Bioinsecticides are naturally-occurring substances from different sources that control insect pests.Ideal bioinsecticides should have low toxicity to non-target organisms.They should also be easily degraded in sewage ...Bioinsecticides are naturally-occurring substances from different sources that control insect pests.Ideal bioinsecticides should have low toxicity to non-target organisms.They should also be easily degraded in sewage treatment works and natural environments,highly effective in small quantities and affect target pests only.Public concerns about possible side-effects of synthetic pesticides have accelerated bioinsecticide research and development.However,to develop bioinsecticides into mainstream products,their high production costs,short shelf-life and often uncertain modes of action need to be considered.This review summarizes current progress on bioinsecticides which are categorized as biochemical insecticides and their derivatives,plant-incorporated protectants,and microbial bioinsecticides.The current constraints that prevent bioinsecticides from being widely used are discussed and future research directions are proposed.展开更多
Mosquitoes(Diptera:Culicidae)are vectors of various pathogens of public health concern,but replacing conventional insecticides remains a challenge.In this regard,natural products represent valuable sources of potentia...Mosquitoes(Diptera:Culicidae)are vectors of various pathogens of public health concern,but replacing conventional insecticides remains a challenge.In this regard,natural products represent valuable sources of potential insecticidal compounds,thus increasingly attracting research interest.Commiphora myrrha(T.Nees)Engl.(Burseraceae)is a medicinal plant whose oleo-gum resin is used in food,cosmetics,fragrances,and pharmaceuticals.Herein,the larvicidal potential of its essential oil(EO)was assessed on four mosquito species(Aedes albopictus Skuse,Ae.aegypti L.,Anopheles gambiae Giles and An.stephensi Liston),with LC_(50) values ranging from 4.42 to 16.80 μg/mL.The bio-guided EO fractionation identified furanosesquiterpenes as the main larvicidal compounds.A GC-MS-driven untargeted metabolomic analysis revealed 32 affected metabolic pathways in treated larvae.The EO non-target toxicity on Daphnia magna Straus(LC_(50)=4.51 μL/L)and its cytotoxicity on a human kidney cell line(HEK293)(IC50 of 14.38 μg/mL)were also assessed.This study shows the potential of plant products as innovative insecticidal agents and lays the ground-work for the possible exploitation of C.myrrha EO in the sustainable approaches for mosquito management.展开更多
Beauveria bassiana (Ascomycota: Cordycipitaceae) is an entomopathogenic fungus used as an ecofriendly insecticide to infect arthropods. B. bassiana also possesses endophytic activity to contribute to plant growth. Thi...Beauveria bassiana (Ascomycota: Cordycipitaceae) is an entomopathogenic fungus used as an ecofriendly insecticide to infect arthropods. B. bassiana also possesses endophytic activity to contribute to plant growth. This study aimed to evaluate the potential insecticidal and endophytic activity of native B. bassiana isolates. The nymphal and adult stages of the apple tree aphid (Aphis pomi) and whitefly (Trialeurodes vaporariorum) were used as targets in bioinsecticidal experiments, and vegetables (beans, tomatoes and cucumbers) were used as targets in biostimulant experiments. The endophytic activity of the B. bassiana strains was assessed after inoculation them to the crop seeds and plants via soil drenching, foliar spraying and seed immersion. In bean plants, seed immersion was the most effective application method. Soil drenching was more effective in the cucumber and tomato plants. The results of in vitro bioassay tests against pests have revealed the LC50 and LT50 values of B. bassiana isolate Col-2. The LC50 of this isolate for A. pomi adults and nymphs was 2.5 × 106 conidia/mL−1;for T. vaporariorum, it was lower 1.8 × 106 conidia/mL−1. Such mortality occurred after 55.49 h. in A. pomi adults and nymphs (LT50), after 62.3 h. in T. vaporariorum (LT50).展开更多
