By Geitner Simmons
Just as hungry hordes of grasshoppers threatened fields during Nebraska’s pioneer era, certain mites and aphids these days pose a significant threat by transmitting viruses to cereal crops. Many gaps remain in the scientific understanding of that transmission, and the University of Nebraska–Lincoln in recent years has taken major steps to pioneer research on these issues.
To spearhead the effort, the university in 2023 hired Shaonpius Mondal, a scientist with deep experience in studying arthropods as virus vectors in agriculture, as an assistant professor of entomology.
Mondal and his team are pursuing multiple advanced research projects studying cereal viruses transmitted by wheat curl mites and aphids. (Aphids are classified as both arthropods and insects; mites are classified only as arthropods.)
Filling in this knowledge can provide a major help to agriculture by enabling more effective practices to contain the threats.
The effects from pest-borne viral infection can be catastrophic. In 2022, the U.S. wheat sector suffered nearly $66 million in losses due to wheat streak mosaic virus, a disease spread by the wheat curl mite.
Another disease transmitter is the bird-cherry oat aphid, a pest common in Nebraska. The aphid spreads barley yellow dwarf virus, a major disease threat to wheat and small grains crops in the U.S. and worldwide.
The research by Mondal and members of his lab is part of the university’s longstanding support for Nebraska’s wheat and cereal crop sector.
Mondal partners with Nebraska Extension to provide outreach on arthropod-borne plant diseases to producers across the state. His current collaborators include the U.S. Department of Agriculture’s Agricultural Research Service in Lincoln and Wooster, Ohio, as well as the University of Nebraska Medical Center and Nebraska Center for Virology, where he is an adjunct faculty member.
Mondal’s previous research experience in pest-vector studies included innovative projects in Idaho (University of Idaho), New York (Cornell University) and California (Agricultural Research Service). He is a member in leading academic societies and serves as an executive board member and treasurer in the International Association for the Plant Protection Sciences, which deals with plant protection issues globally.
Three main experiments are underway in Mondal’s lab:
• Aphids and barley yellow dwarf virus strain complex. Mritunjoy Barman, a postdoctoral research associate, is analyzing the BYDV strain composition present in Nebraska. BYDV-SGV is the most predominant viral strain, as revealed by a statewide wheat and oat leaf sampling. “We also sampled aphids, because aphids are the main vectors of these viruses,” Mondal said. The project has begun field experiments to compare wheat and barley cultivars to determine their susceptibility to a particular BYDV strain.
• Mites and High Plains wheat mosaic virus. Although present in Nebraska wheat fields, much of the virus’s biological and transmission details are unknown. A detailed understanding of virus transmission by the wheat curl mite would be a major help to wheat and corn growers. Sofiya Arora, a master’s student, is analyzing the virus-host and virus-vector interactions. She is studying the distribution of the High Plains virus within different wheat cultivars to understand the virus dynamics.
Her research also focuses on understanding the frequent mixed infections of crops by three mite-transmitted viral threats: Triticum mosaic virus, wheat streak mosaic virus and High Plains virus. It is striking that the High Plains virus recurs so prominently under field conditions, Mondal said.
To determine whether the High Plains virus is being transmitted with higher efficiency than the other two viruses, “we will do some transmission studies including those mixed infections,” he said. “We will prepare mixed infection in wheat plants, then use transmission assays using wheat curl mites to estimate differential transmission.”
• Virus-vector interactions. Nikhitha Gangavarapu, a doctoral student, is working to discover the scientific details of virus transmission by analyzing the microbiome in wheat curl mites.
It is notable that the mites suffer negative health effects when they are reared on plants infected with the Triticum mosaic virus, and at this point scientists don’t know why the mite is so affected, Mondal said. It could be that “the virus is doing some nutritional changes in the plant, or maybe the virus is encoding a viral toxic in the plant,” he said.
Gangavarapu’s research will seek answers on these virus-vector interactions.
Additional research tangents remain to be explored, and Mondal has several on his radar. Coinfection of plants by the barley yellow dwarf virus and cereal yellow dwarf viruses can cause severe harm to crops, for example, and much study is needed to understand the complex factors involved.
Mondal also is interested in studying bacteria in the mite microbiome to understand how they contribute to virus transmission. Once research fills in that scientific knowledge, he said, it might become possible to stop virus transmission using antibiotics.
Source : unl.edu