Victoria Y. Yokoyama

Psyttalia cf. concolor (Hymenoptera: Braconidae) for biological control of olive fruit fly (Diptera: Tephritidae) in California.

Abstract The larval parasitoid, Psyttalia cf. concolor (Szépligeti), reared on Mediterranean fruit fly, Ceratitis capitata (Weidemann), by the USDA–APHIS–PPQ, Guatemala City, Guatemala, was imported into California for biological control of olive fruit fly, Bactrocera oleae (Gmelin), in olives, Olea europaea L. Mean percentage parasitism of olive fruit fly third instars infesting fruit in field cages ranged from 7.0 in Grapevine to 59.7 in Santa Barbara and in free releases ranged from 0 in Grapevine to 10.6 in Santa Barbara after 4- to 6-d exposures. In the laboratory, more parasitoids developed to adults in olive fruit fly larvae that were 11–13 d old than in larvae 8–10 d old. Adult parasitoids lived significantly longer when provided with water than adults without water in environmental chambers at 5°C, 85% RH; 15°C, 65% RH; 25°C, 25% RH; and 35°C, 25% RH. Adult parasitoids lived for 48 d with honey for food and water and 32 d with food and sugar solution at 15°C and 65% RH. Survival of adult parasitoids without food and water in greenhouse tests was ≈4 d in a simulated coastal climate and 1 d in a simulated inland valley climate and was significantly increased by providing food and water. The parasitoid did not develop in the beneficial seedhead fly, Chaetorellia succinea (Costa), in yellow star thistle. The rate of parasitism of walnut husk fly, Rhagoletis completa Cresson, larvae in green walnut husks was 28.4% in laboratory no-choice tests. In choice tests, the rate of parasitism of walnut husk fly versus olive fruit fly larvae in olives was 11.5 and 24.2%, respectively.

Comparative evaluation of two olive fruit fly parasitoids under varying abiotic conditions

Psyttalia lounsburyi (Silvestri) and P. humilis (Silvestri) (Hymenoptera: Braconidae) were evaluated in California for their potential to control the invasive olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Psyttalia lounsburyi is a specialist on B. oleae while P. humilis also attacks other tephritid species. Field cage trials, conducted from 2006 to 2009, were used to compare P. lounsburyi and two populations of P. humilis (Kenya and Namibia) in California’s interior valley and coastal regions. Both parasitoid species reproduced on B. oleae in all trials. Under similar abiotic conditions, offspring production per female was higher in P. humilis than in P. lounsburyi, suggesting that host specificity by P. lounsburyi does not confer a higher efficiency on B. oleae in cultivated olives. Two abiotic factors were shown to impact parasitoid efficiency. First, adult parasitoid survival was poor during periods of high summer temperatures, common to the olive production areas in California’s interior valleys. Second, parasitism levels were lower on B. oleae larvae feeding in larger Ascolano cv. fruit than in smaller Manzanillo cv. fruit. Results are discussed relative to biological control of B. oleae in commercial olives and the usefulness of natural enemies specialized to attack fruit flies in wild olives compared with the larger cultivated olive fruit.

Olive Fruit Fly (Diptera: Tephritidae) in California: Longevity, Oviposition, and Development in Canning Olives in the Laboratory and Greenhouse

ABSTRACT The biology of olive fruit fly, Bactrocera oleae (Rossi), was studied in the laboratory, greenhouse, and in canning olives, Olea europaea L., in relation to California regional climates. Adults survived in laboratory tests at constant temperatures and relative humidities of 5°C and 83%; 15°C and 59%; 25°C and 30%; and 35°C and 29% for 15, 6, 3, and 2 d without provisions of food and water and for 37, 63, 25, and 4 d with provisions, respectively. In a divided greenhouse, adults survived for 8–11 d in the warm side (36°C and 31% RH daytime) ; and in the cool side (26°C and 63% RH daytime) 10 d without provisions and 203 d with provisions. A significantly greater number of adults survived in the cool side than the warm side, and with provisions than without. First and last eggs were oviposited in olive fruit when females were 6 and 90 d old, respectively. The highest number of eggs was 55 per day in 10 olive fruit oviposited by 10 28 d-old females, with maximum egg production by 13–37 d-old females. A significantly greater number of ovipositional sites occurred in all sizes of immature green fruit when exposed to adults in cages for 5 d than 2 d. Adults emerged from fruit with a height of a 1.0 cm or a volume of ≥0.2 cm3. More than seven adults per 15 fruit emerged from field infested fruit with a height of 1.1 cm and volume of 0.1 cm3. Larval length was significantly different among the first, second, and third instars and ranged from 0.7 to 1.6, 2.4–4.3, and 4.8–5.6 mm at 14°C; 0.8–1.1, 1.9–2.9, and 3.9–4.4 mm at 21°C, and 0.7–1.3, 2.4–2.9, and 4.4–4.8 mm at 26°C, respectively. Survival of pupae to the adult stage was significantly lower at 26°C than 14°C or 21°C. The period of adult emergence began at 38, 14, and 11 d over a period of 8, 5, and 1 d at 14, 21, and 26°C, respectively. Findings were related to the occurrence and control of California olive fruit fly infestations.