This study examined the photostabilization of Azadirachtin-A （Aza-A） when exposed to ultraviolet light in the presence of some natural absorbers. Aza-A extract solutions with and without natural UV light absorbers i...This study examined the photostabilization of Azadirachtin-A （Aza-A） when exposed to ultraviolet light in the presence of some natural absorbers. Aza-A extract solutions with and without natural UV light absorbers in methanol were applied onto the surface of glass slides. At particular intervals, the remaining concentration of Aza-A was analyzed by HPLC. Using first-order kinetic equation, the dissipation half-life values （DT^0） for the degradation of Aza-A under ultraviolet radiation were obtained. It indicated that the addition of ferulic acid, gallic acid, and rutin provided moderate degree of photostabilization of Aza-A and that addition of aloin provided the best photostabilization of Aza-A, among these UV absorbers studied. Photostabilization of Aza-A by different UV light absorbers appears to be due to the competitive energy absorption of UV photons by the absorbers molecules. The dissipation half-life values of Aza-A after irradiation under ultraviolet light suggested that the addition of aloin （in 1 ： 1 mol ratio） can provide better photostabilization of azadirachtin molecule.展开更多
The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the...The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the PxABCB1 gene was previously found to be associated with Cry1Ac resistance in the diamondback moth,Plutella xylostella(L.).To directly validate the potential receptor role of PxABCB1 and its contribution to Bt Cry1Ac toxicity in P.xylostella,we used CRISPR/Cas9 to generate a homozygous knockout ABCB1KO strain with a 5-bp deletion in exon 3 of its gene.The ABCB1KO strain exhibited a 63-fold resistance to Cry1Ac toxin compared to the parental DBM1Ac-S strain.Intriguingly,the ABCB1KO strain also exhibited significant increases in susceptibility to abamectin and emamectin benzoate.No changes in susceptibility to various other Bt Cry proteins or synthetic insecticides were observed.The knockout strain exhibited no significant fitness costs.Overall,our study indicates that PxABCB1 can protect the insect against avermectin insecticides on one hand,while on the other hand it facilitates the toxic effect of the Bt Cry1Ac toxin.The results of this study will help to inform integrated pest management approaches against this destructive pest.展开更多
The control of Spodoptera frugiperda is based on synthetic insecticides,so some alternatives are the use of entomopathogenic fungi(EF)and neem extract.The objective of the study was to evaluate in vitro effectiveness ...The control of Spodoptera frugiperda is based on synthetic insecticides,so some alternatives are the use of entomopathogenic fungi(EF)and neem extract.The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S.frugiperda larvae.Six EF were identified by DNA sequencing of ITS regions from three EF(Fusarium solani,Metarrhizium robertsii,Nigrospora spherica and Penicillium citrinum).They were evaluated in concentrations of 1×10⁸spores/mL.In addition,a second bioassay was carried out evaluating only F.solani,M.robertsii and N.sphaerica and the addition of vegetable oil.On the other hand,extraction of secondary metabolites from neem seed(Azadirachta indica)was carried out by performing,mass(g)and solvent volume(mL ethanol and water)combinations,which were subjected to microwaves and ultrasound.Subsequently,these extracts were evaluated in concentrations of 3%,4%and 5%.A survival analysis was performed for each of the bioassays.With respect to the results of the first bioassay,F.solani obtained a probability of survival of 0.476 on the seventh day,while in the second bioassay,M.robertsii obtained 0.488 survival probability.This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%.However,in the evaluation of the neem extract the combination 1:12/70%to 4%caused 84% mortality of larvae.The use of native HE and neem extracts has potential for the control of S.frugiperda.展开更多
Objective: To determine the larvicidal activities of petroleum ether, chloroform, ethyl acetate and methanol fractions of roots and fruits extracts of Astrodaucus persicus from Apiaceae family against malaria vector, ...Objective: To determine the larvicidal activities of petroleum ether, chloroform, ethyl acetate and methanol fractions of roots and fruits extracts of Astrodaucus persicus from Apiaceae family against malaria vector, Anopheles stephensi(An. stephensi).Methods: Twenty five third instar larvae of An. stephensi were exposed to various concentrations(10–160 g/L) of fractions and were assayed according to World Health Organization protocol. The larval mortality was calculated after 24 h treatment.Results: Among tested fractions, the highest larvicidal efficacy was observed from ethyl acetate fraction of fruits extract with 50% and 90% mortality values(LC_(50) and LC_(90)) of34.49 g/L and 108.61 g/L, respectively. Chloroform fraction of fruits extract was the second larvicidal sample with LC_(50) of 45.11 g/L and LC_(90) of 139.36 g/L. Petroleum ether fractions of fruits and roots and methanol fraction of fruits showed moderate toxicity against An. stephensi.Conclusions: Astrodaucus persicus is a potential source of valuable and natural larvicidal compounds against malaria vector, An. stephensi and can be used in mosquitoes control programs as an alternative to synthetic insecticides.展开更多
