Under Adekunle Adesanya’s microscope, tiny black specks are moving across a bean plant’s leaf. Through the lens, they resemble black and yellow balls atop eight translucent legs.
“Those dark spots are spider mites,” explains Adesanya. Distantly related to spiders, these specks don’t hunt prey. “They suck all their water and nutrients from plants.”
His diploma as one of Washington State University’s newest doctors of entomology is just days away. But Adesanya is still hard at work in the lab, tinkering with tests on this nearly invisible arachnid that happens to be one of the world’s most prevalent pests.
“These guys feed on more than 1,400 plant species,” he said. Spider mites ruin important crops like cocoa in his home country of Nigeria, as well as “practically any food plant you have. They’re terrible on hops, strawberries, alfalfa, corn, soybeans, peppermint, apples… the list goes on.”
Hard to spot, these miniscule pests multiply rapidly—so fast, in fact, that they can develop resistance to commonly used pesticides, causing farmers to spray chemicals to little beneficial effect.
“By the time you notice them, they’ve probably destroyed your plants,” said Adesanya. He has made stopping them, sustainably, his specialty.
The best endeavor
Growing up in Lagos, at 18 million people one of the biggest cities in the world, Adesanya nursed boyhood dreams of becoming a soccer star. His mother, however, insisted he go to school, and Adesanya was a standout student at university—so much so that his advisors placed him as an undergraduate researcher in entomology.
Mentally and physically, it was one of his school’s most challenging programs, putting field visits on top of lab research and studies.
“I realized, wow, I can do any kind of science with insects, and still make an impact solving global food security issues,” Adesanya said. “This is the best endeavor!”
Coming to America as a master’s student in 2013, Adesanya studied the Japanese beetle, a devastating pest of crops like cherries and soybean. Master’s in hand, he sought a new challenge, and found the spider mite, an even more voracious pest of crops around the world.
Advised by WSU entomologists Doug Walsh, Fang Rose Zhu and Laura Lavine, Adesanya embarked on farm-saving research while shaping himself as a scientist.
Cycle of pests and struggle
Back home, grandparents on both sides of Adesanya’s family are farmers who raise Nigeria’s chief crops, cocoa and cassava.
“Growing up, I saw them struggle with pest management,” he said. “Their yields were based on luck. They’d pray that this year, they wouldn’t have pests. And if pests came, there were no ready-made solutions. They weren’t rich enough to buy pesticide.”
Bad infestations came every couple of years. Spider mites or cocoa mirid bugs, for example, would devour leaves and weaken plants, drastically shrinking crucial harvests.
When that happened, his grandparents were forced to rent out their own land to make ends meet.
“They had to struggle for the year,” he said. “One day, I hope I have the chance to go back and help farmers like them fight pests.”
The genes of resistance
Doing exactly that from his WSU lab, Adesanya has spent several years studying the genetic roots of spider mites’ tenacity. He is currently finishing up his student research to develop a gene-based test for pesticide resistance.
“Because spider mites multiply so fast, they can quickly build up resistance to whatever chemicals you throw at them,” he said.
Such a test could help farmers quickly learn whether pests on their farms are resistant—and turn to better solutions without wasting chemicals.
“That saves them money, and means less pesticides on the crops they’re growing and in the environment,” he said.
Under the microscope, Adesanya is testing to see if the bacteria that live inside the mites are helping them defeat chemical treatments.
“We need to consider the microbiome they carry with them,” he said.
At WSU, Adesanya collects mites in the field, scouts for natural enemies, and checks to see if pesticides will hurt the mite’s natural enemies and other beneficial insects.
“We want to make sure we’re stopping the mites, but leaving natural predators and pollinators alone,” Adesanya said. “It’s all about the four P’s: pests, predators, pollinators and people—the consumer and the farmer. We care about our bottom line and our health. We don’t want to buy food that is pesticide-laden.”
Adesanya’s research has already drawn notice. Last year, he won the 2018 John Henry Comstock Award from the Pacific Branch of the Entomological Society of America (ESA), the highest honor granted to an entomology graduate student.
After graduation, Adesanya seeks to continue his career in university research and Extension, helping farmers and consumers here in the Northwest and globally.
“This is where you can make the most impact,” he said.