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HomeMy WebLinkAboutCOM 0462.000 2010-2012Dear Participant: COUNTY CLERK COUNTY (l=- HAWAII This letter is to inform you that a Final Environmental Asse eiQt1 T i) e1arRlpursuant to the EIS law (Hawaii Revised Statutes, Chapter 343) and the EIS rules (Administrative Rules, Title 11, Chapter 200) is available beginning Nov. 8, 2011 at the Hawaii OEQC website: http://hawaii.gov/health/environmental/oeqc/index.html/ Project Name: Proposing /Approving Agency: Address: Contact: Biocontrol of Strawberry Guava by its Natural Control Agent for Preservation of Native Forests in the Hawaiian Islands Hawaii Department of Agriculture 1428 S. King St., Honolulu, HI 96814 Dr. Neil Reimer Phone:(808)973 -9522 Email: hdoa.ppc @hawaii.gov Paper copies of the Final EA are available at the following Public Libraries: Island of O`ahu: Hawai`i State Library (South King Street), Kaimuki Regional Library, Kaneohe Regional Library, Hawai`i Kai Regional Library. Island of Kaua`i: Lihue, Koloa and Princeville. Island of Maui: Kahului, Lahaina, Hana, and Makawao. Island of Hawai`i: Hilo, Kailua -Kona, Thelma Parker (Waimea), Naalehu, Bond Memorial (Kapaau), Honokaa, Keaau, Mt. View, Pahoa. Also available at Moloka`i and Lana`i Public Libraries; and University of Hawai`i at Hilo, Edwin Mookini Library; and University of Hawai`i at Manoa, Hamilton Library. Thank you for your participation in the Environmental Assessment process. (Note: The attached Final Environmental Assessment is available on CD, for viewing, in the Office of the County Clerk.) Comm. No. 4402— Ref. To: Ref. Dote, NOV j 2 Biocontrol of Strawberry Guava by its Natural Control Agent for Preservation of Native Forests in the Hawaiian Islands Frequently Asked Questions (FAQs) Note: Page numbers refer readers to detailed discussions and citations in the Final EA, available at http: / /hawaii.gov/ health /environmental/oegc /index.html/ 1. Does strawberry guava really have adverse effects on native species and ecosystems? Invasion by strawberry guava affects hundreds of thousands of acres of native forest across the state of Hawaii. In much of this area its full impact has yet to occur, but tens of thousands of acres of low to mid- elevation rainforests have been overrun by dense thickets up to 30 feet high that suppress native species. Strawberry guava may be the perfect invasive plant. It grows quickly (p. 14); it tends to form dense thickets, crowding out native plant species that are unable to compete for the space (p. 10 -12); it can grow in the shade (p. 30); it produces large amounts of fruit with many seeds spread by pigs and birds to create future generations (p. 9, 58); it is difficult to kill, as it sprouts prolifically from stumps and even cut branches, requiring multiple herbicide applications (p. 30); and it has no known enemies in Hawaii (p. 2). Because of these characteristics, strawberry guava has been recognized as one of the state's most disruptive alien weeds since at least the 1950s (p. 11). Land managers and other observers across Hawaii have witnessed widespread transformation of native forests as strawberry guava has moved in and excluded native species. Attempts to prevent the devastating effects of this invasion using existing mechanical and herbicidal methods have been pursued for decades and continue today, but are widely recognized as inadequate given the scale of the invasion. Strawberry guava is specifically mentioned as a threat to at least 77 species of threatened and endangered plants in Hawai `i (p.43 -44), and habitat destruction by this invader threatens native animals as well (p.45 -46). Along with devastating effects on biodiversity, invasion by strawberry guava adversely impacts cultural resources, scenic beauty, and watershed values in Hawaii. It also is recognized as a major threat in Mauritius, Reunion, the Seychelles, Society Islands, Fiji, Norfolk and elsewhere (p. 9). 2. Aren't there more appropriate species for biocontrol attention? Conservation professionals in Hawaii agree that strawberry guava is among the worst invasive plants threatening Hawaiian forests (p. 14 -17). It has been consistently recognized as a high priority for biological control, along with species such as miconia and kahili ginger, which also are targets of ongoing biocontrol research. Unfortunately, Hawaii has dozens of serious invasive plants which will require investments in careful management, including development of new biocontrol agents, over the coming decades. Prioritizing among these weed targets is indeed an important challenge. 3. Doesn't biocontrol often have severe unintended consequences, as with introduction of cane toad and mongoose? Many people have the mistaken impression that a sugar plantation owner's ill -fated 1883 import of mongooses to control rat populations is a typical example of biocontrol. Actually, biocontrol is the careful and scientific introduction of a highly specialized organism to control the growth or spread of its invasive host organism. Unlike chemical and mechanical approaches, which are expensive and short- lived, biocontrol is cost - effective and long- lasting. By virtue of its specificity, biocontrol also avoids the damaging environmental effects of pesticides that sometimes can occur when they are used on a landscape scale or by inexperienced people (p. 17 -18). Since 1975, when tighter review of biocontrol measures was enacted, more than 50 biocontrol species have been introduced to Hawaii without any adverse effects (p. 36). Some of the invasive species in Hawaii that biocontrol has helped suppress are Koster's curse (also known as Clidemia), ivy gourd, prickly pear cactus, and banana poka (p. 19). 4. Wouldn't it be more effective and efficient to remove strawberry guava thickets by clearing? Negative effects such as erosion would be caused by large -scale land clearing, unlike biological control which has a gradual impact. Herbicides can be effective for control in limited areas with low density infestations, but if used on a large scale and by many landowners, the risk of misapplication and environmental harm increases. At the highest strawberry guava densities, herbicide application to all stems on a given acre can exceed label dosage. Removing strawberry guava manually is extremely labor- intensive. Manual control without the use of herbicide is generally ineffective because of strawberry guava's propensity to resprout from cut stumps and discarded stems (29 -30). Control using existing methods is generally practical only where the plants are readily accessible by roads, a small fraction of the invaded landscape (p. 30- 33). Estimates of the cost of manual removal demonstrate that it is prohibitively expensive across large areas, ranging to over a third of a billion dollars in East Hawaii Island conservation areas alone (Appendix 2). 