Should Nonnative Species Be Introduced as Biocontrols?

Candice Gaukel Andrews January 27, 2015 34
Wisconsin wetland

Wisconsin wetlands are being plagued by purple loosestrife, a nonnative, invasive plant that makes it nearly impossible for native species to grow. ©John T. Andrews

For decades now, climate change has been altering habitats and causing a major shift of ecosystems northward. Unable to adjust quickly enough, some cold-adapted species are being forced to relocate to higher latitudes as warmer temperatures push them out of their traditional environs. For some warm-weather species, habitats are expanding.

Such is the case in Florida, where a mosquito usually found near the equator is moving into Key West, the southernmost U.S. city. The new immigrant is Aedes aegypti, which can spread two diseases: dengue, a viral infection that causes flu-like illness and sometimes death, and chikungunya, which results in fever and severe joint pain. To combat this threat, researchers want to release more Aedes aegypti mosquitoes—genetically modified males that will mate with wild females, whose offspring will then die, thus reducing the population.

Oxitec, the company that is bioengineering the mosquitoes, hopes to release them this spring in Key Haven, a neighborhood of 444 homes on a relatively isolated peninsula at the north end of Key West.

But could introducing more nonnative species—especially genetically modified ones—be more harmful than helpful to the environment and to us?

A battle between aliens is not new

Arctic fox walking

The Arctic fox faces many threats from climate change: shrinking sea ice and tundra habitat, reduced numbers of lemming prey, and increased competition and displacement by the red fox, which is moving northward as temperatures warm. ©Brad Josephs

The strategy proposed for Key West is not the first of its kind. Slowing the spread of exotic plants and insects with the use of chemicals is expensive and often has negative environmental side effects. Finding natural enemies to kill invasive plants or insects is often healthier, more efficient and sustainable.

Last summer, in fact, the National Geographic Society reported that hundreds of thousands of flea-size, parasitic wasps from Pakistan (Tamarixia radiata) were released in California to attack Asian citrus psyllids, potential carriers of a plague called huanglongbing or citrus greening, which could decimate the state’s citrus groves. The U.S. Department of Agriculture recently promised the state $1.5 million to ramp up the program to release about a million wasps a year.

In Wisconsin, “beetle ranchers” are raising tens of thousands of tiny Galerucella pusilla bugs—native to Europe and Asia—that will be turned loose in the wild, where it is expected that they and their insatiable appetites will mow down waves of invasive purple loosestrife, a plant native to northwest Africa, Asia, southeastern Australia and Europe. The plant plagues Wisconsin wetlands, where it grows out of control and makes it nearly impossible for native species to grow.

The Wisconsin Department of Natural Resources says the program is cost-effective and environmentally safe. The bugs have been working everywhere they’ve been released, making them one of the most effective biological control projects ever implemented. Minnesota, which has a similar program, says its bio-control purple loosestrife program saves the U.S. Department of Agriculture and the Minnesota Department of Natural Resources about a million dollars a year. The return on investment amounts to $36 in benefits for every dollar invested.

An out-of-control alien

Another case in point involves the Asian lady beetle (Harmonia axyridis), a native of eastern Asia, which was introduced to the United States by the U.S. Department of Agriculture as a biocontrol for aphids and scale insects. It was originally released in Pennsylvania in 1978 and 1981, but the first overwintering beetles were not recorded until 1993.


For many years, insects have been used as biological controls. ©John T. Andrews

Since 2000, however, populations of the beetle have been increasing uncontrollably in the U.S. and Europe. Germany, especially, has seen a rapid proliferation, and conservationists fear that the Asian lady beetle will outcompete native beetle species. German scientists have now found the reason why this insect is so successful. Apart from strong antibiotic substances and antimicrobial peptides, its body fluid contains microsporidia, which are tiny, fungus-like, protozoa body cells that can cause immense harm. While the Asian lady beetle is obviously resistant to these parasites in its own body, transferred to native species, the cells can be lethal.

So far in the United States, the greatest damage caused by Asian lady beetles is the discomfort they give to homeowners. By the tens of thousands, the beetles tend to congregate in attics, ceilings and wall voids. Due to the warmth of the walls, they will move around and exit into the living areas of the home. In addition to their biting, they exude a foul-smelling, yellow, defensive chemical that will sometimes cause staining on walls and other surfaces. Some people have reported experiencing an allergic reaction and sinus and skin irritations to the excretions.

