Biologists Discover New Insect Species

Its name sounds legendary, but the newly uncovered insect Neuroterus (noo-ROH’- teh-rus) Valhalla does not look or act the part. It is barely a millimeter long and spends 11 months of the year hidden in a crypt.

N. Valhalla has the significant differential of being the first insect species to be characterized along with its completely sequenced genome. The Rice University scientists that found it are preparing to see just how the tiny, non-stinging wasps might have been affected by Houston’s historic February 2021 freeze.

Environment at Rice University

A paper released this month in Systematic Entomology describes the N. Valhalla. Its name is a homage to where it was found: right outside the Rice college student bar Valhalla.

” It would certainly have been a missed opportunity to not name it something related to Rice or Valhalla,” said graduate student Pedro Brandão-Dias, lead author of the paper. Brandão first gathered N. Valhalla from the branches of a large live oak tree close to the campus bar in springtime 2018.

Brandão, a Brazilian, had never seen an oak tree prior to visiting Rice in 2015 for an undergraduate research fellowship in the laboratory of evolutionary biologist Scott Egan, corresponding author of the research study. Brandão went back to Egan’s team in 2018 for graduate school.

Although Brandão’s main research centers on using environmental DNA to detect endangered or intrusive creatures, everybody in the laboratory joins in studying insects of family members Cynipidae each springtime. Referred to as gall wasps, they are a favorite of Egan’s team since they can be gathered from the live oak trees covering Rice’s 300-acre university. In Egan’s eight years at Rice, his laboratory has found at the very least as many new species of gall wasps or predators that attack them.

” At Rice, we highlight learning out by doing,” Egan said. “In my laboratory, undergraduate and graduate students cooperate in the experiential learning process by studying biologically diversified ecosystems on the live oaks outside our front door. With some patience and a magnifying glass, the discoveries never end.”

Species of gall wasps

N. Valhalla and other gall wasps deceive their host tree right into feeding and shielding their young. The wasps lay a biochemical mixture along with their eggs. The chemicals induce the tree to develop a crypt, or gall, around the egg. The gall shelters the egg and also feeds larvae that hatch out from it.

There are approximately 1,000 identified species of gall wasps. Some emerge from spheric brownish galls that form on the bottom of oak leaves. Others form galls inside branches and the others on the tree’s flowers, which is where Brandão initially collected N. Valhalla.

” Once they emerge, they just live three or four days,” Brandão stated of the tiny insects. “They do not consume. Their one purpose is to mate and lay eggs.”

It took nearly four years to identify the new species because N. Valhalla (like many other gallers) lays two times a year. Discovering where N. Valhalla set its eggs in its alternating generation took a little bit of time.

Initial findings

Brandão and labmates first observed N. Valhalla on the huge tree outside Valhalla while they were gathering live oak flowers, or catkins, in late February and early March of 2018. They were trying to find one more species of galler that was recognized to create galls on the flowers. When DNA tests showed two types, the scientists looked closely at their catch and even noticed a couple of smaller-sized insects with lighter-colored legs.

” They lay their eggs into the developing catkins,” Brandão said of N. Valhalla. “They develop in galls on the blossoms, and after that, they arise. This takes place in March. However, the flowers are a one-time thing each year, and by the time they surface, there are no more flowers for them to lay eggs on. They need to lay eggs on different tissue.”

Egan said alternating generations of gallers have actually usually been mistaken for new species in the past. Genomic testing mixed with in-depth monitoring in nature was crucial for establishing N. Valhalla as a distinct species. Learning where the insects went in their alternate generation took both good luck and also effort.

Monitoring N. Valhalla’s behavior

Kelly Weinersmith, an adjunct assistant professor of biosciences and collaborators at the University of Iowa, got the stroke of luck in 2019. Weinersmith sampled galls from a Florida live oak species that differed from the Rice trees where N. Valhalla was found. Weinersmith sent out samples from the Florida trip to Iowa collaborators Andrew Forbes and Anna Ward, which observed that two distinct types of wasps arose from cryptic gall swellings at branch joints. DNA tests revealed that the unknown wasps were the missing generation of N. Valhalla.

” To verify where they were going after they left the flowers, I did an experiment where we provided the wasps several different tissues from the tree and observed them,” Brandão claimed. The plan was to observe N. Valhalla that had just emerged from catkin crypts at Rice, and find them in the act of laying their eggs into a different area of the plant.

With COVID-19 regulations limiting how many people stay in laboratories on campus in early 2020, much of the work fell to Rice undergraduate Camila Vinson. She was living on campus at Brown College.

” We would go out together and gather the catkin galls and tissues for the behavioral tests in Petri dishes, but she had to go daily to the lab to see if any bugs had appeared,” Brandão said. Vinson both cataloged and collected samples of wasps that came out from the catkins and “did the observation experiment where we would put the bugs into a petri dish with several tissues and then observe to see where they go,” Brandão said.

” Since this was during COVID, I took some of them home and placed them in the microscope and took pictures with my phone,” he said.

The team confirmed the petri dish findings by inspecting trees where they had previously collected N. Valhalla. They discovered both emergence holes from old crypts and more than a dozen galls containing larval N. Valhalla.

How does the new species propagate?

According to Brandão, the N. Valhalla generation hatches in live oak catkins turns from eggs to fully formed adults in 2-3 weeks. The cycle takes 11 months for the generation that grows inside branches.

” If they appear at the wrong time, and there are no flowers around, they cannot lay their eggs, and they just die,” Brandão said. “They have to come out at the exact time the tree’s flowering.”

The trees flower at different times from year to year, and it is not clear how the wasps coordinate their appearance with flowering. Vinson was the first to pose the concern of how N. Valhalla might be affected by February 2021’s winter storm, which led to record cold temperatures and delayed live oak flowering across Houston.

“The day the freeze occurred, I asked Pedro, “Is this going to mess up when they emerge or their ability even to reproduce?'” she remembered. Brandão spread the question to an international group of gall wasp scientists. All concurred that it was worthy of follow-up. So Vinson decided to tackle it for her senior thesis. She said it is part of a bigger question about how climate change will impact specialized insects like gall wasps.

“Our gall wasps reside on live oaks from the southern United States all the way down through Mexico,” Vinson explained. “Those environments are not accustomed to the kinds of temperatures we had last February. Furthermore, those kinds of freezes are likely to happen again increasingly more frequently with climate change.

“The important question is, “Are these populations going to be in danger, or can they swiftly adapt? Do they have strategies that go well with a changing climate?'” she said.

Read the original article on PHYS.

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