If the U.S. Department of Agriculture has its way, yet another alien species may call Hawai’i home in the near future. According to a draft environmental assessment prepared last July by the USDA, the U.S. Forest Service (an arm of the USDA) is planning to release a leaf-mining moth on the islands of Hawai’i, Maui, and Kaua’i, in hopes it will reduce infestations of firetree (Myrica faya). In light of questions about the effectiveness and potential range of the moth, however, the USDA has announced it will prepare a second draft EA.
Firetree, or Fayatree as it is sometimes called, is a plant native to the Azores, Madeira, and Canary Islands in the eastern Atlantic. Of all the weeds invading Hawaiian forests, land managers consider firetree to be one of the worst at present, it has taken over some 70,000 hectares in Hawai’i and, without some control measures, will probably con–tinue to expand its range.
There are two reasons firetree is able to establish itself so readily in our islands. First, it is a nitrogen-fixer – that is, it is able to use atmospheric nitrogen through the action of a fungus in its root nodules. This gives firetree a competitive advantage over most native Hawaiian plants growing in nitrogen-poor, volcanic soils. The second reason firetree does so well is due to the Japanese white-eye. This introduced bird eats the tree’s dark red berries and passes out viable seeds. In addition, other introduced species, such as goats and pigs, may disperse seeds.
So far, land managers have been able to control firetree in small areas using chemical and mechanical methods. In the draft envi–ronmental assessment, these methods are explained: “The usual chemical method is to cut the trees and immediately apply Picloram to the stumps. The mechanical method is to remove entire trees. To be effective, tree removal must be supplemented with chemi–cal control.”
Unfortunately, the expense and effort these methods entail cause them to be practical only in small, accessible areas. To control firetree in larger, more remote sites, land managers are looking for a silver bullet which many believe lies in Phyllonorycter myricae (Lepidoptera: family Gracillariidae), the leaf mining moth that the USDA wants to introduce.
In its native habitat, P. myricae reported to be host specific. In other words, the moth needs firetree to complete its life cycle. P. myricae deposits eggs on the leaves of firetree. The eggs develop into caterpillars that mine or chew their way into the leaves. Once in the leaves, the caterpillars pass through several life stages, called instars. In the last instars, the caterpillar causes the most damage to the plant as it devours leaf tissue. Finally the adult moth emerges, having completed its entire development from egg to adult all on the same leaf.
Land managers and conservationists agree that halting the spread of firetree is desirable. But in the rush to do something good for Hawaiian forests, are the responsible authori–ties making informed decisions? Can this moth really control firetree in Hawai’i? On this, the record is not as clear as one might hope.
The state Board of Agriculture has already approved the USDA’s request to introduce the moth. This occurred in January 1997, when the board granted a conditional permit to Dr. Rosemary Leen of the Forest Service’s office in Volcano, Hawai’i. The approval was based on the recommendations of the board’s advisory subcommittee on entomology and the advisory committee on plants and ani–mals. Although some members of each com–mittee expressed reservations about the field release of the moth, in the end, no one voted to deny the permit.
One such reservation pertained to the moth’s effectiveness in controlling firetree. According to meeting minutes, Dr. D. Lance of the USDA’s Agricultural Research Service in Waimanalo felt that Leen had not pro–vided information that would lead him to conclude that releasing the moth would actu–ally produce any benefit. “I see no reason to approve a petition for a release that has a high probability of doing nothing more than add–ing another species to the ecosystem,” the minutes report him as having said.
Bishop Museum’s Dr. Frank Howarth echoed lance’s concern: “Surely more is known on [the moth’s] effects on the target than is presented; otherwise, there is little reason to propose its introduction.” Still, both entomologists recommended approval, albeit with reservations. Lance explained his recommendation by noting, “I wouldn’t want to hold up the release of a potentially valuable biocontrol project.”
