Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2006
Publication Date: 2/1/2007
Citation: Clement, S.L., Hellier, B.C., Elberson, L.R., Staska, R.T., Evans, M.A. 2007. Flies (Diptera: Muscidae, Calliphoridae) are efficient pollinators of Allium ampeloprasum L. (Alliaceae) in field cages. Journal of Economic Entomology. 100(1):131-135. Interpretive Summary: The USDA, ARS seedbank at Washington State University stores over 72,000 accessions of major crops for agricultural sustainability in the United States. On average, 19,000 seed packets of seed are distributed every year to scientists in the U.S. and abroad for new cultivar and crop development. This activity leads to diminished seed supplies in the seedbank, which are replenished via seed production in field nurseries. With this approach, however, there is a risk of unintended hybridization and loss of genetic integrity among accessions of plant species that require insect pollination. To prevent insect-mediated cross pollination, curators at this seedbank use spatial isolation of accessions in field nursery or field cages with suitable insect pollinators. This research by entomologists and horticulturists identified the best and most cost effective insect pollinator for field cage pollination of leek accessions. A fly known as the bottle fly was determined to be the best pollinator and the optimal density for maximum pollination and seed production was found to be 500 flies per cage per week. This research underscores the importance of interdisciplinary, multi-year research to develop seed regeneration protocols for maintenance of important plant genetic resources.
Technical Abstract: In conjunction with efforts to identify efficient insect pollinators for seed multiplication of cross-pollinated plant species stored and maintained by USDA, ARS Western Regional Plant Introduction Station (WRPIS), experiments were conducted to assess and compare the efficiency of the house fly (HF) Musca domestica L. and the bottle fly (BF) Calliphora vicina Robineau-Desvoidy, and different densities of each fly species, to pollinate leek, Allium ampeloprasum L., plant inventory (PI) accessions in field cages for seed yield maximization and high germination. Cages with flowering plants were exposed to 0 flies or stocked with 100, 250, and 500 HF or BF pupae per week for six (2002) and seven (2004) weeks. Seed yield (weight per cage) increased linearly as fly densities (BF or HF) increased from 0 to 500 pupae per week, with 500 fly cages averaging 340.73 g (BF) and 70.45 g (HF) of seed in 2002 (PI 368343) and 615.34 g (PI 168977) and 357.52 g (PI 368343) in 2004 when only the BF was used. For 0, 100, and 250 fly cages, seed yields averaged between 2.25 and 175.29 g in 2002 and 10.66 and 273.05 g in 2004. Mean 100-seed weights between treatments ranged narrowly between 0.40 and 0.45 g in 2002 and 0.33 and 0.39 g in 2004 and germination rates of seed lots from ‘fly cages’ were mostly ' 80% in both years. The BF is an efficient and cost-effective pollinator ($388.97 for pupae and shipping, compared to $2,400 for honey bee nuclei) for caged leek accessions, with 250 and 500 BF pupae per week required to produce sufficient seed (130 g) to fill an accession storage bag in the WRPIS gene bank.