Scent Mimicry... the story of the beewolf and the cuckoo wasp

The European beewolf (Philanthus triangulum) hunts worker honey bees (Apis mellifera) almost exclusively as a food source for offspring (Strohm et al, 2008). The female beewolf paralyses the worker bee and stores several of them in an underground nest chamber up to 1m long (Strohm et al, 2008). The beewolf then closes up the nest entrance and creates a side entrance where she enters and creates a chamber for brood where she will store 1-6 of the paralysed bees – on one she will deposit an egg (Strohm et al, 2008). The female beewolf even licks the bees, depositing a secretion from the postpharyngeal glands that prevents fungal growth on the bee before the egg can hatch, ensuring there are provisions for her young (Herzner et al, 2007). The beewolf then closes up the brood chamber carefully and never has any contact with her offspring, but she makes sure to leave the kids a packed lunch (Strohm et al, 2008).

European beewolf (Philanthus triangulum) and paralysed worker  honey bee (Apis mellifera)

The female beewolf leaves little opportunity for her vulnerable young to be predated on as she waits until after she has collected food before depositing an egg, then immediately closes the chamber (Strohm et al, 2008). The biggest threat to the beewolf is brood parasitism, and it is believed the beewolf has adopted behaviours to avoid hunting when the parasite species is most active known as an ‘enemy-free space strategy’ (Polidori et al, 2010).

cuckoo wasp (Hedychrum rutilans) approaches beewolf (Philanthus triangulum) nest

There is a specialised cuckoo wasp (Hedychrum rutilans) that has adapted to parasitise the beewolf by depositing an egg in with the beewolf offspring and provisions, that egg hatches and the larvae eats both the paralysed bees and the beewolf offspring. It is believed the cuckoo wasp adopts a combination of strategies to prevent being detected by the beewolf. The cuckoo wasp remains motionless or runs away when they run into the beewolf in her nest and the cuckoo wasp doesn’t leave much evidence of their deception (Strohm et al, 2008). The most interesting strategy though is that the cuckoo wasp avoids detection when they are confronted by a beewolf inside her nest by producing scents very similar to that of the beewolf and leaves inconspicuous scent marks when they deposit an egg into the paralysed bee – this is believed to be the first known chemical mimicry in a parasite of a solitary wasp (Strohm et al, 2008).

Below is a video showing an interaction between the small parasitic cuckoo wasp and the much larger beewolf.

References:

Strohm,E, Kroiss, J, Herzner,G, Laurien-Kehnen, C, Boland, W, Schreier, P & Schmitt, T 2008, ‘A cuckoo in wolves' clothing? chemical mimicry in a specialized cuckoo wasp of the European beewolf (Hymenoptera, Chrysididae and Crabronidae)’, Frontiers in Zoology, vol. 5.

Herzner, G, Schmitt, T, Peschke, K, Hilpert, A & Strohm, E 2007, ‘Food wrapping with the postpharyngeal gland secretion by females of the European beewolf Philanthus triangulum’, Journal of Chemical Ecology, vol. 33, pp. 849–859.

Polidori, C, Bevacqua, S & Andrietti, F 2010, ‘Do digger wasps time their provisioning activity to avoid cuckoo wasps (Hymenoptera: Crabronidae and Chrysididae)?’, Acta Ethol, vol. 13, pp. 11-21.

Image 1: Schmidt, Y 2005, Sphecidae of Europe - Hymenoptera Information System, viewed 28 May 2015, <http://uae.hymis.eu/images001/337_Philanthus_triangulum_Juergen_Schmidt_600x400.jpg>

Image 2: Naturalis Historia 2011, Naturalis Historia, viewed 28 May 2015, <http://www.naturalis-historia.de/bilder/Hedychrum%20rutilans%20f10.JPG>

Video: Bee Wolf Wasp v.s. Cuckoo Wasp - slow motion test Corel Video Studio x5 2012, youtube, viewed 28 May 2015, <https://www.youtube.com/watch?v=M3ApIC9B5I4>

Coevolution in Hymenoptera... the Honey Bee vs. the Giant Hornet

Just about everyone is aware of honey bees (Apis sp.); the crop pollinators, covered in fur and ever so adorable. Less people will know about the Giant Hornet (Vespa mandarinia japonica) that is found throughout Asia and a fierce hunter of the honey bees being able to decimate an entire hive on European honey bees (Apis mellifera) in only a couple of hours. They have a body size of 4-5cm, can travel at speeds of 40km/hr and has a stinger over 0.5cm that injects potentially lethal venom and leaves a wound similar to a bullet hole – it is responsible for over 40 deaths a year in Japan alone. Both species are social and although a vast size and weaponry difference, the native Asian honey bees (Apis cerana japonica) have adapted to this predation in a very interesting way.

