Biological Control of Arthropod Pests and Weeds

NON-TECHNICAL SUMMARY: The growing emphasis on environmental and food safety issues has intensified interest in the development of biological controls as a means for controlling pests. The effective use of natural enemies in biological control programs is contingent upon understanding their ecology and that of their targets, their interaction with production practices, and the most effective means of using them. Further exotic pests continue to pose threats to American agriculture and well being, making continued efforts in importation biological control relevant and necessary. At the same time, target and non-target effects of these introductions must be documented to assure the continued value and safety of importation biological control. Resident populations of natural enemies do not always provide adequate levels of pest suppression. In such circumstances, it may be necessary to release native or introduced natural enemies. Success of this option, however, is dependent on effective production, distribution, and release technologies for the natural enemies to be so used (Ridgway, 1998). This proposal addresses each of the aspects of biological control noted above and places them in the overall context of the Southern Region. The project will focus on improving biological control of insects and weeds in the southern region of the US. The outcomes will contribute to improved understanding of the ecology of natural enemies, the interactions of pests and their natural enemies, and the directed use of natural enemies to enhance the sustainability of pest management systems.<P>

APPROACH: <BR>OBJECTIVE 1: Characterize and evaluate the effect of established natural enemies. Evaluation of introduced natural enemies on target species will be accomplished with manipulative experiments, by comparing biological control treatments to experimental units from which biological control organisms have been excluded. Post-release monitoring programs will focus on state or federally listed threatened and endangered species, species that are critical to ecosystems and others. Insect and weed biological control researchers will collaborate during the screening of natural enemies of insect pests. <P> OBJECTIVE 2: Exploration, importation, and assessment of natural enemies for invasive pests. Foreign exploration and surveys will be conducted cooperatively to identify biological control agents in the home range of pest species. The regional project will coordinate surveys and share information regarding planned foreign explorations to make the most efficient use of quarantine facilities. Modern methods will be used to identify countries of origin and biological control agent biotypes. Promising natural enemies will be imported into quarantine facilities for pre-release risk assessment and evaluation of production and biological characteristics. Only natural enemies that have undergone risk assessment will be released from quarantine. <P> OBJECTIVE 3: Implementation, evaluation, and enhancement of biological control. Current and novel pesticides will be assayed in the laboratory, greenhouse and field. Assays will vary because of the diversity of plants, pests, and natural enemies in the tests. Greenhouse studies will assess pesticides and natural enemies under more natural circumstances and provide insights into studies conducted in the field. Field evaluations will characterize effects of pesticides on natural enemy populations and biological control efficacy in relevant production systems. The interactions of natural enemies with transgenic crops will be quantified. Spatial and temporal patterns of natural enemy abundance and diversity in relation to transgenic crops will be characterized through detailed surveys of natural enemies in transgenic and non-transgenic crops. The influence of transgenic plants on natural enemy dynamics at the regional level will be evaluated by manipulating spatial patterns and ratios of transgenic and non-transgenic plantings and examining the population dynamics of the natural enemies within the manipulated system. The effects of transgenic crops on fitness of natural enemies, directly and through the hosts or prey, will be examined by measuring relevant life-history traits, such as longevity, fecundity and host finding. Various cultural practices have gained grower acceptance in the Southern Region. Among the most prominent of these are conservation tillage, cover crops, multiple cropping and crop rotation, and their impact on biological control will be assessed. <P> OBJECTIVE 4: Evaluate the benefits and risks of natural enemies. Studies will measure host/prey suppression by natural enemies in selected commodities and assess the effect of existing natural enemies on the efficacy of introduced biological control agents.