Great Basin Naturalist
Volume 45 Number 2 Article 11
4-30-1985
Pollinators of Astragalus monoensis Barneby (Fabaceae): new host records; potential impact of sheep grazing
Evan A. Sugden University of California, Davis
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Recommended Citation Sugden, Evan A. (1985) "Pollinators of Astragalus monoensis Barneby (Fabaceae): new host records; potential impact of sheep grazing," Great Basin Naturalist: Vol. 45 : No. 2 , Article 11. Available at: https://scholarsarchive.byu.edu/gbn/vol45/iss2/11
This Article 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 Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. POLLINATORS OF ASTRAGALUS MONOENSIS BARNEBY (FABACEAE): NEW HOST RECORDS; POTENTIAL IMPACT OF SHEEP GRAZING
Evan A. Sudden'
.Vbstract.— Important bee specios inhahifini; tlie study area are listed, includiiii; tliose oliserved and collected foratiin
Current sheep grazing practices in the A. nionoensi.s habitat endanger pollinators in four ways: (1) destruction of potential nest sites, (2) destruction of existing nests and contents, (.3) direct trampling of adult bees, and (4) removal of food resources. Exposure of the major bee species to each of these factors is assessed utilizing experimental data and published information.
Astragalus monoensis Barneby, "Mono baceae). Also prominent are Hulsea vestita
Rattleweed" or "Mono Milkvetch," is a pe- Gray and Chnjsothamnus parriji vnlcanicus rennial legume endemic to the California (Greene) Hall & Clem. (Asteraceae), the pri- portion of the Great Basin (Barneby 1964, mary local nectar sources for early and late
Miinz and Keck 1959). It is listed as endan- parts of the summer, respectively (unpubl. gered by the Federal Government (Ayensu data). Other associates are Enophyllum lana- and DeFilipps 1978) and rare and endan- tum var. monoense (Rydb.) Jeps. (Asteraceae), gered by the California Native Plant Society Phacelia frigida Greene (Hydrophyllaceae), (Smith et al. 1980). It occurs in the region Cahjptridiwn umbellatum var. caudiciferum east of the Mono Craters between 7500 and (Gray) Jeps. (Portulacaceae), and Mimulus 8000 feet (22861/4438 m) elevation (Smith et coccineus Congd. (Scrophulariaceae). Eriogo- al. 1980, K. Teare, pers. comm., unpubl. num umheUatum Torr. (Polygonaceae), a data). The number of individual plants in widely insect-utilized nectar source, occvxrs at each population varies from several thousand several sites. to less than 100. A majority of the known A. monoensis A detailed description of A. monoensis ap- populations occur with the above plant asso- pears in Munz and Keck (1959). It is a pa- ciates in isolated sand flats, the soil of which pilionaceous bee flower, as characterized by is composed of coarse gravel and sand of vol- Percival (1965), and produces considerable canic pumice origin. The flats are typically nectar, as evidenced by the regularity of vis- surrounded by a second-growth forest of its to its flowers by bumble bees. Males of the Pinus contorta Doug, ex Loud. (Lodgepole anthidiine ("carder" or "mason") bees An- Pine) and Finns jeffreyi Grev. & Balf. in A. thidium chjpeodentatum and the relatively Murr. (Jeffrey Pine). The forest floor is essen- large Callanthidium formosum (Mega- tially sterile with respect to pollen and nec- chilidae) also frequent the flower. Pollen tar. Hence, the wildflower patches of the from A. monoensis is also collected by these sand flats exist as resource "islands" for pol- and other species. It is an obligate outcrosser, linators. Beetle burrows in many trees and requiring insect transferal of pollen between logs provide abundant nest cavities that are flowers of different plants to set seed (Sugden utilized by solitary bees. Thomomys tal- 1984, R. Barneby, pers. comm.). Plant associ- poides, the Northern Pocket Gopher, inhabits ates are relatively few, dominated by the the sand flats, and its many abandoned bur- nectarless Lupinus duranii Eastw. (Fa- rows are probably utilized by bumble bees as
'Department of Entomology, University of Califorr 9.5616. Present address: The .'Kusti 6-8 College Street, P.O. Box A285, Svdnev South 20()0 N.S.W.. Australia.
