endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (100-1000 square km (about 40-400 square miles)) Historically, the moth was known from the five largest Hawaiian islands from Kauai to Hawaii island (Zimmerman 1958) and probably occurred on all seven major islands. Today it occurs on Hawaii, Maui and Kaloowahe more or less restircted to tracts of dry forest. The species currently occupies about 18% percent of its known historic range which is probably less than the actual original range.
Comments: Inhabits mostly lowland dry forests and shrub lands where the larvae feed on native and a few introduced SOLANACEAE (tobacco family). However adults do wander and larvae have turned up on cultivated Solanaceae.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Very capable of moving between islands, although it is not known to what extent they do so.
Comments: The east Maui population rediscovered in 1984 has persisted by feeding on the rare endemic shrub (NOTHOCESTRUM LATIFOLIUM, which is a candidate for listing) and on the weedy tree tobacco, NICOTIANA GLAUCA (Riotte, 1986; Hawaii Biological Survey, specimen records, 1996). Other species of Nothocestrum are also used regularly. The Kahoolawe population is using the exotic Nicotiana glauca. Note the term foodplant usually refers to larval foodplants and the trm nectar plants to adult food sources. The former term is used to some extent for both in the Draft Recovery Plan. Morning glories and other flowers are nectar sources, only Solanaceae are larval foodplants. Adults do not require food to reproduce but as USFWS (2003) discusses, a good nectar supply almost certainly increases egg production.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 20
Comments: A single population was rediscovered at Kanai, East Maui, in 1984 (Riotte, 1986). That population has persisted. There have been a few discovered since. Most likely all populations on a given island should be treated as a single metapopulatrion occurrence, in which case there would be three. Even if this is not warranted there are probably no more than 5-10.
1 - 2500 individuals
Comments: There is no real basis for estimation even to order of magmitude. Status survey efforts in the late 1970s had concluded that this species was probably extinct. Subsequent reports merely describe the populations as "small" without defining that term even to order of magnitude. Tthis moth was formerly sometimes locally common on Oahu, Maui, and Hawaii (Riotte, 1986; Zimmerman 1958). There are no estimates of current population size and the 2003 Draft Recovery Plan gives no suggestions how such an estimate could be obtained and notes that estimates with mobile, rare species would be especially difficult, if even possible. Furthermore, mark-release-recapture (MRR) is generally impractical without fairly well defined population boundaries (habitats). However the life span of the moths is probably substantially longer (weeks vs. days) than most Lepidoptera for which population estimates have been made, which could be very helpful in getting recaptures and thus possibly useful estimates. There is no other known way besides MRR to reliably estimate Lepidoptera adult numbers in most circumstances and it may simply be too difficult to find and capture adults causing recapture rates to be too low to be useful. There have been extremely few population estimates with any nocturnal moths anywhere. With some pupae in long term diapause at any given time, an estimate based on adults would still in a sense underestimate population.
The best hope for successful MRR might be pheromone lures for males, but these would have to be used very sparingly (perhaps shifting stations for 30-60 minutes per night with none on most nights) to avoid undo disruption of their mate location behavior and arriving males would have to promptly and safely captured, marked, and released soon. Even better might be using tethered reared females as lures and both moths could be marked ventrally and released the same or next evening, depending on how long they remain attached. Tethering is an effective way of securing matings for many Sphingidae, but would have to be tested for safety with this species or a very close surrogate. Problems could arise if females become highly active and fly extensively before mating-which they probably do not. Release of many reared females in the same area could raise larval density and trigger parasite build ups or could cause genetic problems if all females were closely related.
Another difficulty would be interpretation. Even if daily population estimates were possible this species does not resolve into discrete generations. Daily estimates are obviously not an appropriate reporting interval. In most cases with butterfly population estimates the species either has only one generation per year or has two discrete well separated broods such as the Karner Blue has. Population estimates are then for a discrete generation or even both in the same year. For such species effective population size cannot be more but probably is somewhat less than generation size. Probably with Bluckburn's sphinx complete turnover of adults takes several weeks, but any such guess would be a crude approach to estimating generation size and only MRR might (or might not) yield reliable longevity estimates for wild adults. If it were possible to obtain multiple daily estimates by MRR that were either relatively concordant or better had low error margins, estimates for longer intervals are easily made from these by Jolly-Seber or other brood size calculations. If generation size cannot be determined, the number of adults per month might be a reasonable substitute. For now though even daily estimates are not available and might be impossible. Estimates based on larvae would be very difficult since they are probably very cryptic, sparse, and often high off the ground. Further it would be difficult or impossible to determine the proportion of larvae that survive to adults.
