipids. On comparing the amount of nutrients per unit weight for queen-laid and worker-laid eggs, no significant differences were observed. From the results obtained, inferences were made about the natural differences between the eggs from queens, and those produced by laying workers. / Master of Science
120

Methods for controlling two European Honey bee (Apis mellifera L.) pests:  Varroa mites (Varroa destructor, Anderson and Trueman) And Small hive beetles (Aethina tumida)

Roth, Morgan Alicia 11 June 2019 (has links)
Throughout the last five decades, European Honey bee (Apis mellifera) colonies have been heavily damaged by invading Varroa mites (Varroa destructor), and, more recently, small hive beetles (Aethina tumida). These pests infest A. mellifera colonies throughout Virginia, with V. destructor feeding upon the lipids of their hosts and spreading viruses, and A. tumida feeding extensively on hive products and brood. Because V. destructor has historically demonstrated acaricide resistance, this study examined V. destructor resistance to three common acaricides (amitraz, coumaphos, and tau-fluvalinate) throughout the three geographic regions of Virginia using glass vial contact bioassays; the results showed no resistance in the sites tested. To gain better insights into A. tumida pharmacology, several known acetylcholinesterase (AChE) inhibitors and three novel insecticides (previously shown to have low mammalian toxicity) were tested against an A. tumida laboratory colony through in vivo and in vitro bioassays. The results of these bioassays indicated that coumaphos was most selective and topically effective against A. tumida, while only one experimental compound was selective against A. tumida, with 29-fold less potency than coumaphos. These results can help apiculturists in making informed pest management choices and can lead to future studies further examining V. destructor resistance and optimizing A. tumida insecticide treatments. / Master of Science in Life Sciences / Beekeepers throughout the world have experienced great economic loss and observed a troubling decline in European Honey bee colonies over the past fifty years due to Varroa mite infestations. Varroa mites feed on the fat body of bees, depriving them of nutrients and infecting them with various diseases. Attempts made to control Varroa mites with synthetic chemicals throughout the years have led to acaricide resistance. To look at resistance in Virginia’s mite populations, resistance testing was performed on Varroa mite populations throughout the three geographic regions of Virginia, and these studies showed that there was not resistance in these populations. Another significant hive pest that is increasingly prevalent in the United States is the small hive beetle (SHB), which feeds on bee brood and hive products. SHB management tactics are still being explored, and this project tested various known insecticide treatments against small hive beetles and bees, as well as three insecticide treatments that were designed for mosquito control and have low toxicity to mammals. The results of this study showed that, of the insecticides tested, coumaphos was the most selective against SHB. This information can help beekeepers in Virginia make informed choices when deciding how to treat Varroa mite infestations, and can add to the knowledge base of those fighting small hive beetle infestations.

Page generated in 0.0438 seconds