299 300 Great Basin Naturalist Vol. 45, No. 2
nest cavities. Bonihus huntii queens have legs) in the region (pers. inquiry of sheep- been observed entering such burrows, appar- herder). Solitary ground-nesting bee species ently nest-searching (pers. obs.). require specific substrate conditions to estab- The largest populations of Astragalus lish nests (Linsley 1958). Disturbance of the monoensis, which occur on federal land, are soil by sheep hooves probably alters the ac- subjected annually to the influence of sheep ceptability of many potential nest sites. Pithy grazing. This usually occurs in midseason, stems may be broken and trampled by sheep when the plants are in flower and before if near the ground, removing potential cav- most seed is set. In the sand flat region, ities for species that utilize stick nests. 12,000 sheep in herds of up to 2,000 individ- (2) Destruction of existing nests and con- uals may be stationed at springs or watering tents. Ground nesting bees construct delicate tanks near the known A. monoensis popu- burrows and chambers in the soil. Depending the species, the lations (C. Chamberlain, pers. inquiry of on brood chambers may be either close to the surface, sometimes within sheepherders). In the sand flats per se, the three to four inches (Thorp 1969), or several ground is often completely denuded of vege- feet below (Malyshev 1936). Soil disturbance tation where the sheep forage. Over the may destroy all or part of such nests, damage course of several days the grazed area may existing brood and provisions, and/or dis- extend in a continuous swath, 100 m or more place nest-entrance landmarks, which female in width, to cover an entire flat (pers. obs.). bees utilize in orientation to the exact loca- The loose soil of the habitat is subject to ex- tion of their burrows. Many bees construct treme disturbance by the spadelike action of nests in preexisting cavities above the sheep hooves, which may uproot or expose ground, often in hollow sticks. Such nests the crowns of mature plants and destroy may be shattered or disoriented by trampling seedlings (pers. obs.). Typical effects of graz- and exposed to rainfall. Many of the bees ing on the habitat are shown in Figure 1. concerned here are solitary, nonaggressive Although the toxicology of A. monoensis is species and have no means of nest defense unknown, foliage and flowers of the plant are against sheep. often grazed (C. Chamberlain, K. Teare, pers. (3) Removal of food resources. Sheep graz- comm.). Sheep merely passing over a site, i.e. ing greatly reduces the density of many her- not feeding, do less than those al- damage baceous plants. Among these are the nectar lowed to forage (C. Chamberlain, pers. and pollen sources on which local bee popu- comm.). lations subsist. For many species, these re- This paper examines the hypothesis that, in sources may be important to the completion addition to direct disturbance, the plant may of an entire life cycle. (Due to its limited dis- suffer reproductive setback due to the nega- tribution and population size, it is unlikely tive impact of intensive sheep grazing on its that A. monoensis provides all the annual nu- pollinators. These are various bee species, tritional requirements for individuals of any several of which nest in or near the ground single bee species. Its nectar and pollen- sheep where are herded and all of which are yielding plant associates are important in this part of the sand flat community. Postulated respect and are heavily impacted by sheep telow are four types of impact: grazing as reported here.) Destruction potential sites. (1) of nest (4) Direct trampling. Male bees of several Bumblebees often construct their nests in species are known to "sleep" singly or in ag- abandoned rodent burrows, including those gregations on vegetation close to the nest of Thomomys spp. (Thorp et al. 1983). Such sites of females (Linsley 1962, Rust et al. burrows are abundant in and near the A. 1974) or in shallow, temporary burrows or monoensis habitat. Sheep collapse the en- emergence holes (Linsley 1958). Earlv in the trances of these burrows and hence remove season, before nests are constructed, female many potential nest sites from discovery by bees may also rest in similar positions. In this bumblebee queens in the spring. The fre- situation, particularly during the cool hours
(juency of burrow encounter by sheep is in- of night or morning, when bees are torpid dicated by the fact that rodent holes are the and unable to escape, they may be in danger major cau.se of livestock loss (through broken of being trampled by sheep. Astragalus 301 April 1985 Sugden: Pollinators of
^ -iie-
d^^ MP34' ^ #'
