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Papers by hari sharma

Reference Series in Phytochemistry, 2019

Insect and plants have coevolved for millions of years. Plants respond to herbivory through vario... more Insect and plants have coevolved for millions of years. Plants respond to herbivory through various morphological, biochemical, and molecular mechanisms to counter/offset the effects of herbivore attack. These defense strategies against herbivores are wide-ranging, highly dynamic, and could be direct and/or indirect. Direct defense affects the herbivore’s growth and development due to antibiosis because of secondary metabolites produced constitutively and/or induced upon infestation by the insect pests. The indirect defense involves the recruitment of natural enemies of the insect pests. The natural enemies (parasitoids and predators) are attracted by the volatiles produced by the plants in response to insect herbivory. The direct and indirect defensive strategies either act separately or in conjunction with each other. However, insects have the ability to adapt to the plant defensive responses through physiological processes, metabolism and behavior to offset the adverse effects of...

Several technologies are in use for the management o f insect pests, wherein, different protocols... more Several technologies are in use for the management o f insect pests, wherein, different protocols and guidelines are being followed for testing their bioefficacy and biosafety. Therefore, it is important to have a comparative assessment o f bioefficacy and biosafety o f different pest management technologies viz. synthetic pesticides, biopesticides, natural plant products, natural enemies, and genetically modified organisms (GMOs) to the nontarget organisms in the environment. Toxicology and biosafety data should be generated on prescribed animals as per the national and international protocols recommended by the government agencies, FAO, WHO, OECD, and EPA. Natural plant products, natural enemies, and insect-resistant crops developed through conventional and genetic engineering approaches should be viewed differently and safety requirements simplified and relaxed as appropriate, as compared to the synthetic insecticides. Generation o f data on bioefficacy should not only be done in...

Journal of SAT Agricultural …

Cotton bollworm/legume pod borer, Helicoverpa armigera (Hubner), is one of the most devastating c... more Cotton bollworm/legume pod borer, Helicoverpa armigera (Hubner), is one of the most devastating crop pests worldwide (Sharma 2001). It has a wide host range, and feeds on more than 300 plant species. Due to indiscriminate use of insecticides, it has developed high levels of ...

Host plant resistance is an effective means of controlling sorghum midge (Stenodiplosis sorghicol... more Host plant resistance is an effective means of controlling sorghum midge (Stenodiplosis sorghicola). We studied the influence of environmental factors on expression of resistance to sorghum midge in three midge-resistant and two midge-susceptible genotypes. Midge-resistant lines AF 28, ICSV 197, and TAM 2566 suffered 8.8 to 17.3% damage across seven sowings compared to 25.6% damage in ICSV 112, and 69.4% damage in CSH 5. Susceptibility of the midge-resistant lines (AF 28, ICSV 197, and TAM 2566) decreased with an increase in open pan evaporation, maximum and minimum temperatures, and solar radiation; while the midge-susceptible lines (ICSV 112 and CSH 5) showed a poor interaction with these factors. Midge damage in ICSV 197 showed a negative correlation with minimum temperature and relative humidity and positive correlation with sunshine hours, while the reverse was true for CSH 5. Grain growth rate between 0 and 3 days after anthesis was lower in crops sown on 1st October, when AF 28 and ICSV 197 suffered maximum midge damage. Maximum and minimum temperatures and maximum relative humidity influenced the moisture content of the grain, grain growth rate, and sorghum midge damage. There was considerable variation in genotype × environment interaction for expression of resistance to sorghum midge, and the implications of these results have been discussed in relation to development of sorghum cultivars with resistance to this insect.

Crop Protection, 2006

Spotted stem borer, Chilo partellus (Swinhoe), is the most important pest of sorghum in Asia and ... more Spotted stem borer, Chilo partellus (Swinhoe), is the most important pest of sorghum in Asia and South and Eastern Africa, and host plant resistance is an important component for controlling this pest under subsistence farming conditions. Therefore, we studied the antibiosis mechanism of resistance in a diverse array of 20 sorghum genotypes at the seedling stage by incorporating the freeze-dried leaf powder into artificial diet. Freeze-dried sorghum leaf powder at 12.5 g per 250 ml of the standard artificial diet or replacement of chickpea flour in the artificial diet by 50% with sorghum leaf powder can be used to quantify the extent of antibiosis mechanism of resistance to C. partellus in sorghum. There was a significant variation in larval survival, larval and pupal weights, larval and pupal periods, and percentage pupation and adult emergence in diets impregnated with freeze-dried leaf powder of different sorghum genotypes. Sorghum genotypes such as IS 1044, IS 2123, IS 1054, IS 18573, and ICSV 714 showed antibiosis to C. partellus in terms of reduced survival and development. Principal component analysis indicated that there is considerable diversity in sorghum genotypes for antibiosis to C. partellus. Genotypes placed in different groups can be used in resistance breeding programs to diversify the basis of resistance to this pest.

