Graduate Student Formidable Foe For Rice Water Weevil

As a child in Sri Lanka, Dr. Bandara Ratnayake devoured books in English. The titles behind the names of the authors – "M.S." and "Ph.D." – impressed her. That determination to receive more education would help her earn a master's degree and a doctorate from two universities in the United States.

In May, she earned a doctorate from Texas A&M University after several years of balancing school and research in College Station and Beaumont, as well as time with her family. Her tenacity paved the way for more research on host plant resistance to the rice water weevil. Because of her work, scientists may now be able to identify proteins that are toxic to the insect and develop genetically-altered rice varieties.

The rice water weevil is about as long as a pencil eraser. The adults' feeding on the young rice foliage causes scars on the upper leaf surface.

But the larvae cause the real damage. They live underground in the saturated mud and obtain oxygen by piercing the rice plant's roots with spiny projections.

They prune rice roots and cause stunting, delayed maturity, reduced tiller production and increases competition from weeds. Rice water weevils cause an estimated $40 to $120 in damage per acre in a season.

The primary control of the rice water weevil is insecticides; other methods of cultural and biological control have met with little success.

Plant resistance to the pest offers "savings in production costs and a reduction of the pesticide load in the environment," Ratnayake said.

Scientists are developing a rice variety with genes containing proteins toxic to the pest.

"In order to continue the research, the best strategy would be to select a toxic protein against the rice water weevil larvae and insert that gene into rice," she said.

But before that can be done, the insect has to be studied even further since little research has been done on its basic biology.

To study most insects, researchers must raise large populations of the object of study in labs. But to do so requires artificial diets, and none was available for the rice water weevil.

"Ratnayake has forged toward success in the development of an artificial diet specific to the rice water weevil," said Dr. Mo Way of Beaumont, entomologist with the Texas Agricultural Experiment Station and her research advisor.

Ratnayake tested more than 25 artificial diets, but the larvae live underground in mud.

"When bringing the natural environment into the laboratory, microbial agents from the mud contaminate the artificial diet," Way said.

"Progress on developing an artificial diet has been made," Ratnayake said, "and continued work is needed. To my knowledge, this is the first attempt to develop an artificial diet for the rice water weevil."

Ratnayake was able to develop reliable testing techniques to screen the proteins toxic to the larvae. She also developed a method to produce a large number of rice water weevil larvae for laboratory research.

Ratnayake earned her undergraduate degree in entomology in Sri Lanka. She worked for the Sri Lanka Department of Agriculture in a farmer field school educational program for eight years until she and her husband, Sunil, moved to Mississippi. Sunil came to the United States to continue his education, so she did the same, first taking English courses and then working on a graduate degree in entomology. She completed her master's degree in 1995 at Mississippi State University and started working on her doctorate.

In 1998, Sunil took a job in Houston, and then began teaching biology at Blinn College in Bryan. Bandara, who had stopped working on the advanced degree in Mississippi when they moved, began working on it again in 1999 at Texas A&M.

She is thankful to her mother and her sacrifices through the years. Her mother moved to the United States to help take care of the Ratnayakes' children so Bandara could study.

Also, she is grateful to Way and to Dr. Jim Olson, her academic advisor and also an Experiment Station entomologist, for their encouragement, understanding, guidance and support throughout her studies.

Without all of the support she received, "I couldn't have done it," she said. "When I look back, I think it was a long journey with lots of hard work."

Part of the challenge has been the fact the rice water weevil appear only for about three-and-one-half months per year, and could not be raised in a laboratory. So each summer for four years, Ratnayake would pack up her family and move to the Texas A&M System Research and Extension Center in Beaumont to study the insect in its natural environment. Her husband would come down on weekends.

She admitted it was hard on the children. "They had to leave their friends and customary summer activities. My family sacrificed for my studies."

Her daughter, Anu, 19, is pursuing her undergraduate degree at Texas A&M. Her son, Charith, is 8 years old.

What's next? Ratnayake hopes to continue with post doctoral studies at Texas A&M.

"In my mind, I want to be an entomologist with a strong academic background," she said.

"She will no doubt make a mark in the entomological scientific community," Olson said.

Ratnayake received financial support for her studies from Texas rice farmers and RiceTec Inc., a private hybrid rice seed producing company in Alvin.