Senthil-Nathan, Sengottayan
I am interested in eco-friendly pesticides including microorganisms. My program for master, doctoral and post-doctoral programme including insect and plant biochemistry with insect molecular pathology. I'm serving as Associate Editor/Subject Editor for Nature Scientific Reports, Frontiers in Invertebrate Physiology, Florida Entomologist, Journal of Asia-Pacific Entomology, Archives of Phytopathology and Plant Protection and Biopesticide International.
Phone: +914634283066 & senthil@msuniv.ac.in
Address: Sri Paramakalyani Centre for Excellence in Environmental Sciences,
Manonmaniam Sundaranar University,
Alwarkurichi, 627 412, Tamil-Nadu, India
Phone: +914634283066 & senthil@msuniv.ac.in
Address: Sri Paramakalyani Centre for Excellence in Environmental Sciences,
Manonmaniam Sundaranar University,
Alwarkurichi, 627 412, Tamil-Nadu, India
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a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (5989%) and exhibited a signicant reduction
in ACP, ALP and ATPase activities. The combination of Bacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear doseresponse relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic
pesticides in controlling RLF.
decrease in nutritional indices, indicating strong deterrence. Dose response relationships were established with respect to frass production and larval growth. The efciency of conversion of ingested and digested food was considerably reduced.
limonoids. Azadirachtin, salannin and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids
were less active, and were only biologically active at high doses. Azadirachtin was the most potent in all experiments and produced
almost 100% larval mortality at 1 ppm concentration. In general, first to third larval instars were more susceptible to the neem limonoids. Neem products may have benefits in mosquito control programs.
between combined and individual treatment. A synergistic eVect of botanical insecticides and virus was found when combined in low doses. These effects are most pronounced in early instars. Maximum weight loss (59–72%) occurred, when AZA and NPV were combined.
deacetylgedunin, gedunin, 17-hydroxyazadiradione, and deacetylnimbin showed strong antifeedant and growth inhibitor activity against fifth instar larvae of Cnaphalocrocis medinalis, the rice leaffolder, a serious pest of rice in Asian countries. The parameters, used to evaluate the activity of the limonoids were larval food utilization, quantity of ingested and digested food; consumption index and feeding deterrence index. Azadirachtin, salannin, deacetylgedunin showed high bioactivity at all doses, while the other neem limonoids proved to be less active, and only at the higher doses did they display antifeedant activity. Azadirachtin was the most potent in all experiments. Gross dietary utilization (efficiency of conversion of ingested food) of C. medinalis was also decreased after treatment with limonoids. Our results suggest that neem limonoids may be used in IPM programs for rice leaffolder and should be evaluated for efficacy under field conditions.
and deaceytlnimbin on gut enzyme activity of the rice leaffolder larvae was investigated. When fed a diet of rice leaves treated with limonoids in bioassays, gut tissue enzymes—acid phosphatases (ACP), alkaline phosphatases (ALP), and adenosine triphosphatases (ATPase) activities of rice leaffolder (Cnaphalocrocis medinalis) larvae are affected. Azadirachtin was most potent in all experiments. Larvae that were chronically exposed to limonoids showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP, and ATPase activities. These results indicate neem limonoids affects gut enzyme activities. These effects are most pronounced in early instars.
indices and gut enzymes acid phosphatases, alkaline phosphatases, adenosinetriphosphatases, and lactate dehydrogenase of
the rice leaffolder (RLF) Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Larvae were fed a treated rice-leaf diet
containing the seed extract and their midgut was used for enzyme determination. Laboratory experiments showed that the seed extract suppressed the larval activity of C. medinalis even at a low dose. Gross dietary utilization (effciency of conversion of ingested and digested food) of RLF decreased after ingesting the treated rice-leaf diet. Food consumption, digestion, relative consumption rate, effciency of conversion of ingested food, effciency of conversion of digested food, and relative growth rate values declined significantly. As compared to the control, consumption of the extract containing rice-leaf diet resulted in a 69% reduction of the acid phosphatases activity, a 71% reduction of the alkaline phosphatases activity, a 46% reduction of the adenosine triphosphatases activity, and a 52% inhibition of the lactate dehydrogenase activity.