Global warming and climate change will influence activity, diversity, distribution and population... more Global warming and climate change will influence activity, diversity, distribution and population dynamics of insect pests including the grain legumes. Several insect pests damage grain legume crops, of which the pod borer, Helicoverpa armigera; spotted pod borer, Maruca vitrata; spiny pod borer, Etiella zinckenella; pod fly, Melanagromyza obtusa; aphid, Aphis craccivora; defoliators, Spodoptera litura and S. exigua; thrips, Megaleurothrips usitatus and Caliothrips indicus and the bruchid, Callasobruchus chinensis cause extensive losses in grain legumes. The incidence and extent of losses due to these pests varies across seasons, locations, and cropping systems. The pest spectrum on grain legumes will change considerably due to impending global warming and climate change. The geographical distribution of some of the pests might extend to temperate regions in Europe and America, while the outbreaks of some other pests will become more frequent. Several outbreaks of pod borer, H. armi...

Insect and plants have coevolved for millions of years. Plants respond to herbivory through vario... more Insect and plants have coevolved for millions of years. Plants respond to herbivory through various morphological, biochemical, and molecular mechanisms to counter/offset the effects of herbivore attack. These defense strategies against herbivores are wide-ranging, highly dynamic, and could be direct and/or indirect. Direct defense affects the herbivore's growth and development due to antibiosis because of secondary metabolites produced constitutively and/or induced upon infestation by the insect pests. The indirect defense involves the recruitment of natural enemies of the insect pests. The natural enemies (parasitoids and predators) are attracted by the volatiles produced by the plants in response to insect herbivory. The direct and indirect defensive strategies either act separately or in conjunction with each other. However, insects have the ability to adapt to the plant defensive responses through physiological processes, metabolism and behavior to offset the adverse effects of the host plants' defense systems. This process of defensive responses by the host plants and counter defense by the insect pests results in the breakdown of resistance, and evolution of new populations/biotypes of the insect pests. This co-evolution between the plants and insects poses a major threat for developing crop cultivars with stable resistance to the target pest for pest management.

Euphytica, 2018

The noctuid pod borer, Helicoverpa armigera is one of the most damaging pests of chickpea, Cicer ... more The noctuid pod borer, Helicoverpa armigera is one of the most damaging pests of chickpea, Cicer arietinum. The levels of resistance to H. armigera in the cultivated chickpea are low to moderate, but the wild relatives of chickpea have exhibited high levels of resistance to this pest. To develop insect-resistant cultivars with durable resistance, it is important to understand the contribution of different components of resistance, and therefore, we studied antixenosis and antibiosis mechanisms of resistance to H. armigera in a diverse array of wild relatives of chickpea. The genotypes IG 70012, PI 599046, IG 70022, PI 599066, IG 70006, IG 70018 (C. bijugum), ICC 506EB, ICCL 86111 (cultivated chickpea), IG 72933, IG 72953 (C. reticulatum), IG 69979 (C. cuneatum) and IG 599076 (C. chrossanicum) exhibited non preference for oviposition by the females of H. armigera under multi-choice, dualchoice and no-choice cage conditions. Based on detached leaf assay, the genotypes IG 70012, IG 70022, IG 70018, IG 70006, PI 599046, PI 599066 (C. bijugum), IG 69979 (C. cuneatum), PI 568217, PI 599077 (C. judaicum) and ICCW 17148 (C. microphyllum) suffered significantly lower leaf damage, and lower larval weights indicating high levels of antibiosis than on the cultivated chickpea. Glandular and nonglandular trichomes showed negative correlation with oviposition, while the glandular trichomes showed a significant and negative correlation with leaf damage rating. Density of non-glandular trichomes was negatively correlated with larval survival. High performance liquid chromatography (HPLC) fingerprints of leaf surface exudates showed a negative correlation of oxalic acid with oviposition, but positive correlation with malic acid. Both oxalic acid and malic acid showed a significant negative correlation with larval survival. The wild relatives exhibiting low preference for oviposition and high levels of antibiosis can be used as sources of resistance to increase the levels and diversify the basis of resistance to H. armigera in cultivated chickpea.

Journal of Economic Entomology, 2018

Wild relatives of crops are an important source of resistance genes against insect pests. However... more Wild relatives of crops are an important source of resistance genes against insect pests. However, it is important to identify the accessions of wild relatives with different mechanisms of resistance to broaden the basis and increase the levels of resistance to insect pests. Therefore, we evaluated 15 accessions of wild relatives of chickpea belonging to seven species and five genotypes of cultivated chickpea for their resistance to pod borer, Helicoverpa armigera, which is the most damaging pest of chickpea. The test genotypes were evaluated for resistance to H. armigera using detached pod assay. Data were also recorded on activity of the digestive enzymes in the midgut of the larvae fed on different wild relatives of chickpea. All the wild chickpea genotypes suffered lower pod damage and weight gained by the third-instar larvae of H. armigera was lower when fed on them compared with the cultivated chickpea.

