Michael Stout

Michael Stout.
Title Department Head and Professor
Department Entomology Department
E-mail MStout@agcenter.lsu.edu
Address 1 404 Life Sciences Building, LSU
Baton Rouge, LA 70803
Phone 225-578-1628
Fax 225-578-1643

Books and book chapters

Heinrichs, E.A., Nwilene, F.E., Stout, M.J., Hadi, B.A.R., and Freitas, T. 2017. Rice insect pests and their management. Burleigh Dodds Science Publishing, Cambridge, UK (ISBN: 978 1 78676 196 5; www.bdspublishing.com).

Stout, M.J. 2020. Plant-insect interactions, host-plant resistance, and pest management. In: Kogan, M. and L. Higley (eds.). Integrated management of insect, mite and nematode pests in agriculture - Vol 2: Current and Future Developments in IPM. Burleigh Dodds Science Publishing , Cambridge, UK.

Stout, M. J., H. Kurabchew, and G. L. D. Leite. 2018. Host plant resistance in tomato. In: Wakil, W. (ed.), Sustainable Management of Arthropod Pests of Tomato. Elsevier, Oxford, UK.

Refereed journal articles

Souza, B. H. S., E. Costa, Z. Ribeiro, B. Perlatti, M. Cruz, M. Forim, A. Boiça Jr., and M.J. Stout. 2021. Soybean leaf age and plant stage influence expression of resistance to velvet bean caterpillar and fall armyworm. Chemoecology https://doi.org/10.1007/s00049-021-00360-6.

Villegas, J.M., B.E. Wilson, and M.J. Stout. 2021. Integration of host plant resistance and cultural tactics for management of root- and stem- feeding insect pests in rice. Frontiers in Plant Science, in press.

Bhavanam, S. and M. J. Stout. 2021. Seed treatment with jasmonic acid and methyl jasmonate induces resistance to insects but reduces plant growth and yield in rice, Oryza sativa. Frontiers in Plant Science, in press.

Bhavanam, S., B. Wilson, B. Blackman, and M.J. Stout. 2021. Biology and management of the rice stink bug (Hemiptera: Pentatomidae) in rice, Oryza sativa. Journal of Integrated Pest Management, 12 (1): 20

Lanka, S.K., Davis, J.A., Elderd, B., and M.J. Stout. 2021. Jasmonic acid-induced resistance to fall armyworm in soybeans: variation among genotypes and tradeoffs with constitutive resistance. Basic and Applied Ecology, in press.

Bernaola, L., Butterfield, T.S., T.H. Tai, and M.J. Stout. 2021. Epicuticular wax rice mutants show reduced resistance to the rice water weevil and fall armyworm. Environmental Entomology, doi: 10.1093/ee/nvab038.

Wilson, B.E., J.M. Villegas, M.J. Stout, and K.J. Landry. 2021. Relative yield loss from stem borers (Lepidoptera: Crambidae) and rice water weevil (Coleoptera: Curculionidae) in rice. Journal of Economic Entomology, doi: 10.1093/jee/toab046

Villegas, J.A., Wilson, B.E., and Stout, M.J. 2021. Assessment of Tolerance and Resistance of Inbred Rice Cultivars to Combined Infestations of Rice Water Weevil (Coleoptera: Curculionidae) and Stemborers (Lepidoptera: Crambidae). Entomologia Experimentalis et Applicata, doi: 10.1111/eea.13054.

Villegas, J.A., Wilson, B.E., Way, M.O., Gore, J., and Stout, M.J. 2021. Tolerance to Rice Water Weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), Infestations among Hybrid and Inbred Rice Cultivars in the Southern U.S. Crop Protection 139: 105368.

Bernaola, L.* and M.J. Stout. 2020. The effect of mycorrhizal seed treatments on rice growth, yield, and tolerance to rice water weevil injury. Journal of Pest Science, 94: 796=807.

Kraus, E.C., R. Guerra, and M.J. Stout. 2020. Evaluation of Nicaraguan rice varieties for resistance to rice delphacid: Potential sources for breeding programs. Southwestern Entomologist 45: 79-87.

