S1073: Biological Control of Arthropod Pests and Weeds
(Multistate Research Project)
S1073: Biological Control of Arthropod Pests and Weeds
Duration: 10/01/2018 to 09/30/2023
Statement of Issues and Justification
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.
Related, Current and Previous Work
Summary of accomplishments of previous research. The Southeastern Region has a strong record of research and implementation in biological control (Appendix 1) that target multiple weeds and insect pests (Appendix 2). The four predecessors of this Multistate Research Project tackled a variety of these problems and successfully affected various target pest populations in this region. The initial SR regional projects (S-192 and S-238) were focused primarily on importation biological control. The objectives of S-267 were broadened to reflect the widening interests in conservation and augmentation biological control in the Southern Region. The objectives of S-303 were expanded to incorporate novel technologies (e.g., transgenic varieties, cultural practices, selective pesticides) and needs (e.g., suppression of invasive species, alternative pest management tools, cost-effective and environmentally sound pest management) in the Southern Region. S-1034 built upon successes of past projects on biological control in the Southern Region and new technologies and emerging needs. S-1058 further built on the prior multistate collaborations to address emerging weeds and insect pests. Below we review the major accomplishments achieved for each key objective (also see Appendix 1 for recent publications), as well as previous work outside of this project in support of the new objective 4.
Objective 1: To discover, assess, and release new biological control agents
The weevil, Larinus minutus, is established and effective for reducing the seed of spotted knapweed in Arkansas and other states (Minteer et al. 2014, 2016). The red imported fire ant now has two species of parasitoids established in Arkansas that are reducing populations of this exotic pest. The first major goal was to characterize and evaluate the effect of these and other natural enemies. Further work is needed to characterize the distribution of these biocontrol agents for fire ants and knapweed in Arkansas, and whether introduction of new agents will improve establishment success
Biological control research was conducted against the hemlock woolly adelgid: 1) Located a suitable site to implement a multi-tactical IPM approach combining biological and chemical control (Benton et al., 2015), 2) Assessed the impact of the multiple biological control agents released against hemlock woolly adelgid on eastern hemlock, 3) Cooperated in a multistate approach to determine the establishment of Laricobius nigrinus (Wiggins et al.,2016), 4) Investigated the use of whole-tree cages to promote and evaluate establishment, reproduction, and survival of L. osakensis and Sasajiscymnus tsugae, 5) Evaluated mortality of eastern hemlock in biologically treated areas using spatial analyses, 6) Assessed establishment of field populations of S. tsugae and L. nigrinus, and 7) Determined seasonality and impact of established natural enemies following large whole-tree canopy releases. Additionally, the braconid, Spathius agrili, was collected from areas of release against emerald ash borer in Tennessee (Hooie, et al. 2014).
Laboratory host specificity of Calophya terebinthifolii was determined with no-choice oviposition and gall formation experiments on potted Brazilian peppertree plants maintained in a Florida greenhouse (Cuda, et al., 2016). On average, 220.3 eggs were deposited on the target weed and survival to the adult stage was 42.7%. Gall initiation occurred on Schinus molle, followed by rapid death of first instars. Eggs laid on other non-target species either desiccated before they hatched or first instars were unable to induce gall formation, leading to death of the immatures. Normal gall development and subsequent adult emergence of C. terebinthifolii occurred only on Brazilian peppertree, which confirmed the insect is a Brazilian peppertree specialist (Prade et al., in prep). A colony of the stem boring weevil, Apocnemidophorus pipitizi, produced a total of 45,918 adults with a 1:1 sex ratio.
