Western North American Naturalist

Volume 61 Number 4 Article 14

11-15-2001

Mortality of the endangered Wright fishhook (Sclerocatus wrightiae) By an -borer (Cerambycidae: semipunctatum)

Ronald J. Kass Intermountain Ecosystems, L.C., Springville,

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Recommended Citation Kass, Ronald J. (2001) "Mortality of the endangered Wright fishhook cactus (Sclerocatus wrightiae) By an Opuntia-borer beetle (Cerambycidae: Moneilema semipunctatum)," Western North American Naturalist: Vol. 61 : No. 4 , Article 14. Available at: https://scholarsarchive.byu.edu/wnan/vol61/iss4/14

This Note is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 61(4), © 2001, pp. 495–497

MORTALITY OF THE ENDANGERED WRIGHT FISHHOOK CACTUS ( WRIGHTIAE) BY AN OPUNTIA-BORER BEETLE (CERAMBYCIDAE: MONEILEMA SEMIPUNCTATUM)

Ronald J. Kass1

Key words: demographic monitoring, beetle, mortality, population decline.

Sclerocactus wrightiae Benson (Wright fish- punctatum infesting the genus Sclerocactus. hook) is a small, white-flowered barrel cactus Six species of Moneilema are recognized in endemic to the in south cen- North America and restrict feeding to the tral Utah. It grows in salt desert shrub and Cactaceae, preferring the genus Opuntia as a pinyon juniper communities at 1460 to 1865 host (Crosswhite and Crosswhite 1985). Mon- m (Welsh et al. 1993). Populations are typically eilema semipunctatum’s range is the Great small, consisting of 50–100 individuals, and Basin in Nevada and western Utah, south to restricted to fine-textured derived from northern Baja California, and east to the Col- the Mancos Shale, Morrison, Summerville, orado Plateau in Utah, southwestern Colorado, Curtis, Entrada, and Carmel formations. northwestern New Mexico, and northern Ari- was listed as an zona (Linsley and Chemsak 1984). by the U.S. Fish and Linsley and Chemsak (1984) discussed feed- Wildlife Service on 11 October 1979 (USFWS ing and mating habits of the genus Moneilema. 1979). It was listed based on its narrow distri- Adult are large, black, nocturnal, and bution, small population size, and threats from flightless. They become active at dusk and mining and natural gas development (Mutz et climb up and down the cactus stem, feeding at al. 1985). Past inventories (Welsh 1980, Neese the base or in the stem crown. Mating occurs 1987, Kass 1989) have extended its distribu- at night on top of the and may continue tion from approximately Ferron in Emery throughout the night. Females choose a suit- County southwest to Hanksville in Wayne able ovipositor site near the base of the plant County, Utah (Fig. 1). and deposit eggs. After hatching, the larvae Long-term demographic monitoring plots attempt to enter the plant, and during the sec- were established throughout the range of S. ond or third instar the larvae begin to tunnel wrightiae to assess various aspects of its life into the plant. A pupal cell is constructed in history and reproductive biology. During the the fall either in or within hollowed-out 1993–2000 field seasons, a small, white beetle stems. larva was discovered infesting cacti at all 3 During the 1993–2000 monitoring period, plots. Upon close examination, cacti were M. semipunctatum accounted for 23% of the often found with external chew marks, pro- combined mortality at all 3 plots. Similar per- nounced constrictions between growth seg- centages have been observed throughout the ments, and a spongy and chlorotic appearance. remaining range of S. wrightiae (Kass personal These abnormalities led to decreased vigor, observation). Size class analysis of beetle- lower fecundity, and eventual death in the killed stems (n = 25) indicated 16% mortality same or subsequent years. Beetle larvae were in size class 2 (2–4 cm wide), 44% mortality in captured and reared in captivity and later size class 3 (4–9 cm wide), and 40% mortality identified as the Opuntia-borer beetle (Ceram- in size class 4 (cacti >9 cm wide; Table 1). bycidae: Moneilema semipunctatum LeConte). Beetles did not infest the smallest size class This is the first published report of M. semi- (0–2 cm wide), and so mortality in size class 1

1Intermountain Ecosystems, L.C., 270 East 1230 North, Springville, UT 84663.