Objective:To identify the larvieidal activity of the seagrass extracts.Methods:Seagrass extracts,Syringodium isoelifolium(.S.isoetifolium),Cymodocea serrulata and Hulophila beccarii,were dissolved in DMSO to prepare a...Objective:To identify the larvieidal activity of the seagrass extracts.Methods:Seagrass extracts,Syringodium isoelifolium(.S.isoetifolium),Cymodocea serrulata and Hulophila beccarii,were dissolved in DMSO to prepare a graded series of concentration.Batches of 25 early 4th instars larvae of Aedes aegypti(Ae.aegypti) were transferred to 250 ml.enamel bowl containing199 mL of distilled water and 1 mL of plant extracts(0.01 mg- 0.1 mg).After 24 h the mortality rate was identified with the formulae[(%of lest mortality-%of control mortality)/(100-%of control morlality)]× 100.Each experiment was conducted with three replicates and a concurrent control group.A control group consisted of 1 mL of DMSO and 199 mL of distilled water only.Results:The root extract of S.isoelifolium showed maximum larvicidal activity with minimum concentration of extract of LC_(50)= 0.0604 ± 0.0040)μg/mL with lower confidence limit(LCL)-upper confidence limit(UCL) =(0.051-0.071) and LC_(90)=0.0972 μg/mL followed by leaf extract of S.isoelifolium showed LC_(50)=(0.062 ± 0.005)μ'g/mL.The regression equation of pool and leaf extract of S.isoelifolium for4th instar larvae were Y =4.909- 1.32x(R^2= 0.909) and Y= 2.066+ 1.2x(R^2 =0.897) respectively.The results of the preliminary photochemical constituents shows the presence of saponin,steroids,terpenoid,phenols,protein and sugars.Conclusions:from the present study the ethanolic extracts of seagrass of S.isoelifolium possesses lead compound for development of larvieidal activity.展开更多
The last volcanic eruption of the Puyehue-Cordon-Caulle Volcanic Complex in the Andes cordillera of western South America, occurring on 4 June 2011, ejected pyroclastic materials that were accumulated in a wide region...The last volcanic eruption of the Puyehue-Cordon-Caulle Volcanic Complex in the Andes cordillera of western South America, occurring on 4 June 2011, ejected pyroclastic materials that were accumulated in a wide region of the northern Patagonia (Argentina), affecting the environment and health of residents within the area. The aim of this work was to evaluate the practicability of using this waste material as a lowcost carrier for mycopesticide formulations. Beauveria bassiana is a recognized fungal agent for arthropod biologic control. Lengthy storage is critical for the development of mycoinsecticide formulations. Accordingly, the search for adequate materials to improve the shelf life of biocontrol products becomes desirable. First, several analytical techniques were employed to characterize the pyroclast physicochemically;then the viability of the fungal conidia was evaluated after an 18-month storage in the volcanic material. Finally, the pathogenicity of the conidia after that prolonged maintenance in the vehicle was assessed on the beetle Alphitobius diaperinus, an insect pest in poultry houses that causes major economic losses. The results from those bioassays proved auspicious for the eventual utilization of the pyroclast as a bioinsecticide carrier especially since the formulation had proven to be stable for at least 18 months under a wide range of environmental conditions. The constant moisture in a closed environment within a 5°C - 40°C temperature range insures a viable state during storage. The results indicate that what would otherwise be volcanic waste may be utilized as an efficient, abundant, inexpensive, and environmentally innocuous carrier of entomopathogenic fungi.展开更多