Gary Gill, director of the state Office of Environmental Quality Control, voiced similar concerns at a meeting of the advisory committee on plants and animals. According to minutes of that meeting, Mr. Gill asked why this moth should be released in Hawai’i when lab tests show that the moth “will not cause significant damage to firetree and thus not achieve control of the weed.” Myron Isherwood of the state Department of Agriculture’s plant inspection branch re–sponded that the moth caused about 15 per–cent damage to firetree in the Azores. And, he added, biocontrol often relies on “a complex of natural enemies” to achieve significant control of a weed. In Hawai’i, introduction of P. myricae might help achieve such a com–plex, since it would be the third species released for biocontrol of firetree here. The two other species are a fungus (Septoria myricae) and another moth (Caloptilia nr. schineila). (The Caloptilia moth was intro–duced in the early 1990s. No environmental assessment was done for this, nor does the USDA seem to know whether caloptilia even continues to exist in the areas of its release. This makes difficult the argument that the introduction of P. myricie will act synergisti–cally with Caloptilia in the war on firetree.)
During the period for public comment on the draft environmental assessment, I raised additional concerns about the potential effec–tiveness of P. myricae, in light of the likely presence of natural enemies here already. In my letter of September 8, 1997, I questioned the value of releasing the moth in an area where it may be heavily parasitized by wasps. Some parasitoid wasps (in the Braconid, Eulophid, and Chalcidid families) may al–ready be in Hawai’i. If these parasitized P. myricae, they could severely reduce the moth’s effectiveness as a biocontrol agent.
Dr. Ronald Hennessey, with the USDA’s Animal and Plant Health Inspection Service headquarters in Maryland, responded to me a week later. Hennessey, a co-author of the draft environmental assessment, stated that “when APHIS prepares environmental assess–ments and issues release permits, it concerns itself with questions of environmental safety but not efficacy. Natural enemies may in–deed, as you indicated, suppress populations of introduced natural enemies, but this is not a safety issue.” However, the USDA now says it will be preparing a second, revised draft EA for the release of P. myricae.
Other concerns raised by the subcommittee on entomology pertained to laboratory tests that examined whether or not P. myricae might develop on non-target species found in Hawai’i. Subcommittee member Dr. Mary Purcell was bothered that “host testing was done with no replication.” She asked, “Is this standard procedure?” She also asked whether the moth was exposed to potential host plants at stages when they would be most attractive to the moth.
Dr. V. Chang at the Hawai’i Agricultural Research Center in Alea was troubled by the finding that the moth laid eggs on potted papaya plants. He recommended further tests to ensure that the moth larvae could not develop into the adult stage on this host.
Ultimately, these concerns were overrid–den. Subcommittee members Dr. M. Johnson (University of Hawai’i Department of Entomology) and Lance were won over by Leen’s data that P. myricae was indeed host-specific – that is, it won’t harm plants other than firetree.
In addition, Dr. Scott Miller, formerly with Bishop Museum, consulted with an expert lepidopterist at the Smithsonian Insti–tute, Dr. Don Davis. According to Miller, Davis “indicated that all the true Phyllonorycter species known to him are restricted in their feeding to a single plant genera [sic].” However, when I spoke di–rectly with Davis, he said that while the moths did tend to be very host-specific, they can indeed complete their life cycle on plants other than their customary hosts.
Hawai’i might put the claim of host-specificity to a severe test. According to an article by Funasaki et al. in the Proceedings of the Hawaiian Entomological Society (1988), 23 species released for biocontrol between 1890 and 1985 have attacked native Hawaiian plants and insects. During this period, a total of 679 species were released in the islands as biocontrol agents. (This does not count spe–cies introduced for horticultural or orna–mental purposes that later became pests.) Of these, 243 became established. Thus, nearly to percent of the established biocontrol spe–cies attack native Species. Clearly, some of the species introduced in the late 19th century and early 20th century were more destructive than intended.
Defenders of biocontrol will quickly point out that in 1944 the Board of Agriculture adopted a policy to review the release of alien species for biocontrol programs. Since that time, more than 75 percent of the species approved for release attack only their target organisms. And this track record is improv–ing. For example, 96 percent of the estab–lished organisms released for biocontrol be–tween 1970 and 1985 have been reported to attack only their intended targets (Funasaki et al, 1988).
In the article by Funasaki et al. the current philosophy of biocontrol programs is explained: “entomologists engaged in biocontrol programs in Hawai’i… seek natu–ral enemies which are highly host specific whenever possible and … recommend for release only those species which are judged not to be a threat to non-target organisms by virtue of their proven host specificity, their ecological specificity, or the lack of suitable hosts among the native biota.”
