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Annual Reports

1997UC IPM Competitive Grants Program

Biological Controls

Biological control is narrowly defined here as the use of predators, parasites, pathogens, competitors, or antagonists to control a pest. Efforts of the UC IPM Project should address those problems that have a reasonable chance of implementation within three years. An area of special interest for IPM funding is work to establish effective biological control in field situations. The Project would support studies of indigenous or introduced biological control agents to determine their efficacy, how they can be manipulated by cultural or other management practices to improve their efficacy, and how they are affected by pesticides. The Project would support development of methods for growers and PCAs to use in evaluating potential effectiveness of existing biological control agents in relation to pest populations and potential crop damage.

Investigator must describe how proposed practices could fit into the current production or management systems and detail mechanisms for transferring methods or tools to field use.

New Projects Funded for 1997-98
Continuing Projects Funded for 1997-98
Projects that Ended in 1996-97
Final Reports for Projects that Ended in 1996

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New Projects Funded for 1997-98

CAN SURFACTANTS ENHANCE BIOLOGICAL CONTROL OF FIRE BLIGHT?

Enhancing biological control of diseases and frost damage by combining antagonistic bacteria with penetrating surfactants. (Year 1 of 3; $19,008)

Principal Investigators: S. E. Lindow, Plant and Microbial Biology, Berkeley

Objectives: Determine the extent to which surfactants can enhance the population size of A506 (an antagonistic bacterium that is a registered biological control agent) on pear and apple.

Determine if the biological control of fire blight disease and frost injury to pear and apple is greater in the presence of a surfactant with very low surface tension than when the antagonist is applied in water alone.



A SEARCH FOR SOFT SCALE PARASITES

Augmentative biological control of soft scale pests of citrus, olives, and landscape ornamentals. (Year 1 of 2; $16,000)

Principal Investigators: R. F. Luck, Entomology, Riverside; J. G. Morse, Entomology, Riverside; K. M. Daane, Center for Biological Control, Berkeley/Kearney Agricultural Center, Parlier

Objectives: In laboratory experiments, evaluate black scale and brown soft scale as rearing hosts for five of the seven species of parasitoids we have in culture.

Conduct seven series of preliminary field-cage experiments with promising parasitoids (black scale on olives and citrus; citricola scale on citrus; and black, brown soft, green shield, and tulip tree scales on ornamentals), and develop quality control criteria for insectary production of the most promising parasitoid species.



COMBINING NEMATODES AND PARASITOIDS FOR BIOLOGICAL CONTROL

The potential of utilizing the parasitoid Diglyphus begini and the entomopathogenic nematode Steinernema carpocapsae for control of the leafminer, Liriomyza trifolii. (Year 1 of 1; $25,000)

Principal Investigators: M. P. Parrella, Entomology, Davis; R. B. Sher, Entomology, Davis

Objectives: Evaluate the performance of Diglyphus begini and Steinernema carpnocapsae used together for biocontrol of Liriomyza trifolii.

Verify effectiveness of the best timing release program under commercial greenhouse conditions utilizing commercially grown cucumbers.

 

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Continuing Projects Funded for 1997-98

SPOT TREATMENTS FOR ANTS

Electronic spot spray applicator for ant management in orchards and vineyards. (Year 2 of 2; $14,041)

Principal Investigators: K. Giles, Biological and Agricultural Engineering, Davis; P. A. Phillips, UC IPM Project, Ventura County

Objectives: Develop an automatic, lightweight, ATV-mounted electronic system for spot spraying against honeydew foraging ants at the trunk/soil interface in tree crops and vines.

Quantify the physical performance and ant control efficacy of the mechanical spot treatments with conventional hand sprays and band sprays.

Summary of Progress: The preliminary system for electronic detection and spot spraying for orchard and vineyard trunks has been designed and assembled. The system consists of an ultrasonic range detector, an electrically-activated spray valve and nozzle, a pressurized spray reservoir, a data interface system, and a laptop computer for control and data collection. Software has been written for control of the system and allows the system performance to be altered in response to crop conditions.

