Bogbean Buckmoth Evaluation

Part 1 COSSARO candidate species at risk evaluation form – June 2010

Bogbean Buckmoth (Hemileuca sp.)

Current designations:

GRANK – G1Q
NRANK Canada – N1
COSEWIC – Endangered (November 2009)
SARA – Not listed
General Status Canada – Not listed
ESA 2007 – Endangered (2010)
SRANK – S1
General Status Ontario – Not listed

Distribution and status outside Ontario:

Eastern Ontario and upper New York state. S1 in both NY and ON.

Eligibility criteria

Native status

✔ Yes. First discovered in Ontario in 1977, but no evidence that Bogbean Buckmoth is introduced.

Taxonomic distinctness

✔ Yes? Taxonomic rank of Ontario populations is unclear. Sometimes treated as a member of the Hemileuca maia complex or as a subspecies of H. nevadensis. Bogbean Buckmoth differs from H. nevadensis, and the H. maia species complex in having a different primary larval food plant (Menyanthes trifoliata vs. Salix or Quercus), different habitat requirements and morphological differences of larvae and minor morphological differences of adults (NatureServe 2008). Legge et al. (1996) refers to Bogbean Buckmoth as an Evolutionarily Significant Unit. Bogbean Buckmoth is the only Hemileuca sp. in Ontario.

Designatable units

Single Designatable Unit. The Ontario locations are located within about 50 km in the Ottawa Valley.

Priority-setting criteria

Recent arrival

✔ No. First discovered in Ontario in 1977, but probably not a recent arrival given its limited dispersal capability.

Non-resident

✔ No. Established breeding populations in Ontario.

Primary criteria (rarity and declines)

1. Global rank

   ✔ Endangered. G1Q

2. Global decline

   Insufficient Information. Populations fluctuate widely between years. NatureServe (2010) cites a large to moderate (25-90%), long-term global decline associated with habitat loss, but source of these numbers is unknown.

3. Northeastern North America ranks

   ✔ Endangered. S1 in both in New York and Ontario (100%).

4. Northeastern North America decline

   ✔ Insufficient Information. Populations fluctuate widely between years. NatureServe (2010) cites a large to moderate (25-90%), long-term global decline associated with habitat loss, but source of these numbers is unknown.

5. Ontario occurrences

   ✔ Endangered. Two "location" (COSEWIC 2009; NHIC 2010). Number of occurrences not provided by NHIC (2010).

6. Ontario decline

   ✔ Insufficient Information. Population sizes vary widely from year to year, which makes determination of long-term trends difficult, particularly since Ontario populations have been monitored only intermittently.

7. Ontario’s conservation responsibility

   ✔ Endangered. The species' total Ontario population comprises over 25% of the global population, at least in some years. In 2008, the Ontario population was approximately 6000 adults. Estimates of the global population total ranges from about 2500 to 10,000 adults.

Secondary criteria (threats and vulnerability)

1. Population sustainability

   ✔ Insufficient Information. Populations fluctuate widely from year to year.

2. Lack of regulatory protection for exploited wild populations

   ✔ Not in any category. May be occasional taken by collectors, but unlikely to threaten populations. Proposed Endangered federally by COSEWIC in November 2009.

3. Direct threats

   ✔ Threatened. Invasive plant species including Phragmites, Glossy Buckthorn, and Narrow-leaved Cattail occur in or near all Ontario sites. Phragmites in particular has the potential to crowd out Buckbean because it forms dense monospecific stands. At the present rate of spread, all habitats of the Bogbean Buckmoth may be affected within a decade (COSEWIC 2009).

   All Ontario populations are within provincially significant wetlands and/or ANSIs that experience some degree of protection from direct development.

   Water level manipulation on White Lake can drown larvae. White Lake water levels are manipulated to benefit cottagers on the lake. Spray programs to control gypsy moths may have killed Bogbean Buckmoth larvae at White Lake Fen.

4. Specialized life history or habitat-use characteristics

   ✔ Not in any category. Host plant is common (S5) but fen habitat is relatively uncommon in southern Ontario.

COSSARO criteria met (primary/secondary)

• Endangered – 4/0
• Threatened – 0/1
• Special concern – 0/0

Summary

Bogbean Buckmoth (Hemileuca sp.) is a black and white, day-flying, silkworm moth. Although it has not yet been described as a new species or subspecies, it is distinguished from other buckmoths by habitat, preferred food plant, and attributes of the larvae. Bogbean Buckmoth is found only in eastern Ontario and upper New York State and is the only buckmoth occurring in Ontario. The larvae feed primarily on Buckbean (Menyanthes trifoliata) in fens. Adults emerge in September, mate, and die within a few days. The primary threat to this species is invasive plant species including Phragmites, Glossy Buckthorn, and Narrow-leaved Cattail that occur in or near all Ontario sites and threaten to crowd out Buckbean or otherwise alter the fen habitat. Bogbean Buckmoth is classified as Endangered in Ontario.

Information sources

COSEWIC. 2009. COSEWIC Status Report on Bogbean Buckmoth Hemileuca sp. Two month Interim Status Report

Legge, J.T., R. Roush, R. Desalle, A.P. Vogler, B May. 1996. Genetic criteria for establishing evolutionarily significant units in Cryan’s buckmoth. Conservation Biology 10, 85–98.

Natural Heritage (NHIC) 2010. Website. Accessed May 2010

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 6.1. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. Accessed May 2010.

Appendix 1

Northeastern North America rank, status and decline

[for each jurisdiction list SRANK or not present. Include any information available re declines]

Occurs as a native species in 2 of 29 northeastern jurisdictions
SRANK or equivalent information available for 2 of 2 jurisdictions = (100%)
S1, S2, SH, or SX in 2 of 2 = (100%)

Part 2 Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

No. Populations fluctuate widely. No clear decline over the last 3 generations or 10 years.

Criterion B – small distribution and decline or fluctuation

Endangered. B1ab(iii)+2ab(iii). The species has a very restricted distribution. Extent of Occurrence is 195 km². Area of Occupancy is 20 km² based upon a 2X2 grid. Quality of habitat declining with invasion of Phragmites.

Criterion C – small population size and decline

No. The total population size is likely a few thousand adult individuals on average, but there is no clear evidence of decline.

Criterion D – very small or restricted

Threatened. Area of Occupancy is 20 km² based upon a 2X2 grid. Two Ontario locations All habitats in Ontario could be affected by invasive plant species within a decade.

Criterion E – quantitative analysis

N/A. No Population Viability Analyses have been conducted.

Rescue effect

No. Given its habitat specificity, disjunct distribution of fen habitat, and distance from other populations in the United States, localized extirpations in Ontario will not be recolonized from New York populations.