Vegetable fields are often contaminated by heavy metals,and Spodoptera exigua is a major vegetable pest which is stressed by heavy metals mainly by feeding.In this study,cadmium accumulation in the tissues of S.exigua...Vegetable fields are often contaminated by heavy metals,and Spodoptera exigua is a major vegetable pest which is stressed by heavy metals mainly by feeding.In this study,cadmium accumulation in the tissues of S.exigua exposed to cadmium and its effects on the growth and development of the parents and the offspring were investigated.Under the stress of different concentrations of cadmium(0.2,3.2,and 51.2 mg kg^(-1)),the cadmium content in each tissue of S.exigua increased in a dose-dependent manner.At the larval stage,the highest cadmium accumulation was found in midgut in all three cadmium treatments,but at the adult stage,the highest cadmium content was found in fat body.In addition,the cadmium content in ovaries was much higher than in testes.When F1S.exigua was stressed by cadmium and the F_(2)generation was not fed a cadmium-containing diet,the larval survival,pupation rate,emergence rate and fecundity of the F_(2)generation were significantly reduced in the 51.2 mg kg^(-1)treatment compared to the corresponding F1generation.Even in the F_(2)generation of the 3.2 mg kg^(-1)treatment,the fecundity was significantly lower than in the parental generation.The fecundity of the only-female stressed treatment was significantly lower than that of the only-male stressed treatment at the 3.2 and 51.2 mg kg^(-1)cadmium exposure levels.When only mothers were stressed at the larval stage,the fecundity of the F_(2)generation was significantly lower than that of the F1generation in the 51.2 mg kg^(-1)treatment,and it was also significantly lower than in the 3.2 and 0.2 mg kg^(-1)treatments.The results of our study can provide useful information for forecasting the population increase trends under different heavy metal stress conditions and for the reliable environmental risk assessment of heavy metal pollution.展开更多
It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity i...It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.However,to date,which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.In this study,33 CTL genes were identified from S.exigua.Based on the number of carbohydrate-recognition domains(CRDs)and the domain architectures,they were classified into three groups:(1)nineteen CTL-S(single-CRD),(2)eight immulectin(dual-CRD)and(3)six CTL-X(CRD with other domains).RT-qPCR analysis revealed that expression levels of SeCTL-S15,IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva,respectively.Knockdown of SeCTL-S15 significantly increased Bt susceptibility,as indicated by reduced survival and larval weight.These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S.exigua.Our results provide new insights into CTL function in insects.展开更多
[Objective] The aim was to learn the resistance of different tissues and organs of transgenic cotton to Spodoptera exigua (Hbner). [Method] Flowers,the 1st,the 3rd,the 6th and the 14th leaves from the top of 33B,GK1...[Objective] The aim was to learn the resistance of different tissues and organs of transgenic cotton to Spodoptera exigua (Hbner). [Method] Flowers,the 1st,the 3rd,the 6th and the 14th leaves from the top of 33B,GK12 and SGK321 were used to feed S. exigua neonates respectively. Survival larvae and dead ones were counted on the 3rd,the 7th,the 10th,the 16th and the 19th day; meanwhile,the pupae amount was recorded,and the pupae weight was measured at the 24th h after pupation. [Result] The survival curves,pupation rates and pupae weights of S. exigua feeding on different tissues of transgenic cotton were not significantly different from those of S. exigua feeding on the corresponding tissues of conventional cotton; pupation rate of S. exigua feeding on different leaves of the same cotton variety were not significantly different from each other,but all higher than that of S. exigua feeding on the flowers of that cotton; and there were no differences among pupation weights of S. exigua feeding on different leaves or flowers of the same cotton variety. [Conclusion] Transgenic cotton showed weak resistance to S. exigua. Hence,in the transgenic cotton fields,more attention should be paid to occurrence trend of S. exigua and its control.展开更多
[ Objective] In order to offer foundation for further study and exploration of the strain against pests, the pathogenicity of V. lecanfi MZ041024 strain against L. exigua was proved. [ Method] Under different spore co...[ Objective] In order to offer foundation for further study and exploration of the strain against pests, the pathogenicity of V. lecanfi MZ041024 strain against L. exigua was proved. [ Method] Under different spore concentrations of V. lecanii MZ041024 strain, the pathogenicity against 2^nd instar larvae of Laphygma exigua was determined using dipping method. [ Result ] The results showed that LC.50of V. lecanfi MZ041024 strain against 2M instar larvae of L. exigua under the concentration of 4.5 ×10^5 -4.5 ×10^8 spores/ml were 1.367×10^7, 3.245×10^6, 3.202 ×10^5 and 7.803 × 10^4 spores/ml. [ Conclusion] V. lecanfi MZ041024 strains had strong pathogenicity against L. exigua, so it had better control effect on L. exigua.展开更多
[Objective] The study was aimed to determine and evaluate control effect and security of 20% tebufenozide SC against Spodoptera exigua HObner, which would provide technical support for its promotion and utilization. [...[Objective] The study was aimed to determine and evaluate control effect and security of 20% tebufenozide SC against Spodoptera exigua HObner, which would provide technical support for its promotion and utilization. [ Method] By using foliar spray method, control effects of different concentration of 20% tebufenozide SC and 25 g/L deltamethrin EC against S. exigua were determined. [ Result] 20% tebufenozide SC had better control effects on S. exigua. After spraying for 3 and 7 d, control effects of 20% tebufenozide SC in each treatment could reach 81% and 84%, which was higher than 25 g/L deltamethdn EC treatment. [ Conclusion] 20% tebufenozide SC for controlling S. exigua had good effect, which had permanent effectiveness for over 7 d. It also caused less environmental pollution, and was safe to cabbage, being the ideal pesticide for controlling S. exigua in vegetables.展开更多
