Andre Pires da Silva, a University of
Texas at Arlington assistant professor of biology, is one of five principal investigators
on a recent effort to map the genome of the two-spotted spider mite, or
Tetranychus urticae, one of agriculture’s most resilient and detrimental pests.
Spider mite (Image from www.insectimages.org)
Pires da Silva, an evolutionary
biologist, examined and interpreted the genome results to learn more about the
spider mite’s reproduction. He found that the genes involved in determining
what sex offspring develop into are unlike any other known examples in
A paper on the project is being
published Thursday in the journal Nature. The lead author is Miodrag Grbić, a
researcher at The University of Western Ontario. Pires da Silva is one of 55
co-authors, a group that includes scientists from Spain, Belgium, France,
Portugal, Chile, Germany and Switzerland.
The sequencing represents the first
complete Chelicerate genome. Chelicerates are the second-largest animal group
on Earth and includes spiders, ticks and mites. One goal of the U.S. Department of
Energy-funded research is to find new ways to combat the spider mite and other
pests. The estimated cost of chemical
pest control of spider mites is more than $500 million worldwide.
“Spider mites are a huge problem for
agriculture because they are very difficult to get rid of,” said Pires da Silva.
“They’re very small, they reproduce in huge numbers and they become very easily
resistant to chemicals used to try to control them.”
The information from the genome-sequencing
project has provided insight into how the spider mite evolves and interacts
with the plants it is attacking, researchers said.
“We have discovered this creature’s
gene set, and more importantly, we believe we have found its Achilles heel so
that we can begin development of non-pesticide, alternative pest control
measures,” says Grbić, a biology professor in Western’s Faculty of Science.
Spider mite reproduction is similar to
bees. Eggs that are fertilized become females and those that are unfertilized
develop into males. Pires da Silva’s role in the sequencing project was to look
at the newly revealed genome and try to discern how this gender determination
process developed. After
comparing the spider mite to known genomes, such as fruit fly, bee and mouse,
he found that genes involved in gender determination in the spider mite are
likely very different.
“With this project, we now know that
genes involved in sex determination in other animals are not involved in sex
determination for the spider mite,” Pires da Silva said. “The genome sequence
gave us that first step. If we can figure out which genes do play a role in sex
determination, we may be able to manipulate those functions to control the
spider mite population.”
Pires da Silva’s laboratory at UT
Arlington also has been exploring sex determination in the Rhabditis, a
nematode worm about 1 mm long that produces both males, females and
hermaphrodites. He believes methods developed in that research could be useful
in further study of the spider mite.
"Dr. Pires da Silva is on the cutting-edge of explorations
that will allow scientists to address a serious agricultural concern while
learning more about evolutionary biology,” said Pamela Jansma, dean of the UT
Arlington College of Science. “Revealing
the structure of the spider mite's genome has opened up a world of
possibilities for researchers. We are proud he is a part of this effort."
da Silva’s work is representative of the groundbreaking discoveries taking
place at The University of Texas at Arlington, a comprehensive research
institution of 33,439 students in the heart of North Texas. Visit www.uta.edu to learn more.