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A negative correlation between constitutive and inducible resistance across plant populations is expected for a variety of reasons; however, empirical evidence for such trade-offs remain ambiguous, particularly for crop plants. The current study investigated the relationship between constitutive and inducible resistance in vegetative-stage soybeans (V5-V6) against larvae of the generalist defoliator, Spodoptera frugiperda. Eighteen soybean genotypes differing in their constitutive resistance to coleopteran or lepidopteran defoliators were used over four experiments. Exogenous jasmonic acid (JA, 2 mM) was used to induce plants. Constitutive resistance of each genotype was estimated by measuring weight gains, foliar consumption, and foliar conversion efficiency in short-term feeding assays on excised leaf disks of terminal trifoliate leaves of plants not treated with JA. JA was applied to plants immediately after removing leaf material for assays of constitutive resistance, and induced resistance was estimated 48 h after application of JA using leaf disks from the remaining leaf tissue of the same trifoliate used for measuring constitutive resistance. Larval weight gains before JA treatments revealed genotypic variability in constitutive resistance. . Overall, reductions in weight gain (28.7% to 76.7%), foliar consumption (3.7% - 65%) and conversion efficiency (10.9% - 42.2%) were found in JA treatments. Significant (P < 0.05) or marginally significant (P < 0.10) negative correlations between constitutive resistance (larval weight gains on non-induced plants) and induced resistance (differences in weight gains before and after induction) were found in all four experiments, suggesting tradeoff between the two modes of resistance does exist in soybean for this herbivore. Additional evidence for tradeoffs between constitutive and inducible resitance was also found in the analysis of consumption data. Comparisons of consumption and conversion efficiencies suggest that similar antibiotic and antixenotic factors are involved in constitutive and inducible resistance to fall armyworm in soybean.
Srinivas K. Lanka; Bret D. Elderd; Jeffrey A. Davis; Michael J. Stout. Jasmonic acid-induced resistance to fall armyworm in soybeans: Variation among genotypes and tradeoffs with constitutive resistance. Basic and Applied Ecology 2021, 56, 97 -109.
AMA StyleSrinivas K. Lanka, Bret D. Elderd, Jeffrey A. Davis, Michael J. Stout. Jasmonic acid-induced resistance to fall armyworm in soybeans: Variation among genotypes and tradeoffs with constitutive resistance. Basic and Applied Ecology. 2021; 56 ():97-109.
Chicago/Turabian StyleSrinivas K. Lanka; Bret D. Elderd; Jeffrey A. Davis; Michael J. Stout. 2021. "Jasmonic acid-induced resistance to fall armyworm in soybeans: Variation among genotypes and tradeoffs with constitutive resistance." Basic and Applied Ecology 56, no. : 97-109.
Residual effects of pyrethrin + methoprene aerosol dispensed at 4 and 16-µm particle sizes and an untreated control, was assessed against late-stage larvae of Trogoderma inclusum (LeConte), the larger cabinet beetle, and T. variabile (Ballion), the warehouse beetle. Treated arenas were stored at 25, 30, 35, and 40 °C and bioassays were conducted at 1, 3, or 6 weeks post-treatment. Larval development was monitored through adult emergence to compare the efficacy of treatments by using both the percentage of normal adult emergence and a developmental index as dependent variables. There was no overall effect of temperature on residual activity as measured using either adult emergence or developmental index values. Both the 4 and 16-µm particle sizes resulted in reduced adult emergence and low developmental index values compared to untreated controls. The insecticide was more effective on T. variabile than on T. inclusum. The impact of particle size varied between species, both particle sizes reduced adult emergence and developmental index in T. variabile, but only the 16-µm particle size resulted in reduction of adult emergence of T. inclusum. Furthermore, there was a reduction in activity of methoprene with residual exposure time. The variations in susceptibility of species to methoprene, differences in efficacy of particle sizes, and decrease in residual persistence at smaller particle sizes highlight the need for attaining optimal particle size to improve overall efficacy of aerosol mixtures containing methoprene.
Srinivas K. Lanka; Frank H. Arthur; James F. Campbell; Kun Yan Zhu. Evaluation of Residual Efficacy of Pyrethrin + Methoprene Aerosol on Two Dermestids: Impact of Particle Size, Species, and Temperature. Insects 2019, 10, 142 .
AMA StyleSrinivas K. Lanka, Frank H. Arthur, James F. Campbell, Kun Yan Zhu. Evaluation of Residual Efficacy of Pyrethrin + Methoprene Aerosol on Two Dermestids: Impact of Particle Size, Species, and Temperature. Insects. 2019; 10 (5):142.
Chicago/Turabian StyleSrinivas K. Lanka; Frank H. Arthur; James F. Campbell; Kun Yan Zhu. 2019. "Evaluation of Residual Efficacy of Pyrethrin + Methoprene Aerosol on Two Dermestids: Impact of Particle Size, Species, and Temperature." Insects 10, no. 5: 142.