soft white wheat (Triticum aestivum L), short-grained white rice (Oryza sativa L.), and durra sorghum (Sorghum bicolor L. Moench). For C. cephalonica, the percentage adult emergence and several fifth-instar food use indices (consumption index, relative growth rate, and efficiencies of conversion of ingested and digested food) were significantly higher for millet-reared than for sorghum-reared larvae. The nutritional indices for wheat- and rice-reared C. cephalonica larvae were intermediate
between the indices for larvae reared on millet and sorghum. The percentage adult emergence and percentage 24-h survival of T. chilonis were significantly higher on eggs of C. cephalonica hosts reared on millet than on eggs of those reared on sorghum. These results suggest that the rearing of
C. cephalonica larvae on a high-quality nutritional source resulted in high-quality eggs, which ultimately resulted in high-quality T. chilonis reared on those eggs. Such an effect has been modeled in ecological theory as a “bottom up cascade.” Improved knowledge of the nutritional ecology of parasitoids and hosts can lead to improved understanding of the ecological mechanisms affecting host plant, host, and parasitoid abundance, as well as to improved efficiency and quality of Trichogramma production in mass rearing programs.
showed strong larvicidal, pupicidal, adulticidal, and antiovipositional activity. The maximum leaf extract concentration tested in this study was 4%, which produced pronounced effects. In general, first and second instars were more susceptible to leaf extract than older insects. Clear dose–response relationships were established, with the highest dose of 4% plant extract causing 97% mortality of first
instars.
dose. Results obtained from the laboratory experiment showed that the seed extracts suppressed the pupal and adult activity of A. stephensi even at low dose. In general, first and second instar larvae were more susceptible to both leaves and seed extracts. Clear dose–response relationships were established with the highest dose of 2% plant extract evoking 96% mortality. Entire development of A. stephensi was inhibited by M. azedarach treatment. Less expensive (less than US$0.50 per 1 kg seed), naturally accruing biopesticide
could be an alternative for chemical pesticides.
pest control programs, such products may have the potential to be used successfully as botanical insecticides. The effect of the neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin on the biology and mortality of rice leaffolder larvae was investigated. In laboratory experiments, treatment with neem limonoids suppressed leaf folding behaviour of C. medinalis. Biological parameters (larval duration, pupal duration adult longevity and fecundity) were also affected by the treatment. Azadirachtin, salannin, and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids were less active, and were only biologically active at high doses. Azadirachtin was most potent in all experiments and produced almost 100% larval mortality at 1 ppm concentration. These results indicate neem limonoids affect the larval behaviour. These effects are most pronounced in early instars.
of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) larvae was investigated. There was a
decrease in enzyme activity relative to the control at all concentrations tested. When fed a diet of rice leaves treated with neem limonoids in bioassays, gut tissue enzyme, LDH levels in rice leaffolder larvae are affected. These results indicate neem limonoids affect LDH activity. These effects are most pronounced in early instar larvae. Azadirachtin was the
most potent in of all the limonoids in all experiments indicating strong enzyme inhibition. Clear dose–response relationships
were established with respect to LDH activity.