The beet armyworm,Spodoptera exigua (Lepidoptera:Noctuidae),is an economically important pest of crops worldwide,attacking plants from over 20 families including trans-continental agricultural cotton,corn and citru...The beet armyworm,Spodoptera exigua (Lepidoptera:Noctuidae),is an economically important pest of crops worldwide,attacking plants from over 20 families including trans-continental agricultural cotton,corn and citrus crops.In this study,performance and subsequent enzyme activity of beet armyworm reared on host plants from five families were investigated.Significant differences were found in development,fecundity and enzyme activity on different host plants.Survival rate was the highest (42.8%) on asparagus lettuce (Lactuca sativar var.asparagina) and the lowest (17.0%) on sweet pepper (Capsicum annuum).Larval duration was the shortest on asparagus lettuce (12.0 d),and was 43.4% longer on sweet peppers (21.2 d).The activity of acetylcholine esterase (AChE) and carboxylesterase (CarE) in 3rd instar larvae,and soluble carbohydrate and crude protein contents in different host plants were determined.AChE activity was the highest in the larvae feeding on Chinese cabbage (Brassica rapa),but declined by nearly 60% on maize (Zea mays) seedlings.The ratio of soluble carbohydrate content to crude protein content in host plants was found to have a positive effect on oviposition and a negative correlation with larval duration and life time (from larval to adult stages) of the insect.展开更多
Cry toxins produced by Bacillus thuringiensis(Bt) are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We...Cry toxins produced by Bacillus thuringiensis(Bt) are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We also identified a cadherin-like gene in S.exigua that could enhance the toxicity of Cry1B and Cry1C.The cadherin-like gene identified from the larvae midgut tissue was cloned by reverse transcription polymerase chain reaction(RT-PCR) and rapid amplification of cDNA ends(RACE).The full-length cDNA of the gene consisted of 5 220 bp encoding 1 740 amino acid with a predicted molecular mass of 196 kD.BLAST search analysis showed that the predicted amino acid sequence had a high sequence identity to the published sequences of cadherin-like proteins from other Lepidoptera insects.Spatial expression of the cadherin-like gene detected by qRT-PCR analysis revealed that the cadherin-like gene was mainly present in the gut of 4th instar larvae and during different life stages.The results suggested that the commercial development of this synergist has the potential to enhance Cry1B and Cry1C toxicity against Lepidoptera insects.展开更多
Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua ( Htthner), were investigated. An obvious synergism effect of the t...Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua ( Htthner), were investigated. An obvious synergism effect of the two insect growth regulators with B. beauveria was observed. When the insect growth regulators at LC50 concentrations (25 × 10^-6 g/L for methoxyfenozide and 1 000 × 10^ -6 g/L for hexaflumuren) were mixed with B. bassiana at the volume ratio of 4: 1, the mixtures achieved the best efficacy. The co-toxicity co-efficient (CTC) of methexyfenozide and B. bass/ana was 285, and that of hexaflumuron and B. bass/ana was 208. Scanning electron microscope observation of the longitudinal section of S. exigua revealed obviously different patterns of integument in different treatment groups.展开更多
Climate change will have a noteworthy bearing on survival, development, and population dynamics of insect pests. Therefore, we contemplated the survival and development of beet army worm, <em>Spodoptera exigua&l...Climate change will have a noteworthy bearing on survival, development, and population dynamics of insect pests. Therefore, we contemplated the survival and development of beet army worm, <em>Spodoptera exigua</em> under different temperatures, (15<span style="white-space:nowrap;">°</span>C, 25<span style="white-space:nowrap;">°</span>C, 35<span style="white-space:nowrap;">°</span>C, and 45<span style="white-space:nowrap;">°</span>C), CO<sub>2</sub> (350, 550, 750 ppm) and relative humidity (55%, 65%, 75% and 85%) regimes. Maximum larval and pupal weights were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C. The growth of <em>S. exigua</em> was faster at 35<span style="white-space:nowrap;">°</span>C (larval period 7.4 days and pupal period 4.5 days) than at lower temperatures. At 15<span style="white-space:nowrap;">°</span>C, the larval period was extended for 61.4 days and there was no adult emergence from the pupae till 90 days. The <em>S. exigua</em> hatchling was absent at 45<span style="white-space:nowrap;">°</span>C. The larval survival ranged from 31.6% - 57.2%, maximum survival was recorded at 25<span style="white-space:nowrap;">°</span>C, and minimum at 45<span style="white-space:nowrap;">°</span>C. The maximum (84.27%) and minimum adult emergence were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C and 35<span style="white-space:nowrap;">°</span>C respectively. Maximum fecundity (384.3 eggs/female) and egg viability (51.97%) were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C. Larval and pupal periods increased with an increase in CO<sub>2</sub> concentration. The highest pupal weights (128.6 mg/larva) were recorded at 550 ppm. The highest larval survival (73.50%) was recorded at 550 ppm and minimum (37.00%) at 750 ppm CO<sub>2</sub>. Fecundity was the highest in insects reared at 550 ppm CO<sub>2</sub> (657.4 eggs/female), and the lowest at 750 ppm. Maximum larval and pupal weights were recorded in insects reared at 75% relative humidity (RH). The growth rate of<em> S. exigua</em> was faster at 85% RH than at lower RH. The larval survival ranged between 40.0% - 58.5%. Maximum adult emergence (88.91%) was recorded in insects reared at 75% RH and minimum at 85% RH. Maximum fecundity (447.6 eggs/female) and the highest egg viability (72.95%) were recorded in insects reared at 75% and 65% RH respectively. Elevated temperatures and relative moistness will diminish the life cycle, while hoisted CO<sub>2</sub> will drag the life expectancy. Therefore, there is a need for thorough assessment of the impact of climatic factors on the population dynamics of insect pests, crop losses, and sustainability of crop production.展开更多
