Location: Insect Behavior and Biocontrol Research
2021 Annual Report
Objectives
Objective 1: Improve the feasibility of using multi-tactic pest control strategies, especially through the improvement of biologically based control methods, for invasive weeds of the southern United States (e.g. tropical soda apple, air potato and Chinese tallow).
Sub-objective 1.A. Develop pre-release techniques that can be used to evaluate the impact of future biological control agents.
Sub-objective 1.B. Determine the role of North American native natural enemies attacking biological control agents on the agents’ population establishment and impact to the targeted weed.
Sub-objective 1.C. Determine release factors that increase successful establishment of weed biological control agents.
Objective 2: Develop biologically based pest control strategies for insect pests of the southern United States.
Sub-objective 2.A. Identify companion plants, commercial products and chemical compounds that i) repel whiteflies and determine their efficacy in limiting pest dispersal into crops (“push” factors), as well as ii) plants and products capable of attracting whiteflies into trap crops to facilitate control (“pull” factors).
Sub-objective 2.B. Evaluate companion or refuge plants that attract or maintain important whitefly predators.
Sub-objective 2.C. Develop an integrated cropping system combining “push-pull” crops or plant products with natural enemy refuges for sustainable biologically-based control of the whitefly.
Sub-objective 2.D. Identify parasitoids with potential as biological control agents for corn silk flies.
Sub-objective 2.E. Determine the Argentine field host range of the potential Argentine cactus moth biological control agent, Apanteles opuntiarum.
Sub-objective 2.F. Determine the effectiveness of a mating disruption technology as a sustainable management option for the cactus moth in commercial cactus production areas.
Sub-objective 2.G. Collect, identify, and distinguish between the complex of Harrisia cactus mealybugs (HCM), their plant hosts, and host specific parasitoids found in Argentina, Puerto Rico, other Caribbean Islands, and Florida.
Sub-Objective 2.H.Identify volatile chemicals from plants or oils repellent to whiteflies as basis for develop for area-wide release of repellents to protect vegetable crops.
Approach
Invasive insect pests and weeds are among the most serious problems facing agricultural and natural ecosystems throughout the United States. This project plan describes research to improve implementation of biologically based tactics for non-pesticide management of insect pests and weeds. The goals will be achieved through acquiring a better understanding of the pest species biology along with the interactions between host plants and natural enemies to support the development of optimized approaches, technologies and strategies for control of a variety of targets. One area of research will address improvement of techniques to enhance release success and increased efficiency of establishment and impact of biological control insect species against invasive weed species, specifically targeting the air potato and Chinese tallow. A second area of research focuses on the development of an integrated vegetable cropping system for control of whiteflies using a “push/pull” pest management approach. A vegetable crop system will be assessed using ‘push’ components consisting of naturally repellent plants or plant compounds, in conjunction with ‘pull’ components that consist of trap crops and refuge plants that naturally harbor whitefly predators. The potential use of parasitoids for reduction of the impact of corn silk flies on sweet corn will also be examined. A third area of emphasis is on the protection of U.S. native cacti from the invasive Argentine cactus moth and the Harissia cactus mealybug complex. Control of the Argentine cactus moth will be assessed through the use of a mating disrupting pheromone along with a potential exotic parasitoid. Control of the Harissia cactus mealybug complex will be based on developing an understanding of the species complex composition, alternative host plant reservoirs and potential parasitoids.Identification of volatile repellent chemicals to whiteflies will be determined as the basis for development of area-wide release of repellents to protect vegetable crops. The outcomes of this research project will improve the sustainability of agricultural production, reduce reliance on pesticides and reduce the environmental degradation caused by invasive pest insect and weed species.