Plants in habitat prior to grazing. Big Sand Flat, June 1980. Fig. 1. (a) Typical aspect of Astragalus monoensis grazing by domestic sheep. foreground are primarily Lupinm duranii. (b) Same view following 302 Great Basin Naturalist Vol. 45, No. 2
Methods divided into three groups based on inferred probability of importance as pollinators of listed are those which ap- Bee species Astragalus monoensis. Group I consists of peared two or more times in occasional col- those species collected or observed foraging lecting during 1979-1982. All specimens on the plant. For these data and number of were collected with a standard insect net and individuals collected and/or observed are in- are currently deposited in the R. M. Bohart dicated, with sex and caste, where appropri- Museum, Department of Entomology, Uni- ate, for those collected. Relative abundance of California, Davis. versity is given as the number of discrete collection For this study, insect "abundance" is de- events (date X locality) resulting in an extant relative individuals fined as the number of voucher specimen. Group II consists of four appearing in occasional collections from the species which, although neither collected nor Astragalus monoensis habitat. observed foraging on A. monoensis, are pol- In recording host plant data from the liter- linator candidates by virtue of their locally ature, a conservative approach was main- great abundance, widely polylectic habits, tained. A host record designated only to and published or observed host records, in- genus was counted as a species record only if cluding other Astragalus spp., Lupinus du- no other species records from that genus ranii, the dominant flowering plant in the in sources consulted. For were given the con- community, and/or other papilionaceous le- generic listings of more than one species, gumes. These bees are robust, moderate to genus records without species designations large in size, and morphologically capable of were not counted. pollinating the A. monoensis flower. Group for Floras and references consulted plant III species have a low or intermediate abun- names and identifications are Munz and Keck dance. Some have been reported to forage on Willis (1959), Taylor (1981), and (1973). other Astragalus spp., and all of them have Plant distributions were obtained by map- published papilionaceous legume host ping the study sites into a grid of one square records. hectare units and sampling randomly near Species from Table 1 are listed in Table 2 the center of each miit with a one square me- with host plant information. To these data ter quadrat sampler. new information has been added from per- Insect densities were obtained from direct sonal observation (Appendix I). For each bee observation of insects on flowers. Two identi- species the total number of published host cal walking transects covering 2.2 km and be- plant families, genera, species, and species of tween 36 and 52 minutes in duration were Astragalus are given. Papilionaceous legume daily made at approximately 11:00 and 14:00 hosts are given as proportions of the total hours. Densities are given as counts per kilo- number of host plant genera and species. All meter per hour to make comparisons with a bee species appearing in Table 2 whose host second study site utilized in project, another specificity is known have been categorized as where transects were of a different length, "polylectic" (many flower hosts), with the ex- and as a partial correction factor for variable ception of Andrena cleodora ssp. cleodora. It duration of transects. is listed as an "oligolege of ceanothus" (re Average ambient temperature at 1 m stricted to a single species or group of closely above the ground is expressed as an average related species of host plants) (Krombein et of three readings per transect. Previous mini- al. 1979). miun temperature is the previous night's low From Table 1, it can be seen that a wide ambient temperature at one meter. All read- diversity of bees is associated with A. mono- ings were taken on a Taylor maximum-mini- ensis. Observed visitors alone represent 3 mum mercury thermometer calibrated in families, 5 genera, and at least 7 species. salted ice water to C. Probable and po.ssible visitors comprise 5 families, 4 genera, and 14 species. The pre- Results dominance of megachilids in this assemblage, particularly in the genera Osmia and Antliid-
Table 1 lists bee species collected in the ium, is a reflection of the general composi- .sand flat region during 1979-1982. The.se are tion of the bee fauna in the dry, high altitude April 1985 SuciDEN: Pollinators of Astragalus 303
Tablk ]. Bee associates of Astnii^dlus niouociisis Hanieliy. Relative aliuiidaiice leters to iniinher of" eollection events in which species appear. \v = worker, (| = (iiieen. in = male. S = extant specimens. () = field observation, R.A. = relative abundance.
Number, sex, Species Date caste SorO R.A.