A pair of degenerate primers was designed, based on the comparison of five insects' GOBP2 gene sequences reported previously. A specific band (about 400bp in length) was amplified from cDNA of Spodoptera exigua an...A pair of degenerate primers was designed, based on the comparison of five insects' GOBP2 gene sequences reported previously. A specific band (about 400bp in length) was amplified from cDNA of Spodoptera exigua antenna and another specific band (about 2kb in length) was amplified from genomic DNA. The two segments were cloned into T-easy vector, respectively. Results of sequencing and structural analysis showed that the full-length of GOBP2Sexi ORF is 426bp, 141 amino acid residues were encoded. The predicted MW and pI are 16.07ku and 5.09 .respectively. There are six conservative Cys locus in the sequence, which is the typical characteristic of OBPs. GOBP2Sexi gene was inserted by two introns between amino acid residue 22 and 23 and between 82 and 83. The length of two introns is 160bp and 1403bp. Results of Northern blot showed that GOBP2 gene expressed specifically in the antenna of Spodoptera exigua, and the expression level is nearly equal in the antenna of male and female moths. The sequence was deposited in GenBank/EMBL and the accession number is AJ294809.展开更多
This paper focuses on parasitic root knot nematodes (Meloidogyne exigua) and how to decrease their pathogenic effect on coffee plants (Coffea arabica), by examining the behaviour of and the interactions between nemato...This paper focuses on parasitic root knot nematodes (Meloidogyne exigua) and how to decrease their pathogenic effect on coffee plants (Coffea arabica), by examining the behaviour of and the interactions between nematodes, coffee plant and arbuscular mycorrhizae (AM). The experiment was carried out at the seedling stage, with six (6) treatments (plants with M. exigua, plants with arbuscular mycorrhizae, plants with both organisms, and the same time, first mycorrhizae plants, then nematodes were inoculated and vice versa). After 5 months the measured variables were: dry biomass (roots and shoot), nematode knots caused by M. exigua in root, nematode juvenile (J2) found in 100.0 g of soil, and mycorrhizal percentage. Plant nutrients (P and N) contents were analysed. Significant differences were found in all the variables, but concentration N content in plants. Plants with mycorrhizae and plants with mycorrhizae and then inoculated with nematodes have the same behaviour. Control plants and plants with nematode and then inoculated with mycorrhizae behave similarly. It is thought that arbuscular mycorrhizae are formed before the nematode infestation, allowing coffee plants to regain the energy lost by the parasitic interaction. AM may help coffee plants with lignifications of the plant cell wall cuticle. As the cuticle thickens it is more difficult for nematodes to penetrate and enter into plant roots. Therefore, arbuscular mycorrhizae help coffee plants to uptake and transport nutrients, improving its nutritional status and stabilizing nematode attacks. It is suggested that symbiotic interactions help neutralize parasitic interactions.展开更多
Peptidoglycan recognition proteins(PGRPs)are a class of molecules that play a critical role in insect immunity.Understanding the function of PGRPs is important to improve the efficiency of microbial insecticides.In th...Peptidoglycan recognition proteins(PGRPs)are a class of molecules that play a critical role in insect immunity.Understanding the function of PGRPs is important to improve the efficiency of microbial insecticides.In this study,we investigated the role of PGRP-LB(a long type PGRP)in insect immunity against viruses using Spodoptera exigua and Spodoptera exigua multiple nucleopolyhedrovirus(SeMNPV)as an insect-virus model.We cloned and identified a PGRP-LB gene from S.exigua;the gene consisted of 7 exons that encoded a polypeptide of 234 amino acids with a signal peptide and a typical amidase domain.Expression analysis revealed that the abundance of SePGRP-LB transcripts in the fat body was greater than in other tissues.Overexpression of SePGRP-LB resulted in a significant decrease of 49%in the rate of SeMNPV-infected cells.In addition,the multiplication of SeMNPV was significantly decreased:a decrease of 79%in the production of occlusion-derived virion(ODV),and a maximum decrease of 50%in the production of budded virion(BV).In contrast,silencing of SePGRP-LB expression by RNA interference resulted in a significant 1.65-fold increase in the rate of SeMNPV-infected cells,a significant 0.54-fold increase in ODV production,a maximum 1.57-fold increase in BV production,and the larval survival dropped to 21%.Our findings show that SePGRP-LB has an antiviral function against SeMNPV,and therefore this gene may provide a target for lepidopteran pest control using virus insecticides.展开更多