Adult corn earworm, Helicoverpa zea (Boddie), feeds on plant exudates soon after emergence from pupa in their natural habitat, and thereafter disperses to suitable host plants for reproduction. The intent of this stud...Adult corn earworm, Helicoverpa zea (Boddie), feeds on plant exudates soon after emergence from pupa in their natural habitat, and thereafter disperses to suitable host plants for reproduction. The intent of this study was to determine if EntrustTM, an organic formulation of spinosad, could be used in a behavioral-based pest management strategy to control H. zea in organic farming systems. In the laboratory, we evaluated the response of the corn earworm to Entrust mixed with sugar solution relative to ingestion, toxicity and proboscis extension. The sucrose solution served as a feeding stimulant and simulated the plant exudate. Lethal concentration of Entrust (LC50 with 95% CLs) for male corn earworm captured in pheromone-baited traps was 0.48 (0.43 - 0.53) mgL-1 for 24 h response. Mean lethal time was 2.56 ± 0.13 h with ingestion of Entrust at 50 mg·L-1. A lethal dose of Entrust at 1000 mg·L-1 inhibited neither ingestion nor proboscis extension response of the insect. A detailed study of the adult corn earworm in the laboratory relative to toxicity after ingestion of Entrust indicates that the pesticide has potential to control the insect when used in an insecticidal bait formulation as part of an attract-and- kill system. Field studies are needed to support the conclusion.展开更多
Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-pro...Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-products as nutrient sources in culture medium, having been used, in this study, the manipueira, a by-product of the processing of the cassava flour. Fermentations were performed in flasks of Erlenmeyer of 500 mL containing 250 mL of culture media, conditioned in shaker at 180 r.p.m. and 28°C, and the media were composed by manipueira, in concentrations that varied between 400 and 1000 mL/L. The time of the process varied between 48 and 120 hours. They appraised the following parameters: cellular growth, the production of spores, the reduction of organic matter (COD analysis) and the variation of reduction sugar. Although there was a proportional cellular growth to the manipueira concentration, the production of spores was similar in all the cases, at the end of the process, in spite of the smallest speed of production of the same ones in the highest concentrations. In relation to the variation of COD, it has, also, a percentile minor of reduction in the highest concentrations. In the analysis of variation of reduction sugars, the higher concentrations are the ones that they present larger slowness in the reduction of this.展开更多
The development of an effective and green bioinsecticide is a research hotspot.This study demonstrated the possibility of using an arsenic(As)hyperaccumulator as a bioinsecticide.When the As concentration in the Pteri...The development of an effective and green bioinsecticide is a research hotspot.This study demonstrated the possibility of using an arsenic(As)hyperaccumulator as a bioinsecticide.When the As concentration in the Pteris vittata fronds exceeded 138 mg kg^(–1),the larva of the hawk moth(Theretra clotho)displayed apparent preference to lower-As-concentration P.vittata fronds.The As concentration in the larva body was as high as 850 mg kg^(–1).Such high concentration of As in the larva body might have been the case that T.clotho lacks a process to exclude As.The larval frass showed an As concentration of only 1%–4%of that in the larva body.The predominant As species in the larva body and frass was As(III)-SH.The percentage of As(III)-SH was slightly higher in the frass than that in the larval body.Chelation with thiols may be a universal detoxification mechanism for As in both plants and insects.In general,the adoption of P.vittata as a bioinsecticide should be feasible.However,the exact processes to achieve this goal still need further study.The mechanism of different animals to detoxify As is another interesting research topic.展开更多
基金This work was supported by the National Natural Science Foundation of China(31872972,31830076)the Shenzhen Science and Technology Program(KQTD20180411143628272)。
文摘Bioinsecticides are naturally-occurring substances from different sources that control insect pests.Ideal bioinsecticides should have low toxicity to non-target organisms.They should also be easily degraded in sewage treatment works and natural environments,highly effective in small quantities and affect target pests only.Public concerns about possible side-effects of synthetic pesticides have accelerated bioinsecticide research and development.However,to develop bioinsecticides into mainstream products,their high production costs,short shelf-life and often uncertain modes of action need to be considered.This review summarizes current progress on bioinsecticides which are categorized as biochemical insecticides and their derivatives,plant-incorporated protectants,and microbial bioinsecticides.The current constraints that prevent bioinsecticides from being widely used are discussed and future research directions are proposed.