Japanese Giant Hornet (Vespa mandarinia japonica) compared to a honey bee (Apis sp.)

V. mandarinia japonica is the only hornet species that have evolved mass predation on other social hymenoptera (Ono et al, 1995). A solo scout hornet will find a food source (for e.g. a honey bee colony) and will kill individual bees to take back to their nest, after several individual kills are made the scout hornet will mark the site with a secretion of a forging site marking pheromone, other foraging nest mates will detect the pheromone and begin killing individual bees as well (Ono et al, 1995). Then things get a little brutal: once there are three or more individual hunting hornets on one hive the hornets attack as one, with each hornet being able to kill 40 bees in a minute with its mandibles - 10-20 hornets can kill over 30,000 bees in one massacre lasting less than 3 hours (Ono et al, 1995).

V. mandarinia japonica attacking an A. mellifera hive and the pile of bodies left from the massacre.

However, the slaughter is what is expected (and seen) when the hornets encounter the introduced European honeybee (A. mellifera). It has been shown that the Japanese Asian honey bee (A. cerana japonica) is able to defend its hive from a mass attack (Ono et al, 1995). A. cerana japonica can detect the hornets pheromone and lure the first scout hornet into the hive by teasing it from the entrance with 100 tasty worker bees who vibrate their abdomens for further temptation - little does the hornet know, there are a thousand bees that have dropped their hive duties and descended from the honeycomb to lie in wait just inside the hive opening (Ono et al, 1995).  As soon as the hornet attacks a bee inside the hive it is engulfed in a ball (‘hot defensive bee ball formation’) of bees that vibrate their bodies, producing high temperatures (47˚C) in the centre of the ball (Ono et al, 1995). But it is not just the temperature that kills the hornet, oh no it gets better – the bees also produce lethal amounts of Carbon dioxide (CO₂) inside the ball that in combination with the high temperatures kills the hornet within 10 minutes (Sugahara & Sakamoto, 2009). It has been found that mixed-species colonies of A. cerana and A. mellifera are able to form this death ball but not as effectively as a pure A. cerana colony (Tan et al, 2011).

A. cerana japonica in the hot defence bee ball formation around v. mandarinia japonica

It is not known as yet exactly how the A. cerana japonica form the defensive ball so quickly as there is some evidence of both acoustic and chemical communication (Ono et al, 1995). It is believed that the V. mandarinia japonica evolved their mass attack as a coevolutionary strategy to counteract the A. cerana japonica defence tactic – the mass attack often works when the bee colony numbers are low, the hornet can then take over the bee’s home and can provide large amounts of food for reproductives (Ono et al, 1995).

References:

Ono, M, Igarashi, T, Ohno, E & Sasaki, K 1995, ‘Unusual thermal defence by a honeybee against mass attack by hornets’, Nature, vol. 377, pp. 334-336.

Sugahara, M & Sakamoto, F 2009,’ Heat and carbon dioxide generated by honeybees jointly act to kill hornets’, Naturwissenschaften, vol. 96, pp. 1133–1136.

Tan, K, Yang, M, Wang, Z, Li, H, Zhang, Z, Radloff, SE, Hepburn, R 2011, ‘Cooperative wasp-killing by mixed-species colonies of honeybees, Apis cerana and Apis mellifera’, Apidologie, vol. 43, pp. 195–200.