Hyblaea puera (H. puera) Cramer (Lepidoptera: Hyblaeidae) under laboratory conditions. This insect defoliates teak, and is
considered as a major pest that strongly influences the development of the teak tree. Chinaberry extracts were found to affect the growth, feeding and oviposition of H. puera. In general, the seed extracts showed high bioactivity at all doses, while the leaf extract, proved to be active, only at the higher doses. Our laboratory experiment showed that the seed extract suppressed the larval activity of H. puera even at low doses. Gross dietary utilization (efficiency of conversion of ingested and digested food) of H. puera decreased after treatment in the diet. The growth of surviving larvae decreased, and no late fourth and early fifth instars completed development on higher dose treatment of both leafs and seed extracts. Food consumption, digestion, relative consumption rate (RCR), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and relative growth rate (RGR) values declined significantly, but concurrently a significant increase in approximate digestibility (AD) was observed. Clear dose–response relationships were established, with the highest dose of 4% seed extract evoking 94% feeding deterrence. Larvae that were chronically exposed M. azedarach extract showed a reduction in weight (65–84%). The less expensive and naturally occurring biopesticide may be an alternative for synthetic pesticides in order to protect forest trees.
The effects of azadirachtin (AZA) and Spodoptera nucleopolyhedrovirus (SpltNPV) on development and mortality of Spodoptera litura Fabricius (tobacco cutworm) were evaluated in the laboratory. The effective concentrations for AZA and SpltNPV were determined and tested as single and combination treatments. AZA and SpltNPV produced synergistic effects on tobacco cutworm mortality in higher dose combination treatment. Combinations of AZA + SpltNPV at 0.25 ppm + 1×103 OBs and 0.50 ppm + 1×106 OBs resulted in a significantly higher larval mortality than treatment with either virus/botanical insecticide alone at the corresponding concentrations. When consumed together (AZA and SpltNPV) larvae died significantly faster compared with larvae consuming SpltNPV or AZA. These results suggest that treatments with AZA and SpltNPV at appropriate combinations of concentration levels may result in improved control of tobacco cutworm compared with treatment with either AZA or virus alone.
(SDD0.33) for 3,24,25-DHCL and BL, respectively] and LC 90 [14.63 ppm (SDD0.36), 13.49 ppm (SDD0.27) for 3,24,25-DHCL and BL, respectively] were identifed by probit analysis. Fourth instars were exposed to various concentrations (1.5, 3, 6, and 12 ppm) of Dysoxylum
triterpenes. Results showed that treated larvae exhibited reduced food consumption and enzyme activity. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined siginificantly but the approximate digestibility of treated larvae was significantly higher as a result of treatment (in particular 6 and 12 ppm). Likewise, the gut enzymes acid phosphatases, alkaline phosphatases, and adenosine triphosphatases were signifcantly inhibited by the Dysoxylum triterpenes. The high biological activity of these triterpenes from Dysoxylum sp. could be used as an active principle during the preparation of botanical insecticides for insect pest like rice leaffolder.
a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (5989%) and exhibited a signicant reduction
in ACP, ALP and ATPase activities. The combination of Bacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear doseresponse relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic
pesticides in controlling RLF.
decrease in nutritional indices, indicating strong deterrence. Dose response relationships were established with respect to frass production and larval growth. The efciency of conversion of ingested and digested food was considerably reduced.
limonoids. Azadirachtin, salannin and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids
were less active, and were only biologically active at high doses. Azadirachtin was the most potent in all experiments and produced
almost 100% larval mortality at 1 ppm concentration. In general, first to third larval instars were more susceptible to the neem limonoids. Neem products may have benefits in mosquito control programs.
between combined and individual treatment. A synergistic eVect of botanical insecticides and virus was found when combined in low doses. These effects are most pronounced in early instars. Maximum weight loss (59–72%) occurred, when AZA and NPV were combined.
deacetylgedunin, gedunin, 17-hydroxyazadiradione, and deacetylnimbin showed strong antifeedant and growth inhibitor activity against fifth instar larvae of Cnaphalocrocis medinalis, the rice leaffolder, a serious pest of rice in Asian countries. The parameters, used to evaluate the activity of the limonoids were larval food utilization, quantity of ingested and digested food; consumption index and feeding deterrence index. Azadirachtin, salannin, deacetylgedunin showed high bioactivity at all doses, while the other neem limonoids proved to be less active, and only at the higher doses did they display antifeedant activity. Azadirachtin was the most potent in all experiments. Gross dietary utilization (efficiency of conversion of ingested food) of C. medinalis was also decreased after treatment with limonoids. Our results suggest that neem limonoids may be used in IPM programs for rice leaffolder and should be evaluated for efficacy under field conditions.