Agriculture, 2019

Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrai... more Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrained by several biotic and abiotic stresses. Therefore, sorghum improvement programs largely focus on developing high-yielding cultivars with multiple traits including stress resistance, bioenergy and nutritional quality. This study was undertaken to meet breeders’ needs to develop such cultivars and identify diverse germplasm sources with multiple traits. The 242 sorghum mini core accessions were evaluated for agronomic traits (yield, maturity, 100-seed weight) in two post-rainy seasons under optimally irrigated and drought conditions and identified 21 accessions as a sources for agronomic traits. The evaluation of mini core revealed 70 accessions resistant to biotic stress, 12 to abiotic stress, 13 for bioenergy traits and 27 for nutritional traits. The 13,390 single nucleotide polymorphism markers on mini core were used to identify genetically diverse accessions with desirable agronomi...

Journal of bioenergetics and biomembranes, Jan 5, 2018

Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) a... more Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) and are frequently used as insecticides against most devastating lepidopteran insect pests. Imidacloprid influenced dose-dependent decline in the state III and IV respiration, respiration control index (RCI), and P/O ratios, in vitro and in vivo. The bioassay indicated its LD50 value to be 531.24 μM. The insecticide exhibited a dose-dependent inhibition on F0F1-ATPase and complex IV activity. At 600 μM, the insecticide inhibited 83.62 and 27.13% of F0F1-ATPase and complex IV activity, respectively, and induced the release of 0.26 nmoles/min/mg protein of cytochrome c. A significant dose- and time-dependent increase in oxidative stress was observed; at 600 μM, the insecticide correspondingly induced lipid peroxidation, LDH activity, and accumulation of H2O2 content by 83.33, 31.51 and 223.66%. The stress was the maximum at 48 h of insecticide treatment (91.58, 35.28, and 189.80%, respectiv...

Archives of insect biochemistry and physiology, Jan 20, 2017

Phthalic acid diamide insecticides are the most effective insecticides used against most of the l... more Phthalic acid diamide insecticides are the most effective insecticides used against most of the lepidopteran pests including Helicoverpa armigera, a polyphagous pest posing threat to several crops worldwide. The present studies were undertaken to understand different target sites and their interaction with insect ryanodine receptors (RyR). Bioassays indicated that flubendiamide inhibited the larval growth in dose-dependent manner with LD50 value of 0.72 μM, and at 0.8 μM larval growth decreased by about 88%. Flubendiamide accelerated the Ca(2+) -ATPase activity in dose-dependent trend, and at 0.8 μM, the activity was increased by 77.47%. Flubendiamide impedes mitochondrial function by interfering with complex I and F0 F1 -ATPase activity, and at 0.8 μM the inhibition was found to be about 92% and 50%, respectively. In vitro incubation of larval mitochondria with flubendiamide induced the efflux of cytochrome c, indicating the mitochondrial toxicity of the insecticide. Flubendiamide ...

Archives of insect biochemistry and physiology, 2017

We characterized trypsin- and chymotrypsin-like serine alkaline proteases from cotton bollworm, H... more We characterized trypsin- and chymotrypsin-like serine alkaline proteases from cotton bollworm, Helicoverpa armigera, for their probable potential application as additives in various bio-formulations. Purification was achieved by using hydroxylapatite, DEAE sephadex and CM sephadex columns, which resulted in increased enzyme activity by 13.76- and 14.05-fold for trypsin and chymotrypsin, respectively. Michaelis-Menten constants (Km ) for substrates of trypsin and chymotrypsin, BApNA and SAAPFpNA, were found to be 1.25 and 0.085 mM, correspondingly. Fluorescent zymogram analysis indicated the presence of five trypsin bands with molecular masses of ∼21, 25, 38, 40, and 66 kDa and two chymotrypsin bands with molecular masses of ∼29 and 34 kDa in SDS-PAGE. The optimum pH was 10.0 and optimum temperature was 50°C for proteolytic activity for the purified proteases. The proteases were inhibited by synthetic inhibitors such as PMSF, aprotonin, leupeptin, pefabloc, and antipain. TLCK and TP...

