Source: UNIV OF CALIFORNIA submitted to
ENHANCING BIODIVERSITY IN AGROECOSYSTEMS TO IMPROVE PEST REGULATION AND SUSTAINABLE PRODUCTION
Sponsoring Institution
NIFA
Project Status
REVISED
Funding Source
Reporting Frequency
Annual
Accession No.
0084860
Grant No.
(N/A)
Project No.
CA-B*-INS-4137-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2007
Project End Date
Sep 30, 2012
Grant Year
(N/A)
Project Director
Altieri, M.
Recipient Organization
UNIV OF CALIFORNIA
(N/A)
BERKELEY,CA 94720
Performing Department
INSECT BIOLOGY
Non Technical Summary
A Certain agricultural diversification practices contribute to amelioration of insect pest problems. B Cover cropping in vineyards and intercropping in vegetable cropping systems are evaluated as a potential IPM strategy. The project examines the effectiveness of cover crops, intrecrops and organic soil management in reducing pest problems in vineyards and brassica crops. Habitat management techniques are proving to be an attractive and effective strategy for organic wine and vegetable producers to complement their ecological pest management schemes. Many farmers are learning about biodiversity enhancement through workshops organized by the California Sustainable Winegrowers Alliance and the Ecological Farming Association, events at which our data is presented. Several farmers in Salinas, Mendocino and Sonoma counties are already applying habitat management in their systems based on our recommendations.
Animal Health Component
80%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2051131107050%
2113110113050%
Goals / Objectives
The main goal of this research project is to elucidate the basic ecological mechanisms at play in diversified cropping systems subjected to organic management, which determine insect pest regulation due to interactions between above and below ground biodiversity or nutrient mediated changes in plant foliage. Through our research then, we will further elucidate how the biological structuring of vineyards (through the use of cover crops), subjected to various organic fertilization regimes sponsor the ecological performance of the agroecosystems. A specific objectives is to assess the entomofauna associated with winter and summer cover crops (buckwheat in rows between vines and alyssum seeded directly under drip line in vine rows) growing beneath the vines, and whether cover crops enhance beneficial arthropods, and if such enhancement in turn impacts insect pests on vines. We will determine the species diversity and abundance levels of the arthropod fauna (herbivores, predators and parasites) associated with the various flowering cover crop species. This information will allow us to understand to what extent beneficial insects depend on such flower resources for continued existence in the vineyards. Using broccoli based cropping systems, we will explore the indirect role that inter-plant competition in intercropped systems plays in pest levels and dynamics. Additive intercropping design experiments (i.e., the target crop has the same density in monoculture and in polyculture) introduce inter-specific plant competition that impacts crop growth that may indirectly influence herbivore levels. The role this plays has not been clearly elucidated because the widely-used additive designs incorporate the effects of plant competition that have not been separated from the effects of the intercropping on pest levels. In addition, cultural methods such as crop fertilization can affect pest pressure, and further confound the intercropping experiments and the interpretation of the results. It is known that soil fertility management may affect plant quality and may therefore affect insect pest abundance (Altieri and Nicholls 2003). Research shows that organically-fertilized crops generally exhibit lower densities of several insect herbivores. Such reductions are commonly observed on organically grown crops, but the direct linkage to fertility is confounded by the increased abundance of natural enemies compared with conventional practices (Altieri et al., 2005). We will conduct additive intercropping experiments to examines whether crop diversity influences aphid abundance and parasitization without plant interspecific competition, and whether such influence is mediated by the application of organic (compost) vs. synthetic fertilizer.
Project Methods
To define agroecosystem management practices that restore habitat complexity in crop systems in order to enhance beneficial biodiversity which play key ecological roles in agroecosystems, such as population regulation, nutrient cycling and sustained yield. Field experiments include designs such as diversification of vineyards with corridors and cover crops and of vegetable crops with intercropping and organic fertilization. We will use a combination of methodologies using agroecology, entomology, agronomy and socioeconomic analysis to assess the impacts of biodiversification on agroecosystem performance.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: This ongoing project provides a scientific evaluation of on-farm habitat management strategies to develop cost-effective biological control options of important arthropod pests of California vineyards. Working collaboratively with ten commercial growers since 2008 the project has centered on evaluating the impact of the conservation biological control strategy of Floral Resource Provisioning (FRP) via several flowering plants on soil quality and population dynamics of leafhoppers and mealybugs in key California wine producing regions. The project measured the impact of intercropping with five flowering plant species, including annual buckwheat, lacy phacelia, sweet alyssum, bishops weed and wild Carrot on the enhancement of biological control of leafhoppers and vine mealy bugs in Napa, Sonoma, and Fresno County vineyards. At most research sites where flowering plants established a reasonable cover during 2011 year, we found: 1. leafhopper nymph densities were found to be significantly lower in flower plots (when compared to control plots) when there was good treatment establishment and high overall leafhopper pressure 2. no significant differences were found in early-season Anagrus sp. (a key biological control agent) density when comparing treatment and control plots; 3. where assessed, no significant difference in leafhopper egg parasitism rates were observed between treatment and control plots 4. significantly higher abundance and diversity of arthropod natural enemies (especially predators) were found in all flower treatment plots 5. the diversity and abundance of arthropod natural enemies varied in treatment plots over each growing season; 6. laboratory and field studies showed enhanced longevity of Anagyrus psuedococci (biocontrol agent of vine mealy bug) under controlled conditions and enhanced rates of parasitism/mortality in the field with FRP compared to control. We conducted training (in Spanish) of farm workers from participating vineyards on February and June 2011. These training sessions were held at 2 participating vineyards in Oakville, CA. The intention was again to provide workers with the overall logic for the research being done in their vineyards and further train them in insect identification and data collection. We held a Grower Cross-Visit on May 2011 at a participating vineyard in Sonoma County. Researchers and growers came together to view treatment establishment at one of the participating vineyards and discuss implementation and management of the flowering ground covers. A summary of the data from the 2010 study was also presented to growers. Growers provided researchers with feedback about criteria for future selection of new flowering ground cover species. A Public Field Day was held on June 2011. At this event the larger wine grape growing community was invited to visit one of the on-farm trials in Rutherford, CA. With over 30 growers in attendance, researchers presented project goals and objectives while participating growers shared information about their experience and involvement with the project to date. PARTICIPANTS: Collaborating Graduate Student Researchers: Albie Miles and Houston Wilson University of California, Berkeley-Department of Environmental Science, Policy and Management Collaborators Growers: 1. Katey Taylor. Constellation Wine US http://iconestateswine.com/wineries/franciscanoakville.htm. 2. Ames Morrison. Medlock-Ames Vineyards http://www.medlockames.com/ 3. David Gates. Ridge Wine http://www.ridgewine.com/ 4. Michael Sipiora. Quintessa Vineyards http://www.quintessa.com/ 5. Rachel Ashley and Dana Estensen. Fosters Wine Estates http://www.am.fostersgroup.com/ 6. Aron Weinkauf. Spottswoode Estates http://www.spottswoode.com/ 7. Sarah Black. Joseph Phelps Vineyards http://www.jpvwines.com/. 8. Randy L. Heinzen. Saintsbury Vineyard: http://www.saintsbury.com/. 9. Philip Coturri, Mayacamas Olds and Robert Schultz. Oakville Ranch Vineyards http://www.oakvilleranchvineyards.com/default.asp. 10. Debby Zygielbaum. Robert Sinskey Vineyards: http://www.robertsinskey.com/ TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Many farmers adopting the various FPR designs have reported that they have been able to cut down on the application of insecticides or the use of organic products for pest control. Some farmers have also reported that the use of certain flower mixtures have brought other benefits such as weed suppression, improvement of soil quality and in some cases improved water storage, a key issue during dry years. The training of farm workers on insect identification and monitoring has proven useful to growers, as more rigorous scouting of fields is ensured. On the other hand, farm workers feel more satisfied in their jobs as they are providing other services other than just physical labor. Farmers cross visits and field days are serving to create a horizontal mechanism for farmers to exchange experiences, ideas and to work collaboratively in improving the sustainable management of their vineyards.