基金granted by the project PRIN 2022“Bioformulations for controlled release of botanical pesticides for sustainable agriculture”(prot.202274BK9L)supported by the Italian Ministry of University and Research(MUR)the Technology agency of the Czech Republic for its financial support concerning botanical pesticide(Project No.FW06010376).
文摘Mosquitoes(Diptera:Culicidae)are vectors of various pathogens of public health concern,but replacing conventional insecticides remains a challenge.In this regard,natural products represent valuable sources of potential insecticidal compounds,thus increasingly attracting research interest.Commiphora myrrha(T.Nees)Engl.(Burseraceae)is a medicinal plant whose oleo-gum resin is used in food,cosmetics,fragrances,and pharmaceuticals.Herein,the larvicidal potential of its essential oil(EO)was assessed on four mosquito species(Aedes albopictus Skuse,Ae.aegypti L.,Anopheles gambiae Giles and An.stephensi Liston),with LC_(50) values ranging from 4.42 to 16.80 μg/mL.The bio-guided EO fractionation identified furanosesquiterpenes as the main larvicidal compounds.A GC-MS-driven untargeted metabolomic analysis revealed 32 affected metabolic pathways in treated larvae.The EO non-target toxicity on Daphnia magna Straus(LC_(50)=4.51 μL/L)and its cytotoxicity on a human kidney cell line(HEK293)(IC50 of 14.38 μg/mL)were also assessed.This study shows the potential of plant products as innovative insecticidal agents and lays the ground-work for the possible exploitation of C.myrrha EO in the sustainable approaches for mosquito management.
文摘Beauveria bassiana (Ascomycota: Cordycipitaceae) is an entomopathogenic fungus used as an ecofriendly insecticide to infect arthropods. B. bassiana also possesses endophytic activity to contribute to plant growth. This study aimed to evaluate the potential insecticidal and endophytic activity of native B. bassiana isolates. The nymphal and adult stages of the apple tree aphid (Aphis pomi) and whitefly (Trialeurodes vaporariorum) were used as targets in bioinsecticidal experiments, and vegetables (beans, tomatoes and cucumbers) were used as targets in biostimulant experiments. The endophytic activity of the B. bassiana strains was assessed after inoculation them to the crop seeds and plants via soil drenching, foliar spraying and seed immersion. In bean plants, seed immersion was the most effective application method. Soil drenching was more effective in the cucumber and tomato plants. The results of in vitro bioassay tests against pests have revealed the LC50 and LT50 values of B. bassiana isolate Col-2. The LC50 of this isolate for A. pomi adults and nymphs was 2.5 × 106 conidia/mL−1;for T. vaporariorum, it was lower 1.8 × 106 conidia/mL−1. Such mortality occurred after 55.49 h. in A. pomi adults and nymphs (LT50), after 62.3 h. in T. vaporariorum (LT50).