Introducing foreign DNA

Wisconsin wetland vertical

Could some introduced, nonnative species prove beneficial to the environment? ©John T. Andrews

According to the World Health Organization, there are no vaccines or cures for dengue or chikungunya. Although right now U.S. cases remain rare, 50 million people annually worldwide get sick with dengue, and the disease kills 2.5 percent of the half million that get severe cases. Chikungunya infected a million people across the Caribbean last year.

Throughout the Florida Keys, insecticides are sprayed year-round from helicopters and on the ground. But since Aedes aegypti don’t travel much and are repeatedly doused with the same chemicals, they have evolved to resist four of the six insecticides used against them.

Oxitec says that in 2012, it released 3.3 million modified mosquitoes over six months in the Cayman Islands, suppressing 96 percent of the targeted bugs. It also claims that a later test in Brazil was just as successful, and both countries now want larger-scale projects.

Some worry, however, about the negative consequences that could result if foreign DNA entered a person’s bloodstream after being bitten by an Oxitec mosquito. Even though Oxitec says only nonbiting male mosquitoes would be released, it is inevitable that some females will escape. And, as with the Asian lady beetle, it remains to be seen what the long–term effects of having an alien—and bioengineered—insect among us will be.

Do you think alien species should be used as biocontrols if they can help native species survive?

Here’s to finding your true places and natural habitats,



  1. Jasmine Ding March 10, 2015 at 11:12 am - Reply

    I agree with Sue, since we have seen too many real examples of introducing anlien species into native eco system then resulting in disasters in Australia. No matter how well scientists and authorities thought they considered, there are something else out of control later. So no, it’s not a choice.

  2. Elizabeth Kemp March 10, 2015 at 11:11 am - Reply

    It seems we as humans aren’t learning the lessons taught by our past actions. Everything has a negative impact at some point. antibiotics are great until drug resistent super bugs evolve. What makes scienitist believe that introducing an alien species or genetically engineering a species won’t lead to large issues. We need to allow the planet earth to react and evolve naturally (including humans) to avoid the risk of “engineering” ourselves into a state in which we cannot survive.

  3. Sue Korecki March 10, 2015 at 11:10 am - Reply

    I don’t agree with introducing species to control another species. There are many examples in Australia where this has not worked, though hopefully now the science is more robust and comprehensive.

  4. Richard Budd February 10, 2015 at 12:49 pm - Reply

    Seems like a good idea, but look at what happened to partula snails when carnivorous Florida rosy wolfsnails were introduced to the Pacific Islands to control the (also deliberately introduced) giant land snails; similarly cane toads in Oz. Introductions require a great deal of care and pre-introduction research.

  5. Govind Bharad February 10, 2015 at 12:47 pm - Reply

    Nonnative may create other problems over a period, as happened in plant species.

  6. Neil Marshall February 10, 2015 at 12:43 pm - Reply

    Man has moved into even the least habitable environments and has assumed the role of superior species. How’s that for the spread of an “invasive species” with an incredibly bad record? Forests gone from every environment, species gone in the tens of thousands in all environments. And here are most of you speaking in “terra forming” terms.

    As “POGO” once said; “We have seen the enemy and he is us”!

  7. Venkatasamy Ramakrishna February 3, 2015 at 1:10 pm - Reply

    The eternal question has always been about what these introduced species turn to once thay have reduced populations of those they were brought in to control.

  8. Douglas Fink February 3, 2015 at 1:09 pm - Reply

    I am in favor of the mosquito release. It sounds like they have done their homework on the bugs. Sterilized males have been released before to lower population levels if I remember correctly. Dengue fever has no cure, really painful disease – hate to come down with that after a vacation

  9. Jeannette DeAngelis February 3, 2015 at 1:02 pm - Reply

    Too many past examples of introduced exotic species getting out of control in the long run, with no backup plan on how to remedy the new, unforeseen infestations. Integrated pest management is only as good as the science behind it.

  10. Glenn Stanis February 3, 2015 at 1:00 pm - Reply

    Very interesting article. I am not an expert, but I always worry anytime we infringe on the natural order of things to get something accomplished. Then again, I guess we knocked the natural order of things off course quite some time ago.

    When I read things like this, it reminds me of my old comic books when some scientist would create something to help mankind, it somehow turns against him, and a superhero would have to fly in and save the day. Unfortunately, we are short on superheroes these days 🙂

  11. Roy DuVerger, MWC February 3, 2015 at 12:58 pm - Reply

    This sounds like another great idea, just like when the University of Florida brought in Love Bugs to control the mosquito problem in Florida. I can imagine this will be just as much a disaster. Bio-engineered crops have done nothing but create major issues to human and environmental health, and if this engineered bug fails and/or causes unexpected environmental issues how do we get rid of it?