The system detects a target by receiving an echo from an ultrasonic emission directed outward from the sprayer. If the echo returns within a preset duration of time after the emission, a spray target is considered to be detected. Once the target is detected, a spray emission from the valve/nozzle is started and continues for a preprogrammed duration of time. The spray is maintained, as a minimum, for as long as the target is detected. When completed, the system will allow trunks, posts, and stakes in orchard and vineyards to be automatically sprayed as a vehicle travels along row middles. The system will be more efficient and faster than handgun spraying and will reduce worker exposure to pesticides.


Photo of Goniozus legneri
Two adults of the parasite Goniozus Legneri lay eggs on the navel orangeworm while a lacewing larva also attacks it.
BIOLOGICAL CONTROL OF NAVEL ORANGEWORM

Evaluation of inoculative releases of Goniozus legneri for navel orange-worm control in almonds. (Year 2 of 3; $27,527)

Principal Investigator: K. M. Daane, Center for Biological Control, Berkeley/Kearney Agricultural Center, Parlier

Objectives: Determine the effect of Goniozus legneri release practices on the population levels of navel orangeworm and G. legneri, and navel orangeworm nut infestation levels.

Determine the effect of incomplete winter sanitation on population levels of G. legneri and consequent navel orangeworm parasitism and nut infestation levels.

Summary of Progress: Almond growers lose millions of dollars to navel orangeworm each season. One management tool is the augmentative release of a beneficial wasp, Goniozus legneri. Currently, growers are using G. legneri release as a replacement (or transitional tool) for insecticide sprays, without the benefit of scientific documentation or economic analysis of this release program.

Our first objective is to determine the effect of G. legneri release practices on the population levels of navel orangeworm and G. legneri. A preliminary analysis indicates that in orchards with low naval orangeworm pressure (e.g., nut infestation rates of <5%), Goniozus release can reduce the navel orangeworm population by up to 40% on any generation. In orchards with high navel orangeworm pressure (e.g., nut infestation rates of >10%), navel orangeworm parasitism rates were generally higher, between 10 to 40%. However, the increase in percent parasitism was not enough to lower pest densities to acceptable levels. The release methods used affected Goniozus effectiveness. The release of Goniozus as either "white-capped" pupae (e.g., newly developed) and "black-capped" pupae (e.g., well-developed pupae that will soon hatch to adults) resulted in significant mortality from ant predation. We suggest that Goniozus be released as adults.

Our second objective is to determine the effect of incomplete winter sanitation on population levels of Goniozus legneri and consequent navel orangeworm parasitism and nut infestation levels (overwintering almonds serve as a host for both navel orangeworm and Goniozus). To investigate, we left sections of commercial orchards unsanitized and then followed the number of navel orangeworm and Goniozus moving out from these unsanitized sections throughout the season. Results suggest that Goniozus did not overwinter as well as the navel orangeworm. For this reason, we suggest that overwintering sanitation continue to be practiced as a navel orangeworm control technique.

We believe that tested guidelines will lead to a greater adoption of augmentation as an IPM practice, potentially leading to further reduction of insecticide use in almonds.

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Projects that Ended in 1996-97

ELECTROSTATIC DELIVERY OF BIOLOGICAL CONTROL AGENTS

Precision, carrierless handling and placement of biocontrol organisms.

Principal Investigator: K. Giles, Biological and Agricultural Engineering, Davis

Objectives: Determine the feasibility of "carrierless" handling, metering, and distribution of biocontrol organisms for field application; specifically, to evaluate the use of electrodynamic techniques for precision delivery and placement of the organisms.

Determine if the bio-control organisms can be electrically charged to useful charge/mass ratios.

Determine the biological effects of electric fields on the viability of biocontrol organisms in the egg, larvae, and adult stages.