Publications

  • Altieri,M.A., C.I.Nicholls, H. Wilson and A. Miles 2010 Habitat management in vineyards: a growers manual for enhancing natural enemies of pests. Laboratory of Agroecology, UC Berkeley. http://agroecology.berkeley.edu/resources/Altieri_2010_habitat_manage ment_in_vineyards.pdf


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: We continued our research and extension project to assess the impact of on-farm plant diversification strategies on biological control of vineyard pests in Napa and Sonoma counties. Six more farmers joined the participatory research aimed at testing management strategies of flowering cover crop species and assessing whether such flower resource provisioning successfully enhances natural enemies of key wine grape pests in California wine grapes. Three years of findings support the hypothesis that cover crop diversification is a key strategy to sponsor the internal regulation of important arthropod pests with a minimum of externally derived pest control inputs. Floral resources were found to attract a greater diversity and abundance of natural enemies which could led to the reduced pest densities observed at most vineyard sites sites. PARTICIPANTS: Vineyard collaborators Saintsbury Vineyard: http://www.saintsbury.com/. Address: 4254 Old Sonoma Rd. Napa, Ca. 94559. Contact: Randy L. Heinzen. E-mail: Randy@Saintsbury.com Oakville Ranch Vineyards: http://www. oakvilleranchvineyards.com/default.asp. Address: 7781 Silverado Trail Napa, CA 94558. Contacts: Philip Coturri, Mayacamas Olds. E-mail: pcoturri@enterprisevineyards.com, mso@enterprisevineyards.com, Icon Estates: http://iconestateswine.com/wineries/franciscanoakville.htm. Address: 801 Main Street St. Helena, CA 94574 (corporate headquarters). Contact: Katey Taylor. E-mail: Katey.Taylor@ iconestateswine.com Robert Sinskey Vineyards: http://www.robertsinskey.com/. Address: Winery: 6320 Silverado Trail Napa, California 94558. Contact: Debby Zygielbaum. E-mail: walkthevine@robertsinskey.com Medlock-Ames Vineyards: www.medlockames.com. Address: 13414 Chalk Hill Road, Healdsburg, CA 95448. Contact: Ames Morrison. E-mail: ames@medlockames.com Ridge Wine: http://www.ridgewine.com/. Address: 650 Lytton Springs Rd. Healdsburg, Ca. 95448. Contact: David Gates. E-mail: dgates@ridgewine.com Quintessa Vineyards: http://www.quintessa.com/. Address: 1601 Silverado Trail, Napa, Ca. 94559. Contact: Michael Sipiora. E-mail: michael@quintessa.com TARGET AUDIENCES: Immediate beneficiaries include those vineyard managers participating in the farm-based research and other growers that attend the extension components of this project ( field days, farmers cross visits, seminars, etc) PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Habitat management techniques are proving to be an attractive and effective strategy for organic wine producers to complement their ecological pest management schemes. Many farmers are learning about biodiversity enhancement through field days, cross-visits and workshops that we organize. After two years of research 25 farmers have included all or some of our five recommended flowering cover crop species in their systems and many have reported lowering costs of production as pesticide use ( organic and/or synthetic) has gone down.

