The snowdrop lectin GNA （Galanthus nivalis agglutinin） has been shown to possess insecticidal activity to a range of economically important insect pests. However, the precise mechanism of insecticidal action of GNA ...The snowdrop lectin GNA （Galanthus nivalis agglutinin） has been shown to possess insecticidal activity to a range of economically important insect pests. However, the precise mechanism of insecticidal action of GNA against insects remains unknown. In this investigation, we attempted to purify and identify receptor（s） responsible for binding of GNA in the larval midgut of a major lepidopteran pest （the cotton leafworm, Spodoptera littoralis） to better understand its mode of action. Therefore, cytoplasmic as well as membrane proteins from 800 larval midguts were chromatographed on a column with immobilized GNA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the proteins eluted from the GNA column followed by sequencing of the GNA-binding proteins and BLAST analyses revealed that the N-terminal sequences of a 24 kDa polypeptide purified from the cytoplasmic and membrane protein fraction revealed sequence similarity to sequences encoding heavy chain homologs of ferritin from Manduca sexta （76% sequence identity）, Calpodes ethlius （80% sequence identity） and Bombyx mori （61% sequence identity）. Furthermore, the N-terminal sequence of a 31 kDa polypeptide from the membrane protein fraction showed sequence similarity to a light chain homolog of ferritin from Manduca sexta （88% sequence identity）.展开更多
Baculoviruses are effective biocontrol agents except of their short persistence under sunlight conditions. Four promising additives containing different groups of antioxidants were tested on cotton plant foliage. Spod...Baculoviruses are effective biocontrol agents except of their short persistence under sunlight conditions. Four promising additives containing different groups of antioxidants were tested on cotton plant foliage. Spodoptera littoralis test insect and its nuclepolyhedrovirus （SpliNPV） are the standard material used in the investigation. Results are based on leaf-bioassays, to test Original Activity Remaining （OAR） and Lethal Infectivity Time to 50% （LIT50）of tested population of the virus after exposure to natural sunlight. The results showed that cacao additive at 10%, sustained 50% of virus activity for five days post application （113.11 hours） and three days and a half （83.33 hours） at 5% concentration. The virus alone treatment sustained 50% of its activity for only 24.07 hours. The obtained results suggested the possibility of prolonging the virus activity on plant foliage under field applications.展开更多
The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores....The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.展开更多
Adult size, longevity, egg load dynamics and oviposition ofMicroplitis rufiventris Kok. which began their development in the first, second, third （preferred hosts） or fourth （non-preferred hosts） instar larvae of ...Adult size, longevity, egg load dynamics and oviposition ofMicroplitis rufiventris Kok. which began their development in the first, second, third （preferred hosts） or fourth （non-preferred hosts） instar larvae of Spodoptera littoralis （Boisd.） were studied. The parasitoid size was largely determined by the initial host size at parasitism. Non-ovipositing females derived from older hosts lived for longer periods than those derived from younger ones. However, the ovipositing females, irrespective of their size, lived for almost the same periods. At emergence, the oviducts of adult females contain a significant amount of mature eggs available for oviposition for a few hours on eclosion day. Egg load increases during the early phase of adult life. The amount of additional mature eggs and rate of egg maturation per hour was greater for wasps derived from preferred hosts compared with those in females derived from non-preferred hosts. The pattern of egg production in M. rufiventris females depended on the availability of hosts for parasitization. Host-deprived females depleted the egg complement with aging; the longer the host deprivation, the lower the oviduct egg load. Marked reduction in both realized or potential fecundity of host-deprived females was observed following host availability. Host privation for more than 3 days induced a marked deficit fecundity pattern through the female＇ s life. The realized fecundity was determined by the interaction among host availability, the number of eggs that are matured over the female＇ s life span, oviposition rate and host size from which the female was derived. These results suggest that： （i） M. rufiventris wasp is a weak synovigenic species; （ii） the maturation of additional eggs is inhibited once the maximum oviduct egg load is reached; （iii） the egg load of the newly emerged female is significantly less than the realized fecundity; and （iv） because M. rufiventris females oviposit fewer eggs when they begin depleting their egg supply at 3 days, augmentative releases will require release immediately following emergence to ensure the highest parasitization rate in the field.展开更多
The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)...The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)-or(S)-(+)-linalool.Only(S)-(+)-linalool production was associated with slower growth of a generalist herbivore,and a large fraction was present as nonvolatile derivatives.We found that variation in volatile linalool and its nonvolatile glycosides mapped to the same genetic locus which harbored the biosynthetic gene,NaLIS,but that free linalool varied more in environmental responses.This study reveals how(S)-(+)-linalool and conjugates differ in their regulation and possible functions in resistance.展开更多
文摘The snowdrop lectin GNA （Galanthus nivalis agglutinin） has been shown to possess insecticidal activity to a range of economically important insect pests. However, the precise mechanism of insecticidal action of GNA against insects remains unknown. In this investigation, we attempted to purify and identify receptor（s） responsible for binding of GNA in the larval midgut of a major lepidopteran pest （the cotton leafworm, Spodoptera littoralis） to better understand its mode of action. Therefore, cytoplasmic as well as membrane proteins from 800 larval midguts were chromatographed on a column with immobilized GNA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the proteins eluted from the GNA column followed by sequencing of the GNA-binding proteins and BLAST analyses revealed that the N-terminal sequences of a 24 kDa polypeptide purified from the cytoplasmic and membrane protein fraction revealed sequence similarity to sequences encoding heavy chain homologs of ferritin from Manduca sexta （76% sequence identity）, Calpodes ethlius （80% sequence identity） and Bombyx mori （61% sequence identity）. Furthermore, the N-terminal sequence of a 31 kDa polypeptide from the membrane protein fraction showed sequence similarity to a light chain homolog of ferritin from Manduca sexta （88% sequence identity）.