The USDA believes that P. myricae is a good candidate for biocontrol because it is reportedly host specific. Moreover, there are no native biota even closely related to firetree – that is, there are no native Hawaiian plants in the Myricaceae family – which Phyllon–orycter might be predisposed to attack.
Lab Tests
In laboratory tests of host-specificity, P. myricae was exposed to 51 families of plants that occur in Hawai’i, as well as to the family Myricaceae. Although eggs developed into adults only on firetree and on a related orna–mental plant (Myrica cenfera), the moth did deposit eggs on plants in six other families. The plants on which eggs were oviposited were maile (Alyxia oliviformis, family Apocynacae, kawau (Ilex anomala, family Aquifollaceae), olapa (Cheirodendron trigynum family Araliaceae), naio (Myoporum sandwicense, family Myoporaceae), poha (Physalis peruviana, family Solanaceae) and papaya (Carica pa–paya, family Caricaceae). Leen and Hennessey, preparers of the draft environ–mental assessment, stated that “many species of Lepidoptera deposit eggs on plants other than their natural hosts when they are closely confined in cages.” And, they concluded, “ releases of P. myricae will not harm non-target species.”
However, other species of Phyllon–orycter moths have proved to be adaptable when it comes to accepting unusual food plants. In my comment letter, I cited three recent pub–lications on this subject. The first appears in a book by Mark Young, The Natural History of Moths (1997), According to Young, in the United Kingdom, Phyllonorycter messanieila usually uses only native oak and beech, but has accepted a non-native host, the Southern Beech native to New Zealand, Australia and South America – which was planted in a botanical garden in Scotland.
The second appears in an article by Buhl et al. (1994). This article reports that a Danish moth, Phyllonorycter leucographeila, pre–ferred Pyracantha coccinea, a member of the Rose family, but occasionally fed on other rose plants in a different genus, namely Craraegus and Cotoneaster.
The third publication is that off Groen (1996), which reports an instance of an adult moth emerging from a food plant in a family other than its usual food plant. Groen cites the case of the moth Phyllonorycter maestingeila emerging from a leaf mine in a legume, wisteria floribunda, whereas its usual foodplant was a beech, Fagus sylvatica (fam–ily: Fagaceae).
In reply, Hennessey contended that “for P. myricae to cause damage in Hawai’i, it would have to shift to a new host across family lines, and this would be very unusual in–deed… I myself do not know of a single documented example in the entire history of biocontrol.”
But given that there are at least three documented cases of Phyllonorycter using new foodplants, the possibility exists that it could happen here, especially since the USDA’s own tests demonstrated that the moth deposited eggs on non-target plant species. What action will the USDA take if P. myricae adapts to a new host, such as the economically valuable papaya or the ecologi–cally important naio? If outbreaks of P. myricae occur, will the Department of Agri–culture be able to control them?
Around the world, controlling outbreaks of Phyllonorycter moths has proved difficult. In scientific journal articles, adjectives such as “pestiferous” and “noxious” are used to describe many species of Phyllonorycter moths. In the Netherlands, there is a concern that Phyllonorycter leucographeila may develop into an important pest on pyracantha (Stigrer and Van Frankenhuyzen 1991). In Israel, Phyllonorycter platani is the main insect pest of the plane trees (Halperin 1990). In Minnesota, the aspen blotch miner, Phyllonorycter salicifoliella, has occurred at extremely high, “epidemic” densities on its quaking aspen host trees for at least a decade (Auerbach 1991). And across the continen–tal United States and in Canada, many species of Phyllonorycter (e.g., P. blancardella P. erataegella, and P. elmaella) are costly control problems in apple or–chards.
The spotted tentiform leafminer, P. blancardella, has been especially difficult to control. The use of insecticides on this species has led to the evolution of its resistance to organophosphorous insecticides, pyrethroids, and methomyl (Pree et al. 1990). Now researchers are evaluating dif–ferent parasitoids of P. blancardella as pos–sible biological controls (e.g., Ridgway and Mahr 1990).
If the population of P. myricae in Hawai’i reaches epidemic proportions, will the USDA then propose to import a biological control agent of the moth itself, or perhaps to spray insecticides over native forests?
