Three biological control programs aimed at tackling invasive species in Hawaii are showing positive economic returns, with two delivering especially strong results, according to a recent economic analysis conducted by the University of Hawaii Economic Research Organization.
The programs target the coffee berry borer, erythrina gall wasp, and fireweed, with all work taking place on the Big Island.
The report found that the biocontrol program targeting the coffee berry borer, a major pest affecting Big Island coffee growers, could deliver up to $42 in benefits for every $1 spent — a benefit-cost ratio of 42 — making it one of the most cost-effective efforts of its kind.
Even under more conservative estimates, the return remains strong at $21 for every $1 invested, with a net economic benefit of $69.1 million. If only a quarter of the expected benefits are realized, the program would still bring in $32.8 million. In all scenarios, it’s expected to pay for itself within two years.
The biocontrol agent, a parasitic wasp called Phymastichus coffea, is expected to reduce the need for costly management practices like Beauveria bassiana spraying and strip-picking. However, the successful establishment of the agent in the field is key to achieving these benefits. Delays in permitting, rearing or release could slow returns, the report noted.
The program targeting the erythrina gall wasp, which once threatened the survival of native wiliwili trees, also shows strong results. With a present value cost of $1.1 million and benefits totaling $27.2 million, the program yields a benefit-cost ratio of 24 and a net present value of $26 million.
The early success of this effort is partly due to the low cost of implementation and long-term ecological and financial gains, including avoided costs associated with listing wiliwili as a federally endangered species, according to the report.
Franny Kinslow Brewer, program manager of the Big Island Invasive Species Committee, said the gall wasp posed a serious threat to native wiliwili trees before biological control was introduced.
“Without the biological control, I think that our native wiliwili was really on the precipice of going extinct,” she said. “That’s how bad that gall wasp was for wiliwili.”
She also stressed the critical state of Hawaii’s native dry forests.
“If you’re someone who is trying to conserve native dry forests, which is the most endangered type of ecosystem in existence in Hawaii. … Dry forest is down to less than 1% of where the coverage used to be … so if you’re a person who is trying to conserve that rarest of the rare land type then obviously the gall wasp is going to be the most impactful.”
Most of the costs in the erythrina gall wasp program have already been spent, though some are still projected as work continues with a second biocontrol agent, the report noted. A portion of the estimated benefit also comes from the Waikoloa Dry Forest Initiative, which has generated millions in revenue since its founding in connection with native tree restoration efforts.
Fireweed, which reduces available forage for cattle, has been a persistent issue for Big Island ranchers. While the introduced biocontrol agent Secusio extensa has established in some areas, its effectiveness has varied, and ranchers have expressed mixed opinions. Benefits will depend on how much the agent helps protect grazing lands over time, according to the report.
Regarding the fireweed problem, Brewer pointed out the additional challenges faced by ranchers.
“If you’re a rancher who is already losing pasture to all these other pests and then you have fireweed moving in, that’s going to further degrade your pasture,” she said.
Brewer also highlighted the extra burden on coffee farmers when trying to mitigate the impacts of the coffee berry borer.
“If you’re a coffee farmer and you have to hire extra help and you have to be working extra hours … that’s a lot of extra work and a lot of economic impact.”
The findings highlight the range of outcomes possible through biological control. While programs like those for coffee and wiliwili can yield fast, large-scale returns, others may take longer and be more variable. Still, all three programs were found to generate more in benefits than they cost.
As invasive species continue to impact Hawaii’s ecosystems and industries, the report suggests biological control can offer a strong return on investment — especially when implemented early and with adequate support.
The results also point to the importance of continued monitoring and region-specific evaluation to ensure long-term success.
Source: The Garden Island
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