Soybean aphids were first discovered in Wisconsin in 2001. Since then, the crop pest has become well established throughout the northern Midwest and the provinces of Ontario and Quebec in Canada. On numerous occasions the soybean aphid has caused very significant economic damage in Ohio.
The tiny pests inflict crop damage due to their potentially suffocating numbers. They can have as many as 12 generations a year and when the populations get large enough, the normally wingless aphids give birth to a winged generation that can spread far distances on the wind, according to Ohio State University Extension.
Because of the potential for ongoing problems from this yield robber in the future, there have been significant funding efforts from the North Central Soybean Research Program, USDA-National Institute of Food and Agriculture and the Center for Applied Plant Sciences at Ohio State University and the Ohio Soybean Council for a broad array of management techniques addressing soybean aphids. One management strategy has been to develop soybean varieties that are resistant to soybean aphids.
“The checkoff in Ohio as well as the North Central region states have put in a lot of investment in developing soybean plants that are resistant to the aphids, but now we have aphids that have overcome that resistance,” said Andy Michel, field crops entomologist at Ohio State University. “The aphids remain an important pest of soybeans in Ohio and with reports of insecticide resistance, they may become an even more important pest.”
To address this challenge, researchers took on the extensive process of sequencing the entire soybean aphid genome to help develop strategies that prevent the spread and increase of aphids capable of breaking aphid resistance. Michel led the effort.
“My laboratory at Ohio State focuses on understanding how soybean aphids are able to overcome aphid resistance in soybean. Through this research, we hope to develop strategies that prevent the spread and increase of aphids capable of breaking aphid resistance. In the course of generating DNA sequences…we were able to sequence the entire soybean aphid genome,” he said. “We now have a really good roadmap for the soybean aphid and understanding all of the genes that are involved that make the aphid such a bad pest for soybean farmers in the north central region.”
The soybean aphid is now the fourth aphid species with a completely described genome and this new information will be a valuable tool moving forward with soybean aphid management.
“It will further advance our ability to identify soybean aphid genes responsible for overcoming resistant soybean, and hopefully lead to a wider use of resistant soybeans,” Michel said. “In addition, as reports of insecticide resistance emerge from colleagues at Minnesota and Iowa, the genome will provide targets to understand resistance and potentially develop markers to monitor the frequency of insecticide-resistant aphids.”
The genome was constructed from soybean aphids collected across the north central United States by collaborators participating in the soybean aphid research group led by Kelley Tilmon at Ohio State University.
“Part of the issue with the aphid is that they are very tiny and they have a very tiny genome. That allowed us to really quickly sequence all of the base pairs in the aphid genome. It took about two or three years to sequence the entire genome and now that we have that library of what the genome is, it should not take us long to figure out what the genes are and better understand the genetic makeup of the aphid that allowed it to become such a pest,” Michel said. “The ultimate goal is really to understand how these aphids are able to overcome resistant plants. By understanding the genes involved we can better target management strategies and use better varieties. Now we are comparing genomes of resistant aphids and non-resistant aphids. What DNA does the resistant aphid have that the other aphid does not?”
This work has been accepted in the journal Insect Biochemistry and Molecular Biology, and is currently available online: Whole genome sequence of the soybean aphid, Aphis glycines. For a reference for soybean aphid management in the North Central region see the NCSRP Soybean Aphid Field Guide.