Cytochrome P450 and UDP-glucosyltransferase (UGT) as phase I and phase II metabolism enzymes, respectively, play vital roles in the breakdown of endobiotics and xenobiotics. Insects can in crease the expression of det...Cytochrome P450 and UDP-glucosyltransferase (UGT) as phase I and phase II metabolism enzymes, respectively, play vital roles in the breakdown of endobiotics and xenobiotics. Insects can in crease the expression of detoxificatio n enzymes to cope with the stress from xenobiotics including insecticides. However, the molecular mechanisms for insecticide detoxification in Spodoptera exigua remain elusive, and the genes conferring insecticide metabolisms in this species are less well reported. In this study, 68 P450 and 32 UGT genes were identified. Phylogenetic analysis showed gene expansions in CYP3 and CYP4 clans of P450 genes and UGT33 family of this pest. P450 and UGT genes exhibited specific tissue expression patterns. Insecticide treatments in fat body cells of S. exigua revealed that the expression levels of P450 and UGT genes were significantly influenced by challenges of abamectin, lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb. Multiple genes for detoxification were affected in expression levels after insecticide exposures. The results demonstrated that lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb induced similar responses in the expression of P450 and UGT genes in fat body cells;eight P450 genes and four UGT genes were co-up-regulated significantly, and no or only a few CYP/UGT genes were down-regulated significantly by these four insecticides. However, abamectin triggered a distinct response for P450 and UGT gene expression;more P450 and UGT genes were down-regulated by abamectin than by the other four compounds. In con elusion, P450 and UGT genes from S. exigua were identified, and different responses to abamectin suggest a different mechanism for insecticide detoxification.展开更多
Apoptosis plays critical roles in multiple biological processes in multicellular organisms.Caspases are known as important participators and regulators of apoptosis.Here,four novel caspase genes of Spodoptera exigua w...Apoptosis plays critical roles in multiple biological processes in multicellular organisms.Caspases are known as important participators and regulators of apoptosis.Here,four novel caspase genes of Spodoptera exigua were cloned and characterized which were designated as SeCasp-1,SeCasp-6,ScCasp-7 and SeCasp-S.Analysis of the putative encoded protein sequences of these SeCasps indicated that SeCasp-1 and ScCasp-7 were possible homologs of executor caspases;SeCasp-8 was a possible homolog of initiator caspases;and SeCasp-6 was a unique caspase of S.exigua that shares low similarity with all the identified insect caspases.Based on baculovirus expression system analyses,SeCasp-1 exhibited similar caspase activity to human caspase-1,-3,-4,-6,-8 and-9;SeCasp-6 presented similar caspase activity to human caspase-2,-3,-4,-6,-8 and-9;SeCasp-7 exhibited similar caspase activity to human caspase-2,-3 and-6;and SeCasp-8 presented similar caspase activity only to human caspase-8.Induction with diiTcrent chemicals revealed that SeCasp-1 showed extreme upregulation after 24 h in the treated fat body cell line(IOZCAS-Spex-II)of S.exigua.Developmental expression analysis revealed that SeCasp-1 was highly transcribed in the larval stages,while SeCasp-6,SeCasp-7,SeCasp-H were down-regulated.The in vivo detection of the relative expression levels of SeCasps in S.eixgua larvae inoculated with different pathogens suggested that SeCasp-J was sensitive to Bacillus thuringiensis infection and that SeCasp-6 was sensitive to baculovirus infection.SeCasp-7 and SeCasp-H showed slight changes under either in vitro chemical apoptosis induction or in vivo pathogen infection.展开更多
Prothoracicotropic hormone (PTTH), a neuropeptide hormone stimulating the prothoracic glands to synthesize ecdysone, plays an important role in regulating postembryonic development in insects. The cDNA encoding PTTH w...Prothoracicotropic hormone (PTTH), a neuropeptide hormone stimulating the prothoracic glands to synthesize ecdysone, plays an important role in regulating postembryonic development in insects. The cDNA encoding PTTH was isolated and sequenced from the beet armyworm, Spodoptera exigua (Spe). The deduced a?mino acid sequence is composed of a signal peptide, a peptide (65 amino acids) of un-known function, and a mature PTTH molecule (111 amino acids). The Spe-PTTH shows similarities (45.5%―70.3%) to other known PTTHs reported in Lepidoptera species, but 7 cysteine r?esidues and the hydrophobic regions were conserved. Whole-mount immunocytochemistry by using an antiserum against recombinant Helicoverpa armigera PTTH showed that Spe-PTTH was synthesized in two pairs of neurosecretory cells in the S. exigua brain. Northern blot analysis demonstrates the presence of a 1.2-kb transcript in the brain. The Spe-PTTH mRNA is detectable at high levels at the wandering larval stage, early pupal stage, and pharate adult stage, suggesting that the Spe-PTTH gene might be corre-lated with molting, metamorphosis, and reproduction.展开更多
Digestive and detoxification enzyme activity and nutrient composition were examined in the body of fourth instar beet armyworms,Spodoptera exigua(Hübner),fed on transgenic Bacillus thuringiensis(Bt) and non-Bt co...Digestive and detoxification enzyme activity and nutrient composition were examined in the body of fourth instar beet armyworms,Spodoptera exigua(Hübner),fed on transgenic Bacillus thuringiensis(Bt) and non-Bt cotton for different time periods.Nutrient composition and specific enzyme activities differed significantly between the S.exigua fed Bt vs.non-Bt cotton.At 1,6 and 24 h,free fatty acid and glucose levels were significantly lower in S.exigua fed on Bt cotton than those fed on non-Bt cotton.S.exigua fed on Bt cotton had significantly higher trypsin and total superoxide dismutase(T-SOD) activities and significantly lower lipase,carboxylesterase and acetylcholinesterase activities than non-Bt fed worms for all feeding time periods.Differences were also observed among feeding times within each cotton variety group.Significantly lower free fatty acid and total amino acid were observed in S.exigua fed on Bt cotton for 24 h than in those fed for 1 h.Significantly lower activities of lipase and trypsin were detected in S.exigua fed on Bt cotton for 24 h than those for 1 and 4 h.However,carboxylesterase and acetylcholinesterase activities in S.exigua fed on Bt cotton for 24 h were significantly higher than those for 1,4 and 6 h.The interaction between cotton variety and feeding time significantly affected the activities of lipase,trypsin,acetylcholinesterase and T-SOD enzymes in S.exigua.Measuring the temporal allocation of protection and detoxification enzyme activities in the body of S.exigua in response to B.thuringiensis can provide a meaningful evaluation on the metabolic tolerance of herbivorous insects under the continuous selection pressure of a toxic protein.展开更多
