(08/04/16) BATON ROUGE, La. – An LSU AgCenter researcher has joined in a research project with a biotechnology company in a grant from the Bill and Melinda Gates Foundation to find a biological insect control for small sweet potato farmers in Africa.

AgCenter entomologist Jeff Davis, who maintains a colony of sweetpotato weevils in the AgCenter, will screen weevils for biological control bacteria provided by AgBiome, a biotechnology company in Research Triangle Park, North Carolina.

The AgBiome project aims to discover beneficial microbes with the ability to control sweetpotato weevils. "We are extremely excited to use AgBiome's technology to benefit smallholder farmers in Africa," said AgBiome entomologist Brooke Bissinger. "It is an honor to be able to contribute to the protection and sustainability of this valuable crop."

The sweetpotato weevil is a historically important pest endemic to south Louisiana and the Gulf South region of the United States, said Tara Smith, entomologist and research coordinator of the LSU AgCenter Sweet Potato Research Station in Chase. It is a very important insect pest of sweetpotato both in the United States and worldwide.

“As recently as the late 1990s, the weevil was a significant problem,” Smith said. “In Louisiana it is now effectively managed through a comprehensive integrated pest management program. There are also regulatory programs in place for the weevil.”

The Louisiana colony of sweetpotato weevils was initially established in an AgCenter laboratory in 2004 and is supplemented yearly with new stock collected from Louisiana sweet potato fields.

“The sweetpotato weevil colony allows scientists to conduct research focused on the biology and ecology of the insect as well as opportunities to conduct baseline toxicological studies to evaluate the efficacy of insecticides and biological control materials for weevil management,” Smith said. “The colony has long been a part of the sweet potato entomological research program.”

Weevils damage sweet potato roots by laying eggs in them, and infested roots have a bitter, off taste, Davis said.

Davis, AgCenter research associate Jeff Murray and LSU entomology graduate student Jie Chen are looking at host plant resistance to the weevil.

“The mechanisms of resistance seem to revolve around egg laying on the storage roots,” Davis said. “Some varieties are more resistant than others.”

Chen is evaluating the weevil colony to find any with resistance to insecticides.

The AgBiome researchers will provide Davis with bacteria that he will screen to find those that provide insecticidal activity. “It’s similar to Bacillus thurengensis,” Davis said. “They will isolate bacteria and we’ll screen them. The bacteria are not pathogenic to the plants and will be safe for everyone.”

The focus of the research is for subsistence farmers in Africa.

AgBiome has already established a collection of plant-associated microbes and has sequenced and annotated the genomes for more than 26,000 microbial strains. The grant will support the isolation, sequencing and testing of microbes associated with U.S. and African sweet potato plants in an effort to discover microbes that are capable of controlling the weevil.

"This is such an incredible opportunity for us at AgBiome," said AgBiome entomologist Chad Keyser. "The scope of this project is so much more than pest control or increasing yields. We've been given the opportunity to make a real impact on the health and livelihood of millions of people."

Sweetpotato weevils in the LSU AgCenter weevil colony crawl over a sweet potato held by LSU graduate student Jie Chen while AgCenter entomologist Jeff Davis, right, and AgBiome entomologists Chad Keyser and Brooke Bissinger observe. Davis will use the colony in Baton Rouge to screen weevils for biological control bacteria provided by AgBiome. Photo by Rick Bogren