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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Research Project #425451

Research Project: Cranberry Genetic Improvement and Insect Pest Management

Location: Vegetable Crops Research

2018 Annual Report

1a. Objectives (from AD-416):
Objective 1: Develop and apply genomic and genetic tools to map and characterize the genetic bases of the key cranberry traits that determine yield. Objective 2: Based on horticultural, genetic, and genomic information, formulate and apply breeding approaches for genetically improving cranberry yield. Objective 3: Determine the development thresholds of key arthropod pests (cranberry fruitworm and Sparganothis fruitworm) to better predict the developmental status of populations in the field. Objective 4: Develop novel, innovative IPM strategies to reduce pesticide use and sustain cranberry yield, quality, and profitability. Objective 5: Develop alternative cranberry production practices that improve water conservation and decrease plant disease.

1b. Approach (from AD-416):
Objective 1: Next-generation sequencing technology will be used to characterize the cranberry genome. The resultant data will be used to discover and mine molecular markers such as SSRs and SNPs. We will then develop high-resolution genetic maps using the developed markers based on several available half-sib F1 mapping populations. Phenotyping will involve collecting data on yield-related traits and other horticultural measurements, including total fruit weight, percent rotten fruit, average berry weight, and fruit quality parameters. These traits will be localized in the linkage map described above. Information derived from the high resolution cranberry linkage map with yield-related will be used to plan strategic crosses. Objective 2: Prior to creating cranberry hybrids, horticultural, genetic, and genomic information will be carefully considered to ensure that strategic crosses are accomplished. A microsatellite marker based fingerprinting assay will be developed for the true-to-type verification of the cranberry cultivars. We will also characterize known cranberry diversity from the breeding programs and collections and samples sent in by growers. Pedigree information will be evaluated in the light of marker information to determine the most likely genotypes or genetic pools associated with each named cultivar and their associated horticultural performance. A series of cranberry hybrids with complementary genetic pools will be created and evaluated. Objective 3: The temperature-specific development rates and degree-day (DD) accumulations associated with cranberry fruitworm (CFW) and Sparganothis fruitworm (SFW) will be determined. Larval growth rates will be measured over a wide range of controlled temperatures. Growth rates will be plotted against temperature, and models will be fit to the dynamic. From these models, the lower and upper development thresholds will be isolated. The thresholds will then be used to generate degree-day (DD) accumulations that can be linked to discrete biological events, such as flight initiation in the field, adult lifespan, ovipositional period, and egg-hatch periods. DD accumulations represent key developmental benchmarks, helping to optimize pest management in the cranberry system. Objective 4: novel insect pest management approaches will be investigated. Two primary tactics will be explored within the cranberry system: pheromone-based mating disruption and trophic position measurement. In partnership with private industry, as well as Wisconsin cranberry growers, the first ever 3-species mating disruption program will be deployed at large scales within commercial marshes. Population suppression of the target pests will be assayed and compared with conventional pest management approaches. Studies of arthropod trophic position will be conducted using stable isotopic analysis of amino acids. Trophic position estimation will reveal the lifetime trophic tendencies of carnivorous species, thereby providing empirical evidence as to which species are actually beneficial for cranberry production.

3. Progress Report:
This is the final report, project terminated March 6, 2018. This progress report relates to Objectives 1 and 2. We studied yield-related traits in cranberry using traditional data collection methods. We also developed high-throughput molecular and trait data collection and visualization software. We applied the software to collect and understand massive amounts of data. We developed thousands of molecular markers, eight high-density molecular maps, and a concomitant composite map, all of which are being used to study, identify, and map genes found to control cranberry traits (mainly yield-related), quality, and other traits of economic importance. We transferred molecular data from cranberry to blueberry and created molecular genetic maps in both species for comparative purposes of the genetic architecture of horticulturally important traits. In the future, these efforts will help breed improved cranberry cultivars and the transfer of genetic information among closely related species such as cranberry and blueberry will increase breeding efficiency and the implementation of marker-assisted breeding. The construction of our composite high-resolution molecular map with trait-makers associations is one of the most important accomplishments in ~200 years of cranberry domestication, breeding, and genetics work. This progress relates to Objectives 3 and 4. The ARS continues to advance the practice of integrated pest management (IPM) in United States cranberries by investigating explicitly the intersection between crop production technology, arthropod biology, and agroecology. Now in its 7th year of research and development, the multi-species pheromone-based mating disruption program in U.S. cranberries has shown that large-scale deployment can be tailored to the Wisconsin cranberry production system. In the process, this work has also revealed a novel mechanism by which insect pheromones protect crops. Specifically, the cranberry plant is able to invoke strong defensive responses when exposed to insect pheromones, and current work is examining how this response can be exploited to further defend the plant from insect attack. Other ARS studies are building on the discovery of two native nematode species in Wisconsin that are highly virulent bio-control agents against cranberry pests. A bio-insecticide has been formulated via mass-propagation of these nematodes and modified field-application systems. Finally, ARS work into bee-microbe interactions has shown that social and non-social bees consume significant microbial protein during larval development. Further, recent findings have revealed that when the microbes are removed from fermenting pollen, the larval bees die; collectively, this suggests that bees are reliant on pollen-borne microbes during development.

