http://www.tsusinvasives.org/dotAsset/3b275f2a-205c-4012-b48a-038a13dddf8f.pdf

Biology and control of Varroa destructor

Background: Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. Methods and Principal Findings: Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in control colonies than CCD-affected colonies. Conclusions/Significance: This is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted.

/pdf/colony-collapse-disorder-a-descriptive-study-4siqce7pxx.pdf

Colony Collapse Disorder: A Descriptive Study

A historical review of managed honey bee populations in Europe and the United States and the factors that may affect them.

Adequate nutrition supports the development of healthy honey bee colonies. We give an overview of the nutritional demands of honey bee workers at three levels: (1) colony nutrition with the possibility of supplementation of carbohydrates and proteins; (2) adult nutrition and (3) larval nutrition. Larvae are especially dependant on protein and brood production is strongly affected by shortages of this nutrient. The number of larvae reared may be reduced to maintain the quality of remaining offspring. The quality of developing workers also suffers under conditions of larval starvation, leading to slightly affected workers. Larval starvation, alone or in combination with other stressors, can weaken colonies. The potential of different diets to meet nutritional requirements or to improve survival or brood production is outlined. We discuss nutrition-related risks to honey bee colonies such as starvation, monocultures, genetically modified crops and pesticides in pollen and nectar.

/pdf/nutrition-and-health-in-honey-bees-v0p1j6ntf3.pdf

Nutrition and health in honey bees

Honey bee colonies are highly dependent upon the availability of floral resources from which they get the nutrients (notably pollen) necessary to their development and survival. However, foraging areas are currently affected by the intensification of agriculture and landscape alteration. Bees are therefore confronted to disparities in time and space of floral resource abundance, type and diversity, which might provide inadequate nutrition and endanger colonies. The beneficial influence of pollen availability on bee health is well-established but whether quality and diversity of pollen diets can modify bee health remains largely unknown. We therefore tested the influence of pollen diet quality (different monofloral pollens) and diversity (polyfloral pollen diet) on the physiology of young nurse bees, which have a distinct nutritional physiology (e.g. hypopharyngeal gland development and vitellogenin level), and on the tolerance to the microsporidian parasite Nosema ceranae by measuring bee survival and the activity of different enzymes potentially involved in bee health and defense response (glutathione-S-transferase (detoxification), phenoloxidase (immunity) and alkaline phosphatase (metabolism)). We found that both nurse bee physiology and the tolerance to the parasite were affected by pollen quality. Pollen diet diversity had no effect on the nurse bee physiology and the survival of healthy bees. However, when parasitized, bees fed with the polyfloral blend lived longer than bees fed with monofloral pollens, excepted for the protein-richest monofloral pollen. Furthermore, the survival was positively correlated to alkaline phosphatase activity in healthy bees and to phenoloxydase activities in infected bees. Our results support the idea that both the quality and diversity (in a specific context) of pollen can shape bee physiology and might help to better understand the influence of agriculture and land-use intensification on bee nutrition and health.

https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0072016&type=printable

Influence of pollen nutrition on honey bee health: do pollen quality and diversity matter?

The colony-level phenotype of an insect society emerges from interactions between large numbers of individuals that may differ considerably in their morphology, physiology, and behavior. The proximate and ultimate mechanisms that allow this complex integrated system to form are not fully known, and understanding the evolution of social life strategies is a major topic in systems biology. In solitary insects, behavior, sensory tuning, and reproductive physiology are linked. These associations are controlled in part by pleiotropic networks that organize the sequential expression of phases in the reproductive cycle. Here we explore whether similar associations give rise to different behavioral phenotypes in a eusocial worker caste. We document that the pleiotropic genetic network that controls foraging behavior in functionally sterile honey bee workers (Apis mellifera) has a reproductive component. Associations between behavior, physiology, and sensory tuning in workers with different foraging strategies indicate that the underlying genetic architectures were designed to control a reproductive cycle. Genetic circuits that make up the regulatory “ground plan” of a reproductive strategy may provide powerful building blocks for social life. We suggest that exploitation of this ground plan plays a fundamental role in the evolution of social insect societies.

https://www.pnas.org/content/pnas/101/31/11350.full.pdf

Reproductive ground plan may mediate colony-level selection effects on individual foraging behavior in honey bees