and deaceytlnimbin on gut enzyme activity of the rice leaffolder larvae was investigated. When fed a diet of rice leaves treated with limonoids in bioassays, gut tissue enzymes—acid phosphatases (ACP), alkaline phosphatases (ALP), and adenosine triphosphatases (ATPase) activities of rice leaffolder (Cnaphalocrocis medinalis) larvae are affected. Azadirachtin was most potent in all experiments. Larvae that were chronically exposed to limonoids showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP, and ATPase activities. These results indicate neem limonoids affects gut enzyme activities. These effects are most pronounced in early instars.
indices and gut enzymes acid phosphatases, alkaline phosphatases, adenosinetriphosphatases, and lactate dehydrogenase of
the rice leaffolder (RLF) Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Larvae were fed a treated rice-leaf diet
containing the seed extract and their midgut was used for enzyme determination. Laboratory experiments showed that the seed extract suppressed the larval activity of C. medinalis even at a low dose. Gross dietary utilization (effciency of conversion of ingested and digested food) of RLF decreased after ingesting the treated rice-leaf diet. Food consumption, digestion, relative consumption rate, effciency of conversion of ingested food, effciency of conversion of digested food, and relative growth rate values declined significantly. As compared to the control, consumption of the extract containing rice-leaf diet resulted in a 69% reduction of the acid phosphatases activity, a 71% reduction of the alkaline phosphatases activity, a 46% reduction of the adenosine triphosphatases activity, and a 52% inhibition of the lactate dehydrogenase activity.
soft white wheat (Triticum aestivum L), short-grained white rice (Oryza sativa L.), and durra sorghum (Sorghum bicolor L. Moench). For C. cephalonica, the percentage adult emergence and several fifth-instar food use indices (consumption index, relative growth rate, and efficiencies of conversion of ingested and digested food) were significantly higher for millet-reared than for sorghum-reared larvae. The nutritional indices for wheat- and rice-reared C. cephalonica larvae were intermediate
between the indices for larvae reared on millet and sorghum. The percentage adult emergence and percentage 24-h survival of T. chilonis were significantly higher on eggs of C. cephalonica hosts reared on millet than on eggs of those reared on sorghum. These results suggest that the rearing of
C. cephalonica larvae on a high-quality nutritional source resulted in high-quality eggs, which ultimately resulted in high-quality T. chilonis reared on those eggs. Such an effect has been modeled in ecological theory as a “bottom up cascade.” Improved knowledge of the nutritional ecology of parasitoids and hosts can lead to improved understanding of the ecological mechanisms affecting host plant, host, and parasitoid abundance, as well as to improved efficiency and quality of Trichogramma production in mass rearing programs.
showed strong larvicidal, pupicidal, adulticidal, and antiovipositional activity. The maximum leaf extract concentration tested in this study was 4%, which produced pronounced effects. In general, first and second instars were more susceptible to leaf extract than older insects. Clear dose–response relationships were established, with the highest dose of 4% plant extract causing 97% mortality of first
instars.
dose. Results obtained from the laboratory experiment showed that the seed extracts suppressed the pupal and adult activity of A. stephensi even at low dose. In general, first and second instar larvae were more susceptible to both leaves and seed extracts. Clear dose–response relationships were established with the highest dose of 2% plant extract evoking 96% mortality. Entire development of A. stephensi was inhibited by M. azedarach treatment. Less expensive (less than US$0.50 per 1 kg seed), naturally accruing biopesticide
could be an alternative for chemical pesticides.