Summary of Progress: Theoretical and experimental analyses investigated the possibility of using electric charging and fields for conveying biological control organisms. Mathematical analysis conducted prior to the experimental period showed that triboelectric charging was unlikely to produce useful charge-to-mass ratios for the relatively large, high-moisture-content eggs. However, a series of field exposure tests indicated that eggs could likely withstand the high electric fields typical of corona and contact charging. Moreover, analysis of the highest possible charge-to-mass ratio (based on dielectric breakdown of air) on eggs and the likely mass flow rate of a field-worthy egg dispensing system, indicated that space charge alone would likely be inadequate for manipulating egg trajectories. Therefore, supplemental electric fields would be required. These analyses implied that corona charging would be used rather than triboelectric charging. In such a case, metering of the eggs into the charging device would present a significant design challenge. Additionally, accurate metering and dispensing of undiluted (carrierless) eggs could alone greatly improve the application process.

The metering of undiluted lacewing eggs was investigated using a three-phase traveling field conveyor design. The flow rate of eggs discharged from the tunnel was measured by collecting the emitted eggs. A detailed experiment investigated the relationship between flow rate and frequencies for sinusoidal electrical waves. Results indicated that voltage and frequency can be used to control the flow rates of individual insect eggs. This technique could be used for field application of eggs.


Photo of parasites
Several new parasites were introduced for managing silverleaf whitefly. Two whitefly nymphs parasitized by Encarsia parasites are shown along with an unparasitized nymph at bottom.
WHITEFLY BIOCONTROL

Enhancement of biological control of the silverleaf whitefly.

Principal Investigators: T. M. Perring, Entomology, Riverside; T. S. Bellows, Entomology, Riverside

Objectives: Increase the diversity of natural enemies through importation, mass rearing, release, and establishment of exotic parasitoids.

Summary of Progress: In the first year of this 3-year study, we introduced a new parasite species, Amitus bennetti, into the Imperial Valley. This parasite is native to the Caribbean and we have observed aggressive parasitism of silverleaf whitefly by this species in both laboratory and greenhouse settings.

Funding received from the UC IPM Project was combined with resources from the Imperial Valley Whitefly Management Committee, the California Cotton Pest Control Board, the California Melon Research Advisory Board, and the University of California Center for Pest Management. Our releases of A. bennetti continued through July 1995 and concluded with the release of 382,800 parasites distributed over 24 locations in urban and agricultural settings near Brawley and El Centro. Amitus bennetti adults were recovered from two urban sites, suggesting possible, but limited, establishment.

Beginning in August 1995 we initiated release of Encarsia n. sp., the second of three parasitoid species planned for release into the Imperial Valley. A total of 66,000 individuals were released, and we have verified recoveries at 21% of the release sites. We believe that Encarsia n. sp. will become established in the Imperial Valley and hopefully will add to the overall mortality of silverleaf whitefly populations in agricultural and urban settings.

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Final Reports for Projects that Ended in 1996

APPLICATION OF PREDACEOUS MITES

Mechanical distribution and physical damage to predators during field releases.

Principal Investigators: K. Giles, Biological and Agricultural Engineering, Davis; H. Studer, Biological and Agricultural Engineering, Davis

Summary of Accomplishments: A mechanical, tractor-mounted system for release of predaceous mites was developed and evaluated in field trials. The system used a rotating cell plate to dispense controlled volumes of solid carriers into which mites had been mixed. The carriers were chilled to prevent mite migration and changes in the uniformity of the mix. The application rate of mixture could be controlled by the sizes of the plate cells, which determined the volume of mix in each "drop," and the speed of the plate, which determined the time between "drops." The system could be calibrated, like a pesticide sprayer, by determining the required drop rate from the desired application rate of mites and the tractor ground speed. An electronic system controlled the plate motor speed. Field testing determined that the system could uniformly deliver viable mites using one-eighth or less of the time and labor required for manual releases.

The use of solid carriers and the mite release technique was evaluated for distribution of green lacewing eggs. The distributor was mounted on a vibration table that simulated the vibration characteristics of a moving tractor. Eggs were passed through the machine and then incubated in environments simulating typical greenhouse conditions and typical field conditions in a grape canopy. Hatching rates of the eggs were not affected by the vibration treatment nor the incubation environment after treatment. These results implied that eggs are durable and can withstand a moderate amount of physical handling without decreasing their potential for hatch in most field conditions.