The influence of plant architecture, specifically the number of leaves and branches, on the foraging behavior of the predatory beetle, Cryptolaemus montrouzieiri, when offered varying densities of the invasive citrus mealybug, Planococcus citri was investigated. In South Carolina, the citrus mealybug is a major pest of horticultural crops in both outdoor production and protected cultures. The biology, ecology and natural enemies of several native and invasive scale insect species, namely cottony maple leaf scale, juniper scale and cottony camellia scale have been reviewed, along with the Madeira mealy bug (Rameshkumar et al, 2013). The natural enemies associated with oak lecanium scale were sampled annually with tissue collection and sticky cards. A total of 16 parasitoid species (Aphelinidae, Encyrtidae, Eulophidae and Pteromalidae), 8 coccinellid species, Chrysoperla rufilabris (Neuroptera) and Tricorynus confusus were found associated with oak lecanium scale. Coccophagus lycimnia other Cocophagus spp. and a Eunotus sp., Blasthorix sp., and Encyrtus sp. were the major parasitoids responsible for 78% parasitism of nymphs and 66% parasitism in adults. A Pachyneuron sp. was the major hyperparasitoid, and Chilocorus stigma and C. rufilabris was the major predators. Parasitoids were most active in late April and May, while the predators were present year round.
Objective 2: To characterize and evaluate the impact of native and introduced agents
Natural enemies were sampled in multiple cropping systems in Kentucky to characterize their role in biological control, using a combination of molecular data, behavioral experiments and field research. Increased levels of vegetation diversity enhanced biological control services afforded by coccinellids. Soybeans were sampled from late vegetative through reproductive plant growth stages at approximately weekly intervals for predaceous insects and spiders. Nabis spp. and Geocoris spp. were the dominant hemipteran predators, with Geocoris spp. more than four times as abundant as Nabis spp. Very few Orius spp. were collected. Harmonia axyridis (57% of total lady beetles) and Coleomegilla maculata (35%) accounted for most of the lady beetles collected, with the remainder being Cycloneda munda. The striped lynx spider was the most abundant spider, accounting for 51% of these predators.
Interactions between Diaeretiella rapae (canola-aphid parasitoid) and Lysiphlebus testaceipes (wheat-aphid parasitoid) were examined in Oklahoma winter canola landscapes. Competition studies were initiated based on sticky trap captures revealing high numbers of wheat-aphid parasitoids in winter canola fields; wheat-aphid parasitoids may be interfering with canola-aphid parasitoids. Initial results indicated that dispersing wheat-aphid parasitoids are disrupting foraging by canola-aphid parasitoids and allowing aphid populations to remain high.
The multi-state project to characterize the natural enemy complex of the lecanium scales, Parthenolecanium corni and P. quercifex, in the urban landscape was completed in 2015 (GA, SC, NC, VA, VT). A total of 22 parasitoid species and 12 coleopteran and neuropteran predators were documented, the most numerous of which were Coccophagus lycimnia (Aphelinidae), Blastothrix spp. (Encyrtidae), Encyrtus spp. (Encyrtidae), Metaphycus spp. (Encyrtidae), Eunotus spp. (Pteromalidae), a Pachyneuron sp. (Pteromalidae), Chrysoperla rufilabris (Chrysopidae), Hyperaspis signata spp. group (Coccinellidae) and Anthribus nebulosus (Anthribidae) (Robayo Camacho and Chong 2015). Species diversity of the parasitoids and predators was similar across the four states. Among the major parasitoids, C. lycimnia was the only species that emerged from scale insect nymphs. The natural enemies were active from early March to September. Parasitism rates ranged from 52 to 92%. Five main parasitoids (Blastothrix sp. 1, Coccophagus lycimnia (Walker), Encyrtus sp. 1, Eunotus spp. and Pachyneuron spp.) emerged from adults and parasitism by these species reduced the fecundity of the scales (Chong et al., 2015).
Research was conducted on the impact of herbivores that attack Brazilian peppertree, including the leaf galling psyllid, Calophya terebinthifolii (Hemiptera: Calophyidae). Potted plants were maintained at a field site at the Universidade Regional de Blumenau (FURB) experimental unit located in Gaspar, Santa Catarina, Brazil. From mid-November 2015 to mid-January 2016, an increase in the number of galled leaves was observed in all the treatments. The high density treatment group reached a maximum of 33 galled leaves on 15 December 2015, followed by the low density group (34 leaves on 11 January 2016), and for comparison the natural treatment group (16 leaves on 11 January 2016). Insecticide applications effectively excluded the psyllid from the control plants for the first three months of the experiment. There appeared to be a reduction in the average number of flowers and fruits produced per plant as a function of psyllid density. Although preliminary, the results of the pre-release efficacy assessment of C. terebinthifolii in southeastern Brazil showed that flower and fruit production of Brazilian peppertree may be negatively impacted by the insect.
