Project : USDA ARS

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Research Project: Improved Biologically-Based Methods for Management of Native and Invasive Crop Insect Pests

Location: Insect Behavior and Biocontrol Research

2021 Annual Report

Objectives
Objective 1: Develop genetically modified (GM) strains by transposon and CRISPR/Cas-mediated transgenesis for improved SIT in fruit fly pests, and new DNA delivery systems to apply this technology to a wider range of insect, including emerging pest species (e.g., caribfly, mexfly, medfly, spotted-winged drosophila). Objective 2: Develop strains of moths transinfected with Wolbachia that produce males with strong cytoplasmic incompatibility for use in the Incompatible Insect Technique (IIT) to reduce pest populations of fall armyworm and corn earworm. Objective 3: Develop CRISPR gene editing in pest moths (e.g., Indian meal moth, fall armyworm, gypsy moth) that target genes critical for acquired biopesticide resistance using both whole insects and cultured insect cells. Objective 4: Develop improved surveillance and detection methods for hidden and invasive pests (e.g., red palm and citrus root weevil, Asian long-horned beetle, Asian citrus psyllid, and stored product insect pests) that incorporate automated collection, processing, and analysis of insect acoustic signals and behavioral activity. Objective 5: Develop improved surveillance of invasive and outbreak insect pests (e.g., corn silk flies and kudzu bug) using visual-cue traps, and improve strategies for detection and prediction of such dispersing pests by understanding the role of visual and other stimuli affecting specific behaviors. Objective 6: Improve area-wide landscape management tactics by developing conservation biological control strategies to mitigate pest populations and attract or support natural enemies (e.g., against fall armyworm). Objective 7: Combine genetic methods with air-transport and climate modeling to describe and predict the distribution and behavior of agricultural pests to facilitate the mitigation of migratory source populations and to identify locations at high risk for infestations by invasive species such as fall armyworm, corn silk fly, soybean looper, Old World bollworm, and corn earworm.

Approach
Research conducted by the Behavior and Biocontrol Research Unit at the Center for Medical, Agricultural and Veterinary Entomology has historically been focused on the development of novel technologies that improve the cost-efficiency of traditional pest control strategies as well as provide environmentally benign alternatives to the use of chemical pesticides. The goals are to improve crop productivity while reducing the environmental impact and costs of pest management. The proposed research integrates different levels of biology that range from the genetic modification of pest insects to generate novel and improved variations of Sterile Insect Technique (SIT) strategies, the manipulation of pest endosymbionts to develop Insect Incompatibility Technique (IIT) strategies, the optimization of acoustic, olfactory, and visual cues to improve pest surveillance and disrupt pest behavior, the application of climate and air transport models to project pest distribution and migration patterns, and the development of landscape strategies for sustainable mitigation of pest populations. This multidisciplinary structure encourages innovation and facilitates synergism between projects. Anticipated accomplishments will initially apply to the control of high priority invasive fruit flies, beetles, psyllids, moths, and corn silk flies through new biologically based methods for pest control, improved capability to monitor pests, and better projections of pest movements to more effectively target the time and place of treatments. The impact will be higher productivity at lower cost for domestic agriculture and new and improved tools to detect and control emerging native and invasive pests.

