Project : USDA ARS

ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Research Project #429868

Research Project: Detection, Control and Area-wide Management of Fruit Flies and Other Quarantine Pests of Tropical/Subtropical Crops

Location: Tropical Crop and Commodity Protection Research

2018 Annual Report

Objectives
The goals of our project plan are to conduct foundational research to create the knowledge base necessary to develop innovative control methods and IPM strategies, and to conduct applied research to produce information and products that improve pest control in tropical agriculture. The four major objectives of our program are: Objective 1: Model pest invasion pathways, and investigate the genomics/genetics, physiology/behavior, population dynamics, biology/ecology, and natural enemies of tropical and subtropical fruit flies and other invasive pests to develop technologies to control (contain, suppress, and eradicate) these pests in Hawaii and the Pacific, the U.S. mainland, and elsewhere. 1A: Build an analysis of emerging tephritid fruit fly genomes, including linkage mapping, uniform and consistent gene structural and functional annotation, and comparative genomic analysis. 1B: Conduct surveys on coffee berry borer (CBB) distribution and abundance on Hawaii Island to provide a baseline for a predictive model that integrates GIS, pest insect population dynamics, host plant phenology, weather data and grower practices to drive area-wide management of CBB on Hawaii Island. Objective 2: Determine physiological, genetic, and biological factors limiting the effectiveness of the sterile insect technique (SIT) and natural enemies in control and eradication of fruit flies and other tropical plant pests of quarantine significance. 2A: Improve the effectiveness of mass reared fruit flies for SIT by quantifying the impact of colony infusion on incorporating wild genetics into the SIT colony, and correlating fly performance with genomic markers. 2B: Investigate parasitoid-fruit fly host interactions from the molecular to the field level. Objective 3: To increase export of tropical fruits and vegetables, improve attractants and trapping systems for surveillance and detection, and develop lures, baits, and reduced risk pesticides for area-wide IPM of fruit flies and/or other tropical plant pests of quarantine significance. 3A: Evaluation of C. capitata, B.dorsalis and B. cucurbitae captures in traps baited with solid trimedlure (TML), methyl eugenol (ME) and raspberry ketone (RK) male lure and insecticide dispensers weathered in Hawaii and California. 3B: Evaluation of mixtures, weathering and chemical degradation of SPLAT-spinosad ME and cue-lure (C-L) for fruit fly control under Hawaii and California conditions. 3C: Evaluation of a new attractant system for detection, monitoring and control of the sweetpotato vine borer, a pest of quarantine significance in Hawaii. Objective 4: Provide baseline information for development of low prevalence and/or pest-free zones, for implementation in Hawaii and the U.S. mainland, to promote or allow unimpeded movement of fruit and vegetable exports. 4A: Create area of low pest prevalence (ALPP) as an independent measure of systems approaches for melon fly. 4B: Utilize models to evaluate the sensitivity of trapping grids for detection and control of insect pests such as tephritid fruit flies. 4C. Effectiveness of foliar and bait sprays against C. capitata, B.dorsalis, B. cucurbitae and B. latifrons.

Approach
Hypothesis 1A: Tephritid genomes have a core set of genes that are related to their proliferation as pests world-wide. If we have trouble generating crosses from a particular species or have issues generating genomic DNA, other species could be sequenced. Approach 1B: Collect baseline data on distribution and abundance of Coffee Berry Borer and associated environmental and climatic data. Then use GIS techniques to produce a region-wide assessment of infestation and economic impact. If this does not work, surveys can be replaced with grower-collected data. Approach 2A: Combine genetic, proteomic and phenotypic data into a synthetic analysis. If portions experiments fail or cannot be integrated, publish portions independently. Approach 2B: Examine tephritid host-parasitoid biology across levels of biological organization to allow integration of foundational knowledge benefiting classical biological control of tephritids. If international releases are impeded by regulatory issues, field work in Hawaii will be done. Hypothesis 3A: Solid male lure wafers with solid insecticidal tape are just as effective, but more convenient and safer to handle than current liquid lure-insecticide formulations used for fruit fly detection programs. If data are inconclusive, chemical analyses of weathered dispensers from trials will at least provide “use pattern” and formulation data for future trials. Hypothesis 3B: Generic combination SPLAT-MAT-spinosad-methyl eugenol/cue-lure mixture will perform as well as Min-U-Gel with naled and ME and C-L separately for fruit fly control/eradication. If the sprayable mixtures are too expensive, recommend addition of small amounts of cue-lure or raspberry ketone to STATIC-spinosad-ME as part of a tank mix. Hypothesis 3C: A binary male attractant system identified with sweetpotato vine borer populations in Vietnam will provide significantly greater male catch in Hawaii populations than male catch in traps baited with an initially identified single compound lure. In cases where low populations are encountered, trials will be shifted to other fields or other time of year where higher populations are present. Hypothesis 4A: Mass trapping using a plant-odor lure, male lure and protein baits can create areas of low pest prevalence (ALPP) in commercial crops and reduce the risk of a mating pair in a consignment when combined with a second measure such as a (less than 99.9986% effective) quarantine treatment. Alternatively, investigate the effects of other independent measures such as poor host status and quarantine treatments. Approach 4B: Develop a biologically-based mathematical model of tephritid traps in a landscape that allows formal quantification of trap network sensitivity. Hypothesis 4C: Current preharvest foliar insecticides being used in IPM systems against other fruit and vegetable pests (e.g., spotted wing drosophila and Asian citrus psyllid) in California and Florida are sufficient to meet quarantine requirements for fruit flies when introduced into Florida and California. Alternatives are to use current practices of either malathion protein bait or GF-120 sprays.

Progress Report
Development of foundational genomic resources for tephritid fruit flies has continued, including submission of Tephritid genomes into National Center for Biotechnology Information (NCBI) and i5k databases, and further publications on improved assemblies, such as a high resolution linkage map for the Medfly. This linkage map has been used to develop diagnostic tools able to discriminate sterile insect technique (SIT) strains from wild (invasive) flies. These tools are now being tested and implemented at the United States Department of Agriculture, Animal and Plant Health Inspection Service/Plant Protection and Quarantine (USDA-APHIS PPQ). In addition, an initial analysis of gene orthology across Tephritid genomes was performed and published as part of a study demonstrating a highly multiplex amplicon sequencing-based technique for generating high quality phylogenomic analyses across tephritid species. We are also improving methods for genome assembly and analysis, including integration of HiC chromatin contact data, single molecular sequencing (Oxford Nanopore), and linked-read data (10X Genomics), towards developing chromosomal scale assemblies. In proteomics research, proteome profiling across development stages for all four pest fruit fly species in Hawaii was continued and is partially complete. Comparative proteome profiling of Bactrocera latifrons development was reported for the first time. This study will supply a wealth of additional information on understanding fruit fly development and improve mass rearing technology. In two genetic sexing lines, the melon fly T1 white pupae line, and the Vienna 8 medfly, colony infusion studies have been performed to evaluate the impact of infusion towards improving fitness traits in the flies. Currently, infused lines are being evaluated for improved fitness, and samples are undergoing genotyping for connecting genetics to behaviors. In addition, proteomic profiling of Bactrocera latifrons across its developmental stages has been performed and published. Significant progress was made on basic studies and field evaluation of area-wide control strategies for fruit flies, coffee berry borer (CBB), and sweet potato vine borer. This has included publications on oriental fruit fly, Medfly and melon fly. In the area of biological control, parasitoid shipments have continued to Senegal. In Senegal, we are examining the survival of Fopius arisanus over both wet, moderate rainfall and dry habitats where mangoes are grown. In Brazil, potential nontarget effects of releases are still being examined by Brazilian colleagues before field releases are allowed by the Brazilian government. In CBB research, data collection in Kona and Kau continued for the 2018 season, including monitoring of populations, plant phenology, management practices and weather conditions as in 2016 and 2017. Geo-referenced data were collected using an electronic system. A statistically justifiable sampling protocol has been finalized and published. A monitoring program has been transferred to collaborators in Puerto Rico, who are starting the program this year based on methods and experience developed in Hawaii. Though data from 2016-2017 have been quality checked, we are awaiting completion of this, the final year of the monitoring program, before publication and general release. Portions of the data have been shared with the University of Hawaii researchers and published. In sweetpotato vine borer research, the binary male attractant system (with Type 1 and Type 2 components) identified with sweetpotato vine borer populations in Vietnam has been shown to similarly provide significantly greater male catch in Hawaii populations compared to male catch in traps baited only with the initially identified Type 1 compound. Certain variations of the Type 1: Type 2 ratio and doses have provided greater than 10-fold increase in male catch compared to catch in traps baited with only the Type 1 component. A lure weathering trial has been completed, with weathered lures collected and awaiting analysis. Although field sweetpotato vine borer populations have been low, little drop-off in male sweetpotato vine borer catch was apparent over the course of a three-month weathering period. Overall, results to date document greatly enhanced trap catch effectiveness of a Type 1 + Type 2 lure combination, compared to catch baited with the Type 1 lure only, with good persistence of the effectiveness of the binary attractant system over time. Chemical degradation and bioassay studies for multilure fruit fly trap dispensers containing three male lures have now been completed for California with four peer-reviewed manuscripts published. Additional studies are ongoing in New Zealand, Australia and Florida. Based on results thus far, trimedlure (TMR) dispensers could potentially be used in place of three individual male lure traps, reducing costs of mainland fruit fly detection programs. Integration of the trapping model into the Agent Based Simulation (ABS) “Medfoes” is complete, the latest version of the software (0.6.2) includes the trapping component as planned. An additional study on oriental fruit fly survival in the field was published containing data on trap sensitivity, plus one on melon fly and its attraction to food lures. Survival experiments in environmental chambers are ongoing to complement existing survival data collected in the field. Research results on foliar chemicals currently being used to control Asian citrus psyllid (ACP) were continued for potential use in a systems approach for fruit flies during quarantines. Studies in Hawaii included a comparison of the effects of 19 foliar pesticides to the current standards (Malathion protein bait or GF-120 Naturalyte Fruit Fly Bait), for the uninterrupted movement of commercial citrus or cherries in the event of future fruit fly quarantines in growing areas of California. Our studies also examined the impact of foliar sprays on beneficial hymenopterous insects. Dimethoate, Malathion, Mustang, Assail, Warrior, Actara and Lorsban consistently produced high fruit fly mortality comparable to the standards. However, many of these foliar insecticides also produced high mortality on natural enemies compared to GF-120 Naturalyte Fruit Fly Bait. Our initial results support development of a systems approach for relief from fruit fly quarantines; however, detrimental effects on natural enemies should be recognized.

Accomplishments
1. Evidence of non-response to male lure based on development in host fruit. The finding that the type of fruit that hosts a fruit fly can influence emerging adult fruit fly responsiveness to male lures is significant. This indicates a novel mechanism driving consistency in the success rate of a given trap; i.e., trap catch variation. While differences in individual and population response levels to particular lures have been observed in Bactrocera and Ceratitis, the only mechanisms suggested to date for how this might occur involve age or exposure or consumption of the lure. ARS scientists in Hilo, Hawaii, realized that closer scrutiny of the role of host fruits is warranted and lists of host plants in outbreak areas in the U.S. mainland might be examined not only for host status but also for the expected responsiveness of any emerging flies. This additional mechanism will help determine the potential sensitivity of the trapping network.

2. Cucumber volatiles improve performance of bait sprays for tephritid pest. Foraging behavior of wild female melon fly, a worldwide pest of economically important cucurbit crops, was examined by ARS scientists in Hilo, Hawaii, and scientists at the University of Massachusetts. Mark and recapture studies in both wild habitats in Kona (dominated by the invasive weed ivy gourd) and cultivated habitats in Kapoho (dominated by papaya orchards) on Hawaii Island were conducted. Many years of field cage and laboratory behavioral studies with laboratory-reared flies have indicated that female melon flies with eggs responded primarily to host odors, while those without eggs responded primarily to protein. Kona results indicated that wilder and color-marked F2 females responded to cucumber odor rather than to protein odor in contrast to captured wild flies without eggs, which responded similarly to protein bait and cucumber odor. Results with captured wild females and color-marked F2 females in Kapoho suggested a significant preference for cucumber odor over protein odor regardless of whether they had eggs in their ovaries; however, protein-deprived, color-marked F2 females responded to both odors in equal numbers. These new findings provide improved Integrated Pest Management control strategies for this species through integration of cucurbit volatiles to baits.

3. Reduced control costs for two important tephritid pests of papaya. Oriental fruit fly and melon fly are two major agricultural pests of papaya that need to be controlled. ARS scientists in Hilo, Hawaii, conducted field studies to quantify attraction of wild male oriental fruit fly and male melon fly to a male annihilation treatment consisting of specialized pheromone and lure application technology with a mixture of the two major male lures methyl eugenol (ME) for oriental fruit fly, cue-lure (C-L) for melon fly and spinosad as a sprayable “reduced risk” control system. These mixtures were compared to individual formulations containing either pure ME or pure C-L and spinosad that would typically be sprayed individually. No difference in effectiveness was found. In areas where both oriental fruit fly and melon fly are pests, such as papaya orchards in Hawaii, a mixture formulation could be used as a generic lure component for two species instead of just one. This provides an economic benefit by reducing “attract and kill” stations by fifty percent.

4. Asian citrus psyllid and spotted wing drosophila control methods also can control tephritid fruit flies. ARS scientists in Hilo, Hawaii, conducted studies that compared the effects of 19 foliar pesticides to the current standards (Malathion protein bait or GF-120 Naturalyte Fruit Fly Bait), for the uninterrupted movement of commercial citrus or cherries in the event of future fruit fly quarantines in California. The impact of foliar sprays on beneficial hymenopterous insects was also examined. Dimethoate, Malathion, Mustang, Assail, Warrior, Actara and Lorsban consistently produced high fruit fly mortality comparable to the standards. However, many of these foliar insecticides also produced high mortality on natural enemies compared to GF-120 Naturalyte Fruit Fly Bait. Detrimental effects on natural enemies was also considered in the design. Preliminary results support a systems approach for relief from fruit fly quarantines considered by the Animal and Plant Health Inspection Service (APHIS).

U.S. DEPARTMENT OF AGRICULTURE

Tropical Crop and Commodity Protection Research: Hilo, HI