Group I— Observed or collected on Astragalus monoensis
Bonihiis [riirolnuiihiis) Imntii CJreenc 8. VII. 79 7w,2q 14.VII.79
H. (Hoi)ihi(is) nciiidcnsis nciddcnsis (>resson 8.VII.79 B. (I'yiohoiuluis) losncscnskii Hadoszkowski 7.VII.79 304 Great Basin Naturalist Vol. 45, No. 2
Table 2. Unweighted host plant data for bee associates of Astnigaltis uwuocnsis Barnehy. Bee species listed alphabetically by group (see Table 1). Data for Apis mellifera omitted. Sources: Kronibein et al. (1979). Moldenke and Neff (1974), Thorp et al. (1983), personal observations reported in Appendi.\ I of this paper. April 1985 Sugden: Pollinators of Astragalus 305
these two species have been collected on L. good pollinators of papilionaceous legumes. duronii. Only O. integra has not been recorded on L. duranii. Andrena priinorum ssp. prunorum
II and A. cleodora ssp. cleodora are the least likely pollinator candidates, but they have in Honeybees, Apis meUifera, are present both been recorded on papilionaceous le- the sand flats at relatively low density, de- gumes. It appears possible that these species spite their apparently great abundance in contribute to pollination of A. monoensis. to wild of the study area comparison bees Table 3 lists Group I, II, and III bee spe- (pers. obs.). It is likely that this relatively re- cies with known or probable nest type and source-depauperate region supports only a respective susceptibility to the three types of few small feral colonies. Honeybees avidly grazing-associated damage described above. collect pollen from L. duranii (pers. obs.). Ground-nesting bumblebees are particularly Pollen tentatively identified as that of A. vulnerable in this regard. Bombus nevadensis in monoensis has been observed pollen trap may be less vulnerable, because it is known samples from experimental honeybee hives at to nest in aboveground cavities on occasion. Little Sand Flat (unpubl. data). Bomhus mor- Anthophora urbana, Colletes consors consors, risoni is a common bumblebee in the study and Andrena spp. represent species whose area. It readily visits L. duranii and has been nests are in jeopardy. The anthidiines, includ- species. Al- recorded on other Astragalus ing Anthidium spp. and Callanthidium for- though its general preference for papilio- mostirn, are apparently flexible in their nest naceous legumes seems somewhat lower than location. They may be exposed to nest or nest that of other bumblebees, it remains a good site damage, depending on their local nest- candidate for pollination of A. monoensis. building habits. Many cavity nesters, princi- Anthophora urbatia is a widely occurring pally Osmia spp., are presumably exempt species that forages on virtually every major from this hazard because their nests are most- pollen or nectar source plant in the sand ly in beetle holes in logs or standing trees flats. It is capable of visiting A. monoensis (pers. obs.). Possible exceptions are species in and probably does so, although its papilio- the Acanthosmioides subgenus, many of naceous legimie host record appears moder- which nest in open, sandy sites in ground ate because of the large diversity of records. burrows. Burrows of Acanthosmioides species
Hoplitis albifrons ssp. argentifrons is the were not found at the study sites but likely most common species associated with Hidsea occur there. An existing population of O. (A.) vestita. Its foraging habits are so flexible that integra at Panum Crater, several kilometers
it frequently visits plants from two widely west of the nearest known A. monoensis pop- disparate taxa on a single foraging flight, e.g., ulation, nests at the base of Lupinus duranii
L. duranii and Miriiidus coccineus or Hulsea plants (pers. obs.). This species is also found vestita and Chrtjsothamnus parryi var. vtd- in ground nests associated with sparse vegeta- canicus (pers. obs.). An intense survey would tion on sand dunes in northwestern California probably show that H. albifrons visits and (D. Gordon, pers. comm.). Nests of O. (A.) pollinates A. monoensis. nigrobarbata also occur at the base of plants (Rozen and Favreau 1967). Grazing hazards are significant for these ground-nesting bees Group III and others that may nest in hollow or pithy Bees in this group are variable in their pol- stems of herbaceous plants, which includes lination potential for A. monoensis. The many of the species from Table 3. smaller species, Anthidium mortnonum, A. te- Small solitary bees are limited in their nuiflorae, Osmia calla, and Hoplitis fulgida flight range (Kapyla 1978) and are therefore ssp. platijura have each been recorded on As- more dependent on local floral resources. tragalus; A. tenuiflorae and O. calla have Since a large proportion of nectar and pollen been collected on L. duranii. The three re- plants may be decimated by sheep grazing in maining megachilids are relatively large, ro- the A. monoensis habitat, solitary bees de- bust species that would be expected to be pendent on such resources may be subject to 306 Great Basin Naturalist Vol. 45, No. 2
