Tag: parasitism

Death from below: the first video of a parasitic wasp attacking caterpillar underwater

Named after fictional monster Godzilla, a parasitic wasp becomes the first observed and filmed to dive underwater for several seconds, in order to attack and pull out caterpillar hosts, so that it can lay its eggs inside them before releasing them back in the water.

A very few species of parasitoid wasps can be considered aquatic. Less than 0.1% of the species we know today have been found to enter the water, while searching for potential hosts or living as endoparasitoids inside of aquatic hosts during their larval stage.

Within the subfamily Microgastrinae (family Braconidae), only two species have previously been recorded to be aquatic, based on their parasitism of aquatic caterpillars of moths. However, none has been known to actually dive in the water.

Recently, during their research work in Japan, Dr. Jose Fernandez-Triana of the Canadian National Collection of Insects and his team found and recorded on camera the first microgastrine parasitoid wasp that dives underwater for several seconds, in order to attack and pull out caterpillar hosts, so that it can lay its eggs inside them before releasing them back in the water.

Interestingly, the wasp, which was described as a new to science species in the open-access, peer-reviewed scientific Journal of Hymenoptera Research, was given the awe-striking name Microgaster godzilla, because its emergence out of the water reminded the scientists of the Japanese iconic fictional monster Godzilla.

In the video, the female wasp can be seen walking over floating plants as it searches for hosts, specifically larvae of the moth species Elophila turbata, which constructs a portable case from fragments of aquatic plants and lives inside it near the water surface. Once the wasp finds one of those cases, it first probes it repeatedly with its antennae, while moving around. Eventually, it forces the larvae to come out of the case and parasitizes it by quickly inserting its ovipositor. In some cases, the wasp has to submerge completely underwater for several seconds, in order to find and pull the caterpillar out of its case. To do this, the species has evolved enlarged and strongly curved tarsal claws, which are thought to be used to grip the substrate as it enters the water and looks for hosts.

A female wasp Microgaster godzilla seeks out a moth caterpillar, dives in the water and pulls it out of its case, in order to parasitize it by quickly inserting its ovipositor.
Video by Dr. Jose Fernandez-Triana

As for the curious choice of name for the new species, Dr. Jose Fernandez-Triana explains:

“The reasons why we decided to use the name of Godzilla for the wasp species are interesting. First, being a Japanese species, it respectfully honours Godzilla (Japanese: ゴジラ, Hepburn: Gōjira), a fictional monster (kaiju) that became an icon after the 1954 Japanese film of the same name and many remakes afterwards. It has become one of the most recognizable symbols of Japanese popular culture worldwide. Second, the wasp’s parasitization behaviour bears some loose resemblance to the kaiju character, in the sense that the wasp suddenly emerges from the water to parasitize the host, similar to how Godzilla suddenly emerges from the water in the movies. Third, Godzilla has sometimes been associated, albeit in different ways, with Mothra (Japanese: モスラ, Hepburn: Mosura), another kaiju that is typically portrayed as a larva (caterpillar) or an adult moth. As you can see, we had biological, behavioural and cultural reasons to justify our choice of a name. Of course, that and having a bit of fun, because that is also an important part of life and science!”

Beyond unusual behaviours and funny names, Dr. Fernandez-Triana wants to emphasize the importance of multidisciplinary work and collaboration. The team that published this paper got to know each other at an international meeting devoted to biological control (The 5th International Entomophagous Insects Conference in Kyoto, Japan, 2017). 

“I was very impressed by several presentations by Japanese grad students, which included video recordings of parasitoid wasp biology. As a taxonomist, I am always impressed with the quality of research done by colleagues in other fields. In this case, we saw an opportunity to combine our efforts to study the wasp in detail and, when we found that it was a new species, we described it together, including adding the filmed behaviour to the original description. Usually, taxonomic descriptions of parasitoid wasps are based on dead specimens, with very few details–often none–on its biology. Thanks to my biocontrol colleagues, we could add more information to what is known about the new species being described. Hopefully we can continue this collaboration and combined approach for future studies”.

Original source:

Fernandez-Triana J, Kamino T, Maeto K, Yoshiyasu Y, Hirai N (2020) Microgaster godzilla (Hymenoptera, Braconidae, Microgastrinae), an unusual new species from Japan which dives underwater to parasitize its caterpillar host (Lepidoptera, Crambidae, Acentropinae). Journal of Hymenoptera Research 79: 15-26. https://doi.org/10.3897/jhr.79.56162

Rarely-seen event of ant brood parasitism by scuttle flies video-documented

While many species of scuttle flies are associated with ants, their specific interactions with their hosts are largely unknown. Brood parasitism (attacking the immature stages, rather than the adult ants), for example, is an extremely rarely observed and little-studied phenomenon. However, a research team from the USA and Brazil, led by Dr. Brian Brown, Natural History Museum of Los Angeles County, have recently video-documented two such occasions. The observations are published in the open access Biodiversity Data Journal.

One of the videos, taken in Brazil, shows female scuttle flies attacking ants evacuating their nest. Having had their colony exposed, worker ants try to carry the brood to the nearest shelter. The flies follow these workers on foot, and bump into them in attempt to make them drop the larvae. The scientists have provided a video of an ant which, when harassed, left a larva in a partially exposed position and fled. Immediately, the fly attacked the larva, laying an egg inside its body. The fact that the flies attack the relatively soft-bodied larvae explains the puzzling structure of the ovipositor (egg-layer) of this species (Ceratoconus setipennis), which appears much less hardened than the ovipositor of species attacking adult ants. As a result of the present observation, however, their association with ants is no longer a mystery.