基金This project was supported by the National Natural Science Foundation of China(30500387)Natural Science Foundation of Jiangsu Province,China(BK2005008).
文摘This study examined the photostabilization of Azadirachtin-A （Aza-A） when exposed to ultraviolet light in the presence of some natural absorbers. Aza-A extract solutions with and without natural UV light absorbers in methanol were applied onto the surface of glass slides. At particular intervals, the remaining concentration of Aza-A was analyzed by HPLC. Using first-order kinetic equation, the dissipation half-life values （DT^0） for the degradation of Aza-A under ultraviolet radiation were obtained. It indicated that the addition of ferulic acid, gallic acid, and rutin provided moderate degree of photostabilization of Aza-A and that addition of aloin provided the best photostabilization of Aza-A, among these UV absorbers studied. Photostabilization of Aza-A by different UV light absorbers appears to be due to the competitive energy absorption of UV photons by the absorbers molecules. The dissipation half-life values of Aza-A after irradiation under ultraviolet light suggested that the addition of aloin （in 1 ： 1 mol ratio） can provide better photostabilization of azadirachtin molecule.
基金the Laboratory of Lingnan Modern Agriculture Project,China(NT2021003)National Natural Science Foundation of China(32022074,32221004 and 32172458)Beijing Key Laboratory for Pest Control and Sustainable Cultivation of Vegetables,Chinese Academy of Agricultural Sciences,and the Innovation Program of the Chinese Academy of Agricultural Sciences(CAAS-CSCB-202303)。
文摘The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the PxABCB1 gene was previously found to be associated with Cry1Ac resistance in the diamondback moth,Plutella xylostella(L.).To directly validate the potential receptor role of PxABCB1 and its contribution to Bt Cry1Ac toxicity in P.xylostella,we used CRISPR/Cas9 to generate a homozygous knockout ABCB1KO strain with a 5-bp deletion in exon 3 of its gene.The ABCB1KO strain exhibited a 63-fold resistance to Cry1Ac toxin compared to the parental DBM1Ac-S strain.Intriguingly,the ABCB1KO strain also exhibited significant increases in susceptibility to abamectin and emamectin benzoate.No changes in susceptibility to various other Bt Cry proteins or synthetic insecticides were observed.The knockout strain exhibited no significant fitness costs.Overall,our study indicates that PxABCB1 can protect the insect against avermectin insecticides on one hand,while on the other hand it facilitates the toxic effect of the Bt Cry1Ac toxin.The results of this study will help to inform integrated pest management approaches against this destructive pest.
文摘The control of Spodoptera frugiperda is based on synthetic insecticides,so some alternatives are the use of entomopathogenic fungi(EF)and neem extract.The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S.frugiperda larvae.Six EF were identified by DNA sequencing of ITS regions from three EF(Fusarium solani,Metarrhizium robertsii,Nigrospora spherica and Penicillium citrinum).They were evaluated in concentrations of 1×10⁸spores/mL.In addition,a second bioassay was carried out evaluating only F.solani,M.robertsii and N.sphaerica and the addition of vegetable oil.On the other hand,extraction of secondary metabolites from neem seed(Azadirachta indica)was carried out by performing,mass(g)and solvent volume(mL ethanol and water)combinations,which were subjected to microwaves and ultrasound.Subsequently,these extracts were evaluated in concentrations of 3%,4%and 5%.A survival analysis was performed for each of the bioassays.With respect to the results of the first bioassay,F.solani obtained a probability of survival of 0.476 on the seventh day,while in the second bioassay,M.robertsii obtained 0.488 survival probability.This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%.However,in the evaluation of the neem extract the combination 1:12/70%to 4%caused 84% mortality of larvae.The use of native HE and neem extracts has potential for the control of S.frugiperda.
