Brood pheromone of the honey bee, (Apis mellifera) has been shown to elicit a wide array of primer and releaser effects on non‐foragers and foragers leading to the regulation of nursing, pollen foraging, and behavioral development such that the behavior of the colony may be regulated by the amount and condition of the larvae. To date, all studies into the effects of brood pheromone have either used uncharacterized whole extracts or a single blend of brood pheromone characterized from a population of honey bees in France. The variation in the relative proportions of the ten fatty‐acid ester components that characterize brood pheromone and some effects of this variation on pollen foraging and sucrose response thresholds were therefore observed. The objectives met in this dissertation were to determine whether changes in brood pheromone component proportions (blend) or amount communicates larval nutritional status and reports the results of observations of nurses and foragers in response to blends of brood pheromone from deprived and‐non deprived larvae, to measure how changes in brood pheromone blend changed pollen foraging behavior and if such changes could account for the pollen foraging differences between Africanized and European bees, and finally to observe the effects of exposure time on brood pheromone blend and to observe whether non‐foragers made contact with the pheromone. Brood pheromone was found to vary by larval rearing environment, but did not elicit the expected behaviors that would support a cue of nutritional status. Brood pheromone also varied significantly by mitochondrial lineage/population source and responses to brood pheromone appeared to be coadapted to blend, suggesting that brood pheromone may be important in race recognition. Finally, brood pheromone varied significantly over time and was found to be removed from sources by bees, suggesting possible mechanisms for loss of effect. Combined the results of this research indicate that brood pheromone blend differences lead to profound changes in colony behavior related to pollen foraging and food provisioning, providing novel tools for colony manipulation and mechanisms for understanding brood rearing division of labor and chemical communication.

North American grasslands and grassland birds have declined drastically due to habitat degradation by fire suppression (i.e., woody encroachment), fragmentation, and conversion to croplands. A better understanding is needed of the relationships among disturbance regimes (e.g., fire), resultant vegetation changes, and grassland bird communities to effectively manage remaining grasslands and grassland birds. I assessed the relationship between post-fire succession, and mean relative abundance and nesting ecology of breeding grassland birds (i.e., nest-site selection and nest success) in mesquite-dominated rangeland of the Texas Rolling Plains, where prescribed fire is used as a tool to manage shrub encroachment. Brush cover, grass cover, and visual obstruction generally increased with post-fire succession, and bare ground decreased with post-fire succession. Species richness, grasshopper sparrows (Ammodramus savannarum), Cassin’s sparrows (Aimophila cassinii), and dickcissels (Spiza americana) responded positively to post-fire succession, and lark sparrows (Chondestes grammacus) responded negatively to post-fire succession.; abundance of these avian groups was low on the control sites. During 2004–2005, 90 grassland bird nests were monitored. I found conflicting results for vegetation parameters important to nest site selection and probability of nest success. For all species except lark sparrows, nest-site location was positively associated with visual obstruction and with grass or forb cover. However, the probability of nest success increased with lower visual obstruction, bare ground cover, or grass cover. Grassland bird abundance, nest-site location, and nest success had differing associations with vegetation variables. These results suggest that to effectively manage remaining grasslands for sustainable breeding grassland bird populations, managers should engage in practices that keep habitat in multiple vegetative successional stages.