The second footage, filmed in Costa Rica, shows an undescribed species of scuttle fly (genus Apocephalus) that fly above the ants. When they spot a worker carrying brood, it would plunge down to it, approach the ant from behind and land on the (in this case) pupa. Then, it flips over onto its back, keeping the pupa between itself and the ant, while it lays an egg into the pupa from an upside-down position.

“The video documentation of two very different types of brood parasitism of ant species by scuttle flies was recorded in two countries within just a few months of one another,” conclude the authors. “This hints at the many remarkable behaviors of phorid flies that may still await discovery by the patient observer. It appears brood parasitism may not be as rare as was once assumed, and that there may be a tremendous amount of information to uncover about these behaviors.”

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Original source:

Brown B, Hash J, Hartop E, Porras W, Amorim D (2017) Baby Killers: Documentation and Evolution of Scuttle Fly (Diptera: Phoridae) Parasitism of Ant (Hymenoptera: Formicidae) Brood. Biodiversity Data Journal 5: e11277. https://doi.org/10.3897/BDJ.5.e11277

New species of parasitic wasp named after ancient god of evil Set shows wicked behavior

Being able to manipulate its host’s behavior while growing inside of it, a new species of parasitic wasp seems to have deservedly received the name of the ancient Egyptian god of evil and chaos Set. Discovered in the southeastern United States, the new species, also called the crypt-keeper wasp, parasitizes crypt gall wasps, which in turn infest live oak. The research team led by Dr. Scott P. Egan of Rice University published their discovery in the open access journal ZooKeys.

Once parasitized, the crypt gall wasp cuts a hole through the gall it has built around itself, and plugs its head in it right before being killed. Meanwhile, the larva of the crypt-keeper wasp feeds, grows, and pupates on the insides of its host. As soon as it is ready to emerge as an adult, it takes a ‘shortcut’ out of the crypt gall straight through the head capsule of its prey, leaving chunks of exoskeleton behind in the ‘crypt’. The team has published a parallel paper (Weinersmith et al. 2017) documenting this manipulation and exploring the fitness benefit to E. set in the journal Proceedings of the Royal Society B.

To justify the comparison between the new wasp and Set, the scientists point out that the deity is said to have control on evil animals, such as hyenas and serpents. Furthermore, according to the ancient Egyptian mythology, he trapped his good-hearted brother Osiris in a crypt and killed him. Then, he chopped his body into small pieces and scattered them all over the world.

The new wasp, described under the name Euderus set belongs to a genus of approximately 77 species with a cosmopolitan distribution. The species is a tiny insect measuring between 1.2 and 2.3 mm in length, but under a microscope, it is one of the most colorful. Its colors are shiny metallic, varying from olive green to turquoise to iridescent blue, depending on lighting and age. Originally discovered near Inlet Beach, Florida, it has now been found across the U.S. Gulf coast, including sites in Georgia, Florida, Mississippi, Louisiana, and Texas.

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Original source:

Egan SP, Weinersmith KL, Liu S, Ridenbaugh RD, Zhang MY, Forbes AA (2017) Description of a new species of Euderus Haliday from the southeastern United States (Hymenoptera, Chalcidoidea, Eulophidae): the crypt-keeper wasp. ZooKeys 645: 37-49. https://doi.org/10.3897/zookeys.645.11117

To kill a wolf spider: Further observation of a spider wasp larva growing on its host

Having been attacked, paralysed and implanted with a wasp egg to its belly, a wolf spider carries on with its life fully mobile and active. At least, until it is time for the larva to reach out for its first solid meal at a certain development stage. The present study, conducted by a Brazilian team of scientists, led by PhD student Hebert da Silva Souza, Universidade Estadual de Campinas, Sao Paulo, and published in the open-access Journal of Hymenoptera Research, follows the entire cycle of larval development from the egg laying through the formation of a full-grown wasp.

The herein observed wasp species, called Paracyphononyx scapulatus, belongs to a well-known group of spider parasites, which after laying their eggs on a paralysed spider, let it recover and continue living fully mobile until the larvae are mature. However, little has been known about this curious behaviour of this wasp species in particular, since previous studies have already showed differences between the separate members of the genus.

To observe the whole cycle of the wasp larval development, the researchers caught a recently parasitised wolf spider and placed it in a plastic container.

While the larva grew and fed on the abdominal hemolymph, which is the analog to the blood in backboned creatures, its host did not show any peculiarities in its behaviour and even kept its routine being active at night and resting during the day. This is suggested to be attributed to the need of the larva to keep its host safe from predators, such as ants, which could otherwise eat the dead body.

However, ahead of its fifth and last development stage, the larva was seen to double its size and, in the morning, twenty days after the hatching of the egg, it killed its host and fully consumed it within the next forty-eight hours. Having left its host, the larva began to search for a place within the container to construct a cocoon, which took it sixteen hours. Thirty-two days later, a fully grown female wasp emerged.

In comparison, a relative of the observed spider wasp is known to manipulate its host’s behaviour, making it to enwrap itself and the larva in a cocoon-like silken structure so that it is protected while feeding. Yet, it is not certain whether the observed larva’s growth in captivity is not the reason why it had not induced similar behaviour.

In conclusion, the authors suggest that further investigation of the interaction between the two species could provide more information about the evolution of this kind of parasitism, which is likely to have developed independently among the wasp groups.

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Original source:

Souza HS, Messas YF, Masago F, dos Santos ED, Vasconcellos-Neto J (2015) Paracyphononyx scapulatus (Hymenoptera, Pompilidae), a koinobiont ectoparasitoid of Trochosa sp. (Araneae, Lycosidae). Journal of Hymenoptera Research 46: 165-172. doi: 10.3897/JHR.46.5833