Pollination of species of Brassicaceae for seed increase at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) has been accomplished for several years by using nucleus hives of honey bees, Apis mellifera L., in field cages. Brassicaceae are cool season crops that need pollination from late April to early June in the north temperate zone. Overwintered hives of honey bees need time to strengthen (i.e., increase their numbers) and thus it is difficult to make enough nuclei to meet our early season pollinations needs. Purchasmg package bees from suppliers in the southern U.S. is an expensive alternative. In this study, three bee species; a solitary bee, Osmza cornifrons (Radoszkowski) (Hymenoptera: Megachilidae); honey bees; and alfalfa leafcutting bees, Megachile rotundata (Fab) (Hymenoptera: Megachilidae), were compared for their utility as early season pollinators of Brassicaceae species in field cages. Osmza cornifrons proved to be equal to or better than leafcutters and honey bees for pollination of Brassicaceae in field cages as measured by seed produced/plant. Future seed increases of Brassicaceae at the NCRPIS will utilize Osmia cornifrons in field cages because they are effective pollinators and they are easily managed

Abel, C. A.

Luhman, R. L.

Wilson, R. L.

English

Name not available

Comparing Three Bee Species for Controlled Pollination of Selected Brassicaceae

University of Northern Iowa

Journal of the Iowa Academy of Science: JIASVolume 106 | Number Article 31999Comparing Three Bee Species for ControlledPollination of Selected BrassicaceaeR. L. WilsonIowa State UniversityC. A. AbelIowa State Universtiy, cabel@iastate.eduR. L. LuhmanIowa State UniversityCopyright © Copyright 1999 by the Iowa Academy of Science, Inc.Follow this and additional works at: https://scholarworks.uni.edu/jiasPart of the Anthropology Commons, Life Sciences Commons, Physical Sciences andMathematics Commons, and the Science and Mathematics Education CommonsThis Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Journal of the Iowa Academy ofScience: JIAS by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu.Recommended CitationWilson, R. L.; Abel, C. A.; and Luhman, R. L. (1999) "Comparing Three Bee Species for Controlled Pollination of SelectedBrassicaceae," Journal of the Iowa Academy of Science: JIAS, 106(1), 1-3.Available at: https://scholarworks.uni.edu/jias/vol106/iss1/3JAN 2 3 2COZ Jour. Iowa Acad. Sci. 106(1):1-3, 1999 Comparing Three Bee Species for Controlled Pollination of Selected Brassicaceae R. L. WILSON, C. A. ABEL and R. L. LUHMANl USDA, Agricultural Research Service, North Central Regional Plant Introduction Station, Iowa State University, Ames, Iowa 50011 Pollination of species of Brassicaceae for seed increase at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) has been accomplished for several years by using nucleus hives of honey bees, Apis mellifera L., in field cages. Brassicaceae are cool season crops that need pollination from late April to early June in the north temperate zone. Overwintered hives of honey bees need time to strengthen (i.e., increase their numbers) _and thus it is difficult to make enough nuclei to meet our early season pollinations needs. Purchasmg package bees from suppliers m the southern U.S. is an expensive alternative. In this study, three bee species; a solitary bee, Osmza cornifrons (Radoszkowsk1) (Hymenoptera: Megachilidae); honey bees; and alfalfa leafcutting bees, Megachile rotundata (Fab) (Hymenoptera: Megachilidae), were compared for their utility as early season pollinators of Brassicaceae species in field cages. Osmza cornifrons proved to be equal to or better than leafcutters and honey bees for pollination of Brassicaceae in field cages as measured by seed produced/plant. Future seed increases of Brassicaceae at the NCRPIS will utilize Osmia cornifrons in field cages because they are effective pollinators and they are easily managed. INDEX DESCRIPTORS: hornfaced bee, mason bee, alfalfa leafcutting bee, honey bee, pollination, Osmia cornifrons, Megachile rotun-data, Apis mellifera. The United States Department of Agriculture-Agricultural Re-search Service North Central Regional Plant Introduction Station (NCRPIS) is part of the National Plant Germplasm System (NPGS). The NPGS is a network of Federal and State institutions and research units dedicated to conserving and encouraging the use of germplasm, most commonly in the form of seeds. Many of the crops maintained at the NCRPIS are cross-pollinated which requires some form of controlled pollination to maintain the genetic integrity of the germ-plasm. Honey bees, Apis mellifera L., have been used at the NCRPIS