Honey bees (Apis mellifera) are the most economically important insect pollinator of agricultural crops in the United States. Honey bee colonies are required for pollination of approximately one-third of the nation’s fruit, vegetable, nut, and forage crops, with an estimated annual value in the billions of dollars. The economic value of a honey bee colony comes from its population size, as large colonies provide the necessary foraging force required for large-scale crop pollination services. A major component of colony strength is its genetic diversity, a consequence of the reproductive mating strategy of the queen known as polyandry. Despite some inherent risks of multiple mating, several studies have demonstrated significant advantages of intracolonial genetic diversity for honey bee colony productivity. Colony-level benefits include better disease resistance, more stable brood nest thermoregulation, and greater colony growth. Instrumental insemination of honey bee queens is a technique to precisely control queen mating, and thereby creates the opportunity to investigate the effects of intracolonial genetic diversity on colony performance. In this dissertation, I first consider the effects of intracolonial genetic diversity on pollen foraging using colonies headed by queens which were instrumentally inseminated with either one or twenty drones to generate colonies of very high or very low intracolonial genetic diversity, respectively. I found that colonies with high intracolonial genetic diversity amass significantly more pollen and rear more brood than colonies with low intracolonial genetic diversity. Of particular interest, colonies with low intracolonial genetic diversity collected a significantly greater variety of pollen types. I discuss these results in the context of scouting and recruiting, and suggest a more efficient foraging strategy exists among genetically diverse colonies. While intracolonial genetic diversity is positively correlated with collected pollen, its effect on the colony’s ability to process and distribute inbound protein resources is unknown. Again using colonies headed by queens instrumentally inseminated with either one or twenty drones, I studied the effects of intracolonial genetic diversity on pollen consumption and digestion by nurse bees, as well as protein allocation among nestmates by assessing total soluble protein concentration of late instar larvae, and total soluble hemolymph protein concentration in both nurses and pollen foragers. I found that nurse bees from colonies with high intracolonial genetic diversity consume and process more protein than nurses from colonies with low intracolonial genetic diversity, even when given equal access to protein resources. Further, both forager hemolymph protein concentrations and larval total protein concentrations were higher among the colonies with high intracolonial genetic diversity. My findings suggest that protein processing and distribution within a honey bee colony is affected by the social context of the hive. I discuss “worker policing”, and the role of nurse bees in modulating the foraging effort. Finally, I assess the standing genetic variability among several colonies sourced from different genetic and geographic locations. Using microsatellite DNA from workers sampled from each colony, I determined allelic richness, gene diversity, and effective mating frequency for each genetic line. I found differences in all three metrics between lines, and for one line in particular, there was no correlation with genetic variation and effective mating frequency, suggesting non-random mating. My results showed very different levels of intracolonial genetic diversity among naturally mated queens. Because of its impact on colony performance, the importance of maintaining genetic diversity in breeding populations is discussed.

No description available.

Excessive honey bee colony losses all over the world are believed to be caused by multiple stressors. In this thesis, I characterized and quantified pathogen levels in honey bee colonies, studied their interactions with each other and with their associated parasite vectors, examined factors that influence their combined impacts on honey bees and developed methods to manage honey bee viruses so that colony losses can be minimized. My baseline study of virus prevalence and concentration in healthy and unhealthy (showing visible signs of disease) colonies in Canada showed that seven economically important viruses (DWV, BQCV, IAPV, KBV, SBV, ABPV, and CBPV) were all widely distributed in Canada. Differences in concentration and prevalence of some viruses were found between unhealthy and healthy colonies but these differences may have been due in part to seasonal or regional effects. Studies of the impact of viruses on worker bee populations over winter showed different factors were correlated with bee loss in different environments. Spring concentrations of DWV and mean abundance of Varroa (Varroa destructor) were positively correlated with bee loss and negatively correlated with spring population size in outdoor-wintered colonies. Fall concentration of IAPV was negatively correlated with spring population size of colonies in indoor-wintering environments but not in outdoor-environments. My study showed that it is important to consider location of sampling when associating pathogen loads with bee loss with Nosema and BQCV. Seasonal patterns of parasites and pathogens were characterized for each wintering methods (indoor and outdoor). My results revealed lower ABPV and Nosema ceranae prevalence and lower DWV concentration in genetically diverse than genetically similar colonies. I showed that within colony genetic diversity may be an important evolutionary adaptation to allow honey bees to defend against a wide range of diseases. In laboratory studies, I showed that feeding DWV to larvae in the absence of Varroa causes wing deformity and decreased survival rates of adult bees relative to bees not fed DWV. Finally, I showed that RNA silencing can be used to reduce DWV concentrations in immature and adult bees, reduce wing deformity in emerging adults, and increase their longevity relative to controls.

Nuolat ieškoma ekologiškų bei saugių preparatų, kuriuos būtų galima panaudoti bitynuose. Vieni iš jų probiotikai. Šiuo metu yra mažai atlikta tyrimų panaudojant probiotikus bitininkystėje. Todėl tyrimai su probiotikais svarbūs moksliniu bei praktinių požiūriu. Atliekant eksperimentą buvo įvertinta probiotiko įtaka bičių produktyvumui, bičių kūnelių SM ir medaus cheminiai sudėčiai. Meduje nustatyta: kadmio, švino kiekiai, redukuotas cukrus, diastazės aktyvumas, sacharozės kiekiai. Bičių kūnelių sausojoje medžiagoje nustatyta: baltymų kiekis, riebalų kiekis, kadmio ir švino kiekiai. Nustatyta, kad naudojant probiotiką pavasarinis viduriavimas išgydomas per keletą dienų bei padidėja perų skaičius aviliuose kas padidina bičių produktyvumą. Praturtinus bičių mitybą probiotiniais preparatais pastebėtas mažesnis kiekis sunkiųjų metalų, o riebalų kiekis padidėjo. Naudojant probiotinį preparatą galima gauti didesnį kiekį medaus ir žiedadulkių atitinkamai 70,5 kg ir 2,7kg. / Constantly looking for eco-friendly and safe products which can be used in apiaries. Some of these probiotics. Currently, there are only few studies using probiotics in beekeeping. Therefore, studies with probiotics are important scientific and practical point of view. The experiment was evaluated the influence of probiotics on productivity of bees, bee cells SM and honey chemical composition. In honey was established: cadmium, plumbum levels, reduced sugar, diastase activity, sucrose levels. Bee cells in dry matter were set: protein, fat, cadmium and plumbum levels. It was established, that the use of probiotic spring diarrhea cured within a few days and an increase in the number of brood in the hives of bees which increases productivity. Enriches bee nutrition probiotic products had lower amount of heavy metals and fat content increased. Using a probiotic preparation can get a larger amount of honey and pollen, respectively, 70.5 kg and 2.7 kg.