Lacewing and other eggs were tested in liquid application systems. Eggs were placed in water suspensions and agitated for up to 3 hours with mechanical and air sparge agitation. Hatching rates slightly decreased with duration time of immersion but the decrease was not significant. Pumping of the suspensions through a small centrifugal pump caused damage to the eggs. Spraying of the egg suspension through a large orifice nozzle did not significantly reduce the hatch rates of the eggs.



NEW MICROBIALS FOR CATERPILLARS

Field evaluation and implementation of selective microbial biopesticides in IPM programs.

Principal Investigator: B. A. Federici, Entomology, Davis

Summary of Accomplishments: Our project focused on a comparative field evaluation of two new viral nuclear polyhdrosis virus (NPV) insecticides, the beet armyworm NPV and the celery looper NPV, being developed for use in IPM programs to control caterpillar pests. The target crop was fresh market tomatoes and the pests were the beet armyworm and tomato fruitworm. The beet armyworm NPV is specific for the beet armyworm, whereas the celery looper NPV is a broad-spectrum virus capable of controlling many noctuid pests. The beet armyworm virus would be the virus of choice in a situation where the beet armyworm is the major or only pest as it is more efficacious than the celery looper virus against the beet armyworm. In situations where the crop is being attacked by a complex of caterpillars (for example the beet armyworm, tomato fruitworm, and loopers), the celery looper virus, or a Bt would be the insecticide of choice due to their greater spectrum of activity.

The virus formulations were formulated at UC Riverside, or by Biosys, Inc. (Columbia, MD) and applied on tomatoes weekly after first fruiting at the UC South Coast Field Station at Irvine, CA. During both years, treatments were made from July through September, and tomatoes were harvested and evaluated for internal and external damage. Controls used in the trials included a standard chemical insecticide (Lannate), a Bt preparation, and untreated plants.

In our trials, the celery looper NPV performed moderately well. At rates considered commercially acceptable, internal and external fruit damage averaged 8% in comparison to 21% in the untreated plots. The beet armyworm NPV applied at a similar rate was slightly better, with a damage level at 7.4%. Damage in most Bt treated plots was about 8%, and in the plots treated with Lannate damage ranged from 2.5%. Neither the viruses nor the Bt products resulted in resurgence of leafminer populations, nor did they cause significant mortality to leafminer parasites. We consider these results quite promising, though improvement of another 50% in efficacy will probably be required to get these materials adopted by growers. Such an improvement should be obtainable by increasing the amount of virus applied, or through improvements of formulation technology currently underway in industry. Permission to market both viruses in California is being sought by Biosys, Inc.



REDUCING CODLING MOTHS IN APPLES

The potential of early season releases of Trichogramma platneri and sanitation practices to reduce codling moth in mating-disrupted apple orchards.

Principal Investigator: N. J. Mills, Environmental Science, Policy and Management, Berkeley

Summary of Accomplishments: In this project we set out to clarify whether the early-season release of Trichogramma egg parasitoids can supplement the control of codling moth. Fruit damage by codling moth was lower in plots with Trichogramma releases and was more pronounced in orchards with a high codling moth pressure. In 1994 damage at harvest in a high-pressure orchard (>500 moths over the season in a high 10 mg trap) declined from 50% in the no-release plots to 16% in release plots in which either 100,000, 400,000 or 800,000 Trichogramma had been released per week through the first generation of the codling moth. Through-season releases at a rate of 100,000 Trichogramma per week did not reduce codling moth damage any more than first-generation-only releases. Results in 1994 suggested that the number of release points in a plot was more important than release rate. In 1995 a more detailed study about the importance of the number of release points in a plot showed a trend of reduced damage with an increase in number of release points; however, the variability between plots was too great for the trend to be statistically significant. Plots provisioned with honey to support longevity of Trichogramma at the parasitoid release points had no greater or lesser parasitism of sentinel eggs nor of codling moth damage than the equivalent plots without honey.