Biochemistry and Biophysics Reports, 2016

Background: Chilo partellus is an important insect pest infesting sorghum and maize. The larvae i... more Background: Chilo partellus is an important insect pest infesting sorghum and maize. The larvae internalize in the stem, rendering difficulties in pest management. We investigated the effects of Capsicum annuum proteinase inhibitors (CanPIs) on C. partellus larvae by in-vitro and in-vivo experiments. Methods: Recombinant CanPI-7 (with four-Inhibitory Repeat Domains, IRDs),-22 (two-IRDs) and insect proteinase activities were estimated by proteinase assays, dot blot assays and in gel activity assays. Feeding bioassays of lab reared C. partellus with CanPI-7 and-22 were performed. C. partellus proteinase gene expression was done by RT-PCR. In-silico structure prediction of proteinases and CanPI IRDs was carried out, their validation and molecular docking was done for estimating the interaction strength. Results: Larval proteinases of C. partellus showed higher activity at alkaline pH and expressed few proteinase isoforms. Both CanPIs showed strong inhibition of C. partellus larval proteinases. Feeding bioassays of C. partellus with CanPIs revealed a dose dependent retardation of larval growth, reduction of pupal mass and fecundity, while larval and pupal periods increased significantly. Ingestion of CanPIs resulted in differential upregulation of C. partellus proteinase isoforms, which were sensitive to CanPI-7 but were insensitive to CanPI-22. In-silico interaction studies indicated the strong interaction of IRD-9 (of CanPI-22) with Chilo proteinases tested. Conclusions: Of the two PIs tested, CanPI-7 prevents induction of inhibitor insensitive proteinases in C. partellus so it can be explored for developing C. partellus tolerance in sorghum. General significance: Ingestion of CanPIs, effectively retards C. partellus growth; while differentially regulating the proteinases.

Arthropod-Plant Interactions, 2016

Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

International Journal of Insect Science, 2016

Flavonoids are important plant secondary metabolites, which protect plants from various stresses,... more Flavonoids are important plant secondary metabolites, which protect plants from various stresses, including herbivory. Plants differentially respond to insects with different modes of action. High performance liquid chromatography (HPLC) fingerprinting of phenols of groundnut ( Arachis hypogaea) plants with differential levels of resistance was carried out in response to Helicoverpa armigera (chewing insect) and Aphis craccivora (sucking pest) infestation. The genotypes used were ICGV 86699, ICGV 86031, ICG 2271 (NCAc 343), ICG 1697 (NCAc 17090), and JL 24. Most of the identified compounds were present in H. armigera- and A. craccivora-infested plants of ICGV 86699. Syringic acid was observed in all the genotypes across the treatments, except in the uninfested control plants of ICG 2271 and aphid-infested plants of ICG 1697. Caffeic acid and umbelliferone were observed only in the H. armigera-infested plants of ICGV 86699. Similarly, dihydroxybenzoic acid and vanillic acid were obse...

Environmental Entomology, 2015

Climate change will have a major bearing on survival and development of insects as a result of in... more Climate change will have a major bearing on survival and development of insects as a result of increase in CO 2 and temperature. Therefore, we studied the direct effects of CO 2 and temperature on larval development and metabolism in cotton bollworm, Helicoverpa armigera (Hü bner). The larvae were reared under a range of CO 2 (350, 550, and 750 ppm) and temperature (15, 25, 35, and 45 C) regimes on artificial diet. Elevated CO 2 negatively affected the larval survival, larval weight, larval period, pupation, and adult emergence, but showed a positive effect on pupal weight, pupal period, and fecundity. Increase in temperature exhibited a negative effect on larval survival, larval period, pupal weights, and pupal period, but a positive effect on larval growth. Pupation and adult emergence were optimum at 25 C. Elevated CO 2 and temperature increased food consumption and metabolism of larvae by enhancing the activity of midgut proteases, carbohydrases (amylase and cellulase), and mitochondrial enzymes and therefore may cause more damage to crop production. Elevated CO 2 and global warming will affect insect growth and development, which will change the interactions between the insect pests and their crop hosts. Therefore, there is need to gain an understanding of these interactions to develop strategies for mitigating the effects of climate change.

Phytoparasitica, 2015

Host plant resistance is an important component of pest management, and information on contributi... more Host plant resistance is an important component of pest management, and information on contribution of different mechanisms of resistance is important for developing cultivars with resistance to the target pests. Therfore, we studied the contribution of different components of resistance in five groundnut genotypes to three insect species occurring in India under field conditions. Plant damage by the larvae of Helicoverpa armigera, Spodoptera litura, and leafhoppers (Empoasca kerri) was evaluated visually on a 1-9 damage rating (DR) scale (1 being <10 % leaf damage, and 9 being >80 % leaf damage). Further, the activities of various plant defensive enzymes [peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), ascorbate peroxidase (APX), lipoxygenase (LOX) and catalase (CAT)], and the amounts of total phenols, condensed tannins, hydrogen peroxide (H 2 O 2), malondialdehyde (MDA) and proteins were also recorded. The genotypes ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697 suffered lower leaf damage by H. armigera and S. litura (DR 2.6-3.2) and E. kerri (DR 2.0-3.2) as compared to JL 24 (DR 7.2 and 6.0, respectively). ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697 exhibited greater enzymatic activity, and had more amounts of phenols, condensed tannins, hydrogen peroxide and proteins than the susceptible check, JL 24. There was a positive association between leaf damage and the activity of the defensive enzymes, and the amounts of phenols, condensed tannins and H 2 O 2. These results suggested that the plant defensive enzymes such as POD, PPO, LOX, PAL, SOD, APX and CAT were involved in genotypic resistance to insects, and the resistant genotypes accumulated phenols, condensed tannins, and H 2 O 2 to impart resistance to insects. This information will be useful for developing groundnut genotypes with resistance to insects for sustainable crop production.