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Fig. 1. Distribution of Sclerocactus wrightiae. was generally the result of dessication or cattle (BLM personal communication). It is possible trampling. that continued beetle mortality may cause a Other mortality sources recorded during shift in population structure: larger cacti with monitoring include blister beetles (Epicauta higher reproductive rates may be replaced sp.), Ord kangaroo rats (Dipodomys ordii), and with smaller cacti with lower reproductive rates. white-tailed antelope ground squirrels (Ammo- Kass (2000) reports a mortality-to-recruitment spermophilus leucurus). Reports from other ratio of approximately 2.5 to 1 since monitor- researchers indicate Moneilema infestations ing began in 1993. Menges (1991) recom- on the federally listed Uinta Basin hookless mends that recruitment be greater than mor- cactus (Sclerocactus glaucus) in Utah (USFWS tality per year to maintain population viability. personal communication) and Mesa Verde cac- These observed mortality rates, coupled with tus (Sclerocactus mesae-verde) in Colorado and increasing anthropogenic threats of commer- New Mexico (Naumann 1989). cial collecting and habitat degradation, indi- Moneilema semipunctatum appears to infest cate a slow decline for S. wrightiae. larger individuals possibly because large indi- viduals are better host . Additional de- I thank Steve Wood (Brigham Young Uni- clines in larger individuals have been observed versity) for identifying the beetles and extend range-wide since inventories for S. wrightiae appreciation to Ron Bolander and Lori Arm- began in 1986. Some of these declines are the strong of the Bureau of Land Management for results of amateur and commercial collecting funding the project. 2001] NOTES 497

TABLE 1. Size-specific mortality by beetles. Values indi- Falk and K.E. Holsingers, editors, Genetics and con- cate numbers and percent of cacti killed by beetles com- servation of rare plants. Oxford University Press, pared to overall percent size class distribution. New York. MUTZ, K.M., E. NEESE, J.L. MILLER, AND G.R. JACOBS. Size class N % beetle killed % size class 1985. Wright fishhook cactus (Sclerocactus wrightiae) 1008Benson recovery plan. Prepared in cooperation with 2 4 16 23 the Wright Fishhook Cactus Recovery Committee, 3114463U.S. Fish and Wildlife Service, Denver, CO. 27 pp. 410406NAUMANN, T. 1989. Population biology of Sclerocactus mesae-verdae: performance report. Unpublished re- TOTAL 25 100 100 port submitted to Colorado Natural Areas Program, Boulder, CO. 21 pp. NEESE, E. 1987. Habitat inventory of Sclerocactus wright- iae and other associated sensitive species. Final report LITERATURE CITED to Bureau of Land Management, Richfield District Office, Richfield, UT. 116 pp. CROSSWHITE, C.D., AND F. S . C ROSSWHITE. 1985. Tricho- U.S. FISH AND WILDLIFE SERVICE. 1979. Determination cereus as a potential nursery crop in southern Ari- that Sclerocactus wrightiae is an endangered species. zona, with discussion of the Opuntia borer (Ceram- Federal Register 44: 58868. bycidae: ) as a serious threat to its WELSH, S.L. 1980. Survey for Sclerocactus wrightiae and cultivation. Desert Plants 7:195–203. aprica. Reports 1–4. Unpublished report KASS, R.J. 1989. Habitat inventory of threatened, endan- for Consolidated Coal Company, Englewood, CO. gered, and candidate plant species in the San Rafael WELSH, S.L., N.D. ATWOOD, S. GOODRICH, AND L.C. HIG- Swell, UT. Final report submitted to the Bureau of GINS. 1993. A Utah flora. 2nd edition. Jones Endow- Land Management, Salt Lake City, UT. 80 pp. ment Fund, Monte L. Bean Museum, Brigham Young LINSLEY, E.G., AND J.A. CHEMSAK. 1984. The Cerambyci- University, Provo, UT. 986 pp. dae of North America, part VII. No. 1: and classification of the subfamily , tribes Received 2 June 2000 Parmenini through Acanthoderini. University of Cal- Accepted 7 August 2000 ifornia Publications in Entomology 102:1–258. MENGES, E. 1991. The application of minimum viable population theory to plants. Pages 45–61 in D.A.