for controlled cage pollination of Brassicaceae for several years. Nucleus hives containing 4,000-6,000 worker bees and a queen are placed into field cages measuring 6.4 X 1.6 X 1.6 m (Ellis et al. 1981). This technique has been used to pollinate sunflower (Helianthus spp.), cucurbits (Cucurbita spp.), cuphea (Cuphea spp.) and some species of Brassicaceae. In general, plants in the Brassicaceae are early, cool season plants. It is difficult to establish enough pollinating nuclei from overwintered colonies to meet the growing demands for pol-linating insects at the NCRPIS. In addition, honey bee management requires considerable labor and cost. Therefore, honey bees were compared to other non-Apis species in earlier studies of pollinating efficiency to determine if there are more efficient ways to pollinate various caged seed increase plots. In many cases, it was found that non-Apis species were effective pollinators (Roath et al. 1990; Wilson et al. 1991; Wilson and Roath 1992). This paper reports the results of comparing three species of bees, Osmia cornifrons, honey bees, and alfalfa leafcutting bees, Megachile rutundata (Fab.), for pollination of selected Brassicaceae in field cages. 1 Department of Agronomy, Iowa State University, Ames 50011. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, martial status, or handicap. Reference to a proprietary product does not imply endorsement by the USDA-ARS or cooperating agencies. The hornfaced bee, Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae), was imported in 1977 from Japan into the eastern United States as an orchard pollinator (Batra 1979). The alfalfa leaf-cutting bee, a native of southeastern Europe, was accidentally intro-duced into eastern North America in the 1930s (Eves et al. 1980). METHODS Two accessions of Brassica rapa (Pl 278766 and PI 392025) were planted in 5 X 5 cm peat pots in the greenhouse on 4 March 1994. On 15 April 1994, all surviving plants (about 135 per accession) were equally divided and transplanted into each of 16 field cages measuring 6.4 X 1.6 X 1.6 m. We used a completely randomized block design with treatments as follows: 4 cages (replicates) each received (1) one honey bee nucleus containing 4,000-6,000 worker bees and a queen, (2) alfalfa leafcutting bees (about 250), (3) 6 straws containing about 48 0. cornifrons, and (4) an untreated control. Plants were harvested when >50% of the siliques had turned brown (late June to early July). Plants in each cage were counted, threshed, and the seeds obtained were cleaned. Grams of seed obtained were divid-ed by the number of plants per cage to calculate the grams of seed/ plant. Data were analyzed using the FACTOR analysis of MSTAT-C (MSTAT Development Team, 1989). When the F-value for treat-ments was significant (P < 0.05), means were separated with the least significant difference (LSD) test (ex = 0.05) included in the RANGE program of MSTAT-C. In 1995, two additional PI accessions were added to the test (PI 209022 {Sinapis alba} and PI 469944 {Brassica napus}). The plants were planted in the greenhouse on the following dates: Pl 209022 (20 February 1995), PI 278766 (3 March 1995), PI 392025 (7 March 1995), and PI 469944 (16 February 1995). All were trans-planted into field plots from 17-24 April 1995. Experimental design and treatments were the same as in 1994. Plants were harvested when >50% of the siliques had turned brown. PI 209022 was har-vested on 17 July 1995, PI 278766 on 11 July 1995, PI 392025 2 JOUR. IOWA ACAD. SCI. 106(1999) Table 1. Seed per plant for two Brassica and one Sinapis species pollinated by 3 different bee species, Ames, IA. SEED PER PLANT (gm)a TREATMENT 1994 1995 ACCESSION HBb ALCC OSMJA<l CONTROL HB ALC OS MIA CONTROL PI 209022 3.7a 3.0a 3.5a l.5b Pl 278766 l.Ob 0.6bc l.6a 0.5c 5.5a 5.8a 6.2a 3.3b Pl 392025 l.2ab l.4a l.7a 0.4b 5.9a 6.6a 6.4a 4.9a PI 469944 8.2ab 9.5a 8.0b 8.Sab aRow means followed by the same letter within years are not significantly different according to the LSD test (P < 0.05) bHoney bee c Alfalfa leafcutting bee <lOsmia corni/rons on 12 July 1995, and PI 467944 from 21-26 July 1995. Seeds were processed as in 1994 and grams of seed/head were calculated. Statis-tical analysis procedures used in 1994 were repeated. RESULTS During 1994, Osmia cornifrons produced significantly more seed/ head on PI 278766 than did the other bees. There was no difference between the bees for seed produced/head on PI 392025 (Table 1). In 1995, Osmia cornifrons was equal to the other bees in the amount of seed produced/plant for 3 of the accessions tested. PI 469944 was the exception. According to Free (1993), Brassica napus are highly self-pollinating