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There are no standard protocols for assessing antibiosis in soybean, Glycine max (L.) (Fabaceae), cultivars to lepidopterans, including tobacco budworm, Chloridea virescens (Fabricius) (Lepidoptera: Noctuidae), an important species that causes damage to soybean crops in several production regions. This study was conducted to assess methodologies to determine the optimal combination of larval density, confinement container size, and plant structure in soybean antibiosis assays to C. virescens. In addition, primary and secondary metabolites in plant structures were analyzed to elucidate potential chemical resistance mechanisms against this lepidopteran. Antibiosis assays to C. virescens in resistant (IAC‐100) and susceptible (BR‐16) soybean cultivars were performed using three larval densities (one, two, and three larvae), two confinement container sizes (150 and 300 ml), and combinations of soybean plant structures (leaves, uncut pods, leaves + uncut pods, cut pods, and leaves + cut pods). Phenol, tannin, fiber, and lignin contents were quantified in the leaves, uncut pods, and grains of the soybean cultivars and related to biological development of C. virescens. Resistance levels in soybean cultivars in antibiosis assays were best differentiated using one larva per 150‐ml confinement container, fed only on soybean leaves. Higher contents of condensed tannins in the leaves of IAC‐100 cultivar may be one of the main chemical mechanisms of resistance to C. virescens. Our study is the first to determine the optimal combination of larval density, confinement container size, and plant structure for antibiosis assays in soybean cultivars to C. virescens. The developed protocol will benefit high‐throughput phenotyping in genetic breeding programs to obtain cultivars resistant to lepidopterans for use in integrated pest management. [ABSTRACT FROM AUTHOR]

The efficacies of some next-generation insecticides against the rice yellow stem borer (YSB), Scirpophaga incertulas (Walk.), and their compatibilities with natural enemies were investigated during 2014 and 2015. Three newer insecticides, chlorantraniliprole 0.4% G, dinotefuran 20% SG, and methoxyfenozide 24% SC, and two commonly used insecticides, carbufuran 5 G and quinalphos 25 EC, were evaluated in the field for their efficacies against YSB and their non-target effects on natural enemies. Application of chlorantraniliprole 0.4% G at 10.96 kg/hm2 resulted in the greatest reduction in YSB infestation (deadhearts and whiteheads) and greatest increase of yield compared to the untreated control plots, followed by methoxyfenozide 24% SC at 0.41 L/hm2, dinotefuran 20% SG at 0.15 kg/hm2, carbufuran 5 G at 10.96 kg/hm2, and quinalphos 25 EC at 1.50 L/hm2. All the insecticides reduced the numbers of predators viz. , lady bird beetles, wolf spiders, carabid beetles, earwigs, green mirid bugs, and damselflies. Numbers of adults of the egg parasitoids Trichogramma sp. , Telenomus sp. and Tetrastichus sp. were significantly reduced in insecticide-treated plots compared to untreated control plots. In all field trials, the harmful effects of the five insecticides were in the following rank order (least harmful to most harmful): chlorantraniliprole 0.4% G, carbufuran 5 G, dinotefuran 20% SG, methoxyfenozide 24% SC, and quinalphos 25 EC. On the basis of reduction in YSB infestation, increase in grain yield, and compatibility with natural enemies, chlorantraniliprole 0.4% G was proved to be the best of all the insecticides for YSB management system, although the study suggested minimizing its retail price for enhancement of cost effectiveness in farmers' fields. [ABSTRACT FROM AUTHOR]

Plant-microbe mutualisms can improve plant defense, but the impact of root endophytes on below-ground herbivore interactions remains unknown. We investigated the effects of the root endophyte Piriformospora indica on interactions between rice ( Oryza sativa) plants and its root herbivore rice water weevil ( RWW; Lissorhoptrus oryzophilus), and how plant jasmonic acid ( JA) and GA regulate this tripartite interaction., Glasshouse experiments with wild-type rice and coi1-18 and Eui1- OX mutants combined with nutrient, jasmonate and gene expression analyses were used to test: whether RWW adult herbivory above ground influences subsequent damage caused by larval herbivory below ground; whether P. indica protects plants against RWW; and whether GA and JA signaling mediate these interactions., The endophyte induced plant tolerance to root herbivory. RWW adults and larvae acted synergistically via JA signaling to reduce root growth, while endophyte-elicited GA biosynthesis suppressed the herbivore-induced JA in roots and recovered plant growth., Our study shows for the first time the impact of a root endophyte on plant defense against below-ground herbivores, adds to growing evidence that induced tolerance may be an important root defense, and implicates GA as a signal component of inducible plant tolerance against biotic stress. [ABSTRACT FROM AUTHOR]

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate some factors that influence the expression of antixenosis in soybean genotypes against Anticarsia gemmatalis Hübner and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Free-choice and no-choice feeding assays were performed with the resistant soybean genotype IAC 100 and the susceptible genotype BRSGO 8360 using A. gemmatalis and S. frugiperda larvae. The following factors that may affect expression of resistance were evaluated: one larva versus two larvae per leaf disc; use of larvae without prior feeding suspension versus larvae starved for 3 h prior to the assay; leaf discs versus entire leaflets; upper part versus lower part of the plant; and, vegetative versus reproductive growth stages. The level of resistance exhibited by the genotype IAC 100 was high enough to not be obscured by the effects of all factors assayed in the present study upon the feeding preference of A. gemmatalis and S. frugiperda larvae. However, our results demonstrate the importance of knowing the optimal conditions for conducting an assay for evaluating resistance of genotypes for specialist and generalist insect species. Utilization of two larvae of A. gemmatalis per leaf disc, not starved before the assays, with leaf discs from the upper part of plants at the reproductive growth stage provided better discrimination of differences in antixenosis expression in soybean genotypes. For S. frugiperda, use of one larva per leaf disc, not starved before the assays, with leaf discs from the lower part of plants at the reproductive growth stage gave more satisfactory results for feeding preference tests. [ABSTRACT FROM PUBLISHER]

Abstract: Induction of resistance to control bacterial blight in rice was studied after treatment with various plant extracts by measuring activities of polyphenol oxidase (PPO), peroxidase (PO), β-1,3-glucanase and a pathogen related (PR) protein. Extracts of four plants (Azardirachta indica, Ages mermelos, Cassia auriculata and Vitex negundo) against bacterial blight were analyzed. Bacterial blight was more effectively controlled by the water and methanol extracts of V. negundo than the other plant extracts. The extracts induced the defense related enzymes such as PPO, PO and β-1,3-glucanase in both pre and post inoculation of Xanthomonas oryzae. The pathogenesis related (PR) protein bands were clearly visible at 33 kDa and 14 kDa in methanol and water extract treated leaves of V. negundo. Elevated enzyme activities and PR protein levels indicate that defense enzymes are responsible for the control the bacterial blight disease rather than antagonism by extracts. The methanol and water extracts of V. negundo suppressed the bacterial blight disease about 73% and 76% over control respectively, under field condition. The plants grown in extract-treated plots were healthy and their leaf surface area was found to be higher than the control and standard. V. negundo effectively controlled the bacterial blight disease under in vitro and in vivo conditions through induced systemic resistance which can be used as an effective biocontrol agent in rice field. [Copyright &y& Elsevier]