Reference Series in Phytochemistry, 2019

Insect and plants have coevolved for millions of years. Plants respond to herbivory through vario... more Insect and plants have coevolved for millions of years. Plants respond to herbivory through various morphological, biochemical, and molecular mechanisms to counter/offset the effects of herbivore attack. These defense strategies against herbivores are wide-ranging, highly dynamic, and could be direct and/or indirect. Direct defense affects the herbivore’s growth and development due to antibiosis because of secondary metabolites produced constitutively and/or induced upon infestation by the insect pests. The indirect defense involves the recruitment of natural enemies of the insect pests. The natural enemies (parasitoids and predators) are attracted by the volatiles produced by the plants in response to insect herbivory. The direct and indirect defensive strategies either act separately or in conjunction with each other. However, insects have the ability to adapt to the plant defensive responses through physiological processes, metabolism and behavior to offset the adverse effects of...

Several technologies are in use for the management o f insect pests, wherein, different protocols... more Several technologies are in use for the management o f insect pests, wherein, different protocols and guidelines are being followed for testing their bioefficacy and biosafety. Therefore, it is important to have a comparative assessment o f bioefficacy and biosafety o f different pest management technologies viz. synthetic pesticides, biopesticides, natural plant products, natural enemies, and genetically modified organisms (GMOs) to the nontarget organisms in the environment. Toxicology and biosafety data should be generated on prescribed animals as per the national and international protocols recommended by the government agencies, FAO, WHO, OECD, and EPA. Natural plant products, natural enemies, and insect-resistant crops developed through conventional and genetic engineering approaches should be viewed differently and safety requirements simplified and relaxed as appropriate, as compared to the synthetic insecticides. Generation o f data on bioefficacy should not only be done in...

Journal of SAT Agricultural …

Cotton bollworm/legume pod borer, Helicoverpa armigera (Hubner), is one of the most devastating c... more Cotton bollworm/legume pod borer, Helicoverpa armigera (Hubner), is one of the most devastating crop pests worldwide (Sharma 2001). It has a wide host range, and feeds on more than 300 plant species. Due to indiscriminate use of insecticides, it has developed high levels of ...

Host plant resistance is an effective means of controlling sorghum midge (Stenodiplosis sorghicol... more Host plant resistance is an effective means of controlling sorghum midge (Stenodiplosis sorghicola). We studied the influence of environmental factors on expression of resistance to sorghum midge in three midge-resistant and two midge-susceptible genotypes. Midge-resistant lines AF 28, ICSV 197, and TAM 2566 suffered 8.8 to 17.3% damage across seven sowings compared to 25.6% damage in ICSV 112, and 69.4% damage in CSH 5. Susceptibility of the midge-resistant lines (AF 28, ICSV 197, and TAM 2566) decreased with an increase in open pan evaporation, maximum and minimum temperatures, and solar radiation; while the midge-susceptible lines (ICSV 112 and CSH 5) showed a poor interaction with these factors. Midge damage in ICSV 197 showed a negative correlation with minimum temperature and relative humidity and positive correlation with sunshine hours, while the reverse was true for CSH 5. Grain growth rate between 0 and 3 days after anthesis was lower in crops sown on 1st October, when AF 28 and ICSV 197 suffered maximum midge damage. Maximum and minimum temperatures and maximum relative humidity influenced the moisture content of the grain, grain growth rate, and sorghum midge damage. There was considerable variation in genotype × environment interaction for expression of resistance to sorghum midge, and the implications of these results have been discussed in relation to development of sorghum cultivars with resistance to this insect.

Crop Protection, 2006

Spotted stem borer, Chilo partellus (Swinhoe), is the most important pest of sorghum in Asia and ... more Spotted stem borer, Chilo partellus (Swinhoe), is the most important pest of sorghum in Asia and South and Eastern Africa, and host plant resistance is an important component for controlling this pest under subsistence farming conditions. Therefore, we studied the antibiosis mechanism of resistance in a diverse array of 20 sorghum genotypes at the seedling stage by incorporating the freeze-dried leaf powder into artificial diet. Freeze-dried sorghum leaf powder at 12.5 g per 250 ml of the standard artificial diet or replacement of chickpea flour in the artificial diet by 50% with sorghum leaf powder can be used to quantify the extent of antibiosis mechanism of resistance to C. partellus in sorghum. There was a significant variation in larval survival, larval and pupal weights, larval and pupal periods, and percentage pupation and adult emergence in diets impregnated with freeze-dried leaf powder of different sorghum genotypes. Sorghum genotypes such as IS 1044, IS 2123, IS 1054, IS 18573, and ICSV 714 showed antibiosis to C. partellus in terms of reduced survival and development. Principal component analysis indicated that there is considerable diversity in sorghum genotypes for antibiosis to C. partellus. Genotypes placed in different groups can be used in resistance breeding programs to diversify the basis of resistance to this pest.

