Source: UNIVERSITY OF CALIFORNIA, RIVERSIDE submitted to
ENHANCED MANAGEMENT OF OLIVE FRUIT FLY IN CALIFORNIA USING ALTERNATIVE TACTICS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0210804
Grant No.
2007-34381-18190
Project No.
CA-R*-ENT-7689-SG
Proposal No.
2007-03187
Multistate No.
(N/A)
Program Code
MX
Project Start Date
Jul 1, 2007
Project End Date
Jun 30, 2009
Grant Year
2007
Project Director
Johnson, M. W.
Recipient Organization
UNIVERSITY OF CALIFORNIA, RIVERSIDE
(N/A)
RIVERSIDE,CA 92521
Performing Department
Entomology, Riverside
Non Technical Summary
Almost 100% of the commercial olives produced in the USA are grown in California. Table olives are mainly grown in California's Central Valley. The olive fruit fly (OLF), Bactrocera oleae (Rossi), is a relatively recent invasive species and is considered the primary olive pest. The presence of OLF maggots or pupae within a single fruit will be enough to cause rejection of a grower's entire crop. The only insecticidal product registered for OLF management is GF-120 NF Naturalyte Fruit Fly Bait. Current management recommendations are to apply GF-120 once weekly or twice monthly. This means that most olive growers transitioned from occasional treatments for black scale and olive scale to as much as 32 treatments in one season for OLF. This added expense is a hardship for growers and has eliminated some individuals from olive production. This frequent use of the insecticide may promote the development of resistance in OLF. We are proposing the continuation of our efforts to 1) establish exotic natural enemies for biological control of OLF throughout California; and 2) utilize knowledge about detrimental impacts of summer temperatures (≥ 100DGF) on OLF survival as a tool to reduce the numbers of GF-120 sprays in mid-July to late August. Thus, we will be incorporating new IPM tactics into the olive agroecosystem to better manage OLF (PMAP goal). We will evaluate and demonstate the effectiveness of these alternative tactics (PMAP goal). Lastly, we will describe and field-demonstrate how these tactics can be economically and effectively integrated into olive production.
Animal Health Component
(N/A)
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1323110107020%
2153110107020%
2153110113030%
2163110113030%
Goals / Objectives
1) Colonize and field evaluate specific parasitoids [e.g., Psyttalia lounsburyi (Hymenoptera: Braconidae)] for biological control of olive fruit fly (OLF); 2) Evaluate the impact of GF-120 treatments on the survival and viability of introduced parasitoids; 3) Verify whether high summer temperatures sufficiently impact OLF survival to permit the elimination of some GF-120 sprays during the summer months; and 4) Educate and demonstrate to olive growers the benefits of using these new tactics.
Project Methods
Obj. 1. Before general field release, selected parasitoid species will be tested in field cages to determine their ability to effectively impact olive fruit fly (OLF) populations under semi-natural conditions. OLF adults will be caged on branches that have susceptible stage olives. After the inoculated OLF reach a development stage that is susceptible to each selected parasitoid species, adult parasitoids will be released into cages. Successful parasitism will be determined, as well as parasitism rates and parasitoid development times. After field cage trials indicate promising candidate species for the various release locations (i.e., interior vs. coastal areas), we will begin general field-releases in California, with cooperation from California Department of Food and Agriculture (CDFA) personnel. Follow-up fruit samples and analyses of population dynamics of flies and parasitoids at release and non-release sites will be conducted to determine field impact, using standard sampling methodologies. Obj. 2. The acute impact of GF-120 on the natural enemies (Psyttalia lounsburyi and P. ponerophaga) of OLF will be quantified by determining parasitoid response (i.e., mortality) to varying concentrations of the product. Colonies of these natural enemies will be established. Three to five-day old adult females and males of each species will be exposed to various concentrations (~ 5 levels of dilution) of GF-120 for three hours and then held for observation for up to 72 hours. A control treatment will also be included. Percentage mortality will be recorded at 12, 24, 48 and 72 hours. Individual experimental treatments will be applied to 10 individuals each and replicated 8 times each for each species / sex combination. Data will be analyzed using probit analysis. We will also look at the impact of weathered GF-120 residues on parasitoid survival by exposing natural enemies to 1, 2, 3, 5, 7, and 10-day old weathered droplets. Obj. 3. Using a flight mill to measure OLF flight distances, we will quantify the impacts of heat stress on the ability of OLF adults to fly. Young OLF adults (10-15 days old) will be exposed to one, two, or three days of diurnal temperature regimes within programmable temperature cabinets. On each day of exposure to a given temperature regime, flies will be given access to a) water and honey-water; b) water only; c) honey-water only; or d) neither water or honey-water. Following a given exposure period (1 to 3 days at a given temperature regime) and water/food treatment, individual OLF adults will be attached to the flight mill and allowed to fly until the insect stops for more than one minute. We will be able to determine the distance flown, flight duration, and flight speed. Data (flight distances, duration, and speed) will be analyzed with three-way ANOVA. Obj. 4. Results from Objectives 1 - 3 will be presented and discussed at grower and consultant oriented-workshops and field days. We will also establish websites that provide information on the management tactics we develop. Information resulting from this project will be published in peer-reviewed scientific journals as well as grower assessable literature.