文摘Baculoviruses are effective biocontrol agents except of their short persistence under sunlight conditions. Four promising additives containing different groups of antioxidants were tested on cotton plant foliage. Spodoptera littoralis test insect and its nuclepolyhedrovirus （SpliNPV） are the standard material used in the investigation. Results are based on leaf-bioassays, to test Original Activity Remaining （OAR） and Lethal Infectivity Time to 50% （LIT50）of tested population of the virus after exposure to natural sunlight. The results showed that cacao additive at 10%, sustained 50% of virus activity for five days post application （113.11 hours） and three days and a half （83.33 hours） at 5% concentration. The virus alone treatment sustained 50% of its activity for only 24.07 hours. The obtained results suggested the possibility of prolonging the virus activity on plant foliage under field applications.
文摘The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.
文摘Adult size, longevity, egg load dynamics and oviposition ofMicroplitis rufiventris Kok. which began their development in the first, second, third （preferred hosts） or fourth （non-preferred hosts） instar larvae of Spodoptera littoralis （Boisd.） were studied. The parasitoid size was largely determined by the initial host size at parasitism. Non-ovipositing females derived from older hosts lived for longer periods than those derived from younger ones. However, the ovipositing females, irrespective of their size, lived for almost the same periods. At emergence, the oviducts of adult females contain a significant amount of mature eggs available for oviposition for a few hours on eclosion day. Egg load increases during the early phase of adult life. The amount of additional mature eggs and rate of egg maturation per hour was greater for wasps derived from preferred hosts compared with those in females derived from non-preferred hosts. The pattern of egg production in M. rufiventris females depended on the availability of hosts for parasitization. Host-deprived females depleted the egg complement with aging; the longer the host deprivation, the lower the oviduct egg load. Marked reduction in both realized or potential fecundity of host-deprived females was observed following host availability. Host privation for more than 3 days induced a marked deficit fecundity pattern through the female＇ s life. The realized fecundity was determined by the interaction among host availability, the number of eggs that are matured over the female＇ s life span, oviposition rate and host size from which the female was derived. These results suggest that： （i） M. rufiventris wasp is a weak synovigenic species; （ii） the maturation of additional eggs is inhibited once the maximum oviduct egg load is reached; （iii） the egg load of the newly emerged female is significantly less than the realized fecundity; and （iv） because M. rufiventris females oviposit fewer eggs when they begin depleting their egg supply at 3 days, augmentative releases will require release immediately following emergence to ensure the highest parasitization rate in the field.
基金This work was funded by the Max Planck Society and advanced Grant No.293926 of the European Research Council(to I.T.B.)in part supported by the Collaborative Research Centre ChemBioSys(CRC 1127)funded by the Deutsche Forschungsgemeinschaft,and the Venture&Innovation Support Program for Chongqing Overseas Returnees(7820100514).
文摘The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)-or(S)-(+)-linalool.Only(S)-(+)-linalool production was associated with slower growth of a generalist herbivore,and a large fraction was present as nonvolatile derivatives.We found that variation in volatile linalool and its nonvolatile glycosides mapped to the same genetic locus which harbored the biosynthetic gene,NaLIS,but that free linalool varied more in environmental responses.This study reveals how(S)-(+)-linalool and conjugates differ in their regulation and possible functions in resistance.