Global warming and climate change will influence activity, diversity, distribution and population... more Global warming and climate change will influence activity, diversity, distribution and population dynamics of insect pests including the grain legumes. Several insect pests damage grain legume crops, of which the pod borer, Helicoverpa armigera; spotted pod borer, Maruca vitrata; spiny pod borer, Etiella zinckenella; pod fly, Melanagromyza obtusa; aphid, Aphis craccivora; defoliators, Spodoptera litura and S. exigua; thrips, Megaleurothrips usitatus and Caliothrips indicus and the bruchid, Callasobruchus chinensis cause extensive losses in grain legumes. The incidence and extent of losses due to these pests varies across seasons, locations, and cropping systems. The pest spectrum on grain legumes will change considerably due to impending global warming and climate change. The geographical distribution of some of the pests might extend to temperate regions in Europe and America, while the outbreaks of some other pests will become more frequent. Several outbreaks of pod borer, H. armi...

Insect and plants have coevolved for millions of years. Plants respond to herbivory through vario... more Insect and plants have coevolved for millions of years. Plants respond to herbivory through various morphological, biochemical, and molecular mechanisms to counter/offset the effects of herbivore attack. These defense strategies against herbivores are wide-ranging, highly dynamic, and could be direct and/or indirect. Direct defense affects the herbivore's growth and development due to antibiosis because of secondary metabolites produced constitutively and/or induced upon infestation by the insect pests. The indirect defense involves the recruitment of natural enemies of the insect pests. The natural enemies (parasitoids and predators) are attracted by the volatiles produced by the plants in response to insect herbivory. The direct and indirect defensive strategies either act separately or in conjunction with each other. However, insects have the ability to adapt to the plant defensive responses through physiological processes, metabolism and behavior to offset the adverse effects of the host plants' defense systems. This process of defensive responses by the host plants and counter defense by the insect pests results in the breakdown of resistance, and evolution of new populations/biotypes of the insect pests. This co-evolution between the plants and insects poses a major threat for developing crop cultivars with stable resistance to the target pest for pest management.

Euphytica, 2018

The noctuid pod borer, Helicoverpa armigera is one of the most damaging pests of chickpea, Cicer ... more The noctuid pod borer, Helicoverpa armigera is one of the most damaging pests of chickpea, Cicer arietinum. The levels of resistance to H. armigera in the cultivated chickpea are low to moderate, but the wild relatives of chickpea have exhibited high levels of resistance to this pest. To develop insect-resistant cultivars with durable resistance, it is important to understand the contribution of different components of resistance, and therefore, we studied antixenosis and antibiosis mechanisms of resistance to H. armigera in a diverse array of wild relatives of chickpea. The genotypes IG 70012, PI 599046, IG 70022, PI 599066, IG 70006, IG 70018 (C. bijugum), ICC 506EB, ICCL 86111 (cultivated chickpea), IG 72933, IG 72953 (C. reticulatum), IG 69979 (C. cuneatum) and IG 599076 (C. chrossanicum) exhibited non preference for oviposition by the females of H. armigera under multi-choice, dualchoice and no-choice cage conditions. Based on detached leaf assay, the genotypes IG 70012, IG 70022, IG 70018, IG 70006, PI 599046, PI 599066 (C. bijugum), IG 69979 (C. cuneatum), PI 568217, PI 599077 (C. judaicum) and ICCW 17148 (C. microphyllum) suffered significantly lower leaf damage, and lower larval weights indicating high levels of antibiosis than on the cultivated chickpea. Glandular and nonglandular trichomes showed negative correlation with oviposition, while the glandular trichomes showed a significant and negative correlation with leaf damage rating. Density of non-glandular trichomes was negatively correlated with larval survival. High performance liquid chromatography (HPLC) fingerprints of leaf surface exudates showed a negative correlation of oxalic acid with oviposition, but positive correlation with malic acid. Both oxalic acid and malic acid showed a significant negative correlation with larval survival. The wild relatives exhibiting low preference for oviposition and high levels of antibiosis can be used as sources of resistance to increase the levels and diversify the basis of resistance to H. armigera in cultivated chickpea.

Journal of Economic Entomology, 2018

Wild relatives of crops are an important source of resistance genes against insect pests. However... more Wild relatives of crops are an important source of resistance genes against insect pests. However, it is important to identify the accessions of wild relatives with different mechanisms of resistance to broaden the basis and increase the levels of resistance to insect pests. Therefore, we evaluated 15 accessions of wild relatives of chickpea belonging to seven species and five genotypes of cultivated chickpea for their resistance to pod borer, Helicoverpa armigera, which is the most damaging pest of chickpea. The test genotypes were evaluated for resistance to H. armigera using detached pod assay. Data were also recorded on activity of the digestive enzymes in the midgut of the larvae fed on different wild relatives of chickpea. All the wild chickpea genotypes suffered lower pod damage and weight gained by the third-instar larvae of H. armigera was lower when fed on them compared with the cultivated chickpea.