Effectiveness of the hydrilla tip mining midge, Cricotopus lebetis Sublette (Diptera: Chironomidae), was assessed in laboratory, semi-field and field studies. Field testing was performed in limnocorrals (1 m diam. x 1 m depth) installed in three ponds at the UF/IFAS Center for Aquatic and Invasive Plants. Over two years, all possible combinations of the hydrilla tip mining midge with a disease causing fungal pathogen [Mycoleptodiscus terrestris Gerd.) Ostaz.] (Mt), and low concentrations of the herbicide imazamox, an acetolactate synthase (ALS) inhibitor, were tested to determine the most effective combination to develop an IPM plan. As with laboratory trials, Cricotopus lebetis and Mt together or in combination with imazamox significantly reduced hydrilla biomass compared to untreated controls.
Objective 3: To develop augmentation and conservation biological control tactics
The widely distributed predatory lady beetle, Hippodamia convergens Guerin (Coleoptera: Coccinellidae), was studied to examine possible introgression of genes from beetles that are mass-collected in California annually and released in eastern North America for augmentative biological control (Amaral, et al. 2015). The average observed heterozygosity was 0.44 and all loci were polymorphic (mean = 20.57 alleles/locus). The number of genetically distinct sub-populations of H. convergens was estimated to be at least two. The analyses indicated that Californian genotypes are admixed within eastern populations of H. convergens. The California populations were larger than all sampled eastern U.S. populations, suggesting recent declines in the latter (Sethuraman et al., 2015).
Augmentation of Tamarixia radiata and other natural enemies of the Asian citrus psyllid was enhanced by improving colonization, rearing, quality control, distribution, release, and evaluation methods. The efficiency was improved for mass rearing T. radiata by the Florida Department of Agriculture and Consumer Services, Division of Plant Industry and other states and countries for biological control of the Asian citrus psyllid, Diaphorina citri. Fifth instar nymphs of D. citri were the preferred host instar and yielded the largest T. radiata progeny with the greatest percentage of females (Kerr et al. 2014).
There was a higher density of all thrips species collected in Florida from flowers in the ‘Festival’ strawberry variety compared with ‘Radiance’ and ‘Sensation’. A high density of thrips also was observed in the peppers and wild Brassica spp.. Several thrips predators were collected from strawberry, Brassica spp., and pepper flowers, including Orius spp., Scolothrips sexmaculatus, and syrphid and coccinellid larvae. The predominant predator was Orius spp., and there was a higher density of Orius spp. in the pepper compared with the strawberry flowers (Funderburk et. al, 2015a, b).
The musk thistle head weevil, Rhinocyllus conicus, was imported into the U.S. for control of musk thistle, Carduus nutans. The weevil continues to expand its range from Northwest Louisiana into southwestern Arkansas. Infestation in Southwest Arkansas has increased from 7.6 weevils per flowerhead in 2010 to 11.0 in 2013. Infested flowerheads increased from 43% to 96% during the same period.
The salvinia weevil, Cyrtobagous salviniae, was imported into the U.S. for control of the invasive aquatic fern, giant salvinia, Salvinia molesta. This weevil was released into Cross Lake in 2013 to investigate its potential as a biocontrol agent in Northwest Louisiana (Micinski, et al., 2016a). In March of 2013, salvinia weevils were released at two sites on the west end of Cross Lake. The first release site was approximately 26,000 m2 and 8300 weevils were released at 12 locations within the area. The second release site was about 52,000 m2 and 13,600 weevils were released at 13 locations within that area. In subsequent samples taken from the release locations, weevil numbers increased from 0.15 weevils/kg of giant salvinia in early May to 10.8 weevils/kg in late September. During the same time period the percentage of sites where weevils were recovered increased from 12.5% to 85.7% (Micinski, et al., 2016b). Mass rearing of weevils for basic biological studies and field releases is underway at the Red River Research Station.