Progress 07/01/07 to 06/30/09

Outputs
OUTPUTS: Objective 1. The parasitoids Psyttalia lounsburyi (Silvestri), Psyttalia cf. concolor (Szepligeti), and P. nr. concolor were permitted for California field release. Field-cage, laboratory, and open field studies investigated factors (e.g., fruit size, summer temperatures, overwintering conditions) potentially affecting parasitoid effectiveness and establishment. Both species successfully parasitized Bactrocera oleae larvae over the year in California's Central Valley and Central Coast areas. Mean parasitism levels in cage studies ranged from 6.2 to 27.4 percent by P. lounsburyi and 31.3 to 94.8 percent by P. concolor. For both species, B. oleae parasitism was always higher on smaller fruit. Parasitoid ovipositor lengths did not permit them to contact all host larvae within large olive fruit. Parasitism levels by P. concolor were higher than P. lounsburyi regardless of fruit size, test dates or locations. In the San Joaquin Valley, low winter temperatures may prevent P. nr. concolor immatures from successfully overwintering. In open field releases on the Central Coast, P. nr. concolor was consistently recovered at release sites. Post-release sampling will be conducted in the future to determine if released parasitoids permanently establish. Objective 2. GF-120 NF Naturalyte fruit fly bait insecticide must be ingested to work. Olfactory tests showed that P. nr. concolor and Scutellista caerulea (black scale parasitoid) were not attracted to odors of blank GF-120 bait, but B. oleae was strongly attracted. When simultaneously offered drops of blank GF-120 bait and black scale honeydew, B. oleae females readily responded to each. Test parasitoids usually fed on honeydew and ignored GF-120. Objective 3. California's San Joaquin Valley is extremely hot during the summer with daily high temperatures consistently over 35 degrees C. Although adult flies could survive for 1-2 weeks and females laid eggs when water and food were provided, fly eggs and larvae could not develop under high field temperatures. Pre-flight exposure to temperature regimes that reflect the summer temperature conditions (low 18.3 degrees C, high 35 or 37.8 degrees C) and deprivation of food significantly reduced B. oleae performance in flight mill tests as much as 40 percent after 1 day compared to non-stressed flies that flew over 1900 m. Flies that survived 3 days of temperature stress flew less than 400 m. Objective 4. Overall 9 meeting presentations (8 locations) and 3 field demonstrations (2 locations) usually 25 minutes each (or longer) were given to growers, consultants, and cooperative extension farm advisors in olive production areas. Twelve additional presentations (submitted papers, symposia, and seminars) were given at scientific meetings and two universities. Educational efforts focused on B. oleae relative to management; impact of high summer temperatures; and on-going efforts to establish effective parasitoid natural enemies. Part of the presentations described the use of web-based temperature maps to provide growers a better understanding of seasonal temperature cycles so they could better estimate when B. oleae may be a greater threat to their olive crops. PARTICIPANTS: Participants included individuals from the University of California (UC) at Riverside, Berkeley, and Davis. Actively coordinating and / or conducting research included a) Marshall W. Johnson, Xin-Geng Wang, Hannah Nadel, and Martha Gerik (UC Riverside); b) Kent M. Daane, Karen R. Sime, Vaughn Walton, and John Andrews (UC Berkeley); and c) Frank G. Zalom (UC Davis). Assisting with preparation of GIS mapping was Kris Lynn-Patterson (UC Kearney Agricultural Center, Parlier, CA). Cooperation and assistance with research efforts were provided by Kim M. Hoelmer, Victoria Yokoyama, Alan A. Kirk, Arnaud Blanchet, Pedro Rendon, and Walker Jones (USDA Agricultural Research Service), Charles Pickett (California Dept of Food and Agriculture), Susan B. Opp (California State University-East Bay, Hayward, CA) and David Headrick (California State University-San Luis Obispo). Also participating were Junaid ur Rehman, Ghulam Jilan, and Mir A. Khan (Quaid-I-Azam University, Islamabad, Pakistan). Assistance with field studies was also provided by the staff at the UC Kearney Research and Extension Center, Parlier, CA, and the UC Lindcove Research and Extension Center, Exeter, CA. Participants also included several olive growers who allowed us to work on their properties. Opportunities for training included a) learning how to use a flight mill to quantify the distances B. oleae adults can fly; and b) generation of GIS maps to identify areas in California where summer heat would potentially kill B. oleae immatures and adults. TARGET AUDIENCES: Clientele benefiting from the studies reported herein included a) the olive growers (both table and oil) of California; b) the California Olive Committee (marketing board); c) the Olive Growers Council (grower cooperative); d) pest management consultants who advise olive growers; e) University of California Cooperative Extension Farm Advisors from the counties of Glenn, Tehema, Butte, Sonoma, Napa, Yolo, El Dorado, Madera, Fresno, Tulare, and Kern; f) the table olive processors who cure olives for table consumption; and g) other researchers investigating solutions to the olive fruit fly problem. PROJECT MODIFICATIONS: The goals of Objective 2 were slightly modified when we discovered that parasitic hymenoptera do not readily feed on the insecticidal product GF-120. Studies were redirected to determine natural enemy and olive fruit fly orientation to droplets of GF-120 and their preferences for GF-120 compared to black scale honeydew, which provides a carbohydrate source for olive fruit fly and the parasitoids within the olive orchards.

