Deborah A. Delaney

The physical, insemination, and reproductive quality of honey bee queens (Apis mellifera L.)

Understanding the reproductive potential (“quality”) of queens bees can provide valuable insights into factors that influence colony phenotype. We assayed queens from various commercial sources for various measures of potential queen quality, including their physical characters (such as their degree of parasitism), insemination number (stored sperm counts), and effective paternity frequency (number of drone fathers among their offspring). We found significant variation in the physical, insemination, and mating quality of commercially produced queens, and we detected significant correlations within and among these various measures. Overall, the queens were sufficiently inseminated (3.99 ± 1.504 million sperm) and mated with an appropriate number of drones (effective paternity frequency: 16.0 ± 9.48). Importantly, very few of the queens were parasitized by tracheal mites and none were found with either Nosema species. These findings suggest possible mechanisms for assessing the potential fitness of honey bee queens without the need for destructive sampling.

Experimentally induced variation in the physical reproductive potential and mating success in honey bee queens

In honeybee colonies, reproduction is monopolized by the queen while her daughter workers are facultatively sterile. Caste determination is a consequence of environmental conditions during development, during which female larvae may become either queens or workers depending on their larval diet. This bipotency introduces significant variation in the reproductive potential of queen bees, with queens raised from young worker larvae exhibiting high reproductive potential and queens raised from older worker larvae exhibiting lower reproductive potential. We verify that low-quality queens are indeed produced from older worker larvae, as measured morphometrically (e.g., body size) and by stored sperm counts. We also show, for the first time, that low-quality queens mate with significantly fewer males, which significantly influences the resultant intracolony genetic diversity of the worker force of their future colonies. These results demonstrate a reproductive continuum of honeybee queens and provide insights into the reproductive constraints of social insects.

Assessing the Mating 'Health' of Commercial Honey Bee Queens

ABSTRACT Honey bee queens mate with multiple males, which increases the total genetic diversity within colonies and has been shown to confer numerous benefits for colony health and productivity. Recent surveys of beekeepers have suggested that ‘poor queens’ are a top management concern, thus investigating the reproductive quality and mating success of commercially produced honey bee queens is warranted. We purchased 80 commercially produced queens from large queen breeders in California and measured them for their physical size (fresh weigh and thorax width), insemination success (stored sperm counts and sperm viability), and mating number (determined by patriline genotyping of worker offspring). We found that queens had an average of 4.37 ± 1.446 million stored sperm in their spermathecae with an average viability of 83.7 ± 13.33%. We also found that the tested queens had mated with a high number of drones (average effective paternity frequency: 17.0 ± 8.98). Queen “quality” significantly varied among commercial sources for physical characters but not for mating characters. These findings suggest that it may be more effective to improve overall queen reproductive potential by culling lower-quality queens rather than systematically altering current queen production practices.

Mating frequencies of Africanized honey bees in the south western USA

Summary Emerging evidence suggests that there are significant adaptive advantages conferred to genetically diverse honey bee colonies through multiple matings with queens. We determined the intracolony genetic diversity of Africanized honey bee (AHB) colonies from a feral population in the south western USA. A total of 1,253 worker offspring were genotyped from 20 feral colonies (all but three of African mitotype), four managed AHB, three managed European honey bee (EHB), and four control colonies (headed by EHB queens instrumentally inseminated with one, two, five, or ten drones, respectively) using eight microsatellite markers. The 17 feral AHB queens mated with an average of 20.0 ± 6.53 (range 10–32) drones, resulting in effective paternity frequencies of 20.0 ± 8.46 (range 10.56–37.53), which is one of the highest mating numbers recorded within the species. Though Africanized honey bee colonies are among the most genetically diverse Apis mellifera yet recorded, their queen mating frequencies are within the expected range of the species overall, including African honey bees in their native range. The factors responsible for these findings are discussed.

Mating frequencies of honey bee queens (Apis mellifera L.) in a population of feral colonies in the northeastern United States.

Across their introduced range in North America, populations of feral honey bee (Apis mellifera L.) colonies have supposedly declined in recent decades as a result of exotic parasites, most notably the ectoparasitic mite Varroa destructor. Nonetheless, recent studies have documented several wild populations of colonies that have persisted. The extreme polyandry of honey bee queens—and the increased intracolony genetic diversity it confers—has been attributed, in part, to improved disease resistance and may be a factor in the survival of these populations of feral colonies. We estimated the mating frequencies of queens in feral colonies in the Arnot Forest in New York State to determine if the level of polyandry of these queens is especially high and so might contribute to their survival success. We genotyped the worker offspring from 10 feral colonies in the Arnot Forest of upstate New York, as well as those from 20 managed colonies closest to this forest. We found no significant differences in mean mating frequency between the feral and managed queens, suggesting that queens in the remote, low-density population of colonies in the Arnot Forest are neither mate-limited nor adapted to mate at an especially high frequency. These findings support the hypothesis that the hyperpolyandry of honey bees has been shaped on an evolutionary timescale rather than on an ecological one.