Image 1: Armstrong, WP 2012, Wayne's Word, viewed 25 May 2015, <http://waynesword.palomar.edu/images2/AsianHornet5c.jpg>

Image 2: unknown contributor (Korean site – etorrent.co.kr), viewed 25 May 2015, <http://cdn9.pikicast.com/card/3d9b7f26-f956-4a5f-9180-8613b4b4f880_20150330173643989.jpg>

Image 3: Hypescience 2014, Hypescience, viewed 25 May 2015, <http://hypescience.com/wp-content/uploads/2014/10/abelhas.jpg>

Australian native bees – a possible ‘plan b’ for crop pollination in Australia?

As mentioned in a previous blog, the worlds honey bee (Apis mellifera) population is under threat from disease, parasites and the fatal phenomena known as Colony Collapse Disorder. Many of the most severe issues (CCD and Varroa mite most notably) have not reached Australia - but thankfully we have a large array of native bees that could become literal life savers to the human population should those problems arise.

Rescued Tetragonula sp. colony that was transferred into a wooden hive. Notice the difference in honey storage - stingless bees store honey in 'pots' and Apis sp. store honey in cells.

Australia has about 10 species of stingless bees (from the genera Tetragonula and Austroplebeia) which are reported to be important crop pollinators of macadamia, mango, lychee and watermelon and may benefit strawberry, citrus, avocado and more (Australian Native Bee Research Centre, 2014). There are many traits that stingless bees possess that would make them comparable to A. mellifera, including the following:

• Polylectic and adaptable – they will visit a variety of plants and will adapt to new species
• domestication – some species can be kept in hives and managed
• perennial colonies – year round foraging
• constancy – workers visit one plant species per trip
• forager recruitment – like the bees recruitment dance, workers provide information to others on location of food sources
• storage of food – their need to continuously stock-up on food despite adequate stores can be mutually beneficial to crops and the bee
• resistant to diseases and parasites that kill A. mellifera

(Heard, 1999).

There is research being done into the effectiveness of Tetragonula carbonaria on pollinating capsicum species in greenhouses and they have been found to be very effective pollinators in confined spaces such as glasshouses (Australian Native Bee Research Centre, 2014).

Tetragonula worker shows her adaptability by stealing some free wax from a candle. image courtesy of Peter O. 

Certain crops require buzz-pollination, or sonication pollen-dispensing, which requires a bee to vibrate its wings at a certain frequency while on a flower allowing it to shed its pollen (Moore, 1996). Research has been done on the use of native Blue Banded bee species Amegilla chlorocyanea in buzz pollination of tomatoes in greenhouses and the findings show that they are very effective visiting up to 1200 tomato flowers per day (Hogendoorn et al, 2007). The video below lets you see and hear the process of Amegilla sp. buzz pollinating a backyard tomato plant.

There are multiple native bee species - including Carpenter (Xylocopa sp.), Blue Banded (Amegillia sp.), Teddy Bear (Amegilla (Asaropoda)) - capable of performing this task and so prevent the need to introduce European bumblebees (Bombus terrestris) to mainland Australia (Australian Native Bee Research Centre, 2014).

Great Carpenter Bee (Xylocopa sp.) buzz pollinating a flower. photo courtesy of Corinne Jordan and the Australian Muse. 

References:

Heard, TA 1999, ‘The role of stingless bees in crop pollination’, Annual Review of Entomology, vol. 44, pp. 183-206.

Hogendoorn, K, Coventry, S & Keller, M 2007, 'Foraging behaviour of a blue banded bee, Amegilla chlorocyanea in greenhouses: implications for use as tomato pollinators’, Apidologie, vol. 38, pp. 86-92.

Moore, PD 1996, ‘The buzz about pollination’, Nature, vol. 384, pp. 27.

Aussie Bee, Australian Native Bee Research Centre, North Richmond NSW, viewed 10 May 2015, <http://www.aussiebee.com.au/croppollination.html>

Image 1: ABC Science, Australian Broadcasting Corporation, Ultimo NSW, viewed 10 May 2015, <http://www.abc.net.au/science/scribblygum/may2003/img/hive.jpg>

Image 2: New stingless bee photos by Peter O, Australian Native Bee Research Centre, viewed 10 May 2015, <http://www.aussiebee.com.au/Images/stingless-bee-petero-1.jpg>