Publications

  • Altieri, M.A., Nicholls, C.I., H. Wilson and A. Miles 2010 Habitat management in vineyards. A growers manual for enhancing natural enemies of pests. Laboratory of Agroecology, University of California, Berkeley. http://agroecology.berkeley.edu/resources/Altieri_2010_habitat_manage ment_in_vineyards.pdf


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: In the fall of 2008, we initiated a research and extension project to assess the impact of on-farm plant diversification strategies on biological control of vineyard pests in Napa and Sonoma counties. The objective of the participatory research is to define the composition and management of flowering cover crop species necessary to successfully enhance natural enemies of key pests in California wine grapes. Preliminary findings support the hypothesis that cover crop diversification can potentially be a key strategy to sponsor the internal regulation of important arthropod pests with a minimum of externally derived pest control inputs. Floral resources provided during the growing season were found to attract a greater diversity and abundance of natural enemies which could led to the reduced pest densities observed at most vineyard sites sites. PARTICIPANTS: Miguel A Altieri and Kent Daane biological control researchers at UC Berkeley, Houston Wilson and Albie Miles UCB graduate students and 12 undergraduate research assistants Collaborating growers: Katey Taylor. Constellation Wine US,Ames Morrison. Medlock-Ames Vineyards,David Gates. Ridge Wine, Michael Sipiora. Quintessa Vineyards,Rachel Ashley and Dana Estensen. Fosters Wine Estates , Aron Weinkauf. Spottswoode Estates, Sarah Black Joseph Phelps Vineyards, and five others TARGET AUDIENCES: Organic and conventional Wine grape growers in Napa and Sonoma counties of California, pest control advisers, extension and research personnel PROJECT MODIFICATIONS: No changes required

Impacts
Habitat management techniques are proving to be an attractive and effective strategy for organic wine producers to complement their ecological pest management schemes. Many farmers are learning about biodiversity enhancement through field days, cross-visits and workshops that we organize. After two years of research 25 farmers have included all or some of our five recommended flowering cover crop species in their systems and many have reported lowering costs of production as pesticide use ( organic and/or synthetic) has gone down.

Publications

  • Altieri, M.A., A. Miles and H. Wilson 2010 Conservation, augmentation and use of native flora to promote biological control in North America In: Arthropod Management in Vineyards . N. J. Bostanian, R. Isaacs & C. Vincent (Eds.) Springer. (In Press)


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: In 2008 we initiated a two-year participatory and on-farm research and extension project involving seven vineyards in Napa and Sonoma Counties. We assessed the effectiveness of non-crop vegetation (e.g., winter and summer cover crops) on the enhancement of functional biodiversity for insect pest suppression in vineyard agroecosystems. The objective of the research is to further define key cover crop species composition and the management of such plants to successfully stimulate cost-effective biological control of key wine grape pests. In the seven vineyards we compared densities of insect pest and associated natural enemies between blocks under agroecological management versus neighboring blocks under farmers management (FM). Data however was not consistent across vineyards given the heterogeneity of vineyards surveyed and the fact that not all farmers were able to implement the complete agroecological treatments as suggested by the research team. In many cases erratic winter and early spring weather affected cover crop establishment and conditioned very low pest densities in most sites where for example nymphal leafhopper densities rarely reached above 3 nymphs per leaf, when threshold levels are considered above 2o or more per leaf. Nevertheless preliminary results from vineyards where experimental blocks represented the optimal cover crop designs, support the hypothesis that cover crop diversification is a key strategy to sponsor the internal regulation of important arthropod pests without the use of synthetically compounded materials and a minimum of externally derived OMRI-listed pest control inputs. As planned we conducted training of farmworkers in Spanish on monitoring methods so that they can assist in data collection and interpretation for pest management decision making. We made special efforts for extensive grower involvement via organization of several cross-visits among participants to share information and experiences, and also one field day open to the wider farming community. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Habitat management techniques are proving to be an attractive and effective strategy for organic wine producers to complement their ecological pest management schemes. Many farmers are learning about biodiversity enhancement through field days, cross-visits and workshops that we organize. We expect next year to have at least 25 additional farmers adopting habitat management in their systems based on our recommendations.

Publications

  • Altieri, M.A. and C.I. Nicholls 2008 Ecologically based pest management in agroforestry systems. In: Ecological basis of Agroforestry. D.R.Batish et. al .eds. CRC Press, Boca Raton. Pp: 95-108


Progress 01/01/07 to 12/31/07

Outputs
The effects of intercropping via competition on crop yields, pest [cabbage aphid Brevicoryne brassicae (L.)] abundance, and natural enemy efficacy were studied in the Brassica oleracea L. var. italica system. From May to December 2004, insect populations and yield parameters were monitored in summer and autumn in broccoli monoculture and polyculture systems with or without competition from Brassica spp. (mustard), or Fagopyrum esculentum Moench (buckwheat), with addition of organic (compost) or synthetic fertilizer. Competition from buckwheat and mustard intercrops did not influence pest density on broccoli; rather, aphid pressure decreased and natural enemies of cabbage aphid were enhanced in intercropping treatments, but this varied with the intercropped plant and season (summer vs. autumn).In compost-fertilized broccoli systems, seasonal parasitization rates of B. brassicae by Diaeretiella rapae (M'Intosh) increased along with the expected lower aphid pressure compared to synthetically fertilized plants

Impacts
Lowering aphid populations in broccoli plants through intercropping with flowers, and applications of compost seems a viable approach to significantly reduce use of external chemical inputs without sacrificing agronomic yields.

Publications

  • Ponti, L, M.A. Altieri and A.P. Gutierrez 2007 Effects of crop diversification levels and fertilization regimes on abundance of Brevicoryne brassicae and its parasitization by Diaeretiella rapae in broccoli. Agricultural and Forest Entomology 9: 209-214


Progress 01/01/06 to 12/31/06

Outputs
The effects of intercropping via competition on crop yields, pest [cabbage aphid Brevicoryne brassicae (L.)] abundance, and natural enemy efficacy were studied in the Brassica oleracea L. var. italica system. From May to December 2004, insect populations and yield parameters were monitored in summer and fall in broccoli monoculture and polyculture systems with or without competition from Brassica spp. (mustard), or Fagopyrum esculentum Moench (buckwheat), with addition of organic (compost) or synthetic fertilizer.Competition from buckwheat and mustard intercrops did not influence pest density on broccoli; rather, aphid pressure decreased and natural enemies of cabbage aphid were enhanced in intercropping treatments, but this varied with the intercropped plant and season (summer vs. fall).In compost-fertilized broccoli systems seasonal parasitization rates of B. brassicae by Diaeretiella rapae (M'Intosh) increased along with the expected lower aphid pressure, when compared to synthetically-fertilized plants.