Wilson, B.E. and M.J. Stout. 2020. Reexamination of the influence of Oebalus pugnax (Hemiptera: Pentatomidae) infestations on rice yield and quality. Journal of Economic Entomology. toaa063, https://doi.org/10.1093/jee/toaa063

Bernaola, L.*, and M.J. Stout. 2019. Effects of arbuscular mycorrhizal fungi on rice-herbivore interactions are soil-dependent. Scientific Reports, 9, Article number: 14037

Kraus EC*, Stout, M.J. 2019. Seed treatment using methyl jasmonate induces resistance to rice water weevil but reduces plant growth in rice. PLoS ONE 14(9): e0222800. https://doi.org/10.1371/journal.pone.0222800.

Kraus, E.C. * and M.J. Stout. 2019. Direct and indirect effects of herbicides on insect herbivores in rice, Oryza sativa. Scientific Reports, 9, Article number: 6998

Kraus, E.C. * and M.J. Stout. 2019. Plant-mediated interactions among above-ground and below-ground life stages of a root-feeding weevil. Ecological Entomology DOI: 10.1111/een.12757

Kraus, E.C. * and M.J. Stout. 2019. Effects of defoliation on the resistance and tolerance of rice, Oryza sativa, to root injury by the rice water weevil, Lissorhoptrus oryzophilus. Entomologia Experimentalis et Applicata, 167: 350-359.

Villegas, J. *, B.E. Wilson, and M.J. Stout. 2019. Efficacy of reduced rates of chlorantraniliprole seed treatment on insect pests of irrigated drill-seeded rice. Pest Mangement Science, DOI 10.1002/ps.5437 .

Rahaman, M.M.* and M.J. Stout. 2019. Comparative efficacies of next-generation insecticides against yellow stem borer and their effects on natural enemies in a rice ecosystem. Rice Science, 26: 157-166.

de Freitas, T.F.S.*, M.J. Stout, and J. Sant’Ana. 2018. Effects of exogenous methyl jasmonate and salicylic acid on rice resistance to Oebalus pugnax. Pest Management Science 75: 744-752.

Bernaola, L. *, Cosme, M., Schneider, R. and Stout, M. 2018. Belowground inoculation with arbuscular mycorrhizal fungi increases local and systemic susceptibility of rice plants to different pest organisms. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2018.00747

Bernaola, L. *, G. Cange**, M.O. Way, J. Gore, J. Hardke, and M.J. Stout. 2018. Natural colonization of rice by arbuscular mycorrhizal fungi in different production areas. Rice Science 25: 169-174.

Saad, M.M. *, M.M. Rahaman*, and M.J. Stout. 2018. Varietal resistance against the rice water weevil in field and greenhouse studies. Environmental Entomology 47: 388-395.

Blackman, B.D. * and Stout, M.J. 2017. Development of rice stink bug, Oebalus pugnax F., nymphs on rice kernels and effects of nymphal feeding on rice yields. Southwestern Entomologist, 42(3):641-650.

Villegas, J. M. *, Way, M.O., Pearson, R.A., and Stout, M.J. 2017. Integrating soil silicon amendment, insecticides, and varietal resistance for management of rice insect pests in drill-seeded rice. Plants, 6, 33.

Lanka, S.K. *, Senthil-Nathan, S., Blouin, D., and Stout, M.J. 2017. Impact of thiamethoxam seed treatment on growth and yield of rice, Oryza sativa. Journal of Economic Entomology 110: 479-486.

Mercer, N.*, Kaller, M., and Stout, M.J. 2017. Diversity of arthropods in farmed wetlands in the Gulf of Mexico Coastal Plain and effects of detrital subsidies. Journal of Freshwater Ecology. Journal of Freshwater Ecology, 32:1, 163-178, DOI: 10.1080/02705060.2016.1253623

Cosme, M.A., Lu J., Erb M, Stout, M.J., Franken P, and Wurst, S. 2016. A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling. New Phytologist 211: 1065-1076.