Consumer demand for local honey

How to best target and attract niche market consumers is an important marketing problem for producers of specialty agricultural products. It is particularly an issue in the honey market where consumers increasingly face media messages regarding threats to honey bee health, honey adulteration and health benefits of locally produced honey. Using auction experiments, this research evaluates consumer behaviour related to informational messages about honey that is produced locally, domestically and internationally. Results from 115 adult consumers show that consumers’ demand for honey varies significantly based on the geographic location of the honey’s production, product packaging and the information they have about the product. Consumers demonstrate greater demand for locally produced honey, especially when provided information about negative aspects of internationally produced honey that include adulteration. This shows that such negative media attention on specialty products offers small producers an opportunity to increase profitability by marketing themselves as a specialized niche alternative.

Novel microsatellite loci reveal high genetic diversity yet low population structure for alfalfa leafcutting bees in North America

The alfalfa leafcutting bee, Megachile rotundata (ALCB) is an economically important pollinator necessary for seed production of the critical forage crop alfalfa, Medicago sativa. The pollinator was accidentally introduced to North America from Europe approximately 70 years ago, and it is primarily produced in Canada and shipped to the United States annually en masse for seed field pollination. We investigate how the large-scale commercial movement of this bee affects the genetic structure of populations in the North American seed growing system and compare the genetic diversity and structure of introduced North American bees with two native European populations. Using 16 newly developed microsatellite loci, we describe the North American population structure of this bee. ALCBs collected from alfalfa seed farms have a degree of genetic variability similar to one native European population, but lower than the second. Considering that the species was accidentally introduced into North America, we anticipated more signature of a founder effect. Despite the level of genetic variability, we found little, if any, genetic structuring across North America, other than that the North American populations were distinct from the European populations sampled. While we detected some sub-structure in North American populations using Bayesian methods, the structuring was without geographic pattern, and we propose it is the result of the intense human management and movement of these bees. The trade and movement of these bees by humans has created a nearly panmictic M. rotundata population across the continent, which has implications relevant to the preservation and conservation of other bee pollinators.

Assessing the Role of Environmental Conditions on Efficacy Rates of Heterorhabditis indica (Nematoda: Heterorhabditidae) for Controlling Aethina tumida (Coleoptera: Nitidulidae) in Honey Bee (Hymenoptera: Apidae) Colonies: a Citizen Science Approach.

Abstract Certain species of entomopathogenic nematodes, such as Heterorhabditis indica Poinar, Karunakar & David, have the potential to be effective controls for Aethina tumida (Murray), or small hive beetles, when applied to the soil surrounding honey bee (Apis mellifera L.) hives. Despite the efficacy of H. indica, beekeepers have struggled to use them successfully as a biocontrol. It is believed that the sensitivity of H. indica to certain environmental conditions is the primary reason for this lack of success. Although research has been conducted to explore the impact of specific environmental conditions—such as soil moisture or soil temperature—on entomopathogenic nematode infectivity, no study to date has taken a comprehensive approach that considers the impact of multiple environmental conditions simultaneously. In exploring this, a multivariate logistic regression model was used to determine what environmental conditions resulted in reductions of A. tumida populations in honey bee colonies. To obtain the sample sizes necessary to run a multivariate logistic regression, this study utilized citizen scientist beekeepers and their hives from across the mid-Atlantic region of the United States. Results suggest that soil moisture, soil temperatures, sunlight exposure, and groundcover contribute to the efficacy of H. indica in reducing A. tumida populations in A. mellifera colonies. The results of this study offer direction for future research on the environmental preferences of H. indica and can be used to educate beekeepers about methods for better utilizing H. indica as a biological control.

Exposure Effects on the Productivity of Commercial Bombus impatiens (Hymenoptera: Apidae) Quads During Bloom in Watermelon Fields

ABSTRACT In light of population declines of honey bees (Apis mellifera L.), research has refocused attention on alternative pollinators and their potential to fulfill pollination services within economically important agricultural crops. Bumble bees are one such alternative, and within the past 20 yr, these pollinators have been reared and sold as commercial pollinators. Investigation into their use has been limited and more research is needed to improve pollinator effectiveness in field settings. Quad pollination units of the commercially reared native bumble bee species, the common eastern bumble bee (Bombus impatiens Cresson), were monitored and evaluated for productivity during peak watermelon [Citrullus lanatus (Thunberg) Matsumura & Nakai] bloom in southern Delaware. Differing colony exposures including various shade structure designs and natural shade were compared to assess the quality of the shade in regards to bumble bee activity during watermelon bloom. Quads receiving different nest treatments were evaluated on the basis of foraging activity and colony weight gain. Results indicated that colonies within quads provided with artificial or natural shade had significantly more foraging activity, weighed more, and produced more cells than colonies in quads placed in the field with no shade. Colonies within quads provided with artificial and natural shade peaked later in terms of foraging and weight gain, suggesting that growers could extend harvest to take advantage of later markets and possible movement into fields that were planted later.