Unveiling Nature’s Horrific Symphony: The Lethal Tactics of Emerald Cockroach Wasps – Manipulating Hosts and Feasting from Within
When someone mentions the word parasite, people usually convulse with disgust at the mere thought of a creature draining the life force from its host whilst living inside it. It is estimated however, by parasitologists that parasites are the most abundant form of life on the planet, encompassing 80% of all living species on this planet. Moreover, parasitism is designated by as more common than traditional predation as a consumer lifestyle1. This statistic may not do much to alleviate those repulsed by this concept and may conjure up more distaste, however the world of parasitology is far more complex and diverse than what meets the eye and their vitality to our ecosystems cannot be overstated. The methods these organisms have honed and perfected via eons of microevolution and macroevolution is the reason they survive today. Not only survive but thrive. This links us back to the notion proposed by Richard Dawkins of the selfish gene; by any means necessary, propagate. They deserve to be admired as they have successfully mastered the art of parasitism in mysterious yet marvellous ways, all unique to one another, which to me is fascinating. This piece will explore the lifecycle of my most favourite example of parasitism, The Emerald Cockroach Wasp. Read on and immerse yourself in the fold of parasitology if you dare…
1. Emerald Elegance, Macabre Mastery: Unveiling the Sinister Tactics of the Emerald Cockroach Wasp
Hailing from the tropical regions of Africa, Pacific islands, South and Southeast Asia, Ampulex compressa, known as the Jewelled Wasp or Emerald Cockroach Wasp was first identified in 1758 by Carl Linnaeus. This species of parasitoid wasp is easier to distinguish from others due to its distinctive metallic turquoise colouration, exclusive to the female members of the species, which leads us to a direct segway to introduce the lifecycle of this intriguing insect, in which solely, the female members of the species partake in; Let’s begin with the the obligate and primary host of the Jewelled Wasp: the common American Cockroach.
Cockroaches are common pests, especially in the United States. An initiative was introduced across the islands of Hawaii to cull the overpopulation of American Cockroach’s in 1941 as a form of biocontrol, but it failed due to volcanic terrain being unfamiliar to the wasps to construct burrows and due to the small scale, the wasps hunt on2.
2. Venomous Stings and Antennae Snips: Unmasking the Ruthless Hunting Tactics of the Emerald Cockroach Wasp
The lifecycle begins with construction of the burrow. Female wasps will dig a small hole within soft soil or will seek out unoccupied mounds or abandoned burrows. They will decorate the entrance of the burrow with stones but will not barricade the entrance just yet. Next, we move onto the hunting stage. Female Jewelled Wasps will actively prowl for American Cockroaches, hunting for them. Once an unfortunate target had been located, the cockroach will struggle against the wasp. When the parasitoid finds an opportunity, it will initiate its attack by stinging the cockroach in the thorax, just above the first pair of legs. The purpose of this sting is to immobilise the cockroach, to prevent its escape from the wasp. A secondary sting is implemented directly into the head of the cockroach, targeting the brain. The purpose of this sting is to induce a catatonic state within the cockroach, known as hypokinesia. This dampens the innate urge to escape the cockroach has from the grasp of predator alongside a reduction in spontaneous walking. Now that the cockroach has been apprehended, the Jewelled wasp will snip of one antenna belonging to the cockroach, exposing a supply of haemolymph. The wasp will drink this haemolymph to rejuvenate itself as now, the Wasp has the task of dragging the cockroach back to its lair. What needs to be expressed with utmost emphasis, is how a miniscule wasp, no longer than 22mm, is able to hunt, subdue and then transport an invertebrate twice its size back to its lair. It will guide the cockroach back to its burrow by tugging on its remaining antenna whilst the cockroach is in this elucidated state. The wasp will need to act fast; during the transport of its prey back to its burrow, the wasp is at its most vulnerable state from potential predators in search of prey they will not need to hunt nor subdue as the strenuous task will have been done for them. Once back at the burrow, the wasp places the cockroach in the centre of its lair, sealing up the opening with rocks, till darkness shrouds the interior.
3. Secrets of Survival: Unveiling the Intriguing Life Cycle of the Emerald Cockroach Wasp – A Fascinating Tale of Life, Adaptation, and Nurturing
The female typically lays a single egg on the exoskeleton of the cockroach. Once the larva has hatched, it will burrow into the flesh of its host by cutting through the cockroaches’ exoskeleton using its mandibles and via the secretion of antimicrobial compounds which ensures the host flesh remains sterile for extended periods of time. Now, this is where the remarkable aspect of this parasitic-host relationship is to be highlighted; the larva possesses the innate knowledge that this nutrient source is its first and it will require this same source to develop from pupa to a full-grown wasp. So, the larva instinctively avoids the consumption of the critical internal organs of the cockroach (i.e., the heart and the brain) to keep the host alive for as long as possible, keeping its nutrient supply as fresh as possible for the longest amount of time. Upon completion of the larva’s first meal, it shall utilise the husk of the cockroach as a cocoon. Eventually, a mesmerising metallic emerald wasp shall emerge from the burrow (if it is a female) to reinitiate the cycle once more.
References:
Daniel L. Preston and Pieter T. J. Johnson (2010) ‘Ecological consequences of parasitism’, .
Jasso-Martínez, J.M. et al. (2021) ‘Midgut transcriptome assessment of the cockroach-hunting wasp ampulex compressa (apoidea: Ampulicidae)’, PloS One, 16(6), pp. e0252221.
Moore, E.L. et al. (2018) ‘Ampulexins: A new family of peptides in venom of the emerald jewel wasp, ampulex compressa’, Biochemistry (Easton), 57(12), pp. 1907-1916.
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