Compatibility of a novel miticide, cyflumetofen (Sultan), with the predatory mites Amblyseius swirskii and Phytoseiuslus persimilis has been evaluated in greenhouses since 2013. The study found that cyflumetofen did not cause elevated acute or residual mortality in both predatory mite species. The new miticide also did not cause a reduction in the reproduction of A. swirskii.
The influence of foliar sprays of insecticides and selective application methods of neonicotinoids on the activity and impacts of natural enemies was investigated in selected urban landscapes in South Carolina. The results demonstrated that foliar applications of organophaphates, pyrethroids and neonicotinoids reduce the populations of both the oak lecanium scale and its associated parasitoids, while horticultural oil and insect growth regulators had negligible impacts on the parasitoids and predators. Applications of imidacloprid and dinotefuran through indirect methods (e.g., soil drench, trunk spray and granules) were found to have minimal impacts on the activities and abundance of natural enemies compared with foliar applications of the same active ingredients.
Three species of parasitoids emerged from cogongrass galls in Florida, including Platygaster orseoliae (Hymenoptera: Platygasteridae), Prospicroscytus mirficus (Hymenoptera: Pteromalidae), and an Aprostocetus sp. (Hymenoptera: Eulophidae) (Overholt et al., 2017). In 2016, adults emerged from 14 of 215 galls (6.5%) collected in February, including six that emerged and died during transport. The other eight adults (2 females and 6 males) emerged within the first two days in quarantine and were placed together in a cage with cogongrass plants. Mating or oviposition were not observed and all parasitoids died within 24 hours of emergence. Plants were held for six weeks but no galls formed, indicating a failure to obtain progeny. From this collection, a subset of galls (n=71) was held individually to allow calculation of parasitism. Aprostocetus spp., P. orseoliae and an unidentified eupelmid emerged from 26 (37%) of galls.
Banker plant systems were improved by examining how species and mixtures of species affect parasitoid efficacy and how they interact with each other and thrips prey to affect impact and release rates (Jandricic et al., 2016). Research also was conducted in North Carolina to assess the compatibility of insecticides with biological control organisms. Research in Georgia is assessing the ecotypic plant species that will establish easily in marginal lands and provide improved pollinator populations and natural enemy populations. To understand how plant stress affects ambrosia beetle attraction and attack rate, research was conducted on water stress. Experiments improved ambrosia beetle IPM by developing a moisture threshold in media that growers can use to make plants less susceptible (Ranger et al., 2016).
Objective 4. To develop integrated pest management programs that have a biological control component. As a new objective for this multistate program, there is no specific progress to report from the previous cycle of this multistate project. However this new objective is the natural progression of some of the work of Objectives 1 to 3, and of work previously done by researchers outside of this project. Incorporation of biologically based controls into best practices for integrated pest management requires a systems approach to testing incorporation of the control into crop production. One approach is to investigate tomato lines bred for acylsugar mediated resistance are a promising example of plant-based biological control (Leckie et al 2012, Smeda et al 2018). While preliminary field trials of tomato lines producing acylsugars, under heavy natural infection by Silverleaf whiteflies in absence of pesticides, showed that the acylsugar tomato lines had 95% or more reduction of SLW eggs and insects at all stages of development, the lines are visited by bees without issue. However, determination of the impacts of these lines on additional insect pest species is also needed, as well as tests of impacts on predators/parasites species that would be a cooperative project among members of this multistate project. Another approach for improving IPM systems is continued work on current management approaches in IPM programs and compatibility with biological control. Multiple participants in this project are working towards these goals.