Table 3. Nesting habits and tvpe of exposure to intensive sheep grazing for bee associates of Astragalus monoensis Bameby. Nest type of a congenor mav be Hsted where information on an A. monoensis associate is imavailable or supplementary. N = potential nest substrate disturbance, C = damage to nests and contents, R = depletion of = = questionable. trophic resources, T direct trampling, ( )
Species Exposure
Group I
Bombtts hitntii April 1985 Sugden: Pollinators of Astragalus 307
Hulsea vestita Lu pinus duranii
Fig. 2. Distributions of (a) Hulsea vestita and (b) Lupinus duranii as mapped in June and July 1980. Both species are perennial. Figure 2a shows the location of the two, one square hectare study plots utilized for insect density transects and the approximate area that was grazed 2 August 1982 (hatched). duranii in response to grazing of adjacent a severe freeze on the evening of 1 August. areas. Extrapolation from this trend would predict In 1982 the density of flower-foraging in- a density close to zero 3 August. Densities for sects was recorded on two study plots at honeybees on Lupinus duranii differed signif- Little Sand Flat before and after sheep were icantly between pre- and postgrazing tran- introduced to the area. The distributions of sects (p = 0.0413), displaying an increase of the dominant plant species at the study site several fold 3 August, despite relatively low appear in Figure 2. On the afternoon of 2 ambient temperature. Note that the relative Augvist, approximately 75% of the flat was proportion of L. duranii removed by grazing grazed by a herd of 2000 sheep (Fig. 2a). Es- was greater than that of H. vestita (Fig. 2a,b). sentially all the aboveground vegetation was Species occurrences on L. duranii also
removed in the grazed area (cf Fig. 1). changed markedly (Table 4). Prior to grazing, Results for the most often observed no more than 3 bee species per day were ob- bee /plant combinations are shown in Figure served (average 1.4), compared to 6 species 3 3. Note that densities of bees increase dra- August. In addition, 5 of the 6 species ob- matically after sheep grazing. Transects from served 3 August had not been observed dur- before and after grazing were compared uti- ing the previous 5 days, and, of the 3 species lizing the Mann-Whitney two sample rank observed prior to grazing, only Apis mellifera test. Differences were not significant for na- was recorded 3 August. Species occurrences unchanged from tive bees on Hulsea vestita (p = 0.1071), al- on Hulsea vestita remained though this analysis does not take into ac- pre- to postgrazing transects, with the excep- coimt the progressive decline in bee densities tion of the appearance of a previously unre- prior to grazing. This was probably due to a corded Osmia sp. and the conspicuous ab-
drop in ambient temperature (Fig. 3) and a , sence of Apis mellifera 3 August. Pre- and decline in nectar availability, accentuated by postgrazing densities of less frequently occur- 308 Great Basin Naturalist
Temp. CO
prev. min. 3
mean dm) 25 27
30i
25-
^ 20-
I 15 d
^ 10-
Date April 1985 Sugden: Pollinators of Astragalus 309
Table 4. Bee species on Liipiiuis duninh '
310 Great Basin Naturalist Vol. 45, No. 2
Literature Cited Krombein, K. v., p. D. Hvrd, Jr., D. R. Smith, and B. D. Burks. 1979. Catalog of Hymenoptera in Ayensu, E. S., and R. a. DeFilipps. 1978. Endangered .\merica north of Mexico. Smithsonian Inst. and threatened plants of the United States. Press, Washington, D.C. Vol. 2 .\pocrita Smithsonian Institution and World Wildlife (.\culeata). Fund, Inc., Washington, D.C. 40.3 pp. Linsley, E. G. 1958. The ecologv of solitarv bees. Hil- Bar.neby, R. C. 1964. Atlas of North American Astraga- gardia 27:54.3-599. Itts. Part II. .57 sec. .Monoenses. Mem. New York 1962. Sleeping aggregations of aculeate Hyme- Bot. Gard. 1.3:964-973. noptera II. Ann. Entomol. Soc. Amer. BoHART, G. E., A.ND G. F. Knowlton. 1952. Yearly pop- 55(2): 148- 164.