基金partially supported by the Open Project Program from the Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization(Ministry of Agriculture and Rural Affairs),China(212103)。
文摘Vegetable fields are often contaminated by heavy metals,and Spodoptera exigua is a major vegetable pest which is stressed by heavy metals mainly by feeding.In this study,cadmium accumulation in the tissues of S.exigua exposed to cadmium and its effects on the growth and development of the parents and the offspring were investigated.Under the stress of different concentrations of cadmium(0.2,3.2,and 51.2 mg kg^(-1)),the cadmium content in each tissue of S.exigua increased in a dose-dependent manner.At the larval stage,the highest cadmium accumulation was found in midgut in all three cadmium treatments,but at the adult stage,the highest cadmium content was found in fat body.In addition,the cadmium content in ovaries was much higher than in testes.When F1S.exigua was stressed by cadmium and the F_(2)generation was not fed a cadmium-containing diet,the larval survival,pupation rate,emergence rate and fecundity of the F_(2)generation were significantly reduced in the 51.2 mg kg^(-1)treatment compared to the corresponding F1generation.Even in the F_(2)generation of the 3.2 mg kg^(-1)treatment,the fecundity was significantly lower than in the parental generation.The fecundity of the only-female stressed treatment was significantly lower than that of the only-male stressed treatment at the 3.2 and 51.2 mg kg^(-1)cadmium exposure levels.When only mothers were stressed at the larval stage,the fecundity of the F_(2)generation was significantly lower than that of the F1generation in the 51.2 mg kg^(-1)treatment,and it was also significantly lower than in the 3.2 and 0.2 mg kg^(-1)treatments.The results of our study can provide useful information for forecasting the population increase trends under different heavy metal stress conditions and for the reliable environmental risk assessment of heavy metal pollution.
基金supported by the National Key Research and Development Program of China(2022YFD1401200)the National Natural Science Foundation of China(32172397).
文摘It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.However,to date,which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.In this study,33 CTL genes were identified from S.exigua.Based on the number of carbohydrate-recognition domains(CRDs)and the domain architectures,they were classified into three groups:(1)nineteen CTL-S(single-CRD),(2)eight immulectin(dual-CRD)and(3)six CTL-X(CRD with other domains).RT-qPCR analysis revealed that expression levels of SeCTL-S15,IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva,respectively.Knockdown of SeCTL-S15 significantly increased Bt susceptibility,as indicated by reduced survival and larval weight.These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S.exigua.Our results provide new insights into CTL function in insects.
基金Supported by National Transgenic Major Project ( Safe Monitoring Technique of Transgenic Organism 2008ZX08012-004)~~
文摘[Objective] The aim was to learn the resistance of different tissues and organs of transgenic cotton to Spodoptera exigua (Hbner). [Method] Flowers,the 1st,the 3rd,the 6th and the 14th leaves from the top of 33B,GK12 and SGK321 were used to feed S. exigua neonates respectively. Survival larvae and dead ones were counted on the 3rd,the 7th,the 10th,the 16th and the 19th day; meanwhile,the pupae amount was recorded,and the pupae weight was measured at the 24th h after pupation. [Result] The survival curves,pupation rates and pupae weights of S. exigua feeding on different tissues of transgenic cotton were not significantly different from those of S. exigua feeding on the corresponding tissues of conventional cotton; pupation rate of S. exigua feeding on different leaves of the same cotton variety were not significantly different from each other,but all higher than that of S. exigua feeding on the flowers of that cotton; and there were no differences among pupation weights of S. exigua feeding on different leaves or flowers of the same cotton variety. [Conclusion] Transgenic cotton showed weak resistance to S. exigua. Hence,in the transgenic cotton fields,more attention should be paid to occurrence trend of S. exigua and its control.
基金Supported by Fund Projects in Education Department of Yunnan Prov-ince"Species and Field Damage Law of Thripidae in Characteristics Crops in Mengzi"(08c0202)~~
文摘[ Objective] In order to offer foundation for further study and exploration of the strain against pests, the pathogenicity of V. lecanfi MZ041024 strain against L. exigua was proved. [ Method] Under different spore concentrations of V. lecanii MZ041024 strain, the pathogenicity against 2^nd instar larvae of Laphygma exigua was determined using dipping method. [ Result ] The results showed that LC.50of V. lecanfi MZ041024 strain against 2M instar larvae of L. exigua under the concentration of 4.5 ×10^5 -4.5 ×10^8 spores/ml were 1.367×10^7, 3.245×10^6, 3.202 ×10^5 and 7.803 × 10^4 spores/ml. [ Conclusion] V. lecanfi MZ041024 strains had strong pathogenicity against L. exigua, so it had better control effect on L. exigua.
基金Supported by Hunan Nature Foundation(07JJ6055)Hunan Provincial Department of Education Foundation(07C362)Hunan Agricultural University Talent Foundation(2006WD026)~~
文摘[Objective] The study was aimed to determine and evaluate control effect and security of 20% tebufenozide SC against Spodoptera exigua HObner, which would provide technical support for its promotion and utilization. [ Method] By using foliar spray method, control effects of different concentration of 20% tebufenozide SC and 25 g/L deltamethrin EC against S. exigua were determined. [ Result] 20% tebufenozide SC had better control effects on S. exigua. After spraying for 3 and 7 d, control effects of 20% tebufenozide SC in each treatment could reach 81% and 84%, which was higher than 25 g/L deltamethdn EC treatment. [ Conclusion] 20% tebufenozide SC for controlling S. exigua had good effect, which had permanent effectiveness for over 7 d. It also caused less environmental pollution, and was safe to cabbage, being the ideal pesticide for controlling S. exigua in vegetables.