The ectoparasitic mite Varroa destructor (Anderson & Trueman) is the most destructive pest of the honey bee, Apis mellifera L., in Europe and the United States. In temperate zones, the main losses of colonies from the mites occur during colony overwintering. To obtain a deeper knowledge of this phenomenon, we studied the mites’ impact on the vitellogenin titer, the total protein stores in the hemolymph, the hemocyte characteristics, and the ecdysteroid titer of adult honey bees. These physiological characteristics are indicators of long-time survival and endocrine function, and we show that they change if bees have been infested by mites during the pupal stage. Compared with noninfested workers, adult bees infested as pupae do not fully develop physiological features typical of long-lived wintering bees. Management procedures designed to kill V. destructor in late autumn may thus fail to prevent losses of colonies because many of the adult bees are no longer able to survive until spring. Beekeepers in temperate climates should therefore combine late autumn management strategies with treatment protocols that keep the mite population at low levels before and during the period when the winter bees emerge.

https://www.bijenhouders.nl/files/Bijengezondheid/AmdaM%20et%20al%202004.%20altered%20physiology%20worker%20infested%20by%20Varroa.pdf

Altered Physiology in Worker Honey Bees (Hymenoptera: Apidae) Infested with the Mite Varroa destructor (Acari: Varroidae): A Factor in Colony Loss During Overwintering?

Le developpement et l'usage largement repandu de l'abeille domestique (Apis mellifera L.) comme organisme modele d'etude necessitent des methodes qui permettent aux chercheurs de travailler avec des ouvrieres adultes issues d'embryons genetiquement manipules. Les protocoles d'elevage in vitro sont prevus pour des ouvrieres d'abeilles et des reines mais peuvent etre imparfaits si une faible variance interindividuelle ou un grand nombre d'abeilles sont necessaires. Nous presentons ici un nouveau protocole pour l'elevage des ouvrieres. L'utilisation d'un modele de ruche mis au point pour le travail au laboratoire nous a permis de recolter, de manipuler et d'introduire des centaines d'oeufs sans ouvrir les ruches durant ces procedes. Les oeufs fraichement pondus ont ete recoltes et ont recu une injection d'eau sans nuclease (lot 1), ou d'ARN a double chaine (ARNds) (lot 2) ou sont restes non traites (lot 3). Ils ont ete maintenus en etuve durant 65 h, puis introduits dans les ruches de laboratoire ou ils ont eclos. Nous avons note 2j plus tard si l'oeuf avait ou non ete accepte. En outre, les caracteristiques physiologiques et morphologiques d'abeilles âgees de 0 a 5 j issues d'oeufs maintenus en etuve et non traites ont ete comparees a celles d'ouvrieres qui etaient nees naturellement dans les colonies (temoins). Les colonies ont accepte un. pourcentage satisfaisant d'oeufs des trois lots (0,44 ± 0,06 ; 0,28 ± 0,05, et 0,53 ± 0,04, respectivement), mais l'acceptation des oeufs du lot 2 (injection d'ARNds) a ete significativement plus faible que celle des deux autres lots (test de Fisher post-hoc : P < 0,05, df = 87). Les caracteristiques physiologiques et morphologiques des ouvrieres d'oeufs manipules, a savoir la teneur totale en proteines de l'hemolymphe, la largeur de la tete, la longueur de l'antenne (scape) et la longueur des veines radiale et mediane, n'etaient pas differentes de celles des temoins (Hotelling's T 2 = 4,7, P = 0,47 et T 2 = 4,9, P = 0,54 pour les ouvrieres âgees de 0 et de 5 j, respectivement). Les resultats montrent que notre methode sera utile pour produire des ouvrieres mutantes lorsque les modifications ne s'expriment pas encore dans le phenotype au cours de la periode larvaire. La technique semble surmonter les principaux problemes associes a l'elevage in vitro et c'est encourageant, car le besoin d'outils pratiques pour elever des ouvrieres genetiquement manipulees augmentera vraisemblablement dans les prochaines annees.

/pdf/a-new-method-for-rearing-genetically-manipulated-honey-bee-207ogyb1c7.pdf

Gro V. Amdam

Papers

Reproductive ground plan may mediate colony-level selection effects on individual foraging behavior in honey bees

Altered Physiology in Worker Honey Bees (Hymenoptera: Apidae) Infested with the Mite Varroa destructor (Acari: Varroidae): A Factor in Colony Loss During Overwintering?

A new method for rearing genetically manipulated honey bee workers

Social Life from Solitary Regulatory Networks:: A Paradigm for Insect Sociality