Hannelie Human

Hannelie Human
University of Pretoria | UP · Department of Zoology and Entomology

PhD (Entomology)

About

46
Publications
30,824
Reads
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Introduction
As an experienced Researcher with a C2 rating from the NRF and a pollination specialist, my research includes the field of pollinator identification, pollination efficiency and ecology, floral biology and ecology, nectar chemistry, biochemistry and the effect of neonicotinoid pesticides on honeybee physiology, behaviour and nutrition. My research aims to increase our understanding of factors that may contribute to the losses of honeybee colonies in South Africa.
Additional affiliations
January 2013 - November 2020
University of Pretoria
Position
  • Lecturer
Description
  • Co-supervision of Honours, Masters and PhD students, lecturing of undergraduate and veterinarian students
January 2009 - November 2020
University of Pretoria
Position
  • A healthy lifestyle for honeybees: effects of diet, toxins and diseases on honeybees
Description
  • My research focuses on behavioural, physiological, chemical aspects and diagnostics of honeybee pests and diseases and colony losses in South Africa. As a pollination specialist, my research includes the field of pollinator identification, pollination efficiency and ecology, floral biology and ecology, nectar chemistry, biochemistry and the effect of neonicotinoid pesticides on honeybee physiology, behaviour and nutrition.
Education
March 2006
University of Pretoria
Field of study
  • Entomology