基金supported by the Chongqing Science & Technology Commission,China (2005BA1014)the Chongqing Education Commission,China (KJ060302)
文摘The beet armyworm,Spodoptera exigua (Lepidoptera:Noctuidae),is an economically important pest of crops worldwide,attacking plants from over 20 families including trans-continental agricultural cotton,corn and citrus crops.In this study,performance and subsequent enzyme activity of beet armyworm reared on host plants from five families were investigated.Significant differences were found in development,fecundity and enzyme activity on different host plants.Survival rate was the highest (42.8%) on asparagus lettuce (Lactuca sativar var.asparagina) and the lowest (17.0%) on sweet pepper (Capsicum annuum).Larval duration was the shortest on asparagus lettuce (12.0 d),and was 43.4% longer on sweet peppers (21.2 d).The activity of acetylcholine esterase (AChE) and carboxylesterase (CarE) in 3rd instar larvae,and soluble carbohydrate and crude protein contents in different host plants were determined.AChE activity was the highest in the larvae feeding on Chinese cabbage (Brassica rapa),but declined by nearly 60% on maize (Zea mays) seedlings.The ratio of soluble carbohydrate content to crude protein content in host plants was found to have a positive effect on oviposition and a negative correlation with larval duration and life time (from larval to adult stages) of the insect.
基金supported by the National Basic Research Program of China(2012CB114104)the National Natural Science Foundation of China (31071694 and 31171858)
文摘Cry toxins produced by Bacillus thuringiensis(Bt) are effective biological insecticides against certain insect species.In this study,bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua.We also identified a cadherin-like gene in S.exigua that could enhance the toxicity of Cry1B and Cry1C.The cadherin-like gene identified from the larvae midgut tissue was cloned by reverse transcription polymerase chain reaction(RT-PCR) and rapid amplification of cDNA ends(RACE).The full-length cDNA of the gene consisted of 5 220 bp encoding 1 740 amino acid with a predicted molecular mass of 196 kD.BLAST search analysis showed that the predicted amino acid sequence had a high sequence identity to the published sequences of cadherin-like proteins from other Lepidoptera insects.Spatial expression of the cadherin-like gene detected by qRT-PCR analysis revealed that the cadherin-like gene was mainly present in the gut of 4th instar larvae and during different life stages.The results suggested that the commercial development of this synergist has the potential to enhance Cry1B and Cry1C toxicity against Lepidoptera insects.
基金Supported by National Key Technology Support Program(2012BAD19B01)
文摘Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua ( Htthner), were investigated. An obvious synergism effect of the two insect growth regulators with B. beauveria was observed. When the insect growth regulators at LC50 concentrations (25 × 10^-6 g/L for methoxyfenozide and 1 000 × 10^ -6 g/L for hexaflumuren) were mixed with B. bassiana at the volume ratio of 4: 1, the mixtures achieved the best efficacy. The co-toxicity co-efficient (CTC) of methexyfenozide and B. bass/ana was 285, and that of hexaflumuron and B. bass/ana was 208. Scanning electron microscope observation of the longitudinal section of S. exigua revealed obviously different patterns of integument in different treatment groups.
文摘Climate change will have a noteworthy bearing on survival, development, and population dynamics of insect pests. Therefore, we contemplated the survival and development of beet army worm, <em>Spodoptera exigua</em> under different temperatures, (15<span style="white-space:nowrap;">°</span>C, 25<span style="white-space:nowrap;">°</span>C, 35<span style="white-space:nowrap;">°</span>C, and 45<span style="white-space:nowrap;">°</span>C), CO<sub>2</sub> (350, 550, 750 ppm) and relative humidity (55%, 65%, 75% and 85%) regimes. Maximum larval and pupal weights were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C. The growth of <em>S. exigua</em> was faster at 35<span style="white-space:nowrap;">°</span>C (larval period 7.4 days and pupal period 4.5 days) than at lower temperatures. At 15<span style="white-space:nowrap;">°</span>C, the larval period was extended for 61.4 days and there was no adult emergence from the pupae till 90 days. The <em>S. exigua</em> hatchling was absent at 45<span style="white-space:nowrap;">°</span>C. The larval survival ranged from 31.6% - 57.2%, maximum survival was recorded at 25<span style="white-space:nowrap;">°</span>C, and minimum at 45<span style="white-space:nowrap;">°</span>C. The maximum (84.27%) and minimum adult emergence were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C and 35<span style="white-space:nowrap;">°</span>C respectively. Maximum fecundity (384.3 eggs/female) and egg viability (51.97%) were recorded in insects reared at 25<span style="white-space:nowrap;">°</span>C. Larval and pupal periods increased with an increase in CO<sub>2</sub> concentration. The highest pupal weights (128.6 mg/larva) were recorded at 550 ppm. The highest larval survival (73.50%) was recorded at 550 ppm and minimum (37.00%) at 750 ppm CO<sub>2</sub>. Fecundity was the highest in insects reared at 550 ppm CO<sub>2</sub> (657.4 eggs/female), and the lowest at 750 ppm. Maximum larval and pupal weights were recorded in insects reared at 75% relative humidity (RH). The growth rate of<em> S. exigua</em> was faster at 85% RH than at lower RH. The larval survival ranged between 40.0% - 58.5%. Maximum adult emergence (88.91%) was recorded in insects reared at 75% RH and minimum at 85% RH. Maximum fecundity (447.6 eggs/female) and the highest egg viability (72.95%) were recorded in insects reared at 75% and 65% RH respectively. Elevated temperatures and relative moistness will diminish the life cycle, while hoisted CO<sub>2</sub> will drag the life expectancy. Therefore, there is a need for thorough assessment of the impact of climatic factors on the population dynamics of insect pests, crop losses, and sustainability of crop production.
