Michael L. Smith

Crowding honeybee colonies in apiaries can increase their vulnerability to the deadly ectoparasite Varroa destructor

When humans switched from hunting honeybee colonies living scattered in the wild to keeping them in hives crowded in apiaries, they may have greatly increased disease transmission between colonies. The effects of clustering colonies were studied. Two groups of 12 colonies, with hives crowded or dispersed, were established in a common environment and left untreated for mites. Drones made many homing errors in the crowded group, but not in the dispersed group. In early summer, in both groups, the colonies that did not swarm developed high mite counts, but the colonies that swarmed maintained low mite counts. In late summer, in the crowded group but not in the dispersed group, the colonies that swarmed also developed high mite counts. All colonies with high mite counts in late summer died over winter; all colonies with low mite counts in late summer survived over winter. Evidently, swarming can reduce a colony’s mite load, but when colonies are crowded in apiaries, this mite-load reduction is erased as mites are spread through drifting and robbing.

How Honey Bee Colonies Survive in the Wild: Testing the Importance of Small Nests and Frequent Swarming.

The ectoparasitic mite, Varroa destructor, and the viruses that it transmits, kill the colonies of European honey bees (Apis mellifera) kept by beekeepers unless the bees are treated with miticides. Nevertheless, there exist populations of wild colonies of European honey bees that are persisting without being treated with miticides. We hypothesized that the persistence of these wild colonies is due in part to their habits of nesting in small cavities and swarming frequently. We tested this hypothesis by establishing two groups of colonies living either in small hives (42 L) without swarm-control treatments or in large hives (up to 168 L) with swarm-control treatments. We followed the colonies for two years and compared the two groups with respect to swarming frequency, Varroa infesttion rate, disease incidence, and colony survival. Colonies in small hives swarmed more often, had lower Varroa infestation rates, had less disease, and had higher survival compared to colonies in large hives. These results indicate that the smaller nest cavities and more frequent swarming of wild colonies contribute to their persistence without mite treatments.

The behavioral regulation of thirst, water collection and water storage in honey bee colonies.

ABSTRACT This study investigated how a honey bee colony develops and quenches its collective thirst when it experiences hyperthermia of its broodnest. We found that a colony must strongly boost its water intake because evaporative cooling is critical to relieving broodnest hyperthermia, and that it must rapidly boost its water intake because a colony maintains only a small water reserve. We also clarified how a colonys water collectors know when to spring into action – by sensing either more frequent requests for fluid or greater personal thirst, or both. Finally, we found that the behavioral flexibility of a colonys water collectors enables them not only to satisfy their colonys current water needs but also to buffer their colony against future extreme water stresses by storing water in their crops and in their combs. Highlighted Article: When a honey bee colony experiences broodnest hyperthermia, its water collectors quickly spring into action after being begged for fluid.

Varroa destructor mites can nimbly climb from flowers onto foraging honey bees

Varroa destructor, the introduced parasite of European honey bees associated with massive colony deaths, spreads readily through populations of honey bee colonies, both managed colonies living crowded together in apiaries and wild colonies living widely dispersed in natural settings. Mites are hypothesized to spread between most managed colonies via phoretically riding forager bees when they engage in robbing colonies or they drift between hives. However, widely spaced wild colonies show Varroa infestation despite limited opportunities for robbing and little or no drifting of bees between colonies. Both wild and managed colonies may also exchange mites via another mechanism that has received remarkably little attention or study: floral transmission. The present study tested the ability of mites to infest foragers at feeders or flowers. We show that Varroa destructor mites are highly capable of phoretically infesting foraging honey bees, detail the mechanisms and maneuvers by which they do so, and describe mite behaviors post-infestation.

Caught in an evolutionary trap: worker honey bees that have drifted into foreign colonies do not invest in ovary activation

Drifting, the phenomenon whereby workers from one colony find their way into a foreign colony, is widespread in social insects. In apiaries of the honey bee Apis mellifera, orientation errors lead to high rates of worker drift. Given that A. mellifera workers in apiaries enter foreign colonies accidentally, do they continue to refrain from laying eggs in the foreign colony, or do they behave in their evolutionary interests and attempt to lay eggs? We propose two hypotheses: the “lost losers” hypothesis, where lost workers do not invest in personal reproduction, and the “lost social parasites” hypothesis, where lost workers detect that they are in a foreign colony and do invest in personal reproduction. Previous work has used complete ovary activation as an assay for testing whether workers invest in personal reproduction, but this may not detect subtle reproductive investments in queenright colonies. We instead look at the full range of ovary activation in natal and non-natal workers, because partial activation may signal preparation for future reproduction. We show that in queenright colonies, non-natal workers have the same low degree of ovary activation as their natal counterparts, which supports the hypothesis that drifted bees are “lost losers” caught in an evolutionary trap.

Honey bee sociometry: Tracking honey bee colonies and their nest contents from colony founding until death

Sociometry is the description and analysis of the physical and numerical attributes of social insect colonies over their lifetimes. Sociometric data, such as worker number and nest size are essential for understanding how colonies develop but are rarely collected. Even Apis mellifera, the most intensively studied social insect, has never received a broad-scale sociometric study. To help fill this gap, we monitored four honey bee colonies living in large observation hives from when they began as swarms (July 2012), to when they died (January 2014). We tracked multiple colony parameters, including worker and drone populations, comb area and use, swarming rate, and colony death. Each colony’s life history is described through its founding, ergonomic, and reproductive stages.

Honey bee sting pain index by body location

The Schmidt Sting Pain Index rates the painfulness of 78 Hymenoptera species, using the honey bee as a reference point. However, the question of how sting painfulness varies depending on body location remains unanswered. This study rated the painfulness of honey bee stings over 25 body locations in one subject (the author). Pain was rated on a 1–10 scale, relative to an internal standard, the forearm. In the single subject, pain ratings were consistent over three repetitions. Sting location was a significant predictor of the pain rating in a linear model (p < 0.0001, DF = 25, 94, F = 27.4). The three least painful locations were the skull, middle toe tip, and upper arm (all scoring a 2.3). The three most painful locations were the nostril, upper lip, and penis shaft (9.0, 8.7, and 7.3, respectively). This study provides an index of how the painfulness of a honey bee sting varies depending on body location.

Partial ovary development is widespread in honey bees and comparable to other eusocial bees and wasps

Honey bee workers have few opportunities for direct reproduction because their ovary development is chemically suppressed by queens and worker-laid eggs are destroyed by workers. While workers with fully developed ovaries are rare in honey bee colonies, we show that partial ovary development is common. Across nine studies, an average of 6% to 43% of workers had partially developed ovaries in queenright colonies with naturally mated queens. This shift by workers toward potential future reproduction is linked to lower productivity, which suggests that even small investments in reproductive physiology by selfish workers reduce cooperation below a theoretical maximum. Furthermore, comparisons across 26 species of bees and wasps revealed that the level of partial ovary development in honey bees is similar to that of other eusocial Hymenoptera where there is reproductive conflict among colony members. Natural variation in the extent of partial ovary development in honey bee colonies calls for an exploration of the genetic and ecological factors that modulate shifts in cooperation within animal societies.

Tanging does not cause flying swarms to settle

Summary Tanging, the act of hitting metal objects together to produce a clanging sound, is used by some beekeepers to induce flying swarms to settle. The effectiveness of this practice is anecdotally supported, but has never been experimentally tested. In this experiment, four swarms were exposed to tanging during the first 255 ± 112 m of their flights to new nest sites. In total, tanging was performed over 1019 m, for 22 min 56 sec. No evidence was found that tanging causes a flying swarm to settle.