Performance Of Psyttalia Humilis (Hymenoptera: Braconidae) Reared From Irradiated Host on Olive Fruit Fly (Diptera: Tephritidae) In California

ABSTRACT The parasitoid Psyttalia humilis (Silvestri) was reared on Mediterranean fruit fly, Ceratitis capitata (Wiedemann), third instars irradiated at 0–70 Gy at the USDA, APHIS, PPQ, Moscamed biological control laboratory in San Miguel Petapa, Guatemala, and shipped to the USDA, ARS, Parlier, CA. Irradiation dose did not affect the parasitoids offspring sex ratio (53–62% females), percentage of unemerged adults (12–34%), number of progeny produced per female (1.4–1.8), and parasitism (19–24%). Host irradiation dose had no significant effect on the forewing length of female P. humilis and its parasitism on olive fruit fly, Bactrocera oleae (Rossi) and offspring sex ratio, but dissection of 1-wk-old female parasitoids reared from hosts irradiated with 70 Gy had a significantly lower number of mature eggs than females from nonirradiated hosts. Longevity of P. humilis adults decreased with increased temperature from 15 to 35°C, regardless of food provisions, gender, and host irradiation dose. Females survived 37–49 d at 15°C with water and food, and only 1–2 d at 35°C without food, whereas males lived shorter than females at all temperatures and food combinations tested. Adult P. humilis reared from fertile C. capitata and aspirated for dispensing in cups lived significantly longer after shipment than those specimens chilled and dispensed by weight. At 21 and 32°C, 50% of parasitoids departed release cages after 180 and 30 min, respectively, but none departed at 12°C. Thirteen shipments of P. humilis (2,980–21,922 parasitoids per shipment) were received between September and December 2009, and seven shipments (7,502–22,560 parasitoids per shipment) were received between October and December 2010 from San Miguel Petapa, Guatemala. Daily number of olive fruit fly adult and percentage female trap captures ranged <1–19 and 8–58% in 2009, and <1–11 and 0–42% in 2010, respectively. The number of parasitoids released ranged 848–12,257 in 2009 and 3,675–11,154 in 2010. Percentage parasitism of olive fruit fly third instars at all locations ranged 0–9% in 2009 and 0–36% in 2010.

Pest Response in Packed Table Grapes to Low Temperature Storage Combined with Slow-Release Sulfur Dioxide Pads in Basic and Large-Scale Tests

Abstract The effect of low temperature storage combined with slow release sulfur dioxide pads was determined in basic laboratory and large-scale commercial tests on western flower thrips, Frankliniella occidentalis Pergande; grape mealybug, Pseudococcus maritimus (Ehrhorn); Pacific spider mite, Tetranychus pacificus McGregor; twospotted spider mite, Tetranychus urticae Koch; and omnivorous leafroller, Platynota stultana Walshingham. Temperatures within the foam containers among the packed clusters decreased from ambient to 2°C within approximately 1 d and ranged from 0.4 to 1.7°C in all tests. Sulfur dioxide concentrations in the foam containers ranged between 0.2 and 1.6 ppm during the 1- to 6-wk storage period in basic tests and 0.5–1.1 ppm during the 1- to 8-wk storage period in the large-scale test. Western flower thrips was completely controlled by a ≥1-wk exposure. Grape mealybug mortality was ≥93% after 2–5 wk exposures and 100% after a 6-wk exposure in basic tests. Pacific spider mite and twospotted spider mite mortality was 98.0 and 99.6%, respectively, after a 6-wk exposure. Mortality of grape mealybug and twospotted spider mite increased significantly at ≥3-wk exposures and Pacific spider mite mortality increased significantly at ≥4-wk exposures. Mortality of the spider mites in general was directly related to the duration of exposure. An 8-wk exposure to low temperature storage combined with slow release sulfur dioxide pads in the large-scale test resulted in 100% mortality of western flower thrips, twospotted spider mite, and omnivorous leafroller. The treatment resulted in <8% survival of grape mealybug and <1% survival of Pacific spider mite in the large-scale test. The combination treatment offers an economical method to attain quarantine control of certain insects and mites.

