Edward E. Southwick

Social control of air ventilation in colonies of honey bees, Apis mellifera

Abstract Fanning behaviour inside the nest of honey bees is an effective mechanism of ventilation. The following results are reported: (1) With only a single small entrance, the fanning is controlled so as to induce tidal ventilation of the nest as in a typical breathing pattern. (2) Periodic active fanning moves an air current out followed by a passive influx of air. (3) Fanning bees show negative phototaxis. (4) The colonial respiratory activity decreases at night following a pronounced day-night cycle.

The honey bee cluster as a homeothermic superorganism

Abstract 1. 1. In winter, oxygen consumption of honey bee ( Apis mellifera L.) clusters resembles that of birds and mammals. 2. 2. Intact clusters of 10–20,000 bees increase metabolism when exposed to cold environmental temperatures. Below 10°C, metabolic rate (W kg −1 ) increases as a function of decreasing ambient temperature following the relation MR = 7.96 — 0.24 T (Fig. 1). 3. 3. Insulative properties of the cluster are estimated and discussed. 4. 4. At moderate ambient temperatures (10–14°C), the cluster “breaks” resulting in a massive increase in total surface area for heat exchange and concomitant large increase in metabolism.

Comparative energy balance in groups of Africanized and European honey bees: ecological implications.

Abstract 1. 1. Groups of honey bees ( Apis mellifera L.) are able to metabolically regulate their central temperature under cold stress. At 2°C, Africanized honey bees in 30 g groups consumed 46.4% more oxygen per unit time holding their core temperatures at 29.0°C compared to European honey bees. 2. 2. Differences in oxygen consumption increase as group sizes decrease. Regression analysis at freezing temperature showed that the two races attain similar costs of energy balance with the same mass when Africanized colonies contain about 20,000 bees and European colonies contain 16,000 bees (Fig. 1). 3. 3. Africanized honey bees tested in groups at temperatures of 2°C and −15°C, showed metabolic rates that were 13–109% higher than those of the temperate region honey bees, but at 22.5°C, the cost of energy maintenance was 54% lower. We predict that physiological and behavioral characteristics combined with climatic conditions in North America will limit the northern distribution of nesting Africanized honey bees to a 120 consecutive day isoline of temperatures not exceeding 10°C during Winter (Fig. 2). In some southern regions of the USA, the Africanized race will have competitive advantage over the European honey bees now extant.

Metabolic energy of intact honey bee colonies

Abstract 1. 1. In late winter, oxygen consumption of honey bee ( Apis mellifera L.) clusters showed marked 24-hr periodicity, even when held under constant temperature conditions. 2. 2. Minimal rates of metabolism (as low as 3.4 w kg −1 ) were usually reached at night ( ca . 0500 hr), and maximum rates (as high as 33.5 w kg −1 ) in midday ( ca . 1400 hr). 3. 3. Colonies with brood showed less excursion in daily metabolic rate, by maintaining higher night-time levels. 4. 4. There is a pronounced decrease in metabolic rate for the intact cluster of 9480–23,394 bees from the rates reported for individuals or small groups of bees.

Social synchronization of circadian rhythms of metabolism in honeybees (Apis mellifera)

ABSTRACT. Groups of honeybee workers (Apis mellifera Linn.; Hymenoptera: Apidae) show endogenous circadian rhythms in metabolic activity. Workers entrained to two different photoperiods, when put together in a group, coordinate their individual metabolic activity cycles into a synchronized group oscillation. Either physical interaction among workers, or a low volatility contact pheromone, is implicated in the control of this oscillating system.

Phenotype interactions in group behavior of honey bee workers (Apis mellifera L.)

SummaryThe alarm reaction of groups of honey bee workers was quantified using a metabolic bioassay. The genetic structure of these groups was varied in order to estimate the effects of worker interactions. Though the group phenotype was mainly determined by additive interactions, nonlinear effects were also found. Mixed worker groups, combined from colonies with similar reactivity in the bioassay, showed a stronger response than pure groups. This phenomenon, analogous to the overdominance model for individuals in classical genetics, has implications for mechanisms of natural and artificial selection in social populations and for the evolution of polyandry in social Hymenoptera.