  12. Jan-Hendrik Keet February 3, 2015 at 12:56 pm - Reply

    Sometimes we just have to ask: what other options do we really have?

    Chemical, mechanical, physical and biological control all have pros and cons. We must figure out which ones are the best for each situation. But we cannot just do nothing.

  13. Paul Looney February 3, 2015 at 12:55 pm - Reply

    After reading the article I do not get the same sense of dread many commenters have expressed. the non-native species is already in the area and causing some issues with health. The proposed solution is to introduce males that are modified to reproduce non viable offspring.

    I agree with those who say this is preferable to chemical solutions. I lived in Singapore where the government REQUIRED citizens to empty water from their potted plants or face a fine. The goal was to suppress an outbreak of dengue fever and suppress the reproduction of the mosquito that passes the disease.

    America, and especially the Key West folk would not stand for that type of government oversight. The proposed control mechanism does not require the people to actually change their habits. While I never had a problem with changing my behavior in Singapore for the common good, I do not see Americans being willing to do the same.

    Thus, this proposed solution is the one with the most potential to actually have an effect. The alternative, spread of Dengue up the peninsula and across the Gulf Coast followed shortly by Chikungunya is not an alternative I am willing to see occur.

    Again, the introduction of the non native species has already occurred. The solution is to modify and control the population. I do not see a problem here.

  14. Hal Michael February 3, 2015 at 12:50 pm - Reply

    The devil is in the details, which need thorough vetting. Some places in Florida are looking at using the invasive water hyacinth to improve water quality, due to man-induce changes. Putting non-natives into a system that is “out of balance” due only to native species is probably a bad idea. But when we have made massive changes in a system, including introductions, and somehow expect the original system to work is wrong-headed. It probably should take more thought and study than currently given but if the knee-jerk response is “no” then what viable alternatives are offered? One of them may work, but we need alternatives and not just no.

  15. Jesse Souki February 3, 2015 at 12:47 pm - Reply

    We use biocontrol in Hawaii. The earliest use I know of was the introduction of the mongoose to control rats and mice. However, mongoose and rodents have different sleep cycles, so instead, the mongoose helped put many of our native endemic bird species on the extinction list. Thankfully we have better science today. Here’s a better example of biocontrol

  16. Michael Schulz February 3, 2015 at 12:45 pm - Reply

    If we didn’t use nonnative biological controls, we’d still have prickly pear cactus covering Australia. Certainly there are some horror stories, but with careful research I think it is preferable to chemicals or allowing them to spread unabated. I think it’s unfair to lump all nonnatives in a box and say that they’re evil. It’s just really important to use parasites over predators, species-specific ones over generalists, and of course plenty of trials and research beforehand.

  17. Valerie Goodness February 1, 2015 at 1:18 pm - Reply

    No, non-natives should not be introduced into native ecosystems as biocontrols. In our compartmentalized western science worldview it is hard to look at the bigger picture which includes its own history. When some one asks me this questions my response is always, 1) what are they selling? and 2) who are their clients? The answer to those two questions usually equal entities who financially benefits from silencing the Indigenous peoples of that region and silencing the precautionary principle. How about if we stop trying to make money for the corporations who benefit from the environmental disturbance they are creating.

  18. Penny King February 1, 2015 at 1:17 pm - Reply

    One word CANE TOADS in Australia.

  19. Dr H. S. Singh Gaharwar February 1, 2015 at 1:17 pm - Reply

    Non-native species may not be introduced in natural habitat but tested and certified species may be introduced in cultivated areas in economic interest. Every country should establish an organisation to examine impact of an non-native species before introduction.

  20. Abiodun Cheke February 1, 2015 at 1:16 pm - Reply

    It is not advisable that nonnative species should be introduced as biocontrols, even from all examples cited and from experience in various places and countries the so stated bio controllers turn out to be more menace to biodiversity and humans in the long term.

  21. T.D. Smith January 30, 2015 at 12:20 pm - Reply

    Where biocontrol agents have worked they have done an excellent job and both the pest species and the biocontrol agents have become minor notes in the invaded ecosystem. Where biocontrol agents have not worked they were very unsuccessful. The suppression of winter moth populations in hardwood forests in southern Nova Scotia through the introduction winter moth parasites has been a success. The massive liberation of irradiated male screwworm flies in the southern United States has been a success. The introduction of a virus for the control mountainash sawfly has been a success. However; the introduction of the Asian lady beetle has not been a success as it displaces native species of lady beetles and they are a major annoyance in the house.

