It’s virtually invisible to the naked eye; only a mere hint of movement from a minuscule grayish dot can be discerned.
Yet, this really small wasp, appropriately named Phymastichus coffea because it targets the coffee berry borer (CBB) pest, may be the salvation that coffee growers across the state have been praying for. In the coming months, researchers in the Dept. of Plant and Environmental Protection Sciences and USDA-ARS plan to deploy thousands of these wasps in coffee-growing areas on the Big Island, and possibly Maui and Oʻahu.
“This biological control agent has the potential to make significant positive economic impacts in the Hawaiʻi coffee industry, and offers an environmentally safe way to manage CBB,” says Mark Wright. “The Hawaiʻi coffee industry is economically and culturally significant, and we hope that this work will improve the lives of many people associated with the industry.”
P. coffea is a parasitoid, meaning that, unlike parasites that live and feed on a host organism, this insect’s larvae will eventually kill their host, he explains. When CBB dig into live fruit, such as coffee beans, they release chemicals that attract the wasp. As a biological control agent, it has been used successfully for a number of years in Central and South America, especially Colombia, for its adverse effects on CBB.
Starting in 2018, live shipments of the wasp were allowed to come into Hawaiʻi under strict quarantine for research. Specifically, for testing on native insects similar to CBB, such as those in the same subfamily as CBB to assure that no unintended impacts on native species are likely to occur, as well as other non-native invasive species in the same genus as CBB.
“We tested on 43 inactive and beneficial species, and confirmed that P. coffea doesn’t attack any native species of insects,” says Mark. “It has also shown potential parasitoid activity against the Tropical Nut Borer, a pest of macadamia nuts.”
Since then, Mark and PEPS grad students David Honsberger and Luis Aristizabal, along with Marisa Wall and Peter Follett of PBARC, have been inching closer and closer to their ultimate goal: releasing thousands of these wasps into coffee-growing regions in the state where CBB has ravaged farms.
“CBB arrived in Hawaiʻi without the natural enemies that keep populations in check in its native range in Africa,” says Peter. “The introduction of the African parasitoid wasp Phymastichus coffea will reunite CBB with its most significant natural enemy from home. Releases of this wasp in coffee in Colombia against CBB have been shown to limit populations to subeconomic levels.”
With approval from the federal APHIS and permit from Hawaiʻi DOA to bring consignments of P. coffea over from Colombia, the current plan is to hold and breed the wasps in quarantine for at least two generations to make sure they’re a pure colony with no contaminants or diseases. Then, PEPS and ARS will mass produce the wasps and release them into the field.
The wasps will fly free, become established and perpetuate, move into the coffee fruits by themselves, then distribute further, says Mark. First stop: likely the Kaʻū area of the Big Island, then possibly Kona, the Waialua area of Oʻahu, and Maui.
“If all goes according to plan, it’ll make a massive impact,” says Mark. “Financially, it will potentially allow the local coffee industry to employ more people, and not rely on pesticides as much. In fact, the wasp’s effectiveness at controlling CBB may be as high as an estimated 50% -- higher than any insecticide options we have.”
“This project has posed many challenges over the years, and has involved numerous people, graduate students, post-doctoral researchers, colleagues at the USDA-ARS, Hawaiʻi Department of Agriculture, and coffee farmers,” he continues. “It has been a great example how collaborative efforts can help us overcome serious challenges and return excellent results.”
Peter adds, “It’s personally satisfying to transfer a tool to Hawaiʻi coffee growers that may help manage their most important insect pest. Tom Greenwell, one of the largest coffee growers in Kona, plans to raise and release the wasp on his farm. That kind of ‘buy in’ gets researchers pumped up!”