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fice, Bakersfield, California. T. 1959. .\ nest of Iiiintii Medler, J. Bombus Greene Clement, S., and R. W. Rust. 1976. The nesting biology (Hymenoptera: Apidae). Entomol. News of three species of Hoplitis King. Pan-Pac. Ento- 70:'l79-182. mol. .52:110-119. 1967. Biology of Ofimici in trap nests in Wisconsin Evans, H. E., and E. G. Linsley. 1960. Notes on a (Hymenoptera: Megachilidae). .\nn. Entomol. sleeping aggregation of solitary bees and wasps. Soc. Amer. 60:338-344. Bull. So. California Acad. Sci. .59(l):.30-37. a. R., Moldenke, and J. L. Neff. 1974. The bees of Cal- Fye, R. E. 1965. Biology of .\poidea taken in trap nests ifornia: a catalogue with special reference to pol- in Northwestern Ontario (Hymenoptera). Cana- lination and ecological research. Intl. Biol. Pro- dian Entomol. 97(8):863-877.' gram, Origin and Structure of Ecosystems. Tech.
Gary, N. E. 1979. Factors that affect the distribution of Reports 74-1 to 74-6. Parts I, II, III,'lV, and VI. foraging honeybees. Proc. IVth Int. Symp. on Pol- MuNZ, p. A., AND D. D. Keck. 19.59. .\ California flora. lination, Maryland Agric. Expt. Sta. Spec. .Misc. Univ. of California Press, Berkeley.
Publ. l:,35.3-.3'58. Parker, F. D. 1975. Nests of the mason bee Osmia tan-
Graenicher, S. 19.35. Bee-faima and vegetation of W'is- neri Sandhouse and O. longulci Cresson with a de- consin. Ann. Entomol. Soc. Am. 28:285-310. scription of the female of O. tiiniwri. Pan-Pac. Heinrich, B. 1979. Bumblebee economics. Harvard Entomol. 51:179-183. Univ. Press, Cambridge, Massachusetts. Parker, F. D., and R. M. Bohart. 1966. Host-parasite Hicks, C. H. 1929. The nesting habits of Anthidium associations in some twig-nesting Hymenoptera monnoutini fragariellum Ckll. (Hyiii.: Megachili- from western North America. Pan-Pac. Entomol. dae). Entomol. News 40:105-110. 42:91-98. HoBBs, G. \. 1965. Ecology of species of Bomhus Latr. Percival, M. S. 1965. Pages 169-170 in Floral biology. Press, Oxford. (Hymenoptera: .\pidae) in southern .\lberta: II. Pergamon Subgenus Bomhias Robt. Canadian Entomol. Ric:hards, K. W. 1978. Nest site selection by bum- 97:120-128. blebees (Hymenoptera: .\pidae) in southern A\- 1967. Ecology of species of Bomhus Latr. (Hyme- berta. Canadian Entomol. 110:301-318. RozEN, G., M. S. Favreau. 1967. Biological notes noptera: Apidae) in southern Alberta. VI. Sub- J. AND genus Pyrohoinbiis. Canadian Entomol. on Dioxys ponionae and on its host. Osiuia nigro- Megachilidae). 9^3:1271-1292. bdibdtd (Hymenoptera: J. New HoBBS, G. A., O., F. York Entomol. Soc. 75:197-203. NUMMI, W. AND J. ViROSTEK. 1962. Managing colonies of bumblebees (Hymenoptera: Rust. R. W., R. W. Thorp, and P. F. Torc hio. 1974. Apidae) for pollination purposes. Canadian Ento- The ecology of Osmia nigrifrons with a com- mol. 94:1121-1132. parison to other Acantliosmioidcs. ]. Nat. Hist. 8:29-47. HoRNixc, D. 1971. New Hymenoptera eiu'iiiies of \ii- thUlitiiii nuinilosiini CJessou. Proc. Entomol. Soc. Seeley, T., .and R. a. .\1orsk. 1976. The nest of the Hon- Washington 73:4.3. ev Bee {Apis nicUifcra L.). Insectes Sociaux P. D., 23:495-512. HiRD, AND J. A. PowEi,),. 19.58. Observations on Smith. P. Coi.k. Sawyer, W. R. the nesting habits of Collctcs stcplumi Tim- J. Jr., J. J. O. and 1980. of rare berlake. Pan-Pac Entomol. .34(3): 147-153. Powell, eds. Inventor\ and endan- Jarninfn, O. 1982. Conservation of endangered plant gered vascular plants of California. 2d ed. Cali- populations: single large or several small re- fornia Native Plant Society, Berkeley, California. serves? Oikos 38:.3()l-.307. Sucden, E. a. 1984. Grazing hazards for plants and pol- linators. Pages 251-255 in N. Ta.sei, ed., Proc. Jaycox, E. R. 1967. Territorial behavior among males of J. Anthiilitnn Ixiuningcn.sc (Hymenoptera: Mega- Vth Intl. Symp. on Pollination; 1983 27-30 Sep- chilidae). tember; V\>rsailles. INR.A, Paris. J. Kansas Entomol. Soc. 40:565-570. Kap^i.a, M. 1978. Foraging distance of a small solitarv TwioH, D. \\\ 1981. C:hecklist of plants of the Mono bee, Clielostoma Diaxillosum (Hymenoptera, iiasin. .Mono Basin Research Group (iontrib. 3. Mogachilidae). Ann. Ent. Fennica 44(2):6.3-64. ISBN 0-939714-01-9.
