There is a critical need in the southern U.S. and globally for new insect, disease and weed biological control for managing both native and exotic organisms (Oerke 2006, Ratcliffe et al. 2017). Biological control contributes to food security and safety by enabling sustainable production and reducing losses due to species that consume or destroy agricultural commodities (Godfray et al. 2010, Foley et al. 2011). Additionally, biological control is needed to manage an abundance of pests and weeds in natural areas without harming non-target and beneficial organisms (Landis et al. 2000). This proposal aims to continue the important work of the past seven Southern Region biological control research projects (S-192, S-238, S-267, SDC-319, SDC-351, S-1034, and S-1058) and expand the effort to develop novel pest management technologies for both crop and environmental protection. Coordinated regional collaboration is fundamental for the success of these efforts because issues to be addressed span large areas of the southern U.S. The proposed project aims to build on the many collaborations and accomplishments of this regional network of scientists engaged in biological control research.

A high level of biological control of new and established arthropod pests and weeds has been achieved in the region. Both specialist and generalist natural enemies can play important roles in biological control. While specialist natural enemies have the advantage of specific adaptations to the pest and host specificity, they can be inflexible. This rigidity can be an issue with changes in host abundance and location, and may also render them unable to survive in varying environmental conditions. In contrast, generalist natural enemies can usually readily adjust to environmental conditions and take advantage of acceptable prey or food resource. However, this ability to utilize alternate prey may disturb an unrelated food web. To develop sustainable biological control strategies, this project will assess the communities of natural enemies that provide valuable service as opposed to individual species acting alone. Efforts are continuing, for example, to increase the impact of the exotic natural enemy, Harmonia axyridis, on target and incidental pest species, as well as continue to determine its effect on other beneficial lady beetle populations. In addition to evaluation of H. axyridis (KY, FL), similar projects have been developed and will continue to characterize aphid natural enemies (OK, KY) and tritrophic interactions with several generalist predators (GA and KY).

Non-native natural enemies approved for field release by USDA-APHIS will be distributed into target pest infestations in the southern U.S. Furthermore, various cultural practices that enhance the action of existing natural enemies have become more popular and gained grower acceptance. Among the most prominent of these are conservation tillage, cover and trap crops, multiple cropping, and crop rotation. All of these practices affect the efficacy of natural enemies, as well as the abundance, timing and distribution of pest species within a field. Understanding how cultural practices interact with biological control also may yield opportunities to manipulate habitats to increase their suitability for natural enemies. However, the effective use of natural enemies in integrated pest management (IPM) programs is contingent on understanding their ecology and that of their targets, and their interactions with production and management practices. Ongoing release programs will build on new and previous evaluation studies on exotic, invasive weeds, e.g., spotted knapweed and tropical soda apple (LA, FL). Biological control programs targeting important exotic insect pests across the Southern Region include parasitoids for the red imported fire ant (AR, FL, GA, LA), hemlock woolly adelgid in several states (UK, SC), and kudzu bug (AL, AR, GA, LA, MS, SC, TN).

Integration of pesticides, natural plant base insect resistance due to secondary metabolites, or transgenic crops are alternative promising methods of insect control. Integration of the use of plant-based insect control mechanism with use of natural enemies will becoming increasingly important, necessitating specific data on natural enemy, crop and pesticide interactions. The hypothesis is that pest management will be most effective and economical if a variety of compatible technologies are developed and employed, rather than attempting to use a single option.  A new technology being developed is breeding tomato for production of acylsugars, which are glandular trichome exudates that control many important insect pests, including but not limited to thrips, whiteflies, aphids and leafminers (Hawthorne et al, 1992; Rodriguez et al 1993; Leckie et al 2012; Leckie et al 2016). Tomato lines producing acylsugars of different chemistries and levels have already been created (Leckie et al 2012, Smeda et al 2016, 2017, 2018), and the best of these lines provide extremely strong control of important insect pests, including an invasive pests (Leckie et al 2012). Furthermore, in some cases the acylsugars result in control of the insect and result in the plant escaping the virus vectored by that insect; to date, this  includes Western Flower Thrips/tomato spotted wilt virus (Smeda et al 2018) and Silver leaf whitefly/tomato yellow leaf curl virus (in preparation). This form of plant based insect/virus control predators/parasites has great potential for lower impact, less toxic management strategies that could also be compatible with the use of insect-based biological control programs in the SE region. Coordinated regional trials are needed to test efficacies and determine best practices for using this strategy in an integrated program and with natural enemies.

Development and implementation of successful biological control programs are dependent on effective communication and coordination across the region. Thus, this multi-state research project will enhance biological control of arthropod pests and weeds in the Southeastern Region of the U.S. through collaboration among practitioners. This multi-state project provides a framework for target pest selection and coordinated research that focuses on pest-natural enemy complexes, addressing both entomology and weed science. Arthropod pest and weed biological control are based on many of the same ecological principles, and researchers from the two fields benefit greatly from information exchange and research collaboration. Although the methodologies for controlling arthropod pests and weeds may differ, the two fields share some of the same scientific issues (e.g., introduction strategies, genetics of colonization, evaluation of natural enemy impact, etc.). Further evidence of the conceptual similarities between these two fields is illustrated by the fact that some individuals involved in this project conduct research in both arthropod pest and weed systems.

Biological control is one of the most selective, cost-effective and environmentally sustainable pest management practices for controlling arthropod pests and weeds. Furthermore, it is increasingly important in IPM and sustainable agriculture as broad-spectrum pesticide use declines. The fundamental principle in applied biological control is to select an appropriate agent or combination of agents that will bring about the desired level of pest suppression with minimal impact on non-target species. Reductions in insecticide and herbicide applications should enable farmers and ranchers to reduce production costs. Although it is difficult to put a monetary value on the savings due to biological control, the benefit: cost ratio generally supports its use in IPM (Naranjo et al. 2015). The Tropical Soda Apple Biological Control Project currently saves ranchers an estimated $11 million annually that would have been spent on chemical and mechanical control of this invasive weed. Another success story is the Mole Cricket Biological Control Project that perpetually saves ranchers approximately $13.6 million annually in pest control costs (Mhina et al. 2016). Successful control of giant salvinia has been achieved along southern regions of Texas and Louisiana, saving hundreds of thousands of dollars annually in mechanical and chemical control. In addition, successful biological control research involving S-1058 members has contributed to TAME Melaleuca (http://tame.ifas.ufl.edu/index.shtml), an effective IPM program for this invasive tree. Considerable ecosystem recovery has been documented during a 17-year period (1997–2014) following the release of biological control agents of the melaleuca tree. Following an 85% reduction in melaleuca trees, the formerly infested areas are gradually changing to more diverse plant communities consisting mostly of native species.