Frequently Asked Questions

The video below provides an overview of the biocontrol process and how it helps Hawaii.  Scroll down for more FAQ and answers.

Q: Why are you proposing to introduce another species that may become invasive?
A: Since 1975, when the State of Hawai’i enacted stringent protocols for biocontrol research and testing, more than 50 biocontrol agents have been released without any adverse effects or switching of hosts. Biocontrol has helped us to sustainably manage widespread pests like panini cactus, wiliwili gall wasp, nettle caterpillar, and banana poka.

Q: What is the agent harms other non-target species such as wild plants or crops: 
A: The entire selection and testing protocol is set up to focus only on the proposed biocontrol agent that is host-specific — they must prove that they cannot impact, live on, or even live out their lifecycle on anything other than the intended invasive species target. Before being approved for release, biological agents are often tested on 100+ native, commercial, and ornamental species found here in Hawai’i to ensure it is specific to its intended host. An agent will not be approved for release if it does not pass the stringent tests.

Q: Won’t a biocontrol agent move on to other plants or hosts after killing off its target?
A: Although some biocontrol agents are capable of killing their hosts, biocontrol never results in complete eradication of the target’s population. Instead, as the target population declines, so does the population of the agent. Highly host-specific agents are so closely dependent on their host that they cannot use other host species, even when faced with starvation. Further, rapid evolution of host switching by a host-specific feeder is extremely unlikely because of the many genetic changes that would have to occur. This process is gradual over thousands to millions of years and has never been observed in over 1,000 cases of invasive plant biocontrol worldwide over the past 100 years.

Q: What will happen if all the target plants disappear?
A: A biocontrol agent is selected in part because it depends on its host for survival. Even the most effective biocontrol does not result in the eradication of its host. It gradually slows the target’s spread so that native plants can grow and balance is restored to our forest.

Q: Won’t infested target plants despoil the beauty of the forest or agricultural lands?
A: visual impacts to the targets will be minor, but increased numbers and health of native plants will have a tremendous scenic benefit.

Q: Doesn’t Hawaiʻi’s failure with the mongoose shows that biocontrol is unreliable?
A: The mongoose was introduced by a private landowner in 1883 with no scientific testing or regulatory oversight and is not at all representative of the modern practice of biocontrol. Today, we require rigorous testing. Since 1975, biocontrol species (including natural enemies for clidemia, banana poka, wiliwili gall wasp, and ivy gourd) have been introduced to Hawaii with no adverse effects. A mistake made a century ago has long since been trumped by a decades-long track record of success.

Q: Was testing of the agent adequate?
A: Rigorous scientific studies to safeguard Hawaiʻi are conducted and approved before release. The agents are subjects of extensive testing to see whether other plants in Hawaiʻi could serve as hosts. Tests are done in the laboratory and in the field on often 100+ plants, including close relatives of the target species, to see if the agent is highly host-specific. Only at the end of this process do state and federal agencies carefully consider a proposed release and approve permits.

Q: Can the agent multiply out of control to extreme densities?
A: Host-specific plant feeder populations are limited by the abundance of their host plants.

Q: Will a new introduced insect cause allergies? 
A: Exposure to humans is typically minimal and less than many other common insects already in Hawaiʻi.

Q: Won’t worse invasive plants will replace the targets?
A: Many of the targets are listed as noxious weeds, some of the most invasive plants in the state, but as an additional management tool, biocontrol can make restoration with native species more feasible.

Q: If we control these invasive weeds manually or chemically, why do we need biocontrol? 
A: Often, target weeds infest thousands of acres across our state, often in steep or remote terrain, making manual or chemical clearing dangerous and a temporary measure at best. These methods can sometimes have negative impacts like erosion or excessive use of herbicides. Most of these pests are not new to the islands, and after decades of effort, it has become clear that biocontrol, used alone or with other methods, is the best and most economical option.

Q: Isn’t biocontrol more expensive than other methods? 
A: While biocontrol usually starts with a fairly large investment, it often followed by a high return and is almost always far more economically feasible than other management tools. The benefits of successful biocontrol can accrue permanently, and the cost of establishing a biocontrol agent for a single target weed is often only a small percentage of annual spending using alternative control methods.

Q: Biocontrol is theoretically ok, but do we really need another insect in Hawaiʻi? 
A: Biocontrol introductions, which are rigorously studied and regulated to ensure the benefits outweigh the risks, have a proven track record of safety and effectiveness. They are a vital tool for our worst invasive species and can offer tremendous benefits to both native forests and our agricultural economy.