Chalkbrood, caused by Ascosphaera apis (Maassen ex Claussen) Olive & Spiltor, is a cosmopolitan fungal disease of honey bee larvae (Apis mellifera L.) for which there is no chemotherapeutic control. Using in vitro larval rearing methods, lysozyme-HCl, a food-grade antimicrobial extracted from hen egg albumen, was found to suppress chalkbrood at levels of 0.75-1.5% (g/mL) of larval diet. In field trials, lysozyme-HCl did not affect adult bee survival or brood production and did effectively suppress the development of chalkbrood disease. Daily chalkbrood mummy production decreased by a factor of 10 in colonies treated with three treatments of 6000 mg of lysozyme-HCl when compared with infected, untreated controls and reduced disease symptoms to levels observed in uninfected colonies. Honey production was also found to be significantly negatively correlated with increased disease severity. Lysozyme-HCl is a promising safe therapeutic agent for the control of chalkbrood in honey bee colonies.

The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park. Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid. The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence. Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire. Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota. Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance. Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.

Thesis (Ph.D. (Biochemistry, Microbiology & Biotechnology)) - Rhodes University, 2005.

Neonicotinoid exposure has been recognised as potentially impacting upon bee health, but whether realistic exposure scenarios are driving declines in bee health is not known. This thesis contributes new insights and perspectives to this research field investigating the use of molecular, physiological and behavioural endpoints as potential ecotoxicological markers for pesticide risk assessment. The thesis presents experimental data for dietary exposures of the European honey bee, Apis mellifera, and the buff-tailed bumble bee, Bombus terrestris, to one of two neonicotinoid pesticides, imidacloprid and thiamethoxam. The first part of this thesis explores impacts of chronic dietary exposures to neonicotinoid pesticides on bee immunocompetence- the ability to mount an immune response- using an artificial challenge to invoke an immune response in adult workers. Levels of phenoloxidase, an enzyme involved in melanisation and part of the bee’s defence system, were largely constitutive and resilient to exposure in honey bees and bumble bees. In honey bees, transient transcriptional changes in antimicrobial effector genes were observed following neonicotinoid exposure, but the physiological antimicrobial response was unaffected. In bumble bees, the induced antimicrobial response was impaired following neonicotinoid exposure, but only when exposed to concentrations likely higher than realistic environmental exposure scenarios. The next phase of this thesis investigates whether transcriptional, physiological and behavioural endpoints associated with the functioning of the honey bee hypopharyngeal gland were altered by imidacloprid exposure. Imidacloprid exposure led to transcriptional changes in foraging genes (associated with the control of temporal polyethism) and major royal jelly proteins (fed to developing larvae by nurse workers) and enzymatic changes in glucose oxidase (an enzyme involved in social immunity), which I hypothesise are linked with hypopharyngeal gland development. Despite these laboratory observations, no behavioural effects were observed in a field setting, monitored using Radio Frequency Identification transponders. Lastly, using RNA-Sequencing to investigate changes across the honey bee transcriptome, this thesis identified a suite of genes that were differentially expressed in adult workers in response to immune challenge and/or dietary neonicotinoid exposure. Wounding and bacterial-like infection led to upregulation of known immune genes, including a peptidoglycan recognition protein and antimicrobial effectors. Chronic exposure to thiamethoxam and imidacloprid led to downregulation of genes associated with several metabolic pathways, such as oxidative phosphorylation, pyruvate- and purine- metabolic pathways, as well as ribosomal activity. Some of these genes identified provide candidates for further study to elucidate functional effects mechanisms and better understand health outcomes, as well as potential new biomarkers for use in pesticide risk assessment. This thesis presents novel findings and offers opportunities for future research that will be of interest to a wide audience, including risk assessors and policy makers, as well as the broader biological community, including ecotoxicologists, insect physiologists and molecular biologists.