Impacts
Lowering aphid populations in broccoli plants through intercropping with buckwheat flowers and applications of compost, seems a viable approach to significantly reduce use of external chemical inputs without sacrificing agronomic yields.

Publications

  • Altieri, M.A. and Nicholls, C.I. 2005. Manage insects on your farm: a guide to ecological strategies. Sustainable Agriculture Network. Handbook Series Book 7. Beltsville, MD


Progress 01/01/05 to 12/31/05

Outputs
In a 17 hectare Sonoma biodynamic vineyard, an island of flowering shrubs and herbs located in the middle of the vineyard provided season-long flower resources and alternate preys/hosts for natural enemies, which slowly built up in the adjacent vineyard. The island and its mix of shrubs and herbs provides flower resources from early April to late September to a number of herbivore insects (pests, neutral non-pestiferous insects and pollinators) and associated natural enemies which build up in the habitat, with some of them dispersing into the vineyard. Clear population gradients were observed for thrips (the only pest species found in the insectory), which increased in abundance in vines farther away from the island . Responding to the abundance of habitat resources in the insectory, predators tended to decrease in abundance in vines 30 and 60 m away . Orius reached significantly lower abundances in vines away from the insectory, a trend that correlated with the densities of thrips .The island acts as a source of pollen, nectar and neutral insects which serve as alternate food to a variety of predators and parasites including Anagrus wasps.

Impacts
Habitat management techniques are proving to be an attractive and effective strategy for organic wine producers to complement their ecological pest management schemes. Many farmers are learning about biodiversity enhancement through workshops organized by the California Sustainable Winegrowers Alliance and in which our data is presented. Several farmers in Mendocino and Sonoma county are already applying habitat management in their systems based on our recommendations.

Publications

  • Altieri, M.A., C.I. Nicholls, L. Ponti and A. York 2005. Designing biodiverse, pest resiliento vineyards through habitat management. Practical Winery and Vineyard XXVII: 16-30
  • Altieri, M.A., L. Ponti and C.I. Nicholls, 2005. Manipulating vineyard biodiversity for improved insect pest management: case studies from northern California. International Journal of Biodiversity Science and Management


Progress 01/01/04 to 12/31/04

Outputs
When flowers were removed from buckwheat or Alyssum plants associated with broccoli in intercropping designs, densities of immature aphids increased dramatically in relation to densities on broccoli intercropped with intact flowering plants. Aphid populations also increased when randomly selected broccoli plants (20 plants in plot containing 400 plants) growing in an organically managed field, where fertilized with a chemical N fertilizer. In such plants immature aphid densities grew rapidly compared to densities in neighboring organic plants in the same field. In plots where broccoli plants were mulched with barley straw, a practice that conserves soil moisture, the crops grew larger, yielded more and experienced less aphid infestation levels than plants growing in plots with bare ground (no mulch). Such trends were even more marked in mulched plots where broccoli was intercropped with favabeans or mustard.

Impacts
Lowering aphid populations in broccoli plants through intercropping with flowers and/or applications of mulch seems a viable approach to reduce use of external chemical inputs without sacrificing agronomic yields.

Publications

  • Nicholls, C.I. and Altieri, M.A. 2004. A rapid, farmer-friendly agroecological method to estimate soil quality and crop health in vinetard systems. Biodynamics 250: 33-40.
  • Nicholls, C.I. and Altieri, M.A. 2004. Designing species-rich, pest suppressive agroecosystems through habitat management. In: Agroecosystem Analysis. Agronomy Monograph 43: 49-61. American Society of Agronomy, Madison.
  • Nicholls, C.I. and Altieri,M.A. 2004. Designing and implementing a habitat management strategy to enhance biological control in agroecosystems. Biodynamics 251: 26-36.


Progress 01/01/03 to 12/31/03

Outputs
Cabbage plants intercropped with buckwheat (Fagopyrum esculentum), and fertilized with organic compost exhibited lower loads of the aphid Brevicoryne brassicae than plants grown in monoculture plots and under chemical fertilizer treatments receiving equivalent amounts of Nitrogen. Pest density reductions in the biodiverse plots were associated with higher numbers of syrphid flies and parasitic wasps (Diaeretiella rapae) attracted by the buckwheat flowers, but also to the lower foliar N content of the organically farmed cabbage. Apparently cabbage plants subjected to chemical fertilization had higher N content in the leaves that coincided with peak aphid population densities in the monocultures.

Impacts
Lowering aphid populations in cabbage plants through intercropping with flowers and applications of compost seems a viable approach to significantly reduce use of external chemical inputs without sacrificing agronomic yields.

Publications

  • Altieri, M.A. and C.I. Nicholls, 2003. Soil fertility management and insect pests: harmonizing soil and plant health in agroecosystems. Soil and Tillage Research 72: 203-211
  • Altieri, M.A. and C.I. Nicholls, 2004. Biodiversity and pest management in agroecosystems. Second Edition. Haworth Press, N.Y.


Progress 01/01/02 to 12/31/02

Outputs
Provision of flowers in the form of summer cover crops (buckwheat and sun flowers) in vineyards enhanced populations of parasitic wasps Anagrus sp. and several predaceous arthropods. Such flowers provided abundant alternative food sources (pollen, nectar and neutral insects) to beneficial insects which moved from the flowers to vines attacking grape leafhoppers and thrips. Mowing the flowers forced movement of greater numbers of Anagrus sp and predators which led to significant reductions of grape herbivores. Mowing however was most effective when timed to coincide with leafhopper oviposition, when eggs were most available for Anagrus wasps. Cover crops were mowed every other row in order to leave flowers in the vineyard as habitat for natural enemies to build-up and exert mortality pressure on second generation leafhoppers.