文摘A pair of degenerate primers was designed, based on the comparison of five insects' GOBP2 gene sequences reported previously. A specific band (about 400bp in length) was amplified from cDNA of Spodoptera exigua antenna and another specific band (about 2kb in length) was amplified from genomic DNA. The two segments were cloned into T-easy vector, respectively. Results of sequencing and structural analysis showed that the full-length of GOBP2Sexi ORF is 426bp, 141 amino acid residues were encoded. The predicted MW and pI are 16.07ku and 5.09 .respectively. There are six conservative Cys locus in the sequence, which is the typical characteristic of OBPs. GOBP2Sexi gene was inserted by two introns between amino acid residue 22 and 23 and between 82 and 83. The length of two introns is 160bp and 1403bp. Results of Northern blot showed that GOBP2 gene expressed specifically in the antenna of Spodoptera exigua, and the expression level is nearly equal in the antenna of male and female moths. The sequence was deposited in GenBank/EMBL and the accession number is AJ294809.
文摘This paper focuses on parasitic root knot nematodes (Meloidogyne exigua) and how to decrease their pathogenic effect on coffee plants (Coffea arabica), by examining the behaviour of and the interactions between nematodes, coffee plant and arbuscular mycorrhizae (AM). The experiment was carried out at the seedling stage, with six (6) treatments (plants with M. exigua, plants with arbuscular mycorrhizae, plants with both organisms, and the same time, first mycorrhizae plants, then nematodes were inoculated and vice versa). After 5 months the measured variables were: dry biomass (roots and shoot), nematode knots caused by M. exigua in root, nematode juvenile (J2) found in 100.0 g of soil, and mycorrhizal percentage. Plant nutrients (P and N) contents were analysed. Significant differences were found in all the variables, but concentration N content in plants. Plants with mycorrhizae and plants with mycorrhizae and then inoculated with nematodes have the same behaviour. Control plants and plants with nematode and then inoculated with mycorrhizae behave similarly. It is thought that arbuscular mycorrhizae are formed before the nematode infestation, allowing coffee plants to regain the energy lost by the parasitic interaction. AM may help coffee plants with lignifications of the plant cell wall cuticle. As the cuticle thickens it is more difficult for nematodes to penetrate and enter into plant roots. Therefore, arbuscular mycorrhizae help coffee plants to uptake and transport nutrients, improving its nutritional status and stabilizing nematode attacks. It is suggested that symbiotic interactions help neutralize parasitic interactions.
基金funded by National Natural Science Foundation of China(31972333)Shandong Provincial Natural Science Foundation(ZR2020MC128,ZR2020MC130)Basic Research Project of Shenzhen Municipal Science and Technology Innovation Committee(JCYJ20190813144407666).
文摘Peptidoglycan recognition proteins(PGRPs)are a class of molecules that play a critical role in insect immunity.Understanding the function of PGRPs is important to improve the efficiency of microbial insecticides.In this study,we investigated the role of PGRP-LB(a long type PGRP)in insect immunity against viruses using Spodoptera exigua and Spodoptera exigua multiple nucleopolyhedrovirus(SeMNPV)as an insect-virus model.We cloned and identified a PGRP-LB gene from S.exigua;the gene consisted of 7 exons that encoded a polypeptide of 234 amino acids with a signal peptide and a typical amidase domain.Expression analysis revealed that the abundance of SePGRP-LB transcripts in the fat body was greater than in other tissues.Overexpression of SePGRP-LB resulted in a significant decrease of 49%in the rate of SeMNPV-infected cells.In addition,the multiplication of SeMNPV was significantly decreased:a decrease of 79%in the production of occlusion-derived virion(ODV),and a maximum decrease of 50%in the production of budded virion(BV).In contrast,silencing of SePGRP-LB expression by RNA interference resulted in a significant 1.65-fold increase in the rate of SeMNPV-infected cells,a significant 0.54-fold increase in ODV production,a maximum 1.57-fold increase in BV production,and the larval survival dropped to 21%.Our findings show that SePGRP-LB has an antiviral function against SeMNPV,and therefore this gene may provide a target for lepidopteran pest control using virus insecticides.
基金the National Natural Science Foundation of China (No. 31272063)the Inn ovation Team Program for Jiangsu Universities (No. 2013).
文摘Cytochrome P450 and UDP-glucosyltransferase (UGT) as phase I and phase II metabolism enzymes, respectively, play vital roles in the breakdown of endobiotics and xenobiotics. Insects can in crease the expression of detoxificatio n enzymes to cope with the stress from xenobiotics including insecticides. However, the molecular mechanisms for insecticide detoxification in Spodoptera exigua remain elusive, and the genes conferring insecticide metabolisms in this species are less well reported. In this study, 68 P450 and 32 UGT genes were identified. Phylogenetic analysis showed gene expansions in CYP3 and CYP4 clans of P450 genes and UGT33 family of this pest. P450 and UGT genes exhibited specific tissue expression patterns. Insecticide treatments in fat body cells of S. exigua revealed that the expression levels of P450 and UGT genes were significantly influenced by challenges of abamectin, lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb. Multiple genes for detoxification were affected in expression levels after insecticide exposures. The results demonstrated that lambda-cyhalothrin, chlorantraniliprole, metaflumizone and indoxacarb induced similar responses in the expression of P450 and UGT genes in fat body cells;eight P450 genes and four UGT genes were co-up-regulated significantly, and no or only a few CYP/UGT genes were down-regulated significantly by these four insecticides. However, abamectin triggered a distinct response for P450 and UGT gene expression;more P450 and UGT genes were down-regulated by abamectin than by the other four compounds. In con elusion, P450 and UGT genes from S. exigua were identified, and different responses to abamectin suggest a different mechanism for insecticide detoxification.