5. Won't the scale insect evolve to eat something else or otherwise harm other plants and animals? The evidence from the native range of Tectococcus ovatus indicates an extremely specialized host relationship, since this insect is found only on Psidium cattleianum (strawberry guava) and its very close relative Psidium spathulatum (a plant found only in Brazil). The host range of this insect in Brazil remains extremely narrow in spite of the great diversity of plant species there, including hundreds of species in the same family as strawberry guava. Close host relationships are quite common between insects and plants, especially gall- forming insects, which are typically very highly specialized to feed on a single host plant or very narrow range of closely related plant species. 'I his is because producing galls requires controlling the growth of plants in precise ways at the cellular level. These insects and their host plants represent stable, ecologically and physiologically intimate relationships that have evolved over many thousands to millions of years (p. 1). Experience with agents for biocontrol of weeds over the last 100 years indicates that host specificity of agents can be evaluated accurately in advance and that use of nontarget species has been almost entirely predictable. Evolution of ability to use host plants in new, unpredictable ways has never been documented in over 1,100 cases of weed biocontrol worldwide (p. 38 -39). 6. Was testing of the scale insect adequate? Scientifically rigorous studies to safeguard Hawaii have been conducted and approved. The scale insect was the subject of extensive testing to see whether other plants in Hawai `i could serve as hosts. Tests on over 100 plants, including close relatives of strawberry guava, have demonstrated that the insect is highly specific (Appendix 1). Only at the end of this process do state and federal agencies carefully consider a proposed release and approve permits (p. 18). All laboratory tests and field studies, which include more than 15 years of observation in Brazil where the scale insect originates, indicate that it is highly specialized to feed on only strawberry guava in Hawaii (p. 36 -38). In its native range the scale insect has never attacked agricultural crops or been otherwise noted as a pest. 7. Isn't strawberry guava fruit essential to feral pigs, and with less fruit, won't pig numbers decline and hunting suffer? The most likely result of a reduction in strawberry guava fruits would be for pigs to consume other available foods. It is unlikely that any significant impact on pig populations would be observed, although gradual changes in localized foraging patterns may occur since pigs are attracted to areas where fruit are abundant. Wild pigs do make use of strawberry guava seasonally, but it is unlikely that the fruits are an essential part of their diet. Although pigs are omnivorous, studies of feral pig diets in Hawai`i have found that plant materials such as ferns and grasses make up most of their diet, which also includes earthworms and carrion for protein. Many high - elevation areas with little strawberry guava on Maui and the Big Island are nevertheless heavily infested with pigs, so substantial populations are likely to persist even if strawberry guava fruit become less abundant. Because dense stands of strawberry guava inhibit human access to forests, it is likely that hunting over the long term would benefit from the biocontrol action (p. 64 -65). 8. Won't reducing strawberry guava fruiting and wood growth have adverse effects on households and businesses that depend on harvesting the fruit or wood for home consumption or selling jelly or other products? The insect's natural presence on strawberry guava in Brazil does not reduce the plant's usefulness for either fruit or wood (p. 7). As the scale insect will not kill strawberry guava plants or taint their fruit, but only reduce fruit production and tree growth, people will still be able to pick fruit and gather the wood, as Brazilians do in their forests where the trees are preyed upon by a far greater multitude of insects. The scale insect may not reach backyard trees isolated from forests because of its limited dispersal ability (p. 1). 9. What will be the effect to the scenic value of the landscape? The leaf galls produced by the scale insect in Brazil do not lead to severe defoliation or deformities in the tree. Severe defoliation would result mainly from an unusual combination of stresses such as prolonged drought, which would also affect most other plants (p. 35, 54). It is worthwhile to note that `ohi`a, celebrated for its grace and beauty in Hawaiian songs and chants, exhibits leaf galls produced by a native co- evolved insect, without any loss of its general attractiveness or that of its surrounding landscape. The majority of residents will be unaware that the scale insect is feeding on individual strawberry guava trees. It should also be noted that many observers who are appreciative of native species and concerned about the effects of strawberry guava find the monotypic thickets an unattractive reminder of devastation of the native forest, and in fact would rather see native species such as `ohi`a on roadsides (p. 66 -67). 10. Doesn't strawberry guava provide essential food for birds and mammals? Ornithologists have observed various non - native birds utilizing strawberry guava fruit, but native birds in general do not consume it. Native birds depend for food on the Hawaiian plants and insects that healthy native forests contain. Rats, mice, and non - native birds all probably benefit somewhat from consumption of strawberry guava fruit, although their use of this food source is not well quantified (p. 39). Any negative impacts on these species generally would be expected to benefit native ecosystems, which suffer a variety of negative impacts from these non - native animals (for example, disruption of native plant and animal Life cycles, and spread of invasive alien plants).