Neonicotinoid seed treatments are widely used in agriculture. In rice, Oryza sativa L., in the southern United States, neonicotinoid seed treatments are used to manage early-season populations of the rice water weevil, Lissorhoptrus oryzophilus Kuschel. In addition to their effects on pests, neonicotinoid seed treatments may benefit crop plants directly by increasing plant growth or altering plant responses to stresses. As part of an effort to assess the overall benefits of thiamethoxam seed treatment in rice, rice emergence, growth, and yield were evaluated. In a growth chamber, rice emergence from the soil was 1–2 d more rapid from treated than untreated seeds. These laboratory results were supported by field experiments that revealed higher stand counts from thiamethoxam-treated plots than from untreated plots. Yields from thiamethoxam treatments were no higher than those from untreated plots under conditions in which weevil larvae were absent, a result inconsistent with the hypothesis that thiamethoxam imparts direct yield benefits. In a series of field experiments conducted to compare the relationship between weevil larval densities and rice yields in plots treated with several rates of thiamethoxam or chlorantraniliprole (another widely used seed treatment insecticide), the relationship between weevil density and yield did not differ markedly among both seed treatments. Overall yields from both seed treatments did not differ significantly, despite more effective control in chlorantraniliprole-treated plots. These results provide strong support for effect of thiamethoxam on early-season growth of rice, but only weak support for its direct effect on rice yields.
S. K. Lanka; S. Senthil-Nathan; D. J. Blouin; M. J. Stout. Impact of Thiamethoxam Seed Treatment on Growth and Yield of Rice, Oryza sativa. The Journal of Biochemistry 2017, 110, 479 -486.
AMA StyleS. K. Lanka, S. Senthil-Nathan, D. J. Blouin, M. J. Stout. Impact of Thiamethoxam Seed Treatment on Growth and Yield of Rice, Oryza sativa. The Journal of Biochemistry. 2017; 110 (2):479-486.
Chicago/Turabian StyleS. K. Lanka; S. Senthil-Nathan; D. J. Blouin; M. J. Stout. 2017. "Impact of Thiamethoxam Seed Treatment on Growth and Yield of Rice, Oryza sativa." The Journal of Biochemistry 110, no. 2: 479-486.
Insecticidal Seed Treatments in Rice,Srinivas K Lanka and Michael J Stout
Srinivas K Lanka And Michael J Stout. Insecticidal Seed Treatments in Rice. Rice Research: Open Access 2015, 3, 1 .
AMA StyleSrinivas K Lanka And Michael J Stout. Insecticidal Seed Treatments in Rice. Rice Research: Open Access. 2015; 3 (2):1.
Chicago/Turabian StyleSrinivas K Lanka And Michael J Stout. 2015. "Insecticidal Seed Treatments in Rice." Rice Research: Open Access 3, no. 2: 1.
Rice in the U.S. is frequently seeded at low rates and treated before sowing with neonicotinoid or anthranilic diamide insecticides to target the rice water weevil. A previous study of the influence of seeding rate on rice water weevil densities showed an inverse relationship between seeding rates and immature weevil densities. This study investigated interactive effects of seeding rate and seed treatment on weevil densities and rice yields; in particular, experiments were designed to determine whether seed treatments were less effective at low seeding rates. Four experiments were conducted over three years by varying seeding rates of rice treated at constant per seed rates of insecticide. Larval suppression by chlorantraniliprole was superior to thiamethoxam or clothianidin, and infestations at low seeding rates were up to 47% higher than at high seeding rates. Little evidence was found for the hypothesis that seed treatments are less effective at low seeding rates; in only one of four experiments was the reduction in weevil densities by thiamethoxam greater at high than at low seeding rates. However, suppression of larvae by neonicotinoid seed treatments in plots seeded at low rates was generally poor, and caution must be exercised when using the neonicotioids at low seeding rates.
Jason Hamm; Srinivas Lanka; Michael Stout. Influence of Rice Seeding Rate on Efficacies of Neonicotinoid and Anthranilic Diamide Seed Treatments against Rice Water Weevil. Insects 2014, 5, 961 -973.
AMA StyleJason Hamm, Srinivas Lanka, Michael Stout. Influence of Rice Seeding Rate on Efficacies of Neonicotinoid and Anthranilic Diamide Seed Treatments against Rice Water Weevil. Insects. 2014; 5 (4):961-973.
Chicago/Turabian StyleJason Hamm; Srinivas Lanka; Michael Stout. 2014. "Influence of Rice Seeding Rate on Efficacies of Neonicotinoid and Anthranilic Diamide Seed Treatments against Rice Water Weevil." Insects 5, no. 4: 961-973.