February 6, 2020
Agricultural trade is crucial in delivering food to consumers worldwide. The benefits range from lower prices to greater variety in our food supply, and most importantly, the ability to reduce food insecurity across the globe. But, as international trade increases, so does the spread of invasive and destructive agricultural pests that can threaten food production and even destabilize our global food supply. Researchers from the University of Virginia’s Biocomplexity Institute are focusing on one pest in particular – the South American tomato leafminer or Tuta absoluta– a tiny moth with the potential to cause devastating damage to tomato and other crops if left unmitigated.
Abhijin Adiga, Hannah Baek, Madhav Marathe and Henning Mortveit from the Institute’s Network Systems Science and Advanced Computing division along with Rangaswamy Muniappan and Joseph McNitt of Virginia Tech’s Feed the Future Innovation Lab for Integrated Pest Management among others led an extensive research study on the spatio-temporal spread of T. absoluta using a network-based multipathway simulator to understand its expansion in South and Southeast Asia. This past October, The Royal Society published, “Assessing the multi-pathway threat from an invasive agricultural pest: Tuta absoluta in Asia," in its Proceedings of the Royal Society B, Biological Sciences journal, detailing the study that began in 2015 through funding from the Integrated Pest Management (IPM) Innovation Lab, a USAID-funded program.
What makes T. absoluta particularly destructive is its ability to mine into plant leaves, removing the photosynthetic ability. Once it has attacked the leaves, it moves to the fruit and soil, then the crates and boxes in which the crops are transported, making the pest especially difficult to destroy, and therefore, easy to transport and spread. Scientists and agriculturalists have been unable to identify any effective mitigation or prevention methods to date. Without mitigation, T. absoluta can cause 80 to 100 percent destruction of an entire crop. And, while T. absoluta is already a serious pest to tomato crops, it will attack eggplant, potato, and pepper plants as well.
Native to South America, T. absoluta was accidentally introduced to Spain in 2006. By 2012, it spread throughout Europe, Africa, Western and Central Asia, and parts of Central America, causing devastating damage to tomato crops, the livelihoods of tomato farmers, and entire economies. In 2013, the IPM Innovation Lab began monitoring the spread, organizing awareness and management workshops in Africa and Asia, and partnering with institutions including UVA’s Biocomplexity Institute to analyze the current spread and future spread scenarios as well as identify food system vulnerabilities.
“For the first time, we performed a multi-pathway analysis of T. absoluta’s spread in South and Southeast Asia, accounting for both natural pathways of spread as well as human-mediated pathways such as trade of host crops,” Adiga said. “We developed a novel network-based artificial intelligence (AI) system that was constructed using data from different domains (climate, host-pest biology, production, trade, demographics, etc.). We used machine learning in conjunction with simulations to analyze current spread and future possible spread scenarios.”
The team’s analysis revealed a high correlation between long-distance movement of T. absoluta and the transport of infested tomato fruits or seedlings. They also identified production centers that are at high risk of invasion, and determined that applying interventions at key production centers can greatly limit the range expansion of the pest. The study not only enabled regions already affected by T. absoluta to mitigate future spread and impact, it has proven extremely beneficial for regions such as North America that have not yet been invaded.
“T. absoluta has not yet invaded the United States,” Muniappan said. “The experience gained in modeling the spread of T. absoluta in Asia has given the advantage of modeling and predicting the possible pathways of spread in the U.S. In the event it is introduced, the federal and state regulatory authorities can immediately take up eradication, prevention, and control measures.”
Other project partners included the Bangladesh Agricultural Research Institute, CIRAD (Senegal), iDE (Nepal), Indian Agricultural Research Institute, Indian Institute of Horticultural Research Institute, and INRA (France).
“This study is an excellent example of interdisciplinary and intercontinental work involving scientists from different countries working collaboratively to address a common problem,” Muniappan said. “Further, methods we developed can now be applied to other pests and pathogens in the future.”
The study published in The Royal Society’s Proceedings of the Royal Society B, Biological Sciences journal served as the foundation for further assessment of the threat T. absoluta poses to the United States, which UVA’s Biocomplexity Institute is currently conducting through a $500,000 grant from the U.S. Department of Agriculture National Institute of Food and Agriculture.
The Royal Society is the independent scientific academy of the U.K. and the Commonwealth, dedicated to promoting excellence in science. The Society’s fundamental purpose is to recognize, promote, and support excellence in science and to encourage the development and use of science for the benefit of humanity.