Impacts
Lowering leafhopper and thrips populations through provision and manipulation of flowering cover crops in vineyards that enhance Anagrus wasps and predators eliminate the need to use chemical and botanical insecticides in grapes while reducing costs without sacrificing yields.

Publications

  • Altieri, M.A. and C.I. Nicholls. 2002. The simplification of traditional vineyard based agroforests in northwestern Portugal: some ecological implications. Agroforestry Systems 56: 185-191.
  • Altieri, M.A. and C. I Nicholls. 2002. Invasive arthropods and pest outbreaks in the context of the ecology of mechanized agricultural systems. In: Invasive arthropods in agriculture: problems and solutions. Pp 1-19. G.I. Hallman and C.P. Schwalbe. Science Publishers Inc. Enfield (NH), USA.


Progress 01/01/01 to 12/31/01

Outputs
Cabbage was subjected to several intercropping regimes with tomatoes, basil, chard, Phacelia sp and Phagopyrum sp, in replicated 10 sq.m plots treated with either chemical or organic fertilizers and compared with the corresponding monoculture. Densities of aphids were markedly lower in the Phacelia and Phagopyrum intercrops, due to the higher abundance of natural enemies attracted by the flowers of the companion plants. Flea beetles on the contrary reached lower abundance in the tomato intercrop apparently due to chemical repellency and in the chard intercrop due to barrier effects of this tall plant on flea beetle movement. Cabbage yields were similar in both monocultures and the basil and Phagopyrum intercrops, exhibiting lower levels in descending order in the Phacelia, chard and tomato intercrops. In all cases, aphid and fleabeetle densities were higher in the chemically treated systems (mono and polycultures) than in the organically fertilized plots.

Impacts
Lowering aphid and flea beetle populations through habitat management has the potential to eliminate the use of chemical insecticides from such crops without sacrificing yields while exploiting the potential role of beneficial insect biodiversity.

Publications

  • Letourneau, D.K. and Altieri, M.A. 1999. Environmental management to enhance biological control in agroecosystems . In. Handbook of Biological Control. Pp: 319-354. Academic Press, N.Y.
  • Nicholls, C.I. and Altieri, M.A. 2000. Manipulating plant biodiversity to enhance biological control of insect pests: A case study of a northern California organic vineyard. In: Agroecosystem sustainability. S.R. Gliessman (ed). Pp: 29-50. CRC Press, Boca Raton, Fl.


Progress 01/01/00 to 12/31/00

Outputs
In cabbage plots with adjacent borders of flowering Phacelia and buckwheat (Phagopyrum), marked gradients in cabbage aphid population densities were observed. Numbers of aphids per plant were significantly lower in plants (up to 5 meters) growing close to the borders than in plants away from the border ( beyond 5 meters). Such differences were correlated with higher numbers of predators (Coccinellidae and Syrphidae) in the area close to the flowering border. In addition aphids on plants close to the border suffered higher parasitization rates by the wasp Diaeretiella rapae.

Impacts
(N/A)

Publications

  • Nicholls, C.I., Parrella, M.P., and Altieri, M.A. 2000. Reducing the abundance of leafhoppers and thrips in a northern California organic vineyard through maintenance of full season floral diversity with summer cover crops. Agricultural and Forest Entomology 2: 107-113
  • Altieri, M.A. and Nicholls, C.I. 2000. Applying agroecological concepts to the development of Ecologically Based Pest Management strategies. In: Professional Societies and Ecologically Based Pest Management. Proc. of a Workshop. National Research Council. Washington, D.C., pp. 14-19.


Progress 01/01/99 to 12/31/99

Outputs
The effect of intercropping systems on cabbage insect pests was evaluated in various urban farms throughout the East Bay Area in northern California. Cabbage plots diversified with buckwheat (Phagopyrum) and Phacelia suffered less attack by flea beetles and cabbage aphids than monocultures or mixtures with beans and/or tomato. Cabbage yields were also higher in polyculture plots that exhibited less pest damage. These results were also confirmed in well controlled and replicated studies conducted at the Gill Tract in Albany, CA. Mechanisms at work seem to be lower apparency of cabbage plants to flea beetles grown between taller buckwheat and Phacelia plants. In the case of aphids the attraction of beneficial insects to the flowers of such plants was a key factor. These predators (mostly Coccinellidae and Syrphidae) moved easily from flowers to nearby cabbage plants thus exerting mortality on aphid populations.

Impacts
(N/A)

Publications

  • Altieri,M. A., Companioni, N., Kanizares, K., Murphy, C., Rosset, P., Bourque, M., and Nicholls, C. I. 1999. The greening of the barrios: urban agriculture for food security in Cuba. Agriculture and Human Values 16: l3l-l40


Progress 06/01/97 to 12/01/98

Outputs
The effect of a flowering summer cover crop on pests and natural enemies in Northern California vineyard systems was studied over two consecutive years. Experimental blocks with a mix of buckwheat and sunflower grown between vines had a lower abundance of grape leafhoppers and western flower thrips and a higher abundance and diversity of their associated natural enemies. These natural enemies included the parasitoid wasp ANAGRUS EPOS, several predatory insects, and spiders. Although ANAGRUS reached high numbers and inflicted noticeable mortality on the grape leafhopper, no differences in egg parasitism rates were observed between blocks with cover crops and monoculture systems. Mowing of cover crops forced movement of ANAGRUS and predators onto adjacent vines, which, in turn, lowered leafhopper densities in such vines. More research is needed, however, on the optimal timing of mowing to fine tune the management of cover crops to maximize biological control. The main factors influencing the two pest insects were abundance and diversity of predators in the cover cropped systems and the possibility that cover crops affect colonization of insect pests which discriminate between vines with and without cover crops. Results indicate that habitat diversification using summer crops support high populations of predators and parasitoids which enhance the biological control of leafhoppers and thrips in vineyards.