Areas requiring further investigation and research mission. The new project will incorporate many of the aspects (importation, conservation, evaluation, etc.) from previous projects but focus on cooperative biological control issues common or likely to be common across the Southern Region including: (1) stink bugs, (2) fire ants, (3) invasive weeds, (4) role of beneficial organisms, including insect resistant crops, in diverse landscapes, and (5) techniques for evaluating biological control programs and risk assessments, based on broad range of control organisms and strategies, and determining how best to incorporate broad based biological controls in agricultural and nonagricultural settings. There is a growing concern on how to improve the quality of agricultural habitats for pollinators and natural enemies, and our group has responded by focusing more attention across the southern states on conservation biological control. The membership includes a diversity of productive scientists (Appendix 1) from the participating states in the Southern Region ranging in expertise from taxonomy to applied field evaluations that will target numerous weeds and insect pests (Appendix 2). Our stakeholders include farmers, land managers, homeowners, green industries, regulatory agencies, and commodity groups.
To discover, assess, and release new biological control agents
To characterize and evaluate the impact of native and introduced agents
To develop augmentation and conservation biological control tactics, especially to improve the quality of agricultural habitats for pollinators
To develop integrated pest management programs that have a biological control component
This project will involve traditional methods of foreign and domestic exploration for discovering and importing new biological control agents with potential to manage arthropod pests (Appendix 2. Evaluation of predation, parasitism and host feeding will be conducted in quarantine and eventually impact on the target organisms will be determined in the field. Candidate agents for augmentation will be made available to government and private sector cooperators. Conservation biological control will involve habitat manipulation and methods for preserving beneficial species. New and improved biological control technologies will address key problems and be delivered via members of this multistate project for improving pest management of invasive pest species. This project will integrate techniques with other IPM tactics and provide Extension support to include natural enemies in pest management systems. Project participants will meet annually to discuss progress as well as propose and refine research methods. Emerging pest problems also will be discussed at the annual meeting and new project ideas developed in response to priority needs. The integration of laboratory, field and molecular approaches will be used to delineate the role of native and recently introduced natural enemies in biological control. These research efforts will enhance our understanding of natural enemy-pest interactions, providing the framework and capability for implementation of biological control. Characterization of synergistic and antagonistic interactions between natural enemies will enable the most effective species to be deployed.
Objective 1: To discover, assess, and release new biological control agents
Classical biological control projects in the Southern region will involve continued foreign exploration, importation and pre-release assessment. Surveys and collections will be conducted in the native range of target organisms to determine the diversity and seasonal activity of the natural enemies. Arthropods will be collected with beat sheets, sticky cards, traps, or nets. Host-range tests will be conducted in quarantine to ensure the safety of the candidate agents. Wapshere's centrifugal phylogenetic method and published molecular phylogenies will be used to develop test plant lists for candidate biocontrol agents. Efforts will be made to assess the host specificity of natural enemies of arthropods including native species and commercially available natural enemies. Risk assessment for weed control projects will follow the guidelines established by the Technical Advisory Group (TAG) for Biological Control of Weeds and for arthropod agents the federal (USDA-APHIS) and state requirements.
Objective 2: To characterize and evaluate the impact of native and introduced agents.
The integration of laboratory, field and molecular approaches will be used to delineate the role of native and recently introduced natural enemies in biological control. Climate matching software and ecological niche modeling will be used to determine the potential distribution of natural enemies. Field evaluations will determine the efficacy of biological control in key production systems and natural areas. Spatial and temporal patterns of natural enemy abundance and diversity in relation to crops and natural systems w ill be characterized through detailed studies of natural enemies in crop land and natural areas needing biological control of weeds. Feeding damage will be measured based on feeding behavior (e.g. leaf area consumed for folivores, stem tunnel length for stemborers, number of galls for stem gallers, reduction in eggs laid (oviposition) developing insects after oviposition, and/or virus transmitted by vector insect species. etc.). Methodologies will include collection of natural infestations for parasitoid emergence, the deployment of sentinel individuals, and trapping of parasitoid adults, and determining the presence/activity of parasites/predators in the plant populations. Mapping the impact of biological control agents of weeds has been improved due to access to remote sensing (drones, high resolution satellites). Reduction in weed densities due to biocontrol and potential recovery of native vegetation will be quantified using drones and other, more traditional, methods (e.g.; post-release surveys, demography studies).