Bale Compression and Hydrogen Phosphide Fumigation to Control Cereal Leaf Beetle (Coleoptera: Chrysomelidae) in Exported Rye Straw

Abstract Control of larvae and adults of cereal leaf beetle, Oulema melanopus (L.), by bale compression and hydrogen phosphide fumigation was studied in rye straw, Secale cereale L., in Aurora, OR. Natural mortality of larvae after transport was 4.0 ± 1.0% (mean ± SEM). Compression (105 kg/cm2) of larvae in standard bales (122 cm long) of rye straw resulted in 100% mortality. Compression of adults in standard bales plus storage of the compressed bales (56 cm long) for 1 d in a freight container resulted in 100% mortality. A KD50 of 102 ppm hydrogen phosphide for 1 h was estimated from the probit regression line developed from dose–response data at 21°C in basic laboratory tests. The LD50s and LD99s were 163 and 6,910 ppm for 2-h exposures and were 18 and 42 ppm for 6-h exposures at 21°C, respectively. A tested dose of 400 ppm for 24 h at 21°C resulted in 100% mortality of the adults. Larvae (n = 10,560) and adults (n = 18,602) did not survive exposure to bale compression followed by hydrogen phosphide fumigation (60 g/28.3 m3) for 3 d in rye straw loaded in freight containers in large-scale tests. Copper plate corrosion values indicating the severity of exposure to hydrogen phosphide were 13 and 12, and mean temperatures of five locations in the freight container were 25 and 26°C in large-scale tests with the larvae and adults, respectively. Hydrogen phosphide concentrations were ≥400 ppm throughout the 3-d fumigation for larvae and during the first day of fumigation for adults. We propose that cereal leaf beetle can be controlled by a single treatment of bale compression followed by a 1-d storage period or by a fumigation in which 400 ppm hydrogen phosphide is maintained for 1 d at 21°C or above. We confirmed that a multiple quarantine treatment of bale compression followed by a 3-d fumigation will control cereal leaf beetle in exported rye straw.

Response of Olive Fruit Fly (Diptera: Tephritidae) to an Attract-and-Kill Trap in Greenhouse Cage Tests

ABSTRACT. A novel attract-and-kill trap for olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), was constructed with yellow corrugated plastic in an inverted cylindrical pan shape formed from a disk and collar. The trap components were tested under three greenhouse temperatures and humidities of warm, hot, and very hot for attractiveness to caged young or older adults. A greater proportion of adults regardless of age were found underneath the devices including disks, cylindrical pans, and pans with pheromone lures and test units of cylindrical pans sprayed with water, insecticidal bait spray, and with lures. The effect was related to lower temperatures on the underside compared with the top and the intolerance of the pest to heat. A circular collar added to the perimeter of the disk that formed the top of the inverted cylinder made the attract-and-kill trap more attractive to adults than the disk alone. Pheromone lures or bait sprays did not increase adult attraction, so were not needed for efficacy. The cylindrical pan was especially attractive to adults when temperatures were high by providing shelter from the heat. At very high temperatures, the pan became unattractive, possibly due to heating of the construction materials. Cylindrical pans sprayed with water on the underside attracted the highest number of adults especially at high temperatures. Greenhouse tests showed that the inverted cylindrical pan design has potential as an attract-and-kill device for olive fruit fly control.

Response of Omnivorous Leafroller (Lepidoptera: Tortricidae) and Onion Thrips (Thysanoptera: Thripidae) to Low-Temperature Storage

Abstract Eggs and first–fifth instars of omnivorous leafroller, Platynota stultana Walshingham, had a mean percentage survival to the adult stage of 60.7–95.2% for nonexposed immatures and 14.5–54.3% for immatures exposed to 1 wk at 0–1°C. Exposures of 2–5 wk resulted in 0–6.7% survival, and a 6-wk exposure resulted in <1% survival of all stages tested. A significant reduction in survival of all larval stages occurred between exposures of 0 and 1 wk and between 1 wk and 2–6 wk. Survival of eggs after exposures of 0 and 1 wk was significantly different than survival after exposures of 2–6 wk. The second instar was the stage least susceptible to low-temperature storage. Adults that were exposed to low temperature for 1 wk in the third through fifth instars laid a mean of 120–289 eggs per female, and the mean percentage viability of the eggs ranged from 56.2 to 71.4%. Mean percentage survival of adults and nymphs of onion thrips, Thrips tabaci Lindeman, was inversely related to the duration of exposure from 1 through 3–6 wk at 0–1 and 5°C and was lower at 0–1 (0.2–52.5%) than at 5°C (17.6–66.6%). Exposure to 0–1°C for 4 wk attained 91.2% control, which increased to 99.8% after 6 wk. Low-temperature storage has potential to control omnivorous leafroller in table grapes, Vitis vinifera L., and onion thrips in onions, Allium cepa L.

