Meteorus stellatus inhabits primary forests of the Okinawa-hontô and Amami-ôshima Islands, subtropical Japan.
“Parasitoid wasps parasitize a variety of organisms, mostly insects,” said lead author Dr. Shunpei Fujie from the Osaka Museum of Natural History and colleagues.
“They lay eggs in the host, a larva of hawk moth in this case, where the wasp larvae later hatch.”
“After eating the host from the inside out, the larvae spin threads to form cocoons, in which they pupate, and from which the adult wasps eventually emerge.”
The new species, named Meteorus stellatus, is a gregarious parasitoid of two hawk moth species in the genus Macroglossum.
The wasp larvae construct single or several unique star-shaped cocoon masses separately suspended by very long threads.
Cocoon masses of Meteorus stellatus: (A) habitus, medium-sized; (B) habitus, exceptionally large-sized and somewhat collapsed in an artificial condition; (C) a medium-sized cocoon mass; (D, E) small-sized cocoon masses; (F) independent cocoons near a cocoon mass; (G) a part of suspending thread, consisting of individual cable. Image credit: Fujie et al., doi: 10.3897/jhr.86.71225.
“Larvae of Meteorus stellatus form star-shaped masses of cocoons lined up in a spherical pattern, suspended by a thread that can reach up to 1 m in length,” the researchers said.
“The structure, 7 to 14 mm wide and 9 to 23 mm long, can accommodate over 100 cocoons.”
“We believe this unique structure helps the wasps survive through the most critical time, i.e. the period of constructing cocoons and pupating, when they are exposed to various natural enemies and environmental stresses,” they added.
“The star shape most likely reduces the exposed area of individual cocoons, thus increasing their defense against hyper-parasitoids (wasps attacking cocoons of other parasitoid wasps), while the long thread that suspends the cocoon mass protects the cocoons from potential enemies like ants.”
“How parasitoid wasps have evolved to form such unique masses instead of the common individual cocoons should be the next thing on our ‘to-research’ list.”
The study appears in the Journal of Hymenoptera Research.
S. Fujie et al. 2021. Stars in subtropical Japan: a new gregarious Meteorus species (Hymenoptera, Braconidae, Euphorinae) constructs enigmatic star-shaped pendulous communal cocoons. Journal of Hymenoptera Research 86: 19-45; doi: 10.3897/jhr.86.71225