pest control programs, such products may have the potential to be used successfully as botanical insecticides. The effect of the neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin on the biology and mortality of rice leaffolder larvae was investigated. In laboratory experiments, treatment with neem limonoids suppressed leaf folding behaviour of C. medinalis. Biological parameters (larval duration, pupal duration adult longevity and fecundity) were also affected by the treatment. Azadirachtin, salannin, and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids were less active, and were only biologically active at high doses. Azadirachtin was most potent in all experiments and produced almost 100% larval mortality at 1 ppm concentration. These results indicate neem limonoids affect the larval behaviour. These effects are most pronounced in early instars.
of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) larvae was investigated. There was a
decrease in enzyme activity relative to the control at all concentrations tested. When fed a diet of rice leaves treated with neem limonoids in bioassays, gut tissue enzyme, LDH levels in rice leaffolder larvae are affected. These results indicate neem limonoids affect LDH activity. These effects are most pronounced in early instar larvae. Azadirachtin was the
most potent in of all the limonoids in all experiments indicating strong enzyme inhibition. Clear dose–response relationships
were established with respect to LDH activity.
Hyblaea puera (H. puera) Cramer (Lepidoptera: Hyblaeidae) under laboratory conditions. This insect defoliates teak, and is
considered as a major pest that strongly influences the development of the teak tree. Chinaberry extracts were found to affect the growth, feeding and oviposition of H. puera. In general, the seed extracts showed high bioactivity at all doses, while the leaf extract, proved to be active, only at the higher doses. Our laboratory experiment showed that the seed extract suppressed the larval activity of H. puera even at low doses. Gross dietary utilization (efficiency of conversion of ingested and digested food) of H. puera decreased after treatment in the diet. The growth of surviving larvae decreased, and no late fourth and early fifth instars completed development on higher dose treatment of both leafs and seed extracts. Food consumption, digestion, relative consumption rate (RCR), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and relative growth rate (RGR) values declined significantly, but concurrently a significant increase in approximate digestibility (AD) was observed. Clear dose–response relationships were established, with the highest dose of 4% seed extract evoking 94% feeding deterrence. Larvae that were chronically exposed M. azedarach extract showed a reduction in weight (65–84%). The less expensive and naturally occurring biopesticide may be an alternative for synthetic pesticides in order to protect forest trees.
The effects of azadirachtin (AZA) and Spodoptera nucleopolyhedrovirus (SpltNPV) on development and mortality of Spodoptera litura Fabricius (tobacco cutworm) were evaluated in the laboratory. The effective concentrations for AZA and SpltNPV were determined and tested as single and combination treatments. AZA and SpltNPV produced synergistic effects on tobacco cutworm mortality in higher dose combination treatment. Combinations of AZA + SpltNPV at 0.25 ppm + 1×103 OBs and 0.50 ppm + 1×106 OBs resulted in a significantly higher larval mortality than treatment with either virus/botanical insecticide alone at the corresponding concentrations. When consumed together (AZA and SpltNPV) larvae died significantly faster compared with larvae consuming SpltNPV or AZA. These results suggest that treatments with AZA and SpltNPV at appropriate combinations of concentration levels may result in improved control of tobacco cutworm compared with treatment with either AZA or virus alone.
(SDD0.33) for 3,24,25-DHCL and BL, respectively] and LC 90 [14.63 ppm (SDD0.36), 13.49 ppm (SDD0.27) for 3,24,25-DHCL and BL, respectively] were identifed by probit analysis. Fourth instars were exposed to various concentrations (1.5, 3, 6, and 12 ppm) of Dysoxylum
triterpenes. Results showed that treated larvae exhibited reduced food consumption and enzyme activity. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined siginificantly but the approximate digestibility of treated larvae was significantly higher as a result of treatment (in particular 6 and 12 ppm). Likewise, the gut enzymes acid phosphatases, alkaline phosphatases, and adenosine triphosphatases were signifcantly inhibited by the Dysoxylum triterpenes. The high biological activity of these triterpenes from Dysoxylum sp. could be used as an active principle during the preparation of botanical insecticides for insect pest like rice leaffolder.