Objective 3: To develop augmentation and conservation biological control tactics
Methods will be developed for mass rearing candidate biological control agents and laboratory colonies will be established of arthropod parasitoids and predators. Life table studies will be conducted to obtain basic biological information about survival, fecundity, longevity and developmental time. Comparisons between different rearing conditions will be performed with an analysis of different demographic parameters. Damage due to tunneling in target weeds will be measured. Mass rearing in greenhouses will provide specimens for basic biological studies, as well as for field releases.
Objective 4: To develop integrated pest management programs that have a biological control component Conventional/ biorational insecticides and ultraviolet-reflective technologies will be evaluated for their potential use with natural enemies in IPM systems. Enclosures and exclosures will be used to study the impact of natural enemies on target pests. Studies will be conducted to determine the effects of cultural practices, such as fertilization and cover crop cultivation, on the natural enemies. Assays of insecticides will be conducted in the laboratory and the field to determine the most compatible insecticides to be used in conjunction with natural enemies.
For plant based biological control, cooperative regional trials will use indoor tests and/or regional field tests (as most appropriate in that year) to determine the impact of insect resistant plants on targeted insect pests, and predators/parasites, to determine the potential for use of plant based resistance, with and without predators/parasites, for integrated pest control in the SE US. The tomato entries used in these trials would be lines or hybrids that produce acylsugars at different levels or of different types.
Measurement of Progress and Results
- There is a diversity of biocontrol programs targeting weed and insect pests that are joined in this project. Outputs will be communicated through publication, individual reporting, and collective annual reporting as part of the regional project (see Appendix 1-publications from 2012-2017). For objective 1, our project will discover new biological control agents and provide information for implementation and testing. This is being conducted to target invasive weeds and insect pests. Within objective 2, which follows objective 1 logically, our project will evaluate the impact of these agents. For objective 3, research efforts will be focused on the development of augmentation and conservation tactics to improve the efficacy of biological control, and monitor the success of establishment and health of biological control communities. Objective 4 follows to integrate these new technologies into IPM strategies both in agricultural contexts and management of invasive species and ornamental pests.
- Another key component of our outputs, in addition to reporting and publishing in scientific journals, is conference symposia and extension presentations to stakeholders. All of our members are asked to speak at local, regional, national and international conferences to provide information on biological control. Through this regional project we will annually compile publications and presentations to help organize, consolidate and communicate biological control information to the southern U.S.
- Results of regional trials of tomato lines with different types or levels of acylsugars will guide the release of the lines and instructional information provided to seed companies, so that the new insect resistant hybrids available to growers will have optimal control for the greatest number of insect pest species
Outcomes or Projected Impacts
- o Programs targeting important exotic insect pests across the Southern Region include releases of parasitoids for the red imported fire ant in AR, FL, GA, LA (e.g., Johnson et al. 2010) and hemlock woolly adelgid in several states (e.g., Hakeem et al. 2010).
- A new, large cooperative project facilitated by USDA-ARS (MS) researchers will involve evaluation and releases of approved natural enemies for the kudzu bug in all states potentially impacted by this exotic pest (AL, AR, LA, MS, SC, TN). The outcomes of research and collaboration from this regional multistate project will reach stakeholders that span natural systems, industry and agricultural stakeholders on biological control.
- Our work will advance IPM and biological control of vegetable pests by determining behavioral responses of the southern green stink bug, Nezara viridula, to selected trap crops (buckwheat and sorghum) at various stages of development. Furthermore, blueberry and small fruit systems have many pests in the south and a new invasive pest has caused significant losses and unsuccessful increase in insecticide use. The sugarcane aphid has become a serious problem, and we will develop and implement an economically and environmentally sound IPM system for suppression of this pest in sweet sorghum fields based upon cultural (planting/ harvest dates) and biological (naturally-occurring aphid predators and parasitoids) controls.