Biology and Management of Insect Pests of Rice (in cooperation with Dr. Blake Wilson)

Over the last 25 years, my program has published over 70 refereed journal articles and over 80 technical articles on the biology and management of insect pests of rice, including the rice water weevil, the rice stink bug, and stem-boring lepidopterans. The results of my laboratory’s research have been used by the U.S. rice industry to transition from the exclusive use of post-flood applications of carbofuran for management of the rice water weevil to the use of a more diversified, effective, sustainable, and safer portfolio of insecticides, including several seed treatments and foliar insecticides. Research by my students has also explored the biological basis and effectiveness of several cultural practices against the rice water weevil, rice stink bug, and stem borers, including planting date, water management, weed management, and seeding rate. Our research has resulted in the adoption of more effective management tactics against both the major pests of rice as well as minor pests such as the South American rice miner and the fall armyworm.

Continued research in this area is needed, however, partly to reduce reliance of current management programs on chemical insecticides and partly because globalization and climate change have resulted in the invasion and establishment or threatened establishment of new insect pests. The expansion of the range of the Mexican rice borer into southwest Louisiana, and the possibility of invasion of Louisiana rice by the rice delphacid, are examples of the latter trend. One result of these changes in the pest complex in Louisiana rice is that pest management research in Louisiana rice is becoming more relevant to pest management in other parts of the rice-producing world.

One focus of current efforts is on an improved understanding of the biology and chemical ecology of the rice stink bug and of the effects of feeding by the rice stink bug on grain yield and quality. Recent research suggests that the current threshold for the use of insecticides against the rice stink bug may be too low, which may be resulting in the application of too much insecticide. Field experiments will be conducted to determine whether raising the threshold for insecticide applications will result in deleterious effects on rice grain quality (peck and broken grains). Greenhouse and laboratory experiments are being conducted to better understand the factors that attract rice stink bugs to developing grains. This latter work will include characterizing the volatiles emitted by rice panicles at various stages of kernel development and the effects of these volatiles on stink bug behavior.

Another area of interest is the use of “perennial” rice lines – lines that can produce several crops over multiple years from a single planting. These lines, if integrated into U.S. production systems, could potentially allow for more sustainable and integrated rice cropping systems (for example, by allowing the establishment of larger populations of beneficial arthropods in rice paddies).

Novel Approaches to Understanding and Deploying Insect-Resistant Crop Varieties (in cooperation with Dr. Blake Wilson)

One management tactic that has been the particular focus of my program’s research is host-plant resistance. Over 10,000 cultivars and unimproved genotypes of rice have been evaluated over the past 50+ years for resistance to the rice water weevil, but no genotypes with high levels of resistance have been found. More recent evaluations of weevil resistance in Louisiana cultivars have confirmed that no cultivars possess high levels of resistance, although the older Texas cultivar ‘Jefferson’ consistently supports lower populations of rice water weevil larvae, and medium-grain varieties such as ‘Jupiter’ consistently support high populations of larvae. Several lines resulting from a cross between ‘Jefferson’ and the susceptible cultivar ‘Cocodrie” show resistance comparable to ‘Jefferson’ and yield and grain quality characteristics comparable to ‘Cocodrie’, and these lines may be valuable for the future development of high-yielding lines with resistance to the rice water weevil. Furthermore, recent field experiments have demonstrated that hybrid rice lines are more tolerant of weevil injury than inbred lines (i.e. hybrids suffer lower yield losses despite being equally infested), and the use of these tolerant lines may be advantageous in fields in which use of insecticides is impossible or undesirable. The plant physiological traits possessed by tolerant varieties that allow them to more effectively withstand weevil feeding are being investigated.

Screening of rice genotypes for resistance to stem-boring lepidopterans and rice delpahcid has only been initiated recently, because these insects have only become threats to Louisiana rice over the past decade. We have shown significant variation in resistance to stem borers in U.S. germplasm, and are currently formulating recommendations based on these results. Germplasm with resistance to the rice delphacid has also been identified.