Agriculture, 2019

Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrai... more Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrained by several biotic and abiotic stresses. Therefore, sorghum improvement programs largely focus on developing high-yielding cultivars with multiple traits including stress resistance, bioenergy and nutritional quality. This study was undertaken to meet breeders’ needs to develop such cultivars and identify diverse germplasm sources with multiple traits. The 242 sorghum mini core accessions were evaluated for agronomic traits (yield, maturity, 100-seed weight) in two post-rainy seasons under optimally irrigated and drought conditions and identified 21 accessions as a sources for agronomic traits. The evaluation of mini core revealed 70 accessions resistant to biotic stress, 12 to abiotic stress, 13 for bioenergy traits and 27 for nutritional traits. The 13,390 single nucleotide polymorphism markers on mini core were used to identify genetically diverse accessions with desirable agronomi...

Journal of bioenergetics and biomembranes, Jan 5, 2018

Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) a... more Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) and are frequently used as insecticides against most devastating lepidopteran insect pests. Imidacloprid influenced dose-dependent decline in the state III and IV respiration, respiration control index (RCI), and P/O ratios, in vitro and in vivo. The bioassay indicated its LD50 value to be 531.24 μM. The insecticide exhibited a dose-dependent inhibition on F0F1-ATPase and complex IV activity. At 600 μM, the insecticide inhibited 83.62 and 27.13% of F0F1-ATPase and complex IV activity, respectively, and induced the release of 0.26 nmoles/min/mg protein of cytochrome c. A significant dose- and time-dependent increase in oxidative stress was observed; at 600 μM, the insecticide correspondingly induced lipid peroxidation, LDH activity, and accumulation of H2O2 content by 83.33, 31.51 and 223.66%. The stress was the maximum at 48 h of insecticide treatment (91.58, 35.28, and 189.80%, respectiv...

Archives of insect biochemistry and physiology, Jan 20, 2017

Phthalic acid diamide insecticides are the most effective insecticides used against most of the l... more Phthalic acid diamide insecticides are the most effective insecticides used against most of the lepidopteran pests including Helicoverpa armigera, a polyphagous pest posing threat to several crops worldwide. The present studies were undertaken to understand different target sites and their interaction with insect ryanodine receptors (RyR). Bioassays indicated that flubendiamide inhibited the larval growth in dose-dependent manner with LD50 value of 0.72 μM, and at 0.8 μM larval growth decreased by about 88%. Flubendiamide accelerated the Ca(2+) -ATPase activity in dose-dependent trend, and at 0.8 μM, the activity was increased by 77.47%. Flubendiamide impedes mitochondrial function by interfering with complex I and F0 F1 -ATPase activity, and at 0.8 μM the inhibition was found to be about 92% and 50%, respectively. In vitro incubation of larval mitochondria with flubendiamide induced the efflux of cytochrome c, indicating the mitochondrial toxicity of the insecticide. Flubendiamide ...

Archives of insect biochemistry and physiology, 2017

We characterized trypsin- and chymotrypsin-like serine alkaline proteases from cotton bollworm, H... more We characterized trypsin- and chymotrypsin-like serine alkaline proteases from cotton bollworm, Helicoverpa armigera, for their probable potential application as additives in various bio-formulations. Purification was achieved by using hydroxylapatite, DEAE sephadex and CM sephadex columns, which resulted in increased enzyme activity by 13.76- and 14.05-fold for trypsin and chymotrypsin, respectively. Michaelis-Menten constants (Km ) for substrates of trypsin and chymotrypsin, BApNA and SAAPFpNA, were found to be 1.25 and 0.085 mM, correspondingly. Fluorescent zymogram analysis indicated the presence of five trypsin bands with molecular masses of ∼21, 25, 38, 40, and 66 kDa and two chymotrypsin bands with molecular masses of ∼29 and 34 kDa in SDS-PAGE. The optimum pH was 10.0 and optimum temperature was 50°C for proteolytic activity for the purified proteases. The proteases were inhibited by synthetic inhibitors such as PMSF, aprotonin, leupeptin, pefabloc, and antipain. TLCK and TP...

Biochemistry and Biophysics Reports, 2016

Background: Chilo partellus is an important insect pest infesting sorghum and maize. The larvae i... more Background: Chilo partellus is an important insect pest infesting sorghum and maize. The larvae internalize in the stem, rendering difficulties in pest management. We investigated the effects of Capsicum annuum proteinase inhibitors (CanPIs) on C. partellus larvae by in-vitro and in-vivo experiments. Methods: Recombinant CanPI-7 (with four-Inhibitory Repeat Domains, IRDs),-22 (two-IRDs) and insect proteinase activities were estimated by proteinase assays, dot blot assays and in gel activity assays. Feeding bioassays of lab reared C. partellus with CanPI-7 and-22 were performed. C. partellus proteinase gene expression was done by RT-PCR. In-silico structure prediction of proteinases and CanPI IRDs was carried out, their validation and molecular docking was done for estimating the interaction strength. Results: Larval proteinases of C. partellus showed higher activity at alkaline pH and expressed few proteinase isoforms. Both CanPIs showed strong inhibition of C. partellus larval proteinases. Feeding bioassays of C. partellus with CanPIs revealed a dose dependent retardation of larval growth, reduction of pupal mass and fecundity, while larval and pupal periods increased significantly. Ingestion of CanPIs resulted in differential upregulation of C. partellus proteinase isoforms, which were sensitive to CanPI-7 but were insensitive to CanPI-22. In-silico interaction studies indicated the strong interaction of IRD-9 (of CanPI-22) with Chilo proteinases tested. Conclusions: Of the two PIs tested, CanPI-7 prevents induction of inhibitor insensitive proteinases in C. partellus so it can be explored for developing C. partellus tolerance in sorghum. General significance: Ingestion of CanPIs, effectively retards C. partellus growth; while differentially regulating the proteinases.