基金part of pharm D thesissupported by a grant of Tehran University of Medical Sciences and Health Services
文摘Objective: To determine the larvicidal activities of petroleum ether, chloroform, ethyl acetate and methanol fractions of roots and fruits extracts of Astrodaucus persicus from Apiaceae family against malaria vector, Anopheles stephensi(An. stephensi).Methods: Twenty five third instar larvae of An. stephensi were exposed to various concentrations(10–160 g/L) of fractions and were assayed according to World Health Organization protocol. The larval mortality was calculated after 24 h treatment.Results: Among tested fractions, the highest larvicidal efficacy was observed from ethyl acetate fraction of fruits extract with 50% and 90% mortality values(LC_(50) and LC_(90)) of34.49 g/L and 108.61 g/L, respectively. Chloroform fraction of fruits extract was the second larvicidal sample with LC_(50) of 45.11 g/L and LC_(90) of 139.36 g/L. Petroleum ether fractions of fruits and roots and methanol fraction of fruits showed moderate toxicity against An. stephensi.Conclusions: Astrodaucus persicus is a potential source of valuable and natural larvicidal compounds against malaria vector, An. stephensi and can be used in mosquitoes control programs as an alternative to synthetic insecticides.
基金Supported by Ministry of Environment and Forest[Grant No.D.O.NO.3/2/2004 CS(M)-11.12.2006]
文摘Objective:To identify the larvieidal activity of the seagrass extracts.Methods:Seagrass extracts,Syringodium isoelifolium(.S.isoetifolium),Cymodocea serrulata and Hulophila beccarii,were dissolved in DMSO to prepare a graded series of concentration.Batches of 25 early 4th instars larvae of Aedes aegypti(Ae.aegypti) were transferred to 250 ml.enamel bowl containing199 mL of distilled water and 1 mL of plant extracts(0.01 mg- 0.1 mg).After 24 h the mortality rate was identified with the formulae[(%of lest mortality-%of control mortality)/(100-%of control morlality)]× 100.Each experiment was conducted with three replicates and a concurrent control group.A control group consisted of 1 mL of DMSO and 199 mL of distilled water only.Results:The root extract of S.isoelifolium showed maximum larvicidal activity with minimum concentration of extract of LC_(50)= 0.0604 ± 0.0040)μg/mL with lower confidence limit(LCL)-upper confidence limit(UCL) =(0.051-0.071) and LC_(90)=0.0972 μg/mL followed by leaf extract of S.isoelifolium showed LC_(50)=(0.062 ± 0.005)μ'g/mL.The regression equation of pool and leaf extract of S.isoelifolium for4th instar larvae were Y =4.909- 1.32x(R^2= 0.909) and Y= 2.066+ 1.2x(R^2 =0.897) respectively.The results of the preliminary photochemical constituents shows the presence of saponin,steroids,terpenoid,phenols,protein and sugars.Conclusions:from the present study the ethanolic extracts of seagrass of S.isoelifolium possesses lead compound for development of larvieidal activity.
文摘The last volcanic eruption of the Puyehue-Cordon-Caulle Volcanic Complex in the Andes cordillera of western South America, occurring on 4 June 2011, ejected pyroclastic materials that were accumulated in a wide region of the northern Patagonia (Argentina), affecting the environment and health of residents within the area. The aim of this work was to evaluate the practicability of using this waste material as a lowcost carrier for mycopesticide formulations. Beauveria bassiana is a recognized fungal agent for arthropod biologic control. Lengthy storage is critical for the development of mycoinsecticide formulations. Accordingly, the search for adequate materials to improve the shelf life of biocontrol products becomes desirable. First, several analytical techniques were employed to characterize the pyroclast physicochemically;then the viability of the fungal conidia was evaluated after an 18-month storage in the volcanic material. Finally, the pathogenicity of the conidia after that prolonged maintenance in the vehicle was assessed on the beetle Alphitobius diaperinus, an insect pest in poultry houses that causes major economic losses. The results from