Impacts
(N/A)

Publications

  • ALTIERI, M. A. and NICHOLLS, C. I. 1998. Biodiversity, ecosystem function and insect pest management in agricultural systems. IN W.W. Collins and C.O. Qualset (eds.), Biodiversity in Agroecosystems. pp. 69-84. CRC Press, Boca Raton.


Progress 01/01/93 to 05/01/97

Outputs
Studies in California and Chile exploring the effects of vegetation diversity on insect communities in vineyard agroecosystems showed that: a) low diversity ground vegetation vineyards had higher numbers of variegated leafhopper (ERYTHRONEURA VARIABILIS) and grape leafhopper (E. ELEGANTULA) and lower diversity and abundance of ground dwelling arthropods than high ground diversity plots; b) vineyards with the leguminous cover crop VICIA ATROPURPUREA had less pest damage by major pests (ERYTHRONEURA) and PSEUDOCOCOUS MARITIMUS. This reduction was attributed to enhanced activity of the parasitoids ANAGRUS spp. and PSEUDAPHYCUS FLAVIDULUS; c) a vegetational corridor cutting across a chardonnay vineyard in northern CA served as a channel for the distribution of natural enemies from the forest into the vineyard. The abundance of leafhoppers and thrips was lower in vines close to the corridor. This was due to higher mortality exerted by enhanced natural enemies. Results suggest that a) cover crops in vineyards act as an "ecological turntable" which enhances the functional biodiversity of the system; b) the corridor serves as a conduit for the dispersion of predators and parasites within the vineyards protecting against pests within the area of influence of the corridor.

Impacts
(N/A)

Publications

  • ALTIERI, M. A. and ROSSET, P. 1996. Agroecology and the conversion of large-scale conventions systems to sustainable management. Int. J. Env. Stu. 50:165-185.


Progress 01/01/96 to 12/30/96

Outputs
I demonstrated that a vegetational corridor connected to adjacent riparian forests and cutting across a chardonnay vineyard in northern California served as a channel for the distribution of natural enemies into the vineyard. The abundance of the grape leafhoppers and thrips in vines immediately adjacent to the corridor were significantly lower than in more distant vines. This was due to higher mortality exerted by predators and parasites which reached higher densities and diversity in vines adjacent to the vineyard. Results suggest that the corridor serves as a conduit for the dispersion of predators and parasites within the vineyard, providing protection against insect pests within the area of influence of the corridor by allowing distribution of natural enemies within a certain range of the vineyard.

Impacts
(N/A)

Publications

  • ALTIERI, M. A. NICHOLLS, C. I., and WOLFE, M. S. 1996. Biodiversity - a central concept in organic agriculture: restraining pests and diseases. Proceedings IFOAM 11th International Scientific Conference, Vol. 1: 91-112, Copenhagen.


Progress 01/01/95 to 12/30/95

Outputs
Vineyards with a ground cover of legumes exhibited a significantly lower incidence of insect pests due to increased abundance and efficiency of predators and parasitoids. Research conducted during the reporting period in vineyards in Fresno, California, and in the Aconcagua Valley of Chile, showed that vineyards that were sown with the leguminous cover crop VICIA ATROPURPUREA had less pest damage by major pests ERYTHRONEUPA VARIABILIS and E. ELEGANTULA in California, and PSEUDOCOCOUS MARITIMUS in Chile. This reduction in pest damage was attributed to the enhanced activity of the parasitoids ANAGRUS spp. and PSEUDOPHYCUS FLAVIDULUS. Cover crop presence and manipulation in vineyards plays the role of an "ecological turntable," which enhances the functional biodiversity of the system, which, in turn, plays a key role in the biological control of insect pests. Cover crops also activate soil biology which positively influences soil fertility.

Impacts
(N/A)

Publications


    Progress 01/01/94 to 12/30/94

    Outputs
    The influence of vineyard floor vegetation diversity on insect pests in Thompsonseedless table grapes was investigated in on-farm research plots located in Fresno county, California. Nymphs of the variegated leafhopper, ERYTHRONEURA VARIABILIS, the grape leafhopper, ERYTHRONEURA ELEGANTULA, as well as ground dwelling arthropods were sampled weekly from June to September in plots with either high or low levels of vineyard floor plant species diversity. The low vegetation diversity treatment had higher numbers of variegated and grape leafhopper nymphs on sample dates in July and August. Ground dwelling arthropod diversity was higher in the high vegetation diversity treatment on most sample dates. No treatment effects were found for the mean number of grape bunches per vine. Mean berry weight was 13% higher in the low vegetation diversity treatment. In a second study, bird species diversity and abundance was compared between a conventional and sustainably managed vineyard. The sustainably managed vineyard showed greater bird species diversity. Abundance of kestrels, shrikes and kingbirds which forage for insects and rodents in vineyards was also higher on the sustainably managed farm.

    Impacts
    (N/A)

    Publications


      Progress 01/01/93 to 12/30/93

      Outputs
      Participatory research strategies were used to conduct insect pest management research in peach agroecosystems in the Central Valley of California. Methodologies modified from Rapid Rural Appraisal were used to collaborate with members of the community based farmer organization, California Clean Growers Association (CCGA). Farmers identified peach twig borer (PTB), ANARSIA LINEATELLA Zeller (Lepidoptera: Gelechiidae) as their most important insect pest and participated in developing, implementing, and revising research directed toward understanding PTB biology and ecology to improve cultural and natural biological control based management practices. The impact of generalist predators on regulating PTB was assessed through predator exclusion experiments conducted at on-farm sites. Partial life tables indicated that predation by the native ant, FORMICA AERATA (Francoeur), was the most important stage specific mortality agent for overwintering and first generation larvae. The impact of other generalist predators on larval survival in these generations was negligible. F. AERATA foragers were frequent visitors at peach leaf extrafloral nectaries. Experimental results indicated that F. AERATA predation reduced larval survival, suggesting that the ant-plant interaction is a case of facultative mutualism resulting in PTB natural biological control.

