|Reitsma, Kathleen - IOWA STATE UNIVERSITY|
|Clark, Lucinda - IOWA STATE UNIVERSITY|
|Brenner, David - IOWA STATE UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: May 8, 2007
Publication Date: June 24, 2007
Citation: Reitsma, K.R., Clark, L.C., Mcclurg, S.G., Hanlin, S.J., Brenner, D.M., Widrlechner, M.P. 2007. Regeneration of self-compatible Pimpinella plants benefits from the addition of fly pollinators. In: Proceedings of the 9th International Pollination Symposium on Plant-Pollinator Relationships - Diversity in Action. p. 144-145. Technical Abstract: Summary: The North Central Regional Plant Introduction Station (NCRPIS), located in Ames, Iowa maintains a large collection of diverse germplasm including 2276 accessions of Umbelliferae representing 43 genera. Although many Umbelliferae are insect pollinated, several species have a significant level of self-pollination . All accessions of umbels conserved at the NCRPIS are regenerated in controlled pollination cages in order to maintain the original genetic diversity of the germplasm. Studies conducted by Wilson et al. in 1985-1988 showed addition of pollinating insects (honey bees and flies) increased seed production in Daucus cages . Curatorial staff expanded this use of insect pollinators to other umbel genera, generally with satisfactory results. To refine our methods, a study was conducted to compare the effectiveness of two fly genera (housefly, Musca domestica L. and blue bottle flies, Calliphora sp.) individually or in combination, as well as investigating the frequency of fly introduction (once or twice weekly) to greenhouse cages of two accessions of Pimpinella. Materials and Methods: We conducted a test consisting of 16 total cages, eight cages each of two accessions of Pimpinella peregrina (Ames 25735 and Ames 25737). Seeds were started in the greenhouse in October 2002; 10-month-old plants were vernalized at 4 C for two months and then returned to the greenhouse at ca 25 C in October 2003. Small isolation cages (127 cm × 51 cm × 76 cm) constructed of 1.27 cm-diameter plastic pipe frames covered with a fine mesh polyester screen were used for this study. Each cage, containing 16 plants, received flies at first flowering in October 2003 until the majority of umbels in a cage had received adequate pollination in March 2004. Insect treatments included: control – no insects, houseflies only – 100 pupae per dose, blue bottle flies only – 100 pupae per dose, and a combination of both flies – 50 housefly pupae and 75 blue bottle fly pupae per dose. One set of each of these treatments (eight cages total) received flies once weekly and another that received flies twice weekly. Cages were assigned to treatments by using a Randomized Complete Block Design generated by MSTAT-C . Seed harvest was completed from February through April 2004. Seeds were cleaned, data collected on cleaned lots and viability testing completed by February 2005. Discussion and Results: Typically, we compare the total amount of seed produced per test cage to determine the optimal treatment. However, in this test, we used a different approach, measuring percent seed viability for each cage. This was because the Pimpinella used in the study was evidently self-compatible, producing seeds in the control cages (with no insects added) through self-pollination. The germination test showed one accession (Ames 25735) had very low percent viability in the control cages, i.e. only 0.5 to 4 % of seeds that developed in these cages had living embryos. The second accession (Ames 25737) appeared to have greater self-fertility with 18 to 21% viability in the control cages. The percent seed viability for both accessions was usually much greater for cages with insect pollinators (up to 93 % viability) than the control cages; thus, it appears it was beneficial to use fly pollinators to increase the amount of viable seed produced in these self-compatible accessions. The most effective pollinator treatment was evidently either houseflies alone or a combination of houseflies and blue bottle flies. Caged plants of Ames 25735 with houseflies alone or with a combination of flies had 69 to 88% viability, while the blue bottle fly only cages had 14 to 34% viability. There was less variation in the pollination results of the two fly species used alone or in combination in the second accession, Ames 25737, where viability for individual fly species varied from 77 to 84% and the combined treatment resulted in 82 to 93% viability. The frequency of introduction of flies to these cages (once versus twice a week) did not differ statistically, i.e. cages with flies introduced only once a week produced as much viable seed as did those cages with flies introduced twice a week. Conclusion: In summary, we can infer three main points from the seed viability data: 1. Self-compatible Pimpinella plants benefit from the addition of fly pollinators; cages with flies all produced more viable seed than did the control cages. 2. If limited to using only one species of fly, the housefly would be a more reliable choice than the blue bottle fly. However, cages with combined species of flies did as well or better than the houseflies alone. 3. Adding pollinators to cages more frequently than once a week showed no significant benefit.