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

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