      Impacts
      (N/A)

      Publications


        Progress 01/01/92 to 12/30/92

        Outputs
        During the last five years this research provided key information that has led to further understanding about the mechanisms that explain reduction of insect pest populations in a series of diversified cropping systems including intercropping systems and crop-weed combinations and cover cropping within orchards. Flea beetle (PHYLOTRETA CRUCIFERSE) abundance was reduced to levels up to 70% in polycultures in relation to broccoli monocultures. Infestation levels of codling moth (CYDIU POMONELLA) were reduced by 30% in orchards with a grass-fava bean cover crop. Validation of cropping designs was conducted in farmers' fields under farmer management in Sebastopol and Salinas proving biological stability and economic viability. Research results have also enriched the existing ecological theory that deals with the relationship between agricultural diversity and biological pest suppression.

        Impacts
        (N/A)

        Publications


          Progress 01/01/91 to 12/30/91

          Outputs
          Diversification of habitat has proved to be an efficient way to reduce insect pest levels in agroecosystems. In non-replicated plots, we found substantially lower flea beetle densities in mixed broccoli-VICIA cropping systems compared to broccoli monoculture. These results were consistent with those from controlled experiments. To investigate if beetle behavior was related to such population reduction, the movement behavior of marked individuals of PHYLLOTRETA CRUCIFERAE Goeze released in plots composed solely of broccoli plants and of broccoli mixed with VICIA FABA or VICIA SATIVA plants, was followed and analyzed. The mean tenure time of beetles was longer in simple than in mixed cultures. Also, more beetles tended to fly out and leave mixed cultures compared to monoculture. This resulted in faster reduction of artificially introduced flea beetle populations in the mixed systems. Flea beetles landing on cover crop plants spent considerable time entangled in VICIA SATIVA branches or attempting to reach the upper part of the tall VICIA FABA plants from which they could fly away. It is possible that the beetles characteristic movement on these two species of cover crops increased their risk of predation and the time and energy expended before they reached suitable host plants. Nevertheless, it seems that the detected flea beetle emigration rates were more than sufficient to account for the population trends observed.

          Impacts
          (N/A)

          Publications


            Progress 01/01/90 to 12/30/90

            Outputs
            We continued our field experiments at the Rural Development Center in salinas. We tested modified practices designed to increase energy efficiency, improve the environment, and strengthen the economy of systems used by small farmers of Mexican origin. Zucchini plots treated with manure amendments proved more productive than those receiving ammonium sulphate fertilizer applied at the recommended rate of 120 pounds per acre, especially during the last 3 weeks of harvest. Cherry tomato yields were higher in plots receiving alternative treatments (weed-free periods and composting) than in the chemically fertilized and pesticide-treated monocultures. The tomato-zucchini polyculture offered a considerable yield advantage. Intercropping zucchini afforded a certain level of pest protection to tomatoes. During mid-season, tomato monocultures exhibited larger populations of the green peach aphid, MYZUS PERSICAE, than the corresponding polycultures. Although aphid attack was somewhat severe in most zucchini treatment plots, differences in aphid abundance were observed between cropping designs. A faster "crash" in aphid populations was observed in the polycultures, apparently due to the effective mortality imposed by the lady beetles, HIPPODAMIA CONVERGENS, whose pupal densities were greater in the polycultures than in monocultures.

            Impacts
            (N/A)

            Publications


              Progress 01/01/89 to 12/30/89

              Outputs
              An interaction apparently mediated by synomones between Diaeretiella rapae (M'Intosh), a primary parasitoid and the cabbage aphid, Brevicoryne brassicae (L.), was investigated under field conditions. Direct application of an allylisothiocyanate emulsion at a rate of 0.25 ml per broccoli plant consistently gave higher aphid parasitization rates and/or number of wasps per plant than those observed on plants treated with 0.25 ml of water or with 0.25 ml of wild mustard extract. These results suggest the existence of a synomone-mediated interaction between the species involved. indicating potential avenues to enhance field parasitization rates through manipulation of the chemical environment of cole cropping systems.

              Impacts
              (N/A)

              Publications


                Progress 01/01/88 to 12/30/88

                Outputs
                The effects of incorporating mustard as a non-crop plant within a broccoli planting were tested for pest regulation. By varying sowing dates of the mustard, a critical period for crop-weed competition was determined, after which time crop competition was insignificant. Mustard sowed one week after broccoli transplanting showed no reduction of broccoli yield and tended to reduce numbers of the cabbage aphid, Brevicoryne brassicae L., while increasing effective predation by syrphid larvae. Mechanisms explaining this effect are discussed in relation to diversity. The data also suggest that mustard serves as a trap crop for pest insects that normally feed on Brassica crops.

                Impacts
                (N/A)

                Publications


                  Progress 01/01/87 to 12/30/87

                  Outputs
                  The effects of a selected mixture of field planted broccoli varieties on the population response of the cabbage aphid Brevicoryne brassicae L., were studied. Stands of broccoli, Brassica oleracea botrytis (L.) composed of a single variety or mixture of varieties were used to examine this problem. Specifically, we evaluated the differences in aphid population densities as affected by variety mixtures, variety proportions, spatial distribution and planting times of different broccoli varieties. Intermingling four broccoli varieties at various proportions resulted in lower abundances of the cabbage aphid on a per plot and per plant basis, when compared to a corresponding monoculture composed of a single broccoli variety A. Aphid densities decreased in plots as diversity increased (that is, lowering the proportion of var. A in relation to the three other varieties). Planting of a preferred variety B, as a border row, fifteen days earlier than variety A afforded significant protection to variety A from aphids.