The incidence of codling moth larvae in fallen fruit and the potential of orchard sanitation as a means of contributing to the management of codling moth was examined in 1993 and 1994. The propensity to drop fruit differed between apple varieties. Removing fallen fruit from the orchard may benefit the management of codling moth in some apple varieties at particular times of the year; for example, biweekly removal of ground fruit in Golden Delicious orchards during the "June drop" and just before harvest, or the removal of ground fruit throughout the season in Gravenstein orchards, has potential to reduce codling moth population increases in subsequent generations. Golden Delicious and Yellow Newtons dropped very few fruit and Jonathan's tended to drop fruit after the codling moth larvae had already left the fruit.



INTEGRATING PREDATOR RELEASE AND ACARICIDES

Evaluation of predatory mite releases in strawberries and the effect of acaricides on the survival and establishment of Phytoseiulus persimilis Anthias-Henriot.

Principal Investigators: P. Phillips, UC IPM Project, Ventura County; J. Newman, UC Cooperative Extension, Ventura County

Summary of Accomplishments: The efficiency and economy of a tractor-mounted, mechanical, predaceous mite releasing device was compared to hand-releasing mites on bean leaves and from conventional plastic bottles. The mechanized release method required only one-fourth the labor of the hand releases and resulted in nearly three times the predator-to-prey ratio as the conventional bottle hand release. The bean leaf hand release resulted in nearly two times the predator-to-prey ratio of the bottle hand release, likely due to the dispersal with a food source and due to less physical handling. However, it was the most labor intensive method. Costs for releases were $3.88/acre for the mechanized tractor (labor, fuel, depreciation) compared to the labor costs of $4.89/acre for the bottle hand release and $5.43/acre for the bean leaf hand release.

The effects of four miticides (Avid, Kelthane, Omite and Vendex) against predaceous mites were also evaluated in both the field and in laboratory bioassays using field-treated and weathered foliage. Results of one lab bioassay experiment showed that Avid and Kelthane reduced the number of eggs laid by female predator mites for 6 weeks after application; the other two miticides showed no reduced oviposition. This same predator suppression by Avid was reflected in the field tests after 6 weeks, with predator mites being reduced by the other miticides as well, but not to the degree of Avid. Other bioassay experiments showed a 2 week suppression of predator mites after application in the field and a 3- to 6-week reduction in eggs. Mite suppression by Avid was greater on pest mites than predator mites. From these results, it is best to wait 2 to 3 weeks after an Avid treatment before releasing predator mites.



IMPROVING PARASITE APPLICATION METHODS

Improving the technology of Trichogramma augmentation against codling moth in walnuts in California.

Principal Investigator: N. J. Mills, Environmental Science, Policy and Management, Berkeley

Summary of Accomplishments: In order to make the application of Trichogramma in walnut orchards more efficient and acceptable to growers, it is important to be able to develop a broadcast application technique that will deliver the Trichogramma parasitized eggs of Ephestia kuehniella into the canopy of the orchard from a tractor-mounted spray applicator. In this project we tested a commercially available Bio-Sprayer designed for delivering benefical insects on the tree foliage. The Bio-Sprayer system applies a slurry of Trichogramma parasitized eggs in a Bio-Carrier solution that sticks them to the orchard foliage.

Although submersion in water did not affect emergence of Trichogramma from parasitized eggs, the parasitized eggs did not survive more than 2 hours after being submerged in a solution of Bio-Carrier. However, aeration of the Bio-Carrier solution significantly enhanced the survival of the parasitized eggs. The flow rate from a single arm of the BioSprayer was about 277ml/minute, but the concentration of parasitized eggs in the slurry emerging from the sprayer was only 35% that of the concentration placed into the spray tank, due primarily to eggs sticking to the walls of the tank. The pattern of distribution of parasitized eggs broadcast by the sprayer varied with distance from the spray arm and height.

Parasitized eggs were found in small batches, rather than singly, after application with the BioSprayer and the emergence rate of Trichogramma adults from these eggs was reduced by about 60%. It was found that the spray arms need to be set at an angle of 75° above horizontal to gain maximum coverage of application for the typical height and row spacing of a walnut orchard, and that release rates be increased by a factor of five to allow for reduced flow rate and survival.

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