Image 3: Great Carpenter Bee sonication - Corinne Jordan, Australian Museum, Sydney, viewed 10 May 2015, <http://australianmuseum.net.au/Uploads/Images/23048/Winner%20open%20215_big.jpg>

Video 1: ‘Australian Blue banded bee. (Amegilla cingulata)’, Youtube, viewed 10 May 2015, <https://www.youtube.com/watch?v=7h0Hm4E6CRk>

Myrmecomorphy: I wish I wish I was an ant... mimicry of ants

Ants; ferocious and efficient predators that can overwhelm prey much larger than themselves through tactical attacks, strong mandibles, a sting or the ability to spray formic acid on their target and the force of sheer numbers. It is no surprise then that ants have had significant impacts on the evolution of other organisms through symbiotic relationships, providing resources and being the subject of mimicry (McIver, 1993). Myrmecomorphy is the term for species that resemble ants morphologically, behavioural, chemically or texturally (McIver, 1993). Over 2000 species of myrmecomorphic arthropods from 54 families have been described so far including spiders, Leaf bugs (Miridae), broad-headed bugs (Alydidae), mantises (Mantidae), and even other Hymenopterans including parasitic wasp species from the Diapriidae family (McIver, 1993).

Parasitic wasp (Bruesopria sp.) inside the nest of its host species, the thief ant (Solenopsis molesta). Young wasps likely feed on the developing ant larvae. Image taken in Kansas, USA courtesy of Alex Wild.

Myrmecomorphic spiders have developed some of the most amazing morphological traits in order to mimic ants considering they are not even in the same taxonomic class. Some species of ant mimic spiders use their extra pair of legs as fake antenna, the cephalothorax has narrowed in the centre used to give the illusion of 3 body segments, some species have enlarged pedipalps/chelicerae used to mimic the ants head, reflective hairs to appear shiny or smooth textured and colour spots to mimic compound eyes are just some of the adaptions made (McIver, 1993).

Aphantochilus rogersi (left) captures a turtle ant (Cephalotes sp.). Image taken in Ecuador courtesy of Alex Wild.

Spiders don’t just use this mimicry in order to prey on the ants, some use batesian mimicry to avoid being eaten themselves. Here in Australia we have an amazing little Green Weaver Ant (Oecophylla smaragdina) mimic - Myrmarachne smaragdina – this species has adopted both morphological and behavioural features of the ants in order to avoid predation and lives near colonies of O. smaragdina without being attacked (Ceccarelli, 2008).

Female Myrmarachne smaragdina – Green weaver ant mimic spider. Photo taken in Darwin courtesy of Dr Greg Anderson.

Male Myrmarachne smaragdina – Green weaver ant mimic spider. Photo taken in Cairns courtesy of Robert Whyte.

References:

McIver, JD 1993, ‘Myrmecomorphy: morphological and behavioural mimicry of ants’, Annual Review of Entomology, vol. 38, pp. 351-379.

Ceccarelli, FS 2008, ‘Behavioral mimicry in Myrmarachne species (Araneae, Salticidae) from North Queensland, Australia’, Journal of Arachnology, vol. 36, no. 2, pp. 344-351.

Image 1: Ant Enemies, Alex Wild: The diversity of insects, viewed 9 May 2015, 2015, <http://www.alexanderwild.com/Ants/Taxonomic-List-of-Ant-Genera/Solenopsis/i-RZcnVdD/1/L/Diapriidae4-L.jpg>  

Image 2: Amazing Arachnids, Alex Wild: The diversity of insects, viewed 9 May 2015, <http://www.alexanderwild.com/Ants/Taxonomic-List-of-Ant-Genera/Cephalotes/i-6WhGGgx/2/XL/Aphantochilus3-XL.jpg>

Image 3 (female): Whyte, R & Anderson, G 2010, Salticidae Jumping spiders, Queensland Museum, viewed 9 May 2015, <http://www.arachne.org.au/_dbase_upl/smaragIMG_0342-resized.jpg>

Image 4 (male): Whyte, R & Anderson, G 2010, Salticidae Jumping spiders, Queensland Museum, viewed 9 May 2015, <http://www.arachne.org.au/_dbase_upl/P1000959Iain__29_Dec_11_Myrm.jpg>