Welcome to our Mound, We Hope you Enjoy your Stay!

Inquiline species are the “lodgers” of the zoological world. They take advantage of the nests that other species make and continue to live commensally with them. This could be considered analogous to parasites creating their homes within the multicellular hosts.

Think of the individuals that make up termite colonies, they consist of soldiers, workers, and reproductive castes and termite colonies are often referred to as “super organisms”. They are unable to survive on their own when outside of the colony and are entirely dependent on each other for movement and for nourishment via pheromone communication.

Block of flats

However there is a distinct difference between inquiline species and parasites, the latter causes damage to the host, whereas the “lodgers” just mischievously take over a section of the nest, creating little destruction to the well-being of the termite colony.

Mounds and nests are perfect examples of architectural excellence in the natural world, who wouldn’t want to live in the grand palace of the termites? In some species there are fungus chambers (a constantly topped up termite pantry) and the entire construction provides stable shelter and defence against predators for the rest of the inhabitants. Most importantly there is adequate climate control which keeps homeostasis in the mound, highly attractive attributes for insects who require stable environmental conditions, “when can we move in?” I hear you buzzing.

Unlike lodgers, inquiline species do not pay rent. My favourite example has to be that of the world’s largest bee, Chalicodoma pluto, also known famously as Wallace’s bee. This species was first discovered in 1859 by Alfred Russell Wallace in the Northern Moluccas in Indonesia. The type specimen was described by Smith in 1861. For a long time the species was considered extinct, as it had not been seen at all both by Indonesian locals and by research scientists. How can they miss such a huge bee? For a start, it is a beastly species compared tothe common honey bee, Apis melifera (Fig.1.) it should be easy to spot! Its sheer size also suggests that it must be making enough racket whilst in flight to make it difficult for their presence to go unnoticed…

Fig.1. Dorsal view of a common honey bee worker, Apis melifera (Left) compared to Chalicodoma pluto (Right). Photograph by J.W. Porter from Messer (1984).

The humble hymenopteran giantwas re-discovered nesting commensally with the arboreal species Microcerotermes amboinensis on three Indonesian islands in 1981 by Adam Catton Messer. It appeared that the C. pluto species were restricted to living in these termite nests and were not discovered in any other habitat. They do this by making tunnels large enough for them to enter the nest and cells to lay their eggs and store their food and frass, kicking the termites out of that section. Another bizarre thing about this species is that the morphology and adaptations of the mandibles were quite unlike bees, but more like stag-beetle mandibles, ideal for collecting resin from dipterocarp trees and pollen from flowering plants to feed their larvae back in the termite nest.

Another fascinating example of these inquiline intruders found in termite nests are the beetle larvae of Pyrearinus termitilluminans (Elateridae).The photograph in Fig.2 shows that the lights are on and someone is at home! It is not just the termites though… In Brazil the old nests of Cornitermes cumulansare the first choice habitat for these larvae as they excavate tunnels from the central to the outer layer of the mounds and poke their green luminous prothoraxes outside. The collective bioluminescence of the larvae creates a biological block of flats with the lights shining through the windows of the mound, which attract flying preys such as termite alates or formicid ants. The adult beetles only lay their eggs in nests that are greater or equal to one meter in height which increases the success rate of having a nice meal.

Fig.2. Parque Nacional das Emas, Goiás, Brazil, luminous termite nest Photograph by S. A. Vanin from Costa & Vanin (2010)

In some cases it is not even one single species but several species at a time that coexist successfully in the nests of termites. Are the termites troubled about sharing their nest with the world’s largest bee? Do they mind if those larvae enjoy some ambient lights in the evenings?

The winner of the Invertebrates category for the Natural History Museum Wildlife Photographer of the year 2014 was Ary Bassous from Brazil. His photograph “Night of the deadly lights” also captured the termite mounds on the savannah of Emas National Park, central Brazil. He described the bioluminescence as “eerie”, but I think it shows how full of energy and life a termite mound can be. The image is a beautiful triumph after attempting to photograph it for nearly 10 years!

Imagine having a completely different species living in your home, like a gorilla living in your attic, what would you do?Inquiline species are an exciting area of entomology that would benefit from more research, both for termite and ant colonies. Who knows what other insect-lodger populations exist out there!

Further Reading:

Bignell, D.E., Roisin, Y., Lo, N., 2011. Biology of Termites: A Modern Synthesis. Springer Publishing. DOI: 10.1007/978-90-481-3977-4

Costa, C. & Vanin, S.A., 2010. Coleoptera Larval Fauna Associated with Termite Nests (Isoptera) with Emphasis on the “Bioluminescent Termite Nests” from Central Brazil”. Psyche, Journal of Entomology. Article ID 723947 doi:10.1155/2010/723947

Messer, C.A., 1984. Chalicoma pluto: The World’s Largest Bee Rediscovered Living Communally in Termite Nests (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Soc. Vol. 57, No.1, PP 165 – 168