Life History and Behavior
Comments: The seasonality of this species is somewhat unclear. Recent documentations of larvae have been from October to May but adults have been collected at least historically in all months. Adults cannot diapause so at least originally all stages must have occurred to some extent all year. USFWS (2003) considers the season to be October to May. There is at least facultative pupal diapause up to about a year. It is unclear how many generations this species has per year but assuming not all pupae diapause (see USFWS, 2003, p. 10) there would definitely be more than one, potentially up to six or seven since a generation takes slightly under two months. Probably between variable diapause and adult longevity, probably about a month if well fed and apparently up to twelve days even without food, the number of generations is undefinable.
Molecular Biology and Genetics
Barcode data: Manduca blackburni
No available public DNA sequences.
Download FASTA File
Statistics of barcoding coverage: Manduca blackburni
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G1 - Critically Imperiled
Reasons: Apparently at the brink of extinction, but maybe recoverable. Habitat and range reduced by about 82% or more, population probably by well over 99%. Now exists as "small" populations on three islands. It is not clear whether recovery goals would or would not result in any viable persistent populations, in large part because USFWS correctly points out that population size is unknown and probably unknowable. Besides habitat destruction there are all of the usual threats from exotics. Such threats from alien biocontrol agents (parasitic Diptera and Hymenoptera) and from ants probably cannot be substantially mitigated and preclude recovery to original densities. Similar threats have eliminated several native Hawaiian LEPIDOPTERA and reduced most others.
Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Other Considerations: The presence of diapausing pupae in the soil most, if not all, of the time does provide some buffer against crashes in adult numbers and against particularly unfavorable periods like droughts or from short-term parasitoid build ups.
Date Listed: 02/01/2000
Lead Region: Pacific Region (Region 1)
Population location: Entire
Listing status: E
For most current information and documents related to the conservation status and management of Manduca blackburni , see its USFWS Species Profile
Global Short Term Trend: Relatively stable to decline of 30%
Comments: Rarity increased between 1940 and 1975 and for a while extinction was presumed (Gagne and Howarth 1985). Although the approximately three known surviving populations are persisting and may be stable.
Global Long Term Trend: Decline of >90%
Comments: USFWS Recovery Plan concludes about an 82% reduction in total range, which would be similar for area of occupancy, but it is exceedingly unlikely that the decline in numbers is anywhere near that small. More likely total numbers have declined by 99%, possibly by more than 99.9%. Species has gone from common to the verge of extinction.
Degree of Threat: Very high - high
Comments: At least exotic parasitoids and predators are pervasive threats. Other threats occur but are probably all less in scope at least.
Biological Research Needs: Better information on adult nectar sources and the prevalence of pupal diapause would be useful in assessing habitat suitability and population viability. Is this the large, long tongue moth that once pollinated Brighamia and other Hawaiian plants (Asquith, 1995)?
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: See Recovery Plan.
Needs: Greatest neeed appears to be protection from exotic parasitoids and predators which may be impossible. Between exotic plants and goats even protection of the habitat and foodplants will be difficult.
Manduca blackburni, commonly known as Blackburn's Sphinx Moth, Hawaiian Tomato Hornworm, and Hawaiian Tobacco Hornworm, is a species of moth in the family Sphingidae. It is endemic to Hawaii. Previously known from all of the main islands, this rare moth is now limited to Maui, the Big Island, and Kahoʻolawe. It is found in coastal mesic and dry forests at elevations from sea level 5,000 ft (1,500 m).
M. blackburni is closely related to the tomato hornworm (M. quinquemaculata), which it also physically resembles. It was listed as an endangered species by the United States Fish and Wildlife Service in 2000, making it the first Hawaiian insect to receive such a status.
Larvae feed on plants in the nightshade family, Solanaceae, especially native ʻaiea (Nothocestrum spp.), but also non-native tomatoes (Solanum lycopersicum), tobacco (Nicotiana tabacum), tree tobacco (N. glauca), jimson weed (Datura stramonium), and eggplant (Solanum melongena). The adult feeds on nectar from native plants such as koali ʻawa (Ipomoea indica) and maiapilo (Capparis sandwichiana).
- "Blackburn’s Sphinx Moth First Hawaiian Insect Added to Endangered Species List" (Press release). United States Fish and Wildlife Service. 2000-02-01.
- "CATE Creating a Taxonomic eScience - Sphingidae". Cate-sphingidae.org. Retrieved 2011-11-01.
- Black, Scott Hoffman. "Moths: Blackburn’s sphinx moth (Manduca blackburni)". The Xerces Society. Retrieved 2010-06-24.
- Richardson, Mike; Dave Hopper (October 2003). Draft Recovery Plan for the Blackburn's Sphinx Moth (PDF). United States Fish and Wildlife Service. Retrieved 2009-03-12.
- "Blackburn’s Sphinx Moth" (PDF). Terrestrial Insects. State of Hawaiʻi. 2005-02-04. Retrieved 2009-03-12.
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