Progress Report
This is the final report for the project 6036-22000-031-00D “Improved Biologically-based Tactics to Manage Invasive Insect Pests and Weeds” which terminated in December 2020. Significant progress resulted from this 5-year project through the objectives: 1) Improve the feasibility of multi-tactic pest control strategies, and 2) Develop biologically based pest control strategies for insect pests. Studies conducted by researchers in Gainesville, Florida, on leaf-eating beetles that control the invasive air potato provided a better understanding and improvement of pre-release techniques and release factors to enhance establishment. After implementation, high levels of establishment and even higher levels of foliar damage to the weeds were detected in a state-wide survey. A better understanding of the seasonal dynamics of a leafminer moth which is a newly introduced potential biological control agent for Chinese tallowtree was obtained and will guide future surveillance of the moth. Examination by researchers in Gainesville, Florida, of native parasitoid attack on the leafminer revealed low rates of parasitism and thus little threat to this biological control agent when it is released. Vegetable crop production is challenged through infestations of pest insects, however biologically-based systems such as “push-pull” systems where pests are pushed from the crop and pulled to a non-target or trap crop, and beneficial parasitoids and predators are augmented with flowering plants, all to provide excellent strategies for organic and small farms. Cultural control of pest insects through planting companion plants that repel pest insects or those that enhance predator populations is promising as demonstrated with plantings of marigold, basil, dill and sweet alyssum that mitigated damage by the sweetpotato whitefly and aphids on the organic vegetable crops of mustard, pak choi and swiss chard in protected structures. Plantings of sunn hemp cover crops maintained an abundance of species and numbers of ground-dwelling beetle predators that enhance biological control of pest insects in adjacent vegetable crops. This demonstrates the importance of planting cover crops for insect pest management. Use of a chemical attractant combined with refuge plants such as sweet alyssum intercropped with targeted vegetable crops successfully attracted beneficial natural enemies such as predacious hover flies against sweetpotato whiteflies and aphids. Use of repellents like mustard plants, mustard oil and garlic oil provide the “push” component of a management strategy for an effective alternative control for white fly infestations. “Pull” components were identified from colored targets, plant volatiles and entire plants evaluated. These components were integrated into a “push-pull” strategy to control whiteflies on vegetable crops. Few parasitoids of the corn silkflies that attack sweet corn were detected in the field, however laboratory studies revealed several species of commercially available pupal parasitoids that were effective for parasitism under varying soil and moisture conditions. The Argentine cactus moth threatens native North American cacti and several tactics for control are promising. A parasitoid species for biocontrol of the Argentine cactus moth discovered in Argentina was confirmed to only attack a single cactus moth species in Argentina. After colonization and transfer to a quarantine facility in Florida, the host range of this parasitoid was again evaluated but against native cactus moths. The lack of alternate hosts indicates little to no risk to non-target species when the parasitoid is released for biocontrol. Modelling the predicted geographic ranges of the Argentine cactus moth as well as the parasitoid revealed strong overlap indicating the potential of the parasitoid for providing control of the cactus moth. A trail-following pheromone from Argentine cactus moth caterpillars was demonstrated to have potential for disruption of establishment of caterpillars on cactus plants. Columnar cacti in protected dry forests in Puerto Rico are under severe threat from Harrisia cactus mealybugs. Surveys for parasitoids of these mealybugs conducted in Argentina, Brazil, Puerto Rico, and Florida revealed two parasitoid species as potential biocontrol agents. After development of rearing protocols and host specificity studies conducted in a Puerto Rico quarantine facility, both species were considered promising biological control agents. Further studies by researchers in Gainesville, Florida, indicated that the parasitoids had little impact on non-target mealybugs. Hurricanes were determined to be instrumental in spread of the Harrisia cactus mealybug on the islands of Puerto Rico Culebra and Vieques. Through use of genetic markers, the Harrisia mealybug was found to be comprised of a complex of at least three different species with differences in host range. As the species present on non-host plant species differed from the species specifically associated with the columnar, there is little risk of the non-cactus Harrisia mealybugs moving onto susceptible cactus host plants which helps target future biocontrol efforts. Accomplishments from this research provide new tools and approaches for biologically based management of insect pests and weeds that threaten environmentally sensitive areas or small farm and organic vegetable production.
Accomplishments