Progress Report
Objective 1: Research was initiated by ARS researchers in Gainesville, Florida, to find genes required to construct to genetically modified lines of important fruit fly pests (Caribfly, mexfly, and spotted wing Drosophila) that can be used for more efficient Sterile Insect Technique strategies of pest control. These include finding genes that cause temperature-sensitive lethality in embryos and larvae, genes that eliminate fly gametes, and regulatory sequences needed to cause these genes to be expressed in the relevant developmental times and cell types. These genetic components will be combined to produce lines that can kill or sterilize field populations when mass released. Genetic promoters active in embryos were isolated from the mexfly and spotted wing Drosophila, with functional testing initiated. Genes specific to fly sperm have been isolated in pest flies and are being tested for function. Genetic vectors required kill female Caribflies at certain temperatures have constructed and await testing. Objective 2: No progress was made due to closure of the laboratory due to COVID-based restrictions and retirement of the principal investigator. Objective 3: No progress was made due to closure of the laboratory due to COVID-based restrictions and retirement of the principal investigator. Objective 4: New acoustic insect detection systems were identified by ARS researchers in Gainesville, Florida, to replace systems no longer commercially available for detection and management of insect pests hidden in stored products, trees, and soil. Two years ago, the previous system (AED-2010) ceased production and, initially, all available replacements were more expensive and less robust for field studies. An inexpensive system for detection of hidden insect infestations in stored products, the Postharvest insect Detection System, manufactured by Custom Engineered Solutions, West Hempstead, NY, was tested successfully against rice weevils and red flour beetle. A TreeVibes system manufactured by Insectronics, Chania, Crete, was tested successfully against rice weevils. Both systems also have potential for applications for management of invasive insect species hidden in trees. Objective 5: Through laboratory testing of visual traps for cornsilk flies, several attractive colors were selected by ARS researchers in Gainesville, Florida, for field testing. Traps are being prepared and initial testing of visual traps initiated. Sex pheromone studies were initiated with development of an assay, initial assays conducted to examine attraction of males and females and preliminary extracts of volatiles from flies obtained. A colony of kudzu bugs has been established and used for initial electroretinogram tests. Objective 6: Research was initiated by ARS researchers in Gainesville, Florida, to identify species found in corn habitats that are potentially important predator species against fall armyworm larvae. Collections sites have been identified and collections are ongoing, though at 25% activity due to COVID-based restrictions. Objective 7: Research was initiated by scientists in Gainesville, Florida, to establish the use of Climex/Dymex software to make projections of locations with climate amenable for permanent populations of fall armyworm with the aim to better understand how infestation and migration patterns might vary with climate change. These climate projection maps were used to analyze fall armyworm distribution patterns in South America and assess the likelihood that fall armyworm from South America contribute to U.S. infestations. Several hundred fall armyworm specimens were obtained from various locations in Asia and Africa that are being analyzed for their genetic relationship with Western Hemisphere populations with the aim to identify the likely source(s) of the recent invasion of fall armyworm into the Eastern Hemisphere.

Accomplishments
1. Testing of affordable and effective acoustic devices for invasive insect detection and management. Invasive insect species often arrive in the United States through trade items in which the insects hide unnoticed until entry into and subsequent shipments into different cities and agricultural areas. Acoustic sensing of movement and feeding activity is one of the best methods of detecting such infestations in warm climates and affordable systems would be a benefit to producers, regulators, and researchers. Scientists in Gainesville, Florida, tested the Postharvest insect Detection System (PDS), manufactured by Custom Engineered Solutions, West Hempstead, NY, and the TreeVibes system manufactured by Insectronics, Chania, Crete. Both systems tested successfully against rice weevils and were shown to have great potential for the management of invasive insect species hidden in trees.

2. Africa is at less risk to fall armyworm infestation than initially believed. The fall armyworm has now been reported through much of Eastern Hemisphere, posing a significant threat to agriculture with the potential for rapid dispersion world-wide. Fall armyworm is subdivided into two groups that differ in their distribution on different plant hosts. This means that the scope of the economic risk posed by invasive fall armyworm is dependent on whether one or both strains are present. Scientists in Gainesville, Florida, found that only the group associated with corn and sorghum infestations were present in substantial numbers. The apparent absence of the group associated with rice, alfalfa, forage grasses, and millet indicates that these crops are not at immediate risk from the current fall armyworm invasion.

3. Isolation of promoters required to produce genetically modified fruit fly pests for enhanced Sterile Insect Technique. Enhanced sterile insect technique for pest fruit flies could substantially reduce costs and yield losses in fruit and vegetable agriculture. Genetic modification allows the creation of fly lines that can potentially make sterile insect technique far more efficient and effective. Scientists in Gainesville, Florida, have isolated and identified promoters with the potential to turn on lethality causing genes in early embryos and gametes. These have the potential to overcome several technical problems that has reduced the efficiency of this technology. This should result in more highly efficient lethality systems for use in sterile insect technique for multiple fruit fly pest species.

U.S. DEPARTMENT OF AGRICULTURE

Insect Behavior and Biocontrol Research: Gainesville, FL