4. Accomplishments
1. Cranberry and blueberry are closely related and recently domesticated fruit crops. Both species are presumed to have a North American origin and likely evolved from a common ancestor, but their evolution is little understood. ARS scientists in Madison, Wisconsin conducted comparative genetic mapping studies between cranberry and blueberry to examine the genetic similarity and to better understand the evolutionary relationships between the two species. A set of common molecular markers was identified, added to existing cranberry and blueberry marker datasets, and used to construct genetic maps for cranberry and blueberry. The two species possessed an exceptionally high degree of genetic similarity based on the shared markers in the developed genetic maps. This high genetic similarity was unexpected since the two species are observably very different, yet approximately 93% of the blueberry genetic map was aligned perfectly to the cranberry map. Thus, this research is important because it indicates that sequencing information and other genetic research will be highly transferable between these two species. Moreover, researchers working on genetics and breeding projects in cranberry and blueberry should work together to make work more transferrable and efficient in both species. The set of 323 universal cranberry/blueberry markers is a unique resource for the research community, and the molecular maps developed will enable future comparative genetic mapping studies, the identification and transfer of genes between studies and species, future studies exploring evolutionary relationships, and conventional/molecular breeding efforts based on shared information.

2. Arthropod fauna of cranberries. Insects represent the most consistent and significant pests of Wisconsin cranberries. ARS scientists in Madison, Wisconsin, have conducted foundational surveys of the arthropod fauna associated with cranberries in both cultivated and wild systems have been described. This reveals the identities of the most significant pest threats (and beneficial species) to cranberries in Wisconsin, which will inform biological control efforts in U.S. cranberries. The diversity of spider fauna is particularly important given the abundance of spiders in cultivated cranberry beds.

3. Conservation bio-control in cranberries. Insects represent the most significant, consistent threat to U.S. cranberries, and most of these pests are suppressed by a diversity of predaceous insects. Conservation of predator populations—particularly spider populations—during springtime flooding has been demonstrated by ARS scientists in Madison, Wisconsin. These conserved bio-control agents were associated with reduced pest numbers, and given that insects tend to be the greatest threat to the cranberry harvest, carnivorous insects help to mitigate the threat. Thus, flooding not only reduces pest populations by directly removing the herbivores, but also allows the carnivores to survive, re-colonize, and suppress pest numbers. Such findings reveal how certain grower practices promote biological control, thereby advancing sustainable farming.

4. Pollinator-microbe symbioses. Pollinators are critical components of cranberry production. Bee larvae (bumble bees and blue orchard bees) appear to require certain pollen-borne microbes, and, when absent, the larvae die. Pollen-borne microbial communities experience major shifts in abundance depending on whether fungicide residues are present or not. ARS scientists in Madison, Wisconsin have further illuminated the relationships between pollen-borne microbes and pollinator populations. Altogether, this suggests that bee larvae require certain microbes within their fermenting pollen provisions and that fungicide residues may alter these microbial communities. Conserving the important microbial symbionts of bees translates into increased survivorship of the single most important pollinators of cranberries.

Review Publications
Steffan, S.A., Singleton, M.E., Draney, M.L., Chasen, E.M., Johnson, K.E., Zalapa, J.E. 2017. Arthropod fauna associated with wild and cultivated cranberries in Wisconsin. Great Lakes Entomologist.
Steffan, S.A., Dharampal, P.S., Diaz-Garcia, L., Currie, C.R., Zalapa, J.E., Hittinger, C.T. 2017. Empirical, metagenomic, and computational techniques illuminate the mechanisms by which fungicides compromise bee health. Journal of Visualized Experiments.
Schlautman, B., Diaz-Garcia, L., Covarrubias-Pazaran, G., Schlautman, N., Vorsa, N., Polashock, J.J., Ogden, E.L., Brown, A., Lin, Y., Bassil, N.V., Buck, E.J., Wiedow, C., McCallum, S., Graham, J., Iorizzo, M., Rowland, L.J., Zalapa, J.E. 2017. Comparative genetic mapping reveals synteny and collinearity between the American cranberry and diploid blueberry genomes. Molecular Breeding. 38:9.
Van Zoeren, J., Guedot, C., Steffan, S.A. 2018. Conserving carnivorous arthropods: an example from early-season cranberry (Ericaceae) flooding. The Canadian Entomologist. 1-9.
Crossley, M.S., Steffan, S.A., Voegtlin, D.J., Hamilton, K.L., Hogg, D.B. 2017. Variable isotopic compositions of host plant populations preclude assessment of aphid overwintering sites. Insects. 8(4):128.