- There are several biological control agents in the pipeline for non-native plants in the southern U.S. For example, petitions of release have been approved for Brazilian peppertree and Chinese tallow which are among the worst upland weeds in Florida and southern U.S., respectively. In 2018, the Chinese flea beetle (Bikashia collaris) could be available for initial field releases in Chinese tallow infestations. Because Chinese tallow infestations occur in almost every state in the Southern Region, this project offers unique opportunities to establish mass rearing facilities, release programs, and extension outputs. Other projects include cogongrass and earleaf acacia, which initiating biological control would contribute to environmentally sustainable management and reduce current costs of management of these highly invasive and noxious weeds that threaten the Everglades
- The cooperative work on testing of acylsugar resistance lines will advance the utilization of this means of insect control while reducing need for pesticidal sprays
Milestones(0):Objective 1: To discover, assess, and release new biological control agents o To save hemlock forests from HWA, predators must be released and established at the onset of an infestation. o To control Brazilian pepper tree permits need to be issued by APHIS PPQ in FY 2018 in order to initiate field releases and evaluations of the psyllid C. latiforceps and the thrips P. ichini. Both insects were recommended for field release by the TAG in 2016 (April and May, respectively). o Permits need to be issued by APHIS PPQ in FY 2018 for Chinese tallow biological control agents in order to initiate field releases and evaluations of the flea beetle B. collaris which was recommended for field release by the TAG in 2016. o Due to expansion of emerald ash borer to southern regions (TX, LA, SC, TN), effectiveness of exotic parasitoids must be evaluated. In addition, efforts should be made to discover parasitoids in southern China which might be more compatible to climates in the Deep South. o In order to initiate host range testing of the gall forming midge O. javanica, a potential biological control for cogongrass, in 2018, preliminary screening of the FL peninsula (high priority) and Gulf coast clones of cogongrass must be completed in Indonesia to determine if the midge will attack Florida cogongrass.
(0):Objective 2: To characterize and evaluate the impact of native and introduced agents o Assessing broad mite biological control will require further identification of predatory mite species present when broad mite densities were reduced on blackberries. It is unknown which predator mite species would be the best biological control agent to release against broad mites in field blackberries. These findings will be helpful for small fruit systems across the south. Further study is needed to understand effects of density and interactions with other species. o Further data needed on predatory link to key pests in blueberry systems. Molecular gut content analysis will be used to assess predatory activity on key pests in blueberry landscapes (2018-22). o Native and introduced natural enemies of additional scale insect species (e.g. false oleander scale and crape myrtle bark scale) will be identified in 2018-2020, and their impacts on the scale insect population and plant health will be assessed in 2020-2022. o The eastward progression of the program to redistribute natural enemies of spotted knapweed in Virginia will reduce spotted knapweed dominance in several important habitats in the region. Reduction of this dominant weed will enhance biodiversity, improve pollinator habitats, reduce roadside mowing challenges and increase motorist visibility at intersections where the weed is not well managed. o Obtain extramural funding in FY2018 to support mass rearing of the hydrilla tip mining midge, C. lebetis, and perform field release/evaluation studies. o The biological control program of giant salvinia will require several steps including the mass rearing of weevils, coordination of releases with stakeholders, and monthly sampling at study sites. Access to mass reared agents early in the growing season will be critical to start the biological control of emerald ash borer and air potato. o Redistribution of the spotted knapweed natural enemies Larinus minutus and Cyphocleonus achates in Virginia during 2019 will require development, submission and approval of a permit request to allow the interstate movement and release of these species (tentatively from Colorado) during 2018. Evaluation of the impact of these two-spotted knapweed natural enemies in 2022 and beyond will require establishment in multiple locales between 2019 and 2021. o Understanding the phenology of biological control agents as they feed on flower heads of knapweeds is necessary before developing a map of established agents, and assessing the loss of effectiveness of the insects due to mowing at biologically inappropriate times before a recommendation can be made. o Determine the impact of acylsugar producing tomato lines and hybrids on a variety of insect pest species in tomato field setting in multiple SE regional states. Since the range of insect pests shown to be impacted by acylsugars is extremely broad, possible insect target include SLW, thrips species, mite species, leafminers, aphids, and stinkbugs.
(0):Objective 3: To develop augmentation and conservation biological control tactics o Assess the influence of buckwheat (Fagopyrum esculeutum) border strips on the seasonal occurrence, abundance, and impact of natural enemies (predators and parasitoids) of sugarcane aphid (2018) and evaluate the effect of planting/harvest dates on sugarcane aphid populations (2019). o The effects of selected pesticides on biological control agents will be documented in diverse agricultural systems (e.g., wheat-canola, urban forestry, ornamental plant) in an effort to conserve and enhance the impact of extant natural enemies. o Efficacy of native natural enemies will be documented and information will inform conservation biological efforts in diverse agroecosystems (aphids, spotted winged drosophila, stink bugs, whiteflies, thrips, scale insects).
(0):Objective 4: To develop integrated pest management programs that have a biological control component o Acylsugars - Tomato growers and potentially other crops would benefit from this research since use of insect resistant tomato hybrids would protect plant health and tomato quality and yield while substantially reducing the use of pesticides and the labor currently spent on insect control. Reduction of pesticide usage would benefit workers and the environment in the agricultural regions. Non-target testing is needed to assess compatibility of using this technology with natural communities and augmentation programs. Similarly, work to determine the degree to which use of plant based resistance/reduction of pesticides would reduce pesticide impact on desirable non target species. This part of the project could be a model for use of other natural plant based resistance mechanisms being discovered. o IPM programs targeting southern green stink bug, Nezara viridula, in multiple crops will improve the ecological sustainability and reduce risks to biodiversity. o Reduced insecticide and further integration of biorational approaches will improve the diversity of beneficial arthropods in agroecosystems. o IPM guides will be developed in 2020-2022 to outline best management practices that incorporate chemical, biological and cultural management tactics for whiteflies, thrips and scale insects in urban forestry and ornamental plant systems.
Projected ParticipationView Appendix E: Participation
Results of the project will be made available to the following target audiences: university and USDA scientists, university Extension specialists, county and multi-county Extension agents, post-doctoral scientists, graduate students, undergraduate students, agricultural producers and consultants, citizen scientists, landowners, forest and land managers, Exotic Pest Plant Councils, agricultural industry and environmental groups, state and federal agencies (NIFA, USFS, NRCS, NPS), and the general public. Biological control information will be disseminated via Extension publications, trainings, grower meetings, papers at professional society meetings, refereed journal articles, newsletters, trade journal articles, short videos, fact sheets, field demonstrations, invasive species workshops, outreach activities, university seminars, presentations at professional society meetings, websites, social media, and field, email, and telephone consultations. Release information on new tomato lines is also provided to national and international seed companies though annual reports, field day presentations, and personal communications.
The Multistate Research Project is coordinated by a technical committee composed of an administrative advisor (non-voting), NIFA Representative (non-voting), one official (appointed by the SAES director) and additional voluntary technical representatives for each participating SAES, technical representatives from 1890 universities, and volunteers from participating USDA laboratories and other research agencies appointed by appropriate administrators. SAES-designated technical committee members are limited to one vote on matters of major importance regardless of the number of representatives from an institution; however, all representatives are allowed to vote on matters that the voting members feel should be decided by all.
All members of the technical committee are eligible for office, regardless of sponsoring agency affiliation. The chair, in consultation with the administrative advisor, will notify the technical committee members of the time and place of meetings (according to the suggestions of the technical committee members), prepare the agenda, and preside at meetings of the technical committee and executive members. The chair and secretary will be responsible for preparing an annual report for the regional project and having it posted on the NIMSS website. The secretary will assist the chair and preside in the chair's absence, record and distribute the minutes, and perform other duties as requested by the technical committee or the administrative advisor. The secretary will be elected for a one-year term by the voting members of the technical committee and will succeed the chair who has served for one or more years.
The technical committee will meet annually to discuss progress, as well as propose and refine research coordination for all objectives. Additionally, emerging pest problems will be discussed and new projects developed in response to a need for multistate collaboration. Summaries of the past year's research from each SAES will be exchanged and placed on the NIMSS website, research plans outlined, the next meeting location and time decided, and a secretary elected. When possible and of benefit, annual meetings will be held jointly with related regional technical committees. The executive committee (chair, past chair, secretary and administrative advisor) has authority to conduct business between annual meetings and perform other duties as requested by the technical committee, including writing and submitting a replacement project every five years.
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