plants and this is evidenced by the seed produced in the no-bee control cages. DISCUSSION Even though Osmia cornifrons did not produce significantly more seed than the other bees for most of the accessions tested, these bees are easier to manage than honey bees and less costly to use than are honey bees and alfalfa leafcurting bees. Consequently, we plan to increase our use of this species in seed regeneration program at NCRPIS. A summary of the cost of managing the three species of bees is given in Table 2. Observation of honey bees in cages showed them to be less effec-tive as an early-season pollinator when the weather was damp and cool. Osmia bees were observed to collect pollen and place it on their abdominal scopa in a dry state, whereas honey bees will wet and pack the pollen when they load their hind tibia scopa. Also, while visiting flowers, the Osmia maintained consistent contact with the stigma and anthers. Honey bees landed on the petals when searching for nectar and didn't come in contact with the stigma. When honey bees were searching for pollen, they effectively harvested pollen which made less available for pollination. On the average, honey bees spent 3.8 seconds/flower visit (15 observations) while Osmia spent 1.5 seconds/flower visit (15 observations). Thus, the Osmia will come in contact with many more flowers than will honey bees. Alfalfa leafcutting bees are relatively inexpensive but must be im-ported from Canada each year. Osmia cornifrons can be increased in the field locally and stored until needed (Wilson and Abel, 1996). In the future, the NCRPIS plans to use 0. cornifrons as exclusive pollinators of Brassicaceae accessions in field cage multiplication plots. Table 2. A summary of costs associated with managing three species of bees. BEE Hornfaced bee ( Osmia cornifrons) Honey bee (Apis mellifera) Alfalfa leafcutting bee (Megachile rotundata) a48 bees/cage @ $0.08/bee b15 min/cage @ $12.00/hr BEE COST/ CAGE $ 3.84a $37.30( $ 0.8oe LABOR TOTAL COSTS/ COST/ CAGE CAGE $3.oob $ 6.84 $6.ood $43.30 $4.00£ $ 4.80 cone 2-lb package/cage @ $31.50/package (includes shipping); bee food costs for corn syrup@ $1.90/gal and pollen@ $2.00 <l30 min/cage @ $12.00/hr e250 bees/cage £20 min/cage @ $12.00/hr ACKNOWLEDGMENTS The authors wish to thank Nate Bye, Brett Roberts, and Ron Schweppe for help in manipulating the bees. This article is a joint contribution from the USDA-ARS and the Departments of Agron-omy and Entomology, Iowa State University. This is Journal Paper No. J-17642 of the Iowa Agricultural and Home Economics Exper-iment Station, Ames, Iowa, Project No. 1018, and supported by Hatch Act and State of Iowa funds. LITERATURE CITED BATRA, S. 1979. Osmia cornifrons and Pithitis smaragdula, two Asian bees introduced into the United States for crop pollination. Proceedings IV th International Symposium on Pollination, Md. Agric. Exp. Sta. Spec. Misc. Publ.l :307-312. ELLIS, M. D., G. S. JACKSON, W. H. SKRDLA, and H. C. SPENCER. 1981. Use of Honey Bees for Controlled lnterpollination of Plant Germ-plasm. HortScience 16:488-491. EVES,]. D., D. F. MAYER, and C. A. JOHANSEN. 1980. Parasites, pred-ators, and nest destroyers of the alfalfa leafcutting bee, Megachile rotun-data. Western Regional Extension Publication 32, Cooperative Extension Service, Washington State University, Pullman. 15 pp. THREE BEES POLLINATING BRASSICACEAE 3 FREE, J. B. 1993. Chapter 20: Cruciferae. In, Insect Pollination of Crops. Academic Press Inc., San Diego, CA. p. 166-189. MSTAT DEVELOPMENT TEAM. 1989. MSTAT-C: A microcomputer pro-gram for the design, management and analysis of agronomic research experiments. MSTAT Development Team, Michigan State University, East Lansing. ROATH, W.W., R. L. WILSON, and C. A. ABEL. 1990. Effects of three insect pollinators on seed yield of two Cuphea species. Program Abstracts of the 102nd. Session, Iowa Academy of Science, No.6:5. WILSON, R. L., and C. A. ABEL. 1996. Storage conditions for maintaining Osmia cornifrons (Hymenoptera: Megachilidae) for use in germplasm pol-lination. Journal of the Kansas Entomological Society 69:270-272. WILSON, R. L., and W. W. ROATH. 1992. Potential of three lepidopteran species as pests and three hymenopteran species as pollinators of Cuphea. Journal of the Kansas Entomological Society 65:316-320. WILSON, R. L., M. P. WIDRLECHNER, and K. R. REITSMA. 1991. Pollination methods for maintaining carrot germplasm collections. FAQ/ IBPGR Plant Genetics Research Newsletter 85:1-3. 

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Comparing Three Bee Species for Controlled Pollination of Selected Brassicaceae

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