Impacts
Results suggest that large cultivated olive fruit create a structural refuge for Bactrocera oleae larvae due to the short-ovipositors of parasitoids (Psyttalia lounsburyi and Psyttalia concolor). These parasitoids would perform better if they were released within trees with small olive fruit. This can be accomplished by releases into cultivars that produce smaller fruit (e.g., Mission, a common cultivar grown for oil content) or into abandoned orchards and roadside ornamental trees that are not irrigated. Findings suggest that domestication of olive fruit via selection for larger fruit for human consumption enhanced B. oleae performance, but reduced parasitoid efficiency. Large domesticated olives may be considered "natural enemy free space" for B. oleae. Field studies show that Psyttalia concolor has significant potential to establish and impact B. oleae in coastal areas, but may have difficulty in the Central Valley due to the inability of parasitoids to complete their developmental cycle during periods of cold temperatures (less than 10 degrees C). More studies are needed to verify this possibility. Use of the insecticide bait GF-120 NF Naturalyte is not directly detrimental to B. oleae or black scale parasitoids that are not attracted to the compound and do not readily ingest it. However, use of GF-120 indirectly impacts parasitoids when B. oleae populations are decimated and B. oleae host larvae are not available for parasitization by Psyttalia species. Studies related to temperature impacts on B. oleae support the theory that high temperatures routinely experienced in the months of July and August in parts of California's Central Valley (e.g., San Joaquin Valley) cause additional mortality compared to cooler seasons. Adult longevity is significantly reduced by high temperatures. B. oleae flight dispersal throughout olive orchards and surrounding habitats is highly reduced as exposure to high summer temperatures increases. This reduced flight ability decreases the insect's chances of finding adequate moisture (for heat relief), water (for drinking), and food to survive hot periods. Heat also reduces the numbers of immature stages developing in olive fruit within the orchard. These results re-enforce the idea that growers and consultants may be able to use historic temperature patterns to estimate times when they can reduce their insecticidal treatments for B. oleae. Many growers in the San Joaquin Valley already reduce their GF-120 bait insecticide application frequency for B. oleae management as summer temperatures increase. Temperature maps also provide growers with information on how quickly high temperatures decrease as August ends and September begins. It is at this time that the olives are most susceptible to B. oleae infestations that will lead to the rejection of the olives at the canning processor's door. It is important that olive growers adopt a surveillance program (e.g., yellow panel traps or McPhail traps) to monitor adult B. oleae densities when summer temperatures are unseasonably low and the possibility for B. olease infestations of ripening fruit exist. These results should lead to more efficient B. oleae management.