Publications

Publications (46)
Article
Nutritional stress due to habitat transformation and loss is one of several factors contributing to current declines in global bee populations. Bees obtain protein from pollen, which in honeybees is consumed and digested by nurse bees. They then distribute the protein to the rest of the colony in the form of hypopharyngeal gland secretions. Little...
Article
For two decades, neonicotinoid insecticides have been extensively used worldwide. Targeting neuronal receptors, they have deleterious effects on the behaviour and physiology of many of many beneficial as well as harmful insects. Bees are exposed to these insecticides in pollen and nectar while providing pollination services to agricultural crops, a...
Article
Over the past decade, in some regions of the world, honey bee (Apis mellifera L.) colonies have experienced rates of colony loss that are difficult for beekeepers to sustain. The reasons for losses are complex and interacting, with major drivers including varroa and related viruses, pesticides, nutrition and beekeeper practices. In these endeavors...
Article
Pollen, the main protein source for honey bees, is mixed with regurgitated nectar or honey during collection and then stored as 'bee bread' before its consumption, mainly by young nurse workers. It has been suggested that storage of pollen improves its nutritional value and digestibility, but there is little evidence for such changes. We fed two fr...
Article
Despite potential links between pesticides and bee declines, toxicology information on honey bee larvae (Apis mellifera) is scarce and detoxification mechanisms in this development stage are virtually unknown. Larvae are exposed to natural and synthetic toxins present in pollen and nectar through consumption of brood food. Due to the characteristic...
Article
Full-text available
Over a decade, declines in honey bee colonies have raised worldwide concerns. Several potentially contributing factors have been investigated, e.g. parasites, diseases, and pesticides. Neonicotinoid pesticides have received much attention due to their intensive use in crop protection, and their adverse effects on many levels of honey bee physiology...
Data
Daily nutrient intake is influenced by the amount of dietary protein, but not by the THX pesticide dose. The panels show the effect of THX doses among different diets. The top panel is the choice experiment, where bees were able to regulate their nutrient intake. The four panels below the line represent the no-choice experiment with the four differ...
Data
Statistical data. (A) Choice experiment. (B) No-Choice experiment–THX Dose effect. (C) No-Choice experiment–Dietary protein effect. (PDF)
Data
Cumulative consumption and details of the different amount of nutrient eaten during the Choice Experiment. Every values are in mg/bee ±s.e.m., except for the P:C ratio columns. The “Cumulative Consumption” column is the same as the last column in Table 1. Honey bees were offered the choice between two unbalanced diets, differing in their P:C ratios...
Article
Varroa destructor is considered the most damaging parasite affecting honeybees (Apis mellifera L.). However, some honeybee populations such as the savannah honeybee (Apis mellifera scutellata) can survive mite infestation without treatment. It is unclear if survival is due to resistance mechanisms decreasing parasite reproduction or to tolerance me...
Article
Full-text available
Honeybee (Apis mellifera L.) pathogens and parasites and the negative effects thereof on honeybee populations remain an issue of public concern and the subject of active research. Africa with its high genetic diversity of honeybee sub-species and large wild population is also exposed to various factors responsible for colony losses in other parts o...
Article
Full-text available
The devastating effects of Varroa destructor Anderson & Trueman on European honeybee colonies (Apis mellifera L.) have been well documented. Not only do these mites cause physical damage to parasitised individuals when they feed on them, they also transmit viruses and other pathogens, weaken colonies and can ultimately cause their death. Neverthele...
Article
The effects of pesticides on honeybee larvae are less understood than for adult bees, even though larvae are chronically exposed to pesticide residues that accumulate in comb and food stores in the hive. We investigated how exposure to a plant alkaloid, nicotine, affects survival, growth and body composition of honeybee larvae. Larvae of Apis melli...
Article
Full-text available
This study reports honey bee, Apis mellifera L., colony losses that occurred in South Africa over two consecutive years. The total losses were 29.6% (95% CI: 22.8-37.5) in 2009-2010 and 46.2% (95% CI: 37.3-55.0) in 2010-2011. Furthermore, the study shows that the capensis worker social parasite, a problem unique to southern Africa, is the main perc...
Article
Full-text available
A variety of methods are used in honey bee research and differ depending on the level at which the research is conducted. On an individual level, the handling of individual honey bees, including the queen, larvae and pupae are required. There are different methods for the immobilising, killing and storing as well as determining individual weight of...
Article
The loss of Apis mellifera L. colonies in recent years has, in many regions of the world, been alarmingly high. No single cause has been identified for these losses, but the interactions between several factors (mostly pathogens and parasites) have been held responsible. Work in the Americas on honeybees originating mainly from South Africa indicat...
Article
Full-text available
American foulbrood is one of the most devastating diseases of the honey bee. It is caused by the spore-forming, Gram-positive rod-shaped bacterium Paenibacillus larvae. The recent updated genome assembly and annotation for this pathogen now permits in-depth molecular studies. In this paper, selected techniques and protocols for American foulbrood r...
Article
Full-text available
In this paper, we describe the use of epidemiological methods to understand and reduce honey bee morbidity and mortality. Essential terms are presented and defined and we also give examples for their use. Defining such terms as disease, population, sensitivity, and specificity, provides a framework for epidemiological comparisons. The term populati...
Article
The loss of Apis mellifera L. colonies in recent years has, in many regions of the world, been alarmingly high. No single cause has been identified for these losses, but the interactions between several factors (mostly pathogens and parasites) have been held responsible. Work in the Americas on honeybees originating mainly from South Africa indicat...
Article
The nutritional needs of bees are receiving renewed attention in the context of declining bee populations and changes in land use that threaten floral resources. We present a comprehensive analysis of the nutritional composition of sunflower (Helianthus annuus L.) pollen, comparing hand-collected, bee-collected and stored pollen. As found in previo...
Article
Full-text available
Sustaining apiculture worldwide has been threatened by bee diseases and unexplained colony losses. African honeybee populations seem healthier and no major losses have been reported despite the presence of all the major pests and diseases. The scattered colonies in the large wild population of the continent might ensure slow pathogen spread and thu...
Article
Full-text available
Sustaining apiculture worldwide has been threatened by bee diseases and unexplained colony losses. African honeybee populations seem healthier and no major losses have been reported despite the presence of all the major pests and diseases. The scattered colonies in the large wild population of the continent might ensure slow pathogen spread and thu...
Article
Full-text available
Small hive beetles, Aethina tumida Murray, (Coleoptera: Nitidulidae) are native to subSaharan Africa where they parasitize honey bee (Apis mellifera L) colonies (Lundie 1940). Small hive beetles feed on pollen, brood and honey inside honey bee hives (Lundie 1940). Pupation occurs in the soil and the transitions from larvae to pupae to adult are vul...
Article
Full-text available
Pollen is the natural source of protein for bees and it is commonly assumed that a high protein content in pollen is beneficial. Investigation of the optimal nutrient ratio for honeybees was prompted by our earlier study showing surprisingly high mortality in caged honeybees fed with the protein-rich pollen of Aloe greatheadii var davyana, although...
Article
Full-text available
Aloe marlothii and A. greatheadii var. davyana are two sympatric winter-flowering succulents that occur in the summer rainfall regions of northern and north-eastern South Africa. Both have flower characteristics that are strongly suggestive of bird pollination, although their nectar differs in volume and concentration. We conducted pollinator exclu...
Article
Nectar concentration is assumed to remain constant during transport by honeybees between flowers and hive. We sampled crop contents of nectar foragers on Aloe greatheadii var. davyana, a major winter bee plant in South Africa. The nectar is dilute (approx. 20% w/w), but the crop contents of bees captured on flowers are significantly more concentrat...
Article
The winter-flowering Aloe greatheadii var. davyana is a major indigenous bee plant in South Africa, widely distributed across the northern summer rainfall areas. Migratory beekeepers take advantage of its highly nutritious pollen for colony increase and strong nectar flow for honey production. We looked at variation on different levels in assessing...
Article
Protein-rich diets are known to promote ovarian and egg development in workers of the honeybee, Apis mellifera, even in the presence of a queen. Since the main source of protein for honeybees is pollen, its quality and digestibility might be important dietary factors determining reproductive capacity. We have compared the effect of two types of pol...
Article
Honeybees are highly efficient at regulating the biophysical parameters of their hive according to colony needs. Thermoregulation has been the most extensively studied aspect of nest homeostasis. In contrast, little is known about how humidity is regulated in beehives, if at all. Although high humidity is necessary for brood development, regulation...
Article
Aloe greatheadii var. davyana is the most important indigenous South African bee plant. Fresh, bee-collected and stored pollen of this aloe was collected and analysed for its nutritional content, including amino acid and fatty acid composition. Highly significant differences were found between the three types of pollen. Collection and storage by th...
Article
This paper deals with the nectary structure and nectar presentation of two species belonging to different sections of the genus Aloe: A. castanea (Anguialoe) and A. greatheadii var. davyana (Pictae). The development of the nectary was studied by means of bright field and fluorescence light microscopy and scanning electron microscopy (SEM) in three...
Article
We investigated the mechanism and efficiency of digestion of two types of pollen, maize, Zea mays, and sunflower, Helianthus annuus, by the spotted maize beetle, Astylus atromaculatus (Melyridae). We found similar and high extraction efficiencies, but different mechanisms of digestion. Osmotic shock was apparently involved in digestion of the large...

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Projects

Projects (4)
Project
Focus on nutrition and other aspects of pollinator health