Ti I'l DiNo. V. L. Krombiin. K. V. 1967. Pages 312-318 in Trap-nesting J.. AND N. Stanton. 1980. Spatiotem- wasps and bees. Smithsonian Inst. Press. poral variation in phenology and abundance of April 1985 Sugden: Pollinators of Astragalus 311
floral resources on shortgrass prairie. Great Basin TnoHP, H. \V., 1). S. HoRNiNC, Jr., and L. L. Dunning. Nat. 40(.3): 197-215. 1983. Bumblebees and cuckoo bumblebees of Thorp, R. W. 1969. Ecology and behavior oi Autho- California (Hymenoptera: Apidae). Bull. Califor- plioid ('(licdidsii (Hvnienoptera: .Apidae). Amer. nia Insect Survey v. 23. 79 pp. Nat. 82(2):321-:337. Midi. Wilms, J. C. 1973. A dictionary of the flowering plants and ferns. VIII ed. Cambridge Univ. Press.
Appendix I. New host records for bees associated with Astaiodlii.s inonocnsis Barneby. Location for all records:
Mono Craters region. Mono County, California. Afitragalus monocnsis records included in text. Table 1. f = female, q = queen, m = male. Host plant abbreviations: C.p.v. = OinisothuDinus pdiryi vulcanictis (Greene) Hall & Clem. (Asteraceae), H.v. = Hulsca vestifa Gray (Asteraceae), L.d. = Lupimis duninii Eastw. (Fabaceae), P.f. = Phacclki frigida Greene (Hydrophyllaceae), E.u. = Erio
Host Number, sex, Species plant Date or caste
Andrcna (Trachandrena) rlcodow clcodom Viereck E.u. 28.VI.'81 E.u.
A. (Plastmndrcna) prunorum j)niui>nnu Cockerell E.u.
.\nthophoridae
Antlioplioid iirlnimi iiiIhiiui Cresson H.v. L.d. C.p.v.
Apidae
Bomhus (Pijrolw)nbus) hiintii Greene H.V. P.f. C.p.v. L.d.
B. {^cpdiafobondius) niorrisoni Cresson P.f.
P.f.
P.f.
P.f. L.d. L.d. L.d. C.p.v. C.p.v.
(Pijwbombus) vosni'scnskii Radoszkowski P.f.
P.f. L.d. C.p.v.
Colletidae
Colletes consors consors Cresson P.f.
P.f. No. 2 312 Great Basin Naturalist Vol. 45,
Appendix I continued.
Host Number, sex, plant Date or caste Species 24.VII.79 CoUanthidiiim formosiim (Cresson) L.d. C.p.v.
Hoplitis (Momimetha) albifrons aroentifrons (Cresson) ^^•<-- L.d. Osmia {Chenosmia) ccilki Cockerell
O. iMonilosmia) dcnsci demo Cresson P-t- L.d.
O. (Nothosmio) ghndeliae CockereW ^1-c. ^^c. O. (Acanthosmia) integra Cresson