Publications

  • Johnson, M. W., Nadel, H., Lynn-Patterson, K., Daane, K. M., and S. Opp, S. 2008. Dont be fooled by the olive fruit fly. CAPCA Advisor XI (5): 76-78.
  • Wang, X.G., Nadel, H., Johnson, M.W., Daane, K.M., Hoelmer, K., Walton, V.M., Pickett, C.P., and Sime, K.R. 2009. Crop domestication relaxes both bottom-up and top-down effects on a specialist herbivore. Basic Appl. Ecol. 10: 216-227.
  • Wang, X.G., Johnson, M.W., Daane, K.M., and Yokoyama, V.Y. 2009. Larger olive fruit size reduces the efficiency of Psyttalia concolor, as a parasitoid of the olive fruit fly. Biological Control 49: 45-51.
  • Wang, X.G., Johnson, M.W., Daane, K.M., and Opp, S.B. 2009. Combined effects of heat stress and food supply on flight performance of olive fruit fly (Diptera: Tephritidae). Ann. Entomol. Soc. Am. 102, 727-734.
  • Daane, K.M., Johnson, M.W., Pickett, C.H., Sime, K.R., Wang, X.G., Nadel, H., Andrews, J.W., and Kirk, A.A. 2009. Biological control of the olive fruit fly in California. Cal. Agr. (In Press).
  • Wang, X.G., Johnson, M.W., Nadel, H., and Daane, K.M. 2009. High summer temperatures affect the survival and reproduction of olive fruit fly (Diptera: Tephritidae). Environ. Entomol. (In Press).
  • Rehman, J.U., Wang, X.G., Johnson, M.W., Zalom, F.G., Daane, K.M., Jilan, G., and Khan, M.A. 2009. Effects of Peganum harmala (Zygophyllaceae) seed extracts on the olive fruit fly and its larval parasitoid, Psyttalia concolor (Hymenoptera: Braconidae). J. Econ. Entomol. (In Press).
  • Daane, M. W., and Johnson, M. J. 2010. Olive fruit fly: Managing an ancient pest in modern times. Ann. Review Entomol. 55 (In Press).