                  Impacts
                  (N/A)

                  Publications


                    Progress 01/01/86 to 12/30/86

                    Outputs
                    Manipulation of ground cover vegetation in apple orchards and vineyards has a substantial impact on the abundance of soil dwelling and foliage inhabiting arthropods. Systems with cover crops are characterized by lower densities of phytophagous insects, less fruit damage, more species of natural enemies and increased predation of artificial prey. Cover crops remain in full bloom throughout the season, produce more biomass, support higher numbers of alternate prey, and seem to harbor the largest complex of predators and parasites. Cover crop manipulation directly affects colonization of insect pests that discriminate among trees with and without cover crops, and retains populations of soil and foliage inhabiting natural enemies by providing alternate food and habitat. Malaise traps placed at abandoned, organic and sprayed apple orchard-woodland interfaces showed the following: low arthropod exchange in the abandoned orchard, a higher natural enemy colonization in organic orchards than in sprayed orchards, and highest rosy apply aphid and leafhopper populations in the sprayed orchard. Predator numbers were highest in the abandoned orchards and lowest in the sprayed, paralleling a decrease in vegetational diversity. Herbivores exhibited the opposite trend. Predation rates were highest in the abandoned orchard and the organic orchard with cover crop.

                    Impacts
                    (N/A)

                    Publications


                      Progress 01/01/85 to 12/30/85

                      Outputs
                      Manipulation of ground cover vegetation in apple orchards and vineyards had a substantial impact on the abundance of soil dwelling and foliage inhabiting arthropods. Systems with cover crops were generally characterized by lower densities of phytophagous insects, less fruit damage caused by insects on the trees, larger populations and more species of natural enemies and increased predation of artificial prey. Cover crops that remained in full bloom throughout the season, that produced more biomass and supported high numbers of alternate prey, seemed to harbor the largest complex of predators and parasites. Apparently, cover crop manipulation can directly affect colonization of insect pests that discriminate among trees with and without cover beneath, and can also help retain populations of soil and foliage inhabiting natural enemies through the provision of alternate food and habitat. The design of proper cover crop-orchard mixtures can result in enhanced biological control of specific pests in existing orchards and vineyards.

                      Impacts
                      (N/A)

                      Publications


                        Progress 01/01/84 to 12/30/84

                        Outputs
                        In tomato plots in California, aphids and lygaeids were more abundant in the weed cover than in the clover mulch, whereas leafhoppers were most common in the clover mulch. Higher numbers of foliage and ground predators were observed in the clover plots and weedy plots, than in the clean cultivated plots. Cabbage aphids and flea-beetle densities were significantly reduced in cauliflower plots with cover. It is not clear if this reduction was due to plant diversity, density or quality effects, or effects of natural enemies in the mulched plots, which exhibited depressed crop growth and yields. Densities of flea beetles were lower per unit collard plant in polycultures composed of nonhost plants or composed of wild mustard than in collard monocultures. Flea beetle abundance differences between mono and polycultures disappeared when mustard flowers were atificially removed. Significantly lower flea beetle numbers occurred in collard rows immediately adjacent to wild mustard borders and augmented in numbers with increased distance away from the border. Collard plants sprayed with wild mustard extracts were more attractive to flea beetles than collard plants sprayed with water.

                        Impacts
                        (N/A)

                        Publications


                          Progress 01/01/83 to 12/30/83

                          Outputs
                          Experiments conducted at Davis, California revealed that densities of the minutepirate bug (Orius tristicolor) and its prey, the western flower thrips (Frankliniella occidentalis) were greater in squash monocultures than in polycultures. The predator exhibited a more rapid colonization in the polycultures and the thrips densities were lower and fell earlier in the season in these systems. Mixed crop habitats seemed more attractive to the colonizing predators. Margins of Brassica kaber along a cauliflower field seemed to affect the distribution of aphids, flea beetles and associated natural enemies within the crop field. No apparent gradient of abundance from the margin towards the center of the plot was apparent. Aphids for example were most abundant on row 3 from the margin, and parasitization rates were highest on rows 2 and 5. Pitfall catches revealed that ants and anthicid beetles were more abundant in the center than in the border of the field. The Brassica plants in the margin attracted more flea beetles than the adjacent cauliflower plants.

                          Impacts
                          (N/A)

                          Publications


                            Progress 01/01/82 to 12/30/82

                            Outputs
                            Results from experiments comparing collard monocultures and polycultures (mixed with beans, fava beans, vetch and Brassica kaber) revealed that polycultures had more species and individuals of beneficial insects. Apparently this trend was due to the greater structural complexity and presence of alternative food resources arising from the mixing of plants of different architectures. Polycultures also had fewer number of herbivores, the aphid Brevicoryne brassicae and the flea beetle Phyllotreta cruciferae. Flea beetle densities per individual collard plant were significantly lower in the plots with B. kaver, because these beetles preferred to feed and/or concentrate on this plant rather than on collards. Thus growing collards intermingled with this plant sets up a trap crop system, which apparently exploits the differences in concentration of mustard oils in the plants. Aphids in monocultures proliferated unchecked because of the lower abundance of natural enemies and because collards growing in bare soil provided ideal colonization conditions.

                            Impacts
                            (N/A)

                            Publications


                              Progress 01/01/81 to 12/30/81

                              Outputs
                              Experiments were conducted to compare intercropping systems with corresponding monocultures in termsof yield potential, incidence of pest insects, performance of natural control agents and weed competition. Significant results include: Herbivorous pests such as Phyllotreta cruciferae and Brevicoryne brassicae reached lower densities in polycultures (collard-bean and brussel sprouts-fava beans, respectively) than in monocultures. The wasp, Diaeretiella rapae was more effective in parasitizing cabbage aphids in polycultures than in monocultures. Intensive cropping pattersn provided increased control of weeds. Weed cover and biomass production was lower in corn-cowpea polycultures than in corn or cowpea monocultures. Similarly bean-collard mixtures suppressed both the number of individuals and total biomass of the weeds, as compared to monoculture collards. Polycultures exhibited a yield advantage over monocultures. Land Equivalent Ratios in the collard-bean polycultures were higher than one, indicating that polycultures overyielded. Results suggest that it would need 2.0 ha of monocultures of collards and/or beans to match the productivity of 1 ha of polyculture.

                              Impacts
                              (N/A)

                              Publications