Mobility of olive fruit fly (Diptera: Tephritidae) late third instars and teneral adults in test arenas.

ABSTRACT The mobility of olive fruit fly, Bactrocera oleae (Rossi), late third instars before pupation, teneral adults before flight, and mature adults restricted from flight were studied under mulches in greenhouse cage tests, in horizontal pipes, vertical bottles and pipes filled with sand, and by observation on smooth laboratory surfaces. Percentage adults emerging from pupae and percentage adult females that escaped soil, fabric, and paper mulches over a soil or sand substrate ranged from 63 to 83, and 40–53%, respectively. Percentage adults emerging from pupae and percentage adult females that walked through the open interior of 1.52–6.10-m horizontal pipes of 1.5–2.0-cm inner diameter ranged from 57 to 81, and 27–61%, respectively. Percentage adults emerging from pupae that escaped through sand depths of 2.5–10.2, and 12.7–20.3 cm, ranged from 68 to 87, and 12–88%; and percentage adult females that escaped ranged from 46 to 58, and 38–70%, respectively. In 15.4-cm-inner-diameter pipes filled with different heights of sand, the highest percentage of the total number of adults that emerged in the control were found from 0 to 20.3 cm, and ranged from 37 to 71%. Ten to 47% of adults were found from 20.3 cm to below the surface, and 6–21% escaped to the top of 20.3–50.8 cm high sand columns. In column heights of 55.9 and 61 cm, pressures at the bottom caused by the weight of the sand above were 91.4 and 99.7 g/cm2, respectively, and a mean of <1 adult escaped to the top. Before pupation, the late third instars were found to travel continuously for 6.9 h over 23.9 m at a speed of 6.0 cm per min, when placed on a smooth surface, at 22.2°C. Teneral females and males that could not fly, made ≈7 stops totaling 11–13 min, walked at a speed of 57–62 cm per min, and began a rest period of 83–84 min duration, at 85–89 min before flight. Males walked a distance of 13.1 m in 22 min, which was greater than females that walked for 9.6 m in 17 min, at 20–22°C and 35% RH. The mobility of the third instars and the teneral adults is discussed in relation to potential control techniques in olive orchards.

Survival of Hessian Fly (Diptera: Cecidomyiidae) Puparia Exposed to Simulated Hay Harvest Conditions, Location and Windrow Drying in Washington and California

ABSTRACT Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae) puparia are of regulatory concern in exported hay, and drying after harvest was evaluated as a cultural control technique for bales shipped from the western states. In total 16,836; 31,122; and 48,051 puparia were tested under drying conditions in environmental chambers, open air on location, and hay windrows, respectively. Regression lines for percentage of total adults emerging from puparia exposed to simulated drying conditions for 1–7 d in environmental chambers was significant for 1 September, Kittitas Valley, WA; 3 June, East Columbia Basin, WA; 15 May and 15 July, San Joaquin Valley, CA; and 15 May, 20 July, and 15 September, Imperial Valley, CA. In open air drying on location for 1–7 d, total percentage of puparia surviving to adults for all exposure days was 0.4% for 18 June, Kittitas Valley; 1.2% for 15 May, San Joaquin Valley; and 0% for 16 July, Imperial Valley; and significantly different between controls and exposure durations. In hay windrow drying for 1–6 d, total percentage of puparia surviving to adults for all exposure days was 5.4% on 28 June and 24.2% on 7 September in timothy, Phleum pretense, in the Kittitas Valley; 3.8% on 28 June in timothy in the East Columbia Basin; 2.2% on 20 July in alfalfa, Medicago sativa, in the San Joaquin Valley; and 6.3% on 21 July in Sudan grass, Sorghum bicolor sudanensis, in the Imperial Valley. The number of puparia surviving to adults in open air drying and in windrows was significantly different between controls and exposure durations for all test dates and locations. Puparial survival in field tests was related to mild temperatures and high humidities. Hay drying with subsequent field baling, storage, and export bale compression is discussed in relation to a systems approach for quarantine control of Hessian fly in exported hay.