Progress 07/01/07 to 06/30/08

Outputs
OUTPUTS: Objective 1. The larval parasitoids Psyttalia lounsburyi (Silvestri) and Psyttalia concolor (Szepligeti) were permitted for field release in California. Field-cage and laboratory experiments were conducted to investigate factors (e.g., fruit size, high summer temperatures, overwintering conditions) potentially affecting parasitoid effectiveness and establishment. Larval parasitoids naturally associated with olive fruit fly in its native range have short ovipositors (3 mm) similar in length to the pulp thickness of wild olives (2 mm). However, cultivated olive fruit are substantially larger (4-8 mm pulp thickness). Ovipositor lengths of P. lounsburyi (1.79 mm) and P. concolor (2.46 mm) did not permit them to contact all host larvae within large olive fruit. Furthermore, more olive fruit fly eggs were laid in larger fruit and larvae developed faster and attained a larger size when developing in olive cultivars with larger fruit (Ascolano & Sevillano). Percentages of female offspring and survival were lowest when reared on smaller fruit cultivars (Mission). Objective 2. Studies were delayed because we could not rear adequate numbers of the parasitoid P. lounsburyi. Studies have been initiated using P. concolor and focus on the behavioral response of both female olive fruit fly and P. concolor to the volatiles of the pure attractant used in bait insecticide GF-120. We plan to evaluate the toxicity of GF-120 on P. concolor and other beneficial parasitoids. All of these studies are currently in progress and no results are available to report at this time. Objective 3. California's San Joaquin Valley is extremly hot during the summer with daily high temperatures consistently over 35 degrees C. Although adult flies could survive for 1-2 weeks and females laid eggs when water and food were provided, fly eggs and larvae could not develop under such high field temperatures. Pre-flight exposure to temperature regimes that reflect the summer temperature conditions (low 18.3 degrees C, high 35 or 37.8 degrees C) and deprivation of food significantly reduced the olive fruit fly flight performance in flight mill tests as much as 40 percent after 1 day compared to non-stressed flies that flew over 1900 m. Flies that survived 3 days of temperature stress flew less than 400 m. Objective 4. Over the report period, 8 meeting presentations (7 locations) and 2 field demonstrations (2 locations) running from 20 to 30 minutes each were given to olive growers, agricultural consultants, and cooperative extension personnel (i.e., Farm Advisors) mainly in California's Central Valley. Educational efforts focused management of olive fruit fly; the impact of high summer temperatures on olive fruit fly adults; and on-going efforts to establish effective parasitoid natural enemies to control olive fruit fly. Part of the presentations described the use of web-based temperature maps at the webpage titled "Interactive Climate Maps for Olive Fly Management Decisions" (http://arcims.gis.uckac.edu/CIMIS/) to provide growers a better understanding of seasonal temperature cycles so they could better estimate when olive fruit fly may be a greater threat to their olive crops. 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
Results suggest that large cultivated olive fruit create a structural refuge for olive fruit fly larvae due to the short-ovipositors of the parasitoids Psyttalia lounsburyi and Psyttalia concolor, and these parasitoids would perform better if they are released within trees with small olive fruit. This can be accomplished by releases into cultivars that produce smaller fruit (e.g., Mission, a common cultivar grown for oil content) or into abandoned orchards and roadside ornamental trees that do not receive routine irrigation. The additional length (ca. 0.7 mm) of the ovipositor of P. concolor compared with P. lounsburyi did give it an advantage. P. concolor was more efficient in parasitizing hosts in small than large fruit, regardless of host density (variable or uniform across fruit sizes) and olive cultivar. We found that body size, as well as the ovipositor length, of female P. concolor were increased when the Mediterranean fruit fly, Ceratitis capitata, was used as the host insect as compared with those reared from olive fruit fly. Larger cultivated fruit also provided a survival advantage to the olive fruit fly because flies developed faster and attained a larger size when in the largest cultivar, and the percentage of female offspring and percentage of survival was lowest from Mission compared to other cultivars. These findings suggest that domestication of olive fruit via selection for larger fruit for human consumption enhanced the performance of the olive fruit fly, but reduced the efficiency of the parasitoid wasps that attack the fly. Large domesticated olives may be considered "natural enemy free space" for olive fruit fly. Studies related to temperature impacts on olive fruit fly support the theory that high temperatures routinely experienced in the months of July and August in parts of California's Central Valley (e.g., San Joaquin Valley) cause additional mortality to the pest compared to cooler seasons. Adult longevity is significantly reduced by high temperatures. The ability of the olive fruit fly to disperse via flight throughout the olive orchard and surrounding habitats is highly reduced as exposure to high summer temperatures increases. This reduction in flight ability decreases the insect's chances of finding adequate moisture (for heat relief), water (for drinking), and food to survive hot periods. Heat also reduces the numbers of immature stages developing in olive fruit within the orchard. These results re-enforce the idea that growers and consultants may be able to use historic temperature patterns to estimate times when they can reduce their insecticidal treatments for olive fruit fly. Many growers in the San Joaquin Valley already alter their spray schedules for olive fruit fly management as the summer heats up. Temperature maps also provide growers with information on how quickly high temperatures drop as summer fades into the fall months. It is at this time that the olives are most susceptible to olive fruit fly infestations that will lead to the rejection of the olives at the canning processor's door. These results should lead to more efficient management of olive fruit fly.

Publications

  • Daane, K.M., K. R. Sime, X. G. Wang, H. Nadel, M. W. Johnson, and V. M. Walton. 2008. Psyttalia lounsburyi (Hymenoptera: Braconidae), a biological control agent for the olive fruit fly in California. Biological Control 44:79-89.
  • Sime, K. R., K. M. Daane, R. H. Messing, X. G. Wang, and M. W. Johnson. Evaluation of Fopius arisanus (Hymenoptera: Braconidae) as a biological control agent for the olive fruit fly in California. 2008. Agricultural and Forest Entomology 10: 1-9.
  • Wang, Xingeng, H. Nadel, M. W. Johnson, K. M. Daane, K. Hoelmer, C. H. Pickett, and Karen R. Sime. 2008. Crop domestication relaxes both top-down and bottom-up effects on a specialist herbivore. Basic and Applied Ecology (in press), 40 pp.
  • Johnson, M. W., K. M. Daane, K. R., Sime, H. Nadel, C. H. Pickett, and Wang, X. G. 2008. Classical biological control introductions to manage olive fruit fly. Biocontrol News and Information 29(1): 3N-4N.