Metabolic response to alarm pheromone in honey bees

Exposure to alarm pheromone elicits increases in oxidative metabolism in Apis mellifera. The following quantitative results are reported: (1) The alarm response, measured by short-term elevated oxygen consumption in each bee, increases with increasing numbers of bees in the test groups. The rate of increase in response per bee shows a group effect which is greatest in small groups (1–100 bees) and remains constant in larger groups (up to 6,700 bees). (2) The pheromone concentration affects the reaction elicited. The greater the dose, the larger is the reaction up to a concentration of 2.4 μg/ml. Greater doses elicit no greater response. (3) Response to the pheromone by winter bees is maximum at 20°C and decreases at air temperatures above or below this value. (4) This metabolic reaction may provide a tool for quantitating temperament of honey bees.

Cooperative metabolism in honey bees: An alternative to antifreeze and hibernation

Abstract 1. 1. The socially organized honey bees ( Apis mellifera L.) gather together in clusters and cooperatively function in homeothermy under conditions of cold stress. 2. 2. When gathered in large clusters, bees maintain a central core temperature of 34°C even during exposure to extreme cold air temperatures down to −80°C. 3. 3. Cold-induced heat production is an inverse function of group size, with maximum mass-specific values equalling those reported for mammals.

Maternal and pre eclosional factors affecting alarm behaviour in adult honey bees (Apis mellifera L.)

SummaryThe inheritance of a group character, the alarm behaviour of honey bee workers (Apis mellifera L.), was analyzed using a metabolic bio-assay. In a diallel test cross of preselected queens and drones, genetic variance and maternal effects on this behaviour were estimated. Crossfostering experiments showed that the hive environment during larval and pupal development has only minor effects on alarm behaviour.ZusammenfassungDie Vererbung eines Gruppenmerkmales, der Alarmierungsreaktion von Arbeiterinnen (Apis mellifera L.) wurde in einem quantitativen Stoffwechseltest überprüft. In einer diallelen Testkreuzung von selektierten Königinnen und Drohnen konnten genetische Varianzkomponenten sowie maternale Effekte geschätzt werden. Experimente, in denen Eier von fremden Pflegevölkern zu Imagines aufgezogen wurden, zeigten, dass die Stockumwelt während der Larval-und Pupalentwicklung keinen Einfluss auf das spätere Alarmverhalten der Arbeiterinnen nimmt.

What Is a Superorganism

Human beings have a very limited capacity to understand complex multidimensional systems and therefore they are in need of models that simplify the degree of complexity. The simplicity of the genetics and the physiology of Escherischia coli, for example, allowed for the tremendous progress in molecular biology. Protozoan eucaryotes with chromosomes and a diploid phase already increase the complexity substantially. Genes in the genome can interact and make the analysis of gene expression less simple. Nevertheless, the physiology and genetics of single cells are relatively transparent, and these cells are common experimental organisms in the molecular biology laboratory (e.g. baker’s yeast, Saccheromyces cerevisiae). The more complex systems must be used whenever questions related to diploid organisms have to be addressed. But what if we want to understand biological mechanisms in more complex organisms that are comprised of more than a single cell? Besides the interaction at the gene level within the cell, we would expect interactions between cells. Even if all these cells contain the identical genetic information, only a part of these genes will be expressed. One cell could well control gene expression in another which would obscure the analysis of individual gene action. The analyses of such interactions at the cell level are particularly well documented in the early development of Drosophila melanogaster embryos, where gene regulation of segmentation was studied in detail (e.g. Nusslein-Vollhard and Wieschaus 1980; McGinnis et al. 1984a,b; Gehring 1987). Nevertheless, we are far from understanding the physiological basis of specialization of cells during development in multicellular organisms.