  22. Pacing Milan January 30, 2015 at 9:14 am - Reply

    One should view the introduction of nonnative organism with caution bcause of its impact on the biodiversity and the absence of natural control. Let us.consider the balance of naturre. An indepth research should be done when introduction of biocon agents will be used esp on the ecosystem.

  23. Umor Gift January 30, 2015 at 9:13 am - Reply

    The introduction of non native species is going to definitely have a wider impact on the biodiversity of the region.

  24. June Pretzer January 30, 2015 at 9:11 am - Reply

    Just the thought of introducing nonnative species as a bio-control gives me shivers.There are so many examples of this going off the rails, of inadequate research, side affects, that I just couldn’t support this.

  25. Raymond Kinney January 29, 2015 at 2:46 pm - Reply

    Always risky, but being faced with the usual alternative of massive pesticide pollution of wetland, water, and human breastmilk across Florida… the science is not very good at clarifying either alternative adequately. If GE mosquitoes have a lot of good science done prior to release to demonstrate risks are probably less than the current alternatives, maybe we will have to roll the dice and hope. I’m just afraid that not enough good science preparation has been done yet. Climate warming and ocean acidification is so rapid that it will wreak havoc with ecologic balances because adaptaion of physiologies can’t keep up. we are in deep doodoo and we are going to have to go through a whole lot of odious decisionmaking to utilize non-native introductions,,, just to try to cope with the rapidity of the changes. We’ll be forced into doing it often and are going to have to rapidly adapt our attitudes towardmany anthropogenic ecologies. IMHO

  26. Jorge Mafuca January 29, 2015 at 2:44 pm - Reply

    Definitely I would contribute that side effects of these introductions be evaluated before they are effected because one might think of solving on problem and end up creating one even bigger one. There so many examples of such doings across the globe on this matter.
    secondly, though its much easier to adopt solutions that have been tested elsewhere with some degree of success., it would be preferable to survey and test for local biological or other solutions rather than bring relatively easier solutions of which long term effects are unknown.

  27. Håvard Hageberg January 29, 2015 at 2:43 pm - Reply

    In my view introducing nonnatives should be a solution to be considered only when other more preferrable options have failed or are unable. In many cases one simply does not have enough information about the many interactions a new organism may have with the ecosystem. I’m sure there are cases where the effect has been just what was intended. But there is a certain element of letting go of some control, whenever you move organisms like this. Additionally, I feel like this is an example of a misplaced belief in the existance of a “quick-fix”.

  28. Maresa Pryor-Luzier January 29, 2015 at 2:40 pm - Reply

    As a life long resident of Florida, I feel very apprehensive towards introducing more non-native species to our state. I know that mosquitos can carry terrible diseases, and if this would cut down on chemical spraying in the state, it should be considered. However, we must look at all the pros and cons before even considering such a tool. Since, our past shows plenty of error in this area.

  29. Sean Morrison January 29, 2015 at 5:27 am - Reply

    I agree with Jessica in that introducing a non-native species can bring about negative outcomes that are unanticipated. Even if the introduction does not have immediate negative effects it could easily cause issues further along their introduction as they assimilate into their foreign niche being Florida. They will not have any natural predators and natural prey may not feed on them since they aren’t from that region.

  30. Laurence Hutchinson January 29, 2015 at 5:25 am - Reply

    Natural biological control elements are part of the ecological structures, human impacts have altered this natural scenario.

  31. Mwende Kusewa January 29, 2015 at 5:24 am - Reply

    There are many success stories of effective biological control using non native species. Climate change I think does cause some challenges in predicting how biological control agents will respond in the environment where they have been introduced.

  32. Lg January 28, 2015 at 10:35 pm - Reply

    My opinion is that they are thinking in a “short term solution” instead on the long run. Besides We (humans ) have alter our Eco systems and now that’s why we face diseases and changes in our planet

  33. Garry Rogers January 27, 2015 at 12:07 pm - Reply

    Though traditional biological control can work, it is difficult to anticipate outcomes. Ecosystem responses are not predictable with the knowledge we have. And we can’t experiment, because no controlled environment will parallel ecosystem complexity and variability. It would be interesting to research this to find what percentage of previous attempts have succeeded. I apologize for not doing the work.

  34. Jessica Goodrich, CIG January 27, 2015 at 10:13 am - Reply

    Anytime we execute an ecosystem management plan, there are always unintended consequences. Bringing in a new nonnative species will also bring in its own set of problems. Using a native method of control is always preferrable.

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