Salute the venerable ensign wasp, killing cockroaches for 25 million
years

Date:
September 28, 2020
Source:
Oregon State University
Summary:
A new study has identified four new species of parasitic, cockroach-
killing ensign wasps that became encased in tree resin 25 million
years ago and were preserved as the resin fossilized into amber.



FULL STORY ==========================================================================
An Oregon State University study has identified four new species of
parasitic, cockroach-killing ensign wasps that became encased in tree
resin 25 million years ago and were preserved as the resin fossilized
into amber.


========================================================================== "Some species of ensign wasps have even been used to control cockroaches
in buildings," OSU researcher George Poinar Jr. said. "The wasps sometimes
are called the harbingers of cockroaches -- if you see ensign wasps
you know there are at least a few cockroaches around. Our study shows
these wasps were around some 20 or 30 million years ago, with probably
the same behavioral patterns regarding cockroaches." Ensign wasps,
of the Hymenoptera order and scientifically known as Evaniidae, earned
their common name because their abdomen resembles a flag; an ensign is a
large flag on a ship, usually flown at the stern or rear of the vessel,
that indicates the ship's nationality.

"As the wasps move about, their 'ensign' is constantly moving up and
down as if they are flag waving," said Poinar, professor emeritus in
the OSU College of Science and an international expert in using plant
and animal life forms trapped in amber to learn more about the biology
and ecology of the distant past.

About 400 species of ensign wasps exist today, distributed across
20 genera.

The wasps live everywhere except polar regions. They typically measure
5 to 7 millimeters in length and don't sting or bite but are lethal for unhatched cockroaches.

A female ensign wasp will look for cockroach egg cases, known as ootheca,
and lay an egg on or in one of the cockroach eggs inside the case. When
the wasp egg hatches, the larva eats the cockroach egg where it was laid.

Successive instars of the larva then consume the other dozen or so eggs
inside the cockroach egg case. Mature wasp larvae pupate within the
cockroach egg case en route to coming out as adults, and no cockroach
offspring emerge from an egg case infiltrated by an ensign wasp.

Analyzing Tertiary period specimens from Dominican amber, Poinar was
able to describe three new species of ensign wasps: Evaniella setifera, Evaniella dominicana and Semaeomyia hispaniola. He described a fourth,
Hyptia mexicana, from Mexican amber. The Tertiary period began 65 million
years ago and lasted for more than 63 million years.

No cockroaches accompanied the wasps in the amber, but three flying
termites were found along with an ensign wasp in one of the Dominican
amber pieces. It's likely the termites were sharing a nest with the
cockroaches and this attracted the wasp, Poinar said.


========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Steve Lundeberg. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. George Poinar. Ensign wasps (Hymenoptera: Evaniidae) in Dominican
and
Mexican amber. Historical Biology, 2020; 1 DOI: 10.1080/
08912963.2020.1818075 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200928093740.htm

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