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“Altruistic self-removal of health-compromised honey bee workers from their hive.” INTRODUCTION:
Honey bees are known for displaying many altruistic (unselfish, self-sacrificing) tendencies. There are many noteworthy altruistic actions performed by the honey bee. The scientists point out that honey bees will attack and sting threats to the hive even though they also end up killing themselves in the process. They gather and share food with the entire hive, and participate in a diffusion of responsibility of care for the offspring of the queen. Honey bee workers display concern for the good of the whole over care for themselves. Bees that are “developmentally deformed” (Rueppell, Hayworth, and Ross 1538) will leave the hive, and “…: diploid males signal their infertile status at an early developmental stage to be cannibalized and preserve colony resources” (Rueppell, Hayworth, and Ross 1538 quoting Santomauro et al., Why did the scientists do this research? The scientists stated that the most important element of altruism in the honey bee worker is that if they become compromised with an illness; a fungus, a toxin etc., they will remove themselves from the colony, effectively committing suicide, in order to protect the rest of the bees. The scientists wanted to show that not only was this phenomena actually happening, but that possible explanations (such as illness making the N e w k i r k | 2
bees forget where the hive was, or that other bees were forcing sick bees from the hive) were either incorrect or not the primary cause. The hypothesis was that honey bees exposed to toxin or illness would promptly leave the colony to protect the masses. They hypothesized further that the actions were in fact altruistic, and weren’t being caused by an increased need to feed (due to being under stress), or being MATERIALS AND METHODS:
They first tested the rate at which young (seven day old) bees died when exposed to the drug hydroxyurea, and exposure to CO2. Then they tested to see how soon compromised bees would vacate the hive after being re-introduced and locked in for a period of time. The next experiment involved attempting to prove that the bees were leaving specifically because they were trying to protect the colony, not because of external factors such as a reaction to the drug or When testing the mortality with the hydroxyurea drug they fed the bees either sucrose mixed with the drug, or a pure sucrose control. For the CO2 test they exposed the bees to a >95% concentration for two hours, and a control group was briefly anaesthetized and tagged. The bees were returned to an observation hive and prevented from leaving. When the bees were allowed to leave the hive they would enter a covered walkway where they could be observed and studied. During the next experiment, attempting to prove that the bees were leaving on their own accord, random samples of bees were collected and put together to study. They were studied in a hive that had access on top of the hive to introduce bees, and eight tubes coming off the exit of the hive so that bees leaving could be collected for study. 500 of the 1000 bees living in the hive were collected and sorted in to test and control groups. The bees were tagged and put into storage N e w k i r k | 3
containers according to which group they were in, and were given free access to sucrose. The control group was given a pure sucrose and water mixture known as “queen candy” (Rueppell, Hayworth, and Ross 1540), the hydroxyurea group was given queen candy with the drug mixed in, and the last group was exposed to CO2. Aside from the administration of the variables the two test groups were treated in the same manner as the control groups were. All groups were returned to the observation hive together and were prevented from leaving for 12 hours. RESULTS:
The initial studies showed that more drugged bees died or went missing than the control bees, and the bees exposed to CO2 had similar patterns. The bees that were treated and kept in captivity died 23.1% of the time, however of those allowed free 95% disappeared on the third day which showed a much higher mortality rate. The experimental bees fed less when given access to food, and distributed the food to the hive less when returned. DISCUSSION:
The scientists report that honey bees will leave the hive if compromised and given the chance to, and do not return. Bees that are compromised and not allowed to leave have a much higher survival rate than the bees that leave. By studying the possibilities of stress feeding or disorientation the experiments the scientists ran showed that bees were leaving and staying away N e w k i r k | 4
Rueppell, O., M.K. Hayworth, and N.P. Ross. "Altruistic Self-Removal of Health-Compromised Honey Bee Workers From Their Hive." Journal of Evolutionary Biology 23.7 JUL2010. 1538-1546.Academic Search Premier. Web. 16 Feb 2012. Santomauro, G., Oldham, N.J., Boland, W. & Engels, W. 2004.Cannibalism of diploid drone larvae in the honey bee (Apis mellifera) is released by odd pattern of cuticular

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