Arthropod-Plant Interactions, 2016

Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

International Journal of Insect Science, 2016

Flavonoids are important plant secondary metabolites, which protect plants from various stresses,... more Flavonoids are important plant secondary metabolites, which protect plants from various stresses, including herbivory. Plants differentially respond to insects with different modes of action. High performance liquid chromatography (HPLC) fingerprinting of phenols of groundnut ( Arachis hypogaea) plants with differential levels of resistance was carried out in response to Helicoverpa armigera (chewing insect) and Aphis craccivora (sucking pest) infestation. The genotypes used were ICGV 86699, ICGV 86031, ICG 2271 (NCAc 343), ICG 1697 (NCAc 17090), and JL 24. Most of the identified compounds were present in H. armigera- and A. craccivora-infested plants of ICGV 86699. Syringic acid was observed in all the genotypes across the treatments, except in the uninfested control plants of ICG 2271 and aphid-infested plants of ICG 1697. Caffeic acid and umbelliferone were observed only in the H. armigera-infested plants of ICGV 86699. Similarly, dihydroxybenzoic acid and vanillic acid were obse...

Environmental Entomology, 2015

Climate change will have a major bearing on survival and development of insects as a result of in... more Climate change will have a major bearing on survival and development of insects as a result of increase in CO 2 and temperature. Therefore, we studied the direct effects of CO 2 and temperature on larval development and metabolism in cotton bollworm, Helicoverpa armigera (Hü bner). The larvae were reared under a range of CO 2 (350, 550, and 750 ppm) and temperature (15, 25, 35, and 45 C) regimes on artificial diet. Elevated CO 2 negatively affected the larval survival, larval weight, larval period, pupation, and adult emergence, but showed a positive effect on pupal weight, pupal period, and fecundity. Increase in temperature exhibited a negative effect on larval survival, larval period, pupal weights, and pupal period, but a positive effect on larval growth. Pupation and adult emergence were optimum at 25 C. Elevated CO 2 and temperature increased food consumption and metabolism of larvae by enhancing the activity of midgut proteases, carbohydrases (amylase and cellulase), and mitochondrial enzymes and therefore may cause more damage to crop production. Elevated CO 2 and global warming will affect insect growth and development, which will change the interactions between the insect pests and their crop hosts. Therefore, there is need to gain an understanding of these interactions to develop strategies for mitigating the effects of climate change.

Phytoparasitica, 2015

Host plant resistance is an important component of pest management, and information on contributi... more Host plant resistance is an important component of pest management, and information on contribution of different mechanisms of resistance is important for developing cultivars with resistance to the target pests. Therfore, we studied the contribution of different components of resistance in five groundnut genotypes to three insect species occurring in India under field conditions. Plant damage by the larvae of Helicoverpa armigera, Spodoptera litura, and leafhoppers (Empoasca kerri) was evaluated visually on a 1-9 damage rating (DR) scale (1 being <10 % leaf damage, and 9 being >80 % leaf damage). Further, the activities of various plant defensive enzymes [peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), ascorbate peroxidase (APX), lipoxygenase (LOX) and catalase (CAT)], and the amounts of total phenols, condensed tannins, hydrogen peroxide (H 2 O 2), malondialdehyde (MDA) and proteins were also recorded. The genotypes ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697 suffered lower leaf damage by H. armigera and S. litura (DR 2.6-3.2) and E. kerri (DR 2.0-3.2) as compared to JL 24 (DR 7.2 and 6.0, respectively). ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697 exhibited greater enzymatic activity, and had more amounts of phenols, condensed tannins, hydrogen peroxide and proteins than the susceptible check, JL 24. There was a positive association between leaf damage and the activity of the defensive enzymes, and the amounts of phenols, condensed tannins and H 2 O 2. These results suggested that the plant defensive enzymes such as POD, PPO, LOX, PAL, SOD, APX and CAT were involved in genotypic resistance to insects, and the resistant genotypes accumulated phenols, condensed tannins, and H 2 O 2 to impart resistance to insects. This information will be useful for developing groundnut genotypes with resistance to insects for sustainable crop production.