The USDA proposes to introduce P. myricae to Hawai’i initially at the Hawai’i Volcanoes National Park and surrounding areas (in–cluding state-owned land), land in the Hamakua region of the Big Island, and on Kaua’i, at Koke’e State Park. In my efforts to learn more about the review process required before the moth could be released, I wrote Gary Gill, director of the state Office of Environmental Quality Control, last De–cember. “Since some moths will be released on state parklands, I believe that an agency of the state of Hawai’i is legally required to prepare an [environmental assessment] pursuant to HRS 343-5(t),” I wrote. “I contend that the release of a non-native species on state lands for the purpose of significantly affecting the environment (al–beit for the benefit of native ecosystems) constitutes a clear use of state lands, and is thus a trigger for the preparation of an EA by a state agency. Moreover, the release of a non-native species for biocontrol purposes is not on the list of exemptions for the Division of State Parks.”
Gill disagreed. In a letter dated January 21, 1998, he wrote: “We can find no precedent under state law in which an EA has been prepared to study the impacts of a biocontrol agent on state land. It is, however, within the authority of state agencies that have discre–tionary approval power over the introduc–tion or release of a biocontrol agent to require an EA if such introduction or release may cause significant environmental effects.”
Gill went on to note that the USDA was completing its environmental assessment of the release of the moth, pursuant to the federal National Environmental Policy Act (NEPA). “We anticipate that when the final NEPA EA is completed and a record of deci–sion issued by the USDA, the moth will be imported subject to the Hawai’i DOA’s per–mit conditions and released on state land under the jurisdiction of the” Department of Land and Natural Resources. The DLNR, Gill noted, “does not intend to process a permit for the release of the moth.”
Gill explained that although alien species introductions are not a trigger under Chapter 343, the state’s environmental review law, they are governed by Chapter 150 A of Hawai’i Revised Statues, the alien species importa–tion law, which, he noted, the state Depart–ment of Agriculture seemed to comply with in this case. In any case, “the environmental review law and the alien species importation law are not mutually exclusive. The agency with discretionary approval over a project has the legal responsibility to determine if HRS 343 applies to the project… Although no state agency has ever determined that HRS 343 applies to the importation of alien species, an agency would be within its powers to do so.”
Gill also pointed out that citizens may file suit in court to “assure the proper implemen–tation of the environmental review law… Ultimately, a judge can decide whether HRS 343 applies to the introduction of alien species or the release of biocontrol agents on state land.”
Finally, Gill told me that, “the increase public awareness and participation in the alien species review process, OEQC is work–ing with the [state Department of Agricul–ture] to publish notice of each application to import alien species. This would be a new feature in our semi-monthly bulletin The Environmental Notice. We hope this will encourage greater public and professional scrutiny of applications to import alien spe–cies into Hawai’i.
Risks exist in every pest control management program. In the case of firetree, for instance, field workers risk injury while using heavy equipment to remove trees. Herbicide appli–cators risk poisoning non-target species, as well as themselves. And, if the Board of Agriculture decides that P. myricae can be “safely” released in Hawai’i, then it risks changing ecosystems all over the state forever. According to the draft environmental assess–ment, biological control agents such as P. myricae generally spread even without the agency of man. In principle, therefore, release of this species at even one site must be consid–ered equivalent to release over the entire area of Hawai’i in which potential host plants occur and in which the climate is suitable for reproduction and development.”
Whether this moth should or shouldn’t be released in Hawai’i is difficult to assess with–out knowing more about the potential ben–efits and costs. No one is saying that P. myricae is a panacea. In fact, it seems doubtful that the moth alone can control infestations of firetree. In essence then, the Department of Agriculture is permitting three alien species- the two moths, and the fungus -into Hawai’i to control just one weed.
In a state that laments alien invasions in televised public service announcements, this seems sadly ironic.
In addition, around the world, this genus of moth has proven to be adaptable to new foodplants. Control of outbreaks is difficult and costly. The rush to halt the spread of firetree should not blind decision-makers to these facts.
Theresa Menard is a graduate student in the Department of Zoology at the University of Hawai`i, Manoa (e-mail: [email]tcabrera@hawaii.edu[/email]).
Volume 8, Number 9 March 1998
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