Our third instalment of delving into cognition and other cool facts about highly social insects.
The grand finale of our trilogy is the stingless bee group. This is the least studied group out of other highly social bees (bumblebees and honeybees). However this does not make them any less interesting as these bees are full of secrets and mysterious behaviours that are yet to be understood.
As a brief introduction stingless bees are found all across the tropics and subtropics of the world and include 600 species, 11 of them in Australia (Gruter, 2020). Contrarily to their highly popular cousins, the stingless bees remain understudied and little is known about their cognition abilities. However in the past decades the research on stingless bees has ramped up and countries like Brazil and Costa Rica have carried out most of the research on these fascinating little insects. Join us today for a brief, fun and interesting summary on what is known about their learning behaviour so far.
It’s getting hot in here…
Heat is an incredibly important factor which hives must cope with, especially those in hotter climates, as the cognitive abilities of bees can be impacted by even a change of 2 degrees from what they are used to. This is also quite applicable in a time where temperatures are rising and there is significant decline in our pollinators, something which we at PlantingSeeds are working to reduce this impact by putting beehives into schools creating an interconnected highway of pollinator friendly areas.
Research has delved into how stingless bees manage the increase in temperature of the hive. Honey bees have been known to fan their wings to a significant degree in order to increase the circulation of air within hives, however there has been limited information given on stingless bees. This research delves into that gap in the literature identifying that the stingless bees were able to cool their hive to a maximum of 1.6 degrees cooler than the control hive.
This research identifies that this happens due to active behaviours of stingless bees such as fanning and water collection. They were able to measure this distinction by having two hives, one control and one with a brood of stingless bees. They were able to measure water collection by anaesthetising the bees with CO2, and measuring the crop content which they had brought, this was considered to be water if it contained less than 2% sugar. The fanning of the bees was measured by counting how many individual bees were fanning within the hive. Overall the results were that 20% of both colonies collected water and that fanning was positively correlated with the brood temperature indicating that both actions are related to decreasing temperature.
So just like humans who need a fan and a glass of water when they are hot, bees undertake their own behaviours to ensure that they and their brood are kept cool during hot periods.
Are you getting a coffee buzz? Cause i’m not
It may surprise you but bees are in fact impacted by caffeine in a similar way to humans. Where we may get a buzz if we have two or three cups, bees also get a buzz from caffeine. Plants and bees have a strong relationship, with plants providing pollinators with pollen and other foods and pollinators assisting in the reproduction of these plants. In some plants nicotine and caffeine are added to the pollen which has been shown to have an impact on different bees.
This research into caffeine and how it impacts bees, drastically differs between bee species and context. For instance caffeine impacts European Honeybees (Apis meliferra) by impacting their foraging behaviour, increasing the amount of nectar bees drink, improving learning performance and increasing recruitment and persistence to the nectar sources. Indicating similar behaviours to how we focus better after having a cup of coffee. These studies thus suggest that realistic levels of caffeine increase foraging abilities of both Honeybees and Bumblebees, however this can cause issues for hives as bees may focus on caffeinated nectar sources rather than sources with higher quantities of sugar.
In trying to identify if this has the same effect on Stingless bees (P. droryana) researchers tested how stingless bees respond to caffeine. The experiment was designed through training bees to go to certain artificial feeders 10 m away from the main colony then changing the sucrose levels by adding caffeine to the feeders and counting how many bees attended each feeder within a time period. The results were that there was no significant difference between feeders indicating bees did not change their behaviour after having caffeine. One of the reasons raised for this is because Stingless bees are potentially more used to the caffeine and are able to break it down quicker before it affects them.
Stingless bees are able to resist caffeine in a way that other bees aren’t because of their exposure to plants which have caffeine within their pollen. We think it’s important at PlantingSeeds to know some of these differences between species so that you are considered when planting, if you would like further information on the best types of plants for different pollinators go to our website.
One bee told another bee
When forager bees fly out on a scout for food and they find a tasty flower patch, they collect pollen and nectar and bring it back into the hive. What happens then is very interesting. Through a process called reactivation the active foragers communicate with other foragers inside of the colony about the food sources nearby. This process can happen through trophallaxis. In which the foragers that brought food exchange this food with other foragers through their little tongues. Taking the meaning of kiss and tell to a whole new level.
Another way to communicate is through jostling with other foragers and vibrating the body. Minimal behaviours such as thoracic vibrations without any physical contact can be enough to give information about the yummy food source. In some species even the playback of sound was enough to help other foragers find the food source! The other nestmates will then assess the quality of the food and forage for it depending of course on how yummy the actual food source is.
The hansel and gretel strategy
Another amazing way stingless bees communicate is through pheromone trails. These are basically little trails of odours that help the bees find themselves within the environment. Just like Hansel and Gretel leaving little pieces of bread crumbs around a forest trail. The bees mark with scents, they stop at any landing sites (i.e. leaves, rocks, soil, human constructions), rub their bodies, mouthparts and flap their wings leaving a special perfume on specific sites to help themselves and other nestmates also find their way.
Also, let’s remember the term Waggle dance is coined specifically for the honeybees. This means that stingless bees do not dance inside of the hive in order to tell information about the food sources. A big advantage of pheromone trails compared to the waggle dance is that these trails are done in a 3-dimensional set up contrary to a 2-dimensional set up, which adds a whole bunch of extra information. For instance, imagine you are in a rainforest with different levels of canopies and trees everywhere with different heights. Scent trails would come particularly handy in this type of environment.
That is all for our Bee-autiful trilogy of highly social bees. We hope you learned a lot about the three types of highly social bees. We learned that honey bees can count to 5 and know the concept of zero, that bumblebees can play and move little balls around to get food rewards and that stingless bees can communicate with scent trails. How amazing are bees!
Watch this space for more series related to the social cognition of our pollinators.
References:
Grüter, C. (2020). Stingless Bees. Cham, Switzerland: Springer International Publishing.
Frisch, K. V. (1967). The Dance Language and Language and Orientation of Bees. https://link.springer.com/content/pdf/10.1007%2F978-3-030-60090-7.pdf
Lindauer, M., & Kerr, W. E. (1960). Communication between the workers of stingless bees. Bee world, 41(2), 29-41.
Koethe, S., Fischbach, V., Banysch, S., Reinartz, L., Hrncir, M., & Lunau, K. (2020). A comparative study of food source selection in stingless bees and honeybees: scent marks, location, or color. Frontiers in plant science, 11, 516.
Nieh, J. C. (2004). Recruitment communication in stingless bees (Hymenoptera, Apidae, Meliponini). Apidologie, 35(2), 159-182.
T. Peng et al., Resource profitability, but not caffeine, affects individual and collective foraging in the stingless bee Plebeia droryana, Journal of Experimental Biology 222: 10, 13 May 2019,
DOI: 10.1242/jeb.195503
Vollet-Neto, A., Menezes, C. & Imperatriz-Fonseca, V.L. Behavioural and developmental responses of a stingless bee (Scaptotrigona depilis) to nest overheating. Apidologie 46, 455–464 (2015). https://doi.org/10.1007/s13592-014-0338-6