基金the National Natural Science Foundation of China(31700141,31872027)Changsha Science and Technology Plan Project(kq 1901033)Double first-class construction project of Hunan Agricultural University.
文摘Apoptosis plays critical roles in multiple biological processes in multicellular organisms.Caspases are known as important participators and regulators of apoptosis.Here,four novel caspase genes of Spodoptera exigua were cloned and characterized which were designated as SeCasp-1,SeCasp-6,ScCasp-7 and SeCasp-S.Analysis of the putative encoded protein sequences of these SeCasps indicated that SeCasp-1 and ScCasp-7 were possible homologs of executor caspases;SeCasp-8 was a possible homolog of initiator caspases;and SeCasp-6 was a unique caspase of S.exigua that shares low similarity with all the identified insect caspases.Based on baculovirus expression system analyses,SeCasp-1 exhibited similar caspase activity to human caspase-1,-3,-4,-6,-8 and-9;SeCasp-6 presented similar caspase activity to human caspase-2,-3,-4,-6,-8 and-9;SeCasp-7 exhibited similar caspase activity to human caspase-2,-3 and-6;and SeCasp-8 presented similar caspase activity only to human caspase-8.Induction with diiTcrent chemicals revealed that SeCasp-1 showed extreme upregulation after 24 h in the treated fat body cell line(IOZCAS-Spex-II)of S.exigua.Developmental expression analysis revealed that SeCasp-1 was highly transcribed in the larval stages,while SeCasp-6,SeCasp-7,SeCasp-H were down-regulated.The in vivo detection of the relative expression levels of SeCasps in S.eixgua larvae inoculated with different pathogens suggested that SeCasp-J was sensitive to Bacillus thuringiensis infection and that SeCasp-6 was sensitive to baculovirus infection.SeCasp-7 and SeCasp-H showed slight changes under either in vitro chemical apoptosis induction or in vivo pathogen infection.
基金Supported by the National Basic Research Program of the Ministry of Science and Technology, People’s Republic of China (Grant No. 2006CB102001)The nucleotide sequence data reported in this article have been submitted to Gen-Bank and have been assigned the accession number AY628763
文摘Prothoracicotropic hormone (PTTH), a neuropeptide hormone stimulating the prothoracic glands to synthesize ecdysone, plays an important role in regulating postembryonic development in insects. The cDNA encoding PTTH was isolated and sequenced from the beet armyworm, Spodoptera exigua (Spe). The deduced a?mino acid sequence is composed of a signal peptide, a peptide (65 amino acids) of un-known function, and a mature PTTH molecule (111 amino acids). The Spe-PTTH shows similarities (45.5%―70.3%) to other known PTTHs reported in Lepidoptera species, but 7 cysteine r?esidues and the hydrophobic regions were conserved. Whole-mount immunocytochemistry by using an antiserum against recombinant Helicoverpa armigera PTTH showed that Spe-PTTH was synthesized in two pairs of neurosecretory cells in the S. exigua brain. Northern blot analysis demonstrates the presence of a 1.2-kb transcript in the brain. The Spe-PTTH mRNA is detectable at high levels at the wandering larval stage, early pupal stage, and pharate adult stage, suggesting that the Spe-PTTH gene might be corre-lated with molting, metamorphosis, and reproduction.
基金supported by the National Basic Research Program of China (Grant No. 2006CB102004)the National Natural Science Foundation of China (Grant No. 30800724)New Detecting Technology of Exogenous Gene Protein (Grant Nos. 2008ZX08012-004 and 2009ZX08011-013B)
文摘Digestive and detoxification enzyme activity and nutrient composition were examined in the body of fourth instar beet armyworms,Spodoptera exigua(Hübner),fed on transgenic Bacillus thuringiensis(Bt) and non-Bt cotton for different time periods.Nutrient composition and specific enzyme activities differed significantly between the S.exigua fed Bt vs.non-Bt cotton.At 1,6 and 24 h,free fatty acid and glucose levels were significantly lower in S.exigua fed on Bt cotton than those fed on non-Bt cotton.S.exigua fed on Bt cotton had significantly higher trypsin and total superoxide dismutase(T-SOD) activities and significantly lower lipase,carboxylesterase and acetylcholinesterase activities than non-Bt fed worms for all feeding time periods.Differences were also observed among feeding times within each cotton variety group.Significantly lower free fatty acid and total amino acid were observed in S.exigua fed on Bt cotton for 24 h than in those fed for 1 h.Significantly lower activities of lipase and trypsin were detected in S.exigua fed on Bt cotton for 24 h than those for 1 and 4 h.However,carboxylesterase and acetylcholinesterase activities in S.exigua fed on Bt cotton for 24 h were significantly higher than those for 1,4 and 6 h.The interaction between cotton variety and feeding time significantly affected the activities of lipase,trypsin,acetylcholinesterase and T-SOD enzymes in S.exigua.Measuring the temporal allocation of protection and detoxification enzyme activities in the body of S.exigua in response to B.thuringiensis can provide a meaningful evaluation on the metabolic tolerance of herbivorous insects under the continuous selection pressure of a toxic protein.