Because traditional approaches to identifying resistant lines have met with limited success (especially against the rice water weevil), our lab has been exploring other approaches to identifying resistant genotypes and elucidating mechanisms underlying resistance. For example, we have recently shown that mutant rice lines deficient in the production of epicuticular waxes (developed by Tom Thai, USDA-ARS) are more susceptible to the rice water weevil and fall armyworm. Preliminary data suggest that breeding for increased yields over the past 100 years has resulted in a measurable decline in the resistance of rice cultivars to the rice water weevil. Recent cooperative efforts with Drs. Adam Famoso and Brijesh Anjira (rice breeders, H. Rouse Caffey Rice Research Station) have involved screening chromosome segment substitution lines for resistance to rice water weevils and stem borers and testing lines segregating for leaf pubescence.

Recently, a line of research has been initiated with mutant rice lines deficient in their ability to take up silicon (Si) from the soil (also developed by Dr. Tai). Past research in rice suggests that Si uptake not only enhances biomechanical resistance to insect pests (via increased tissue

toughness) but also biochemical resistance (via interactions with the jasmonic acid signaling pathway). Research with these lines seeks to elucidate the relative importance of biomechanical and biochemical resistance against various rice pests.

Plant-insect microorganism interactions

Crop plants are focal organisms for complex and intricate interactions among arthropods and microorganisms. Among these interactions, the interactions of plants with endophytic fungi, ectomycorrizal fungi, plant growth-promoting bacteria, and pathogenic microorganisms can have profound impacts on herbivore preference and performance. Our lab has demonstrated that colonization of rice with mycorrhizae in the greenhouse and field increases the susceptibility of rice to a wide range of organisms, including rice water weevils, fall armyworms, stem borers, and the causal agent of sheath blight. However, mycorrhizal colonization my also increase the tolerance of rice and other crop plants to both above-ground and below-ground injury. A number of experiments are currently being conducted to assess the impact of mycorrhizal inoculation on the resistance of rice, soybean, and maize to insect pests, with an emphasis on fall armyworm. Other experiments are being conducted to elucidate potential direct and plant-mediated interactions among rice stink bugs and pathogenic microorganisms that attack developing rice grain, such as the causal agents of false kernel smut and bacterial panicle blight (collaboration with Jong Ham, LSU Plant Pathology).

Plant Phenotypic Plasticity and Pest Management

Plant resistance is a plastic trait – that is, the level of plant resistance expressed by a plant is contingent on the plant’s history of prior exposure to biotic and abiotic stresses or signals. Expression of plant resistance can also depend on plant or tissue age or stage. Plant phenotypic plasticity may have important implications for pest management, but these have not been sufficiently investigated. A series of published and unpublished studies over the past decade have demonstrated that, although feeding by rice water weevil and fall armyworm on rice can induce resistance to other insects that feed later on rice, these plant-mediated interactions probably have little impact on pest management in the field. However, there may be other ways in which plant phenotypic plasticity may be important in pest management. Experiments involving silicon soil amendments have shown that adding sources of silicon to the soil may stimulate the resistance of rice plants to stem borers and other pests. Moreover, our lab has shown that treating rice seeds or spraying plants with jasmonic acid or methyl jasmonate (plant hormones involved in plant responses to herbivory) may stimulate resistance to pests without reducing crop yields. Ongoing work seeks to explore how elicitors of resistance can be used in pest management and to elucidate the mechanisms involved in elicitor-induced resistance. Another area of interest is the use of “biostimulants” to stimulate not only plant resistance but also stimulate plant tolerance of biotic and abiotic stresses and enhance crop yields.

ENTM 7002: Plant Resistance to Arthropods

Prereq.: consent of instructor. 3 hrs. lecture; 3 hrs. lab. Detailed examination of the mechanistic basis of plant-insect interactions, with special reference to host-plant resistance in agricultural systems; integrates relevant concepts from diverse fields including insect physiology, plant physiology, plant biochemistry and ecology; evaluation of the current theoretical basis for research in plant-insect interactions; laboratory demonstrations and exercises emphasize the techniques used in host-plant resistance research.

Professor and Head, Department of Entomology, Louisiana State University

Interim Director, School of Plant, Environmental, and Soil Sciences, Louisiana State University

Co-Director, Center for Research Excellence in Plant Biotechnology and Crop Development

B.A. 1989 University of California, Berkeley
Ph.D. 1996 University of California, Davis

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The LSU AgCenter and the LSU College of Agriculture