Project : USDA ARS

ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Research Project #430081

Research Project: Improved Biologically-Based Methods for Insect Pest Management of Crop Insect Pests

Location: Insect Behavior and Biocontrol Research

2017 Annual Report

Objectives
Objective 1. Develop new transgenic conditional lethal strains for sexing and sterility in tephritid and drosophilid fruit flies to be used in the sterile insect technique, produce redundant lethality systems for ecological safety, and transgenic technology for emerging pest species such as the Asian citrus psyllid. Objective 2. Develop paratransgenic strains that eliminate the ability of host populations to vector plant disease by using Wolbachia cytoplasmic incompatibility to drive pathogen immunity throughout populations of key pests such as Asian citrus psyllid, glassy-winged sharpshooter, and potato/tomato psyllid. Objective 3. Develop automated acoustic methods for improved surveillance and detection of hidden and invasive pests such as red palm and citrus root weevils and Asian long-horned beetle that will facilitate more rapid information collection/processing by use of big data technologies. Objective 4. Develop improved visual-cue trap systems for surveillance of invasive and outbreak insect pests such as Asian citrus psyllid and corn silk fly, and improve strategies for detecting and predicting the dispersal of these pests by understanding the role of visual and other stimuli in affecting their behavior. Objective 5. Develop predictive models for fall armyworm migration pathways that are shifting due to climate change, and improve area-wide landscape management tactics for these pests by developing cover crop and biological control strategies to control them. Sub-objective 5.A. Develop genetic methods to monitor fall armyworm population behavior and air transport models to describe and predict its migration pathways and potential changes in infestation patterns due to climate change. Sub-objective 5.B. Improve area-wide landscape management tactics by developing cover crop and other strategies to mitigate pest populations such as fall armyworm, and attract or support natural enemies and pollinators.

Approach
The experimental approaches to achieve these objectives is multidisciplinary and integrates genetics, ecology, behavior, and engineering to address various stages of control, from molecular genetics leading to autocidal strain development to predicting changes in pest migration in response to global climate change. These approaches will apply, initially, to high priority invasive fruit flies, beetles, psyllids, fall armyworm and corn silk flies, and will include studies for development of molecular genetics methods for gene discovery and manipulation to develop genetically-modified pest strains to suppress wild populations, or eliminate their ability to vector pathogens of plant disease; development of detection and surveillance methods for optimization of acoustic, chemical and visual-cue detectors for detection and surveillance of hidden, invasive and outbreak pests; and biological control studies to develop predictive models to target shifting migrations of noctuid pests in response to climate change, and development of improved area-wide landscape management tactics to mitigate pest populations and attract natural enemies and pollinators.

Progress Report
The efforts of the Insect Behavior and Biocontrol Unit during FY 2017 resulted in significant progress towards all five objectives and subobjectives for this project. Significant progress was made under Objective 1 to produce temperature sensitive sterile male-only strains for the invasive pest spotted winged Drosophila. This provides a proof of principle demonstrating the synthetic creation of sterile males-only strains for more highly efficient sterile insect technique (SIT) population suppression programs against the spotted winged Drosophila and other insect pest species. Under Objective 2 a system was created that provides a visual marker for the presence of the obligate intracellular endosymbiotic bacterium, Wolbachia, and how it communicates with its host cell. The expression of the marker gives a direct confirmation that the bacteria produce materials that are transferred into the host cell. Under Objective 3 an acoustic trap was developed for the mosquito Aedes aegypti that captured a significantly greater proportion of males than were captured in a standard Center for Disease Control trap. Additionally, a device that mimics female-produced courtship vibrations of the Asian citrus psyllid has been developed and refined to trap males. Similar technology has been used to produce vibrational signals that disrupt mating by confusing or distracting the males. Under Objective 4 behavioral responses to colors were determined for optimal attraction of two of the major corn silk-fly pest species. Incorporation of these color cues provides the basis for development of an effective visually-based trap system for surveillance and management of these pests in sweet corn. Under Objective 5A the likelihood of fall armyworm movements within the Lesser Antilles islands in the southern Caribbean was investigated and showed that population movements across these islands are likely to be sporadic and limited with no significant impact to continental populations. Under Objective 5B the summer cover crop plant, sunn hemp cultivar AU Golden, was shown to provide many of the benefits of traditional cover crops but because it produces substantially more flowers in low seeding rate plots there were significantly larger numbers of pollinating insects attracted that can contribute to pollination of local flowering plants.

Accomplishments
1. Migration of pest and invasive insects. The fall armyworm is the primary pest of corn production in South America and in portions of the southeastern United States. In 2016, severe outbreaks of fall armyworm were reported in several western and central African countries, representing the first indication of the species establishing itself in the Eastern Hemisphere. The voracious feeding and long-distance flight behaviors exhibited by fall armyworm indicate a significant threat to African agriculture with the potential for rapid dispersion throughout the hemisphere. ARS researchers in Gainesville, Florida, collaborated with those at national and international universities to collect and genetically characterize moth specimens from several agricultural regions in the African nation of Togo. Genetic analyses confirmed the fall armyworm identification of the specimens, estimated host strain identity, and tested for the presence of the Puerto Rico Bt-resistance allele. The haplotype and marker data were used to extrapolate the most likely Western Hemisphere source locations. This information will be critical for future efforts to monitor, predict, and control the spread of this invasive pest in the Eastern Hemisphere.

2. Temperature sensitive sterile male-only strains. A temperature sensitive sterile male-only strain for the invasive pest spotted winged Drosophila. ARS researchers in Gainesville, Florida, collaborated with those at national and international universities to mutate a gene that controls sex determination using a gene editing system and makes it temperature sensitive. At low rearing temperatures in the laboratory, the gene produces a normal fly but at higher temperatures like those found in the natural environment only sterile males are produced. This provides a proof of principle for the synthetic creation of sterile males-only strains for more highly efficient sterile insect technique (SIT) population suppression programs for the spotted winged Drosophila and other insect pest species.

3. Development and testing of acoustic trap for yellow fever mosquito. Aedes aegypti mosquitoes are a globally spreading threat to human health due to their expansion into new areas and their spread of important pathogens, including Zika virus, dengue, chikungunya and yellow fever. Improved technology for capturing males in peridomestic environments is necessary to augment monitoring. ARS researchers and university students at Gainesville, Florida, investigated methods to combine multiple stimuli attractive to male Aedes aegypti mosquitoes into a highly effective trap employing visual cues shown in specific light wavelengths and/or acoustic cues from speakers broadcasting sounds mimicking female wingbeats. More males were found in traps that combined both visual and sound cues than were found in traps with none or only one. Potential applications are being assessed to incorporate these visual and acoustic cue sources into new, innovative trapping programs.

4. Visual attractants for corn silk-flies. Silk flies are the most severe ear-infesting pests of sweet corn production in Florida which is the major producer of fresh market sweet corn in the U.S. Precise timing of insecticide applications are critical for obtaining high market yields, however there is no standardized surveillance method to guide optimal insecticide delivery. Laboratory studies conducted by ARS researchers in Gainesville, Florida, have established optimal colors for attraction of two of the major corn silk-fly pest species. This information provides the basis for development of an effective visually-based trap system for surveillance and management of these pests and to ultimately enhance efficiency of production in fresh market sweet corn.

5. Substantial flowering in cover crops attracts large numbers of pollinating insects. Cover crop and weedy refuge plants in vegetable and row crop agroecosystems offer a potential to attract and maintain populations of beneficial insects. ARS researchers in Gainesville, Florida, found that the summer cover crop plant, sunn hemp, cultivar AU Golden, provides many of the benefits of traditional cover crops. However, because of its ability to produce lots of flowers, sunn hemp plantings attract insect predators. Additionally, the research showed that in low seeding rate plots, ‘AU Golden’ produced substantially more flowering which attracted larger numbers of pollinating insects.

6. Development of a Bacterial Communication Reporter System. The obligate intracellular endosymbiotic bacterium, Wolbachia, communicates with its host cell. To examine how intracellular bacteria communicate, ARS researchers in Gainesville, Florida, modified a genetic reporter system based on the yeast two component system so that the host cell produces a fluorescent protein when infected by a bacterial infection. The bacteria were modified to produce and deliver a yeast protein that triggers host cell expression of the green fluorescent protein. This system provides a visual marker for the presence of an intracellular bacterium and a direct confirmation that the bacteria produce materials that are transferred into the host cell.

U.S. DEPARTMENT OF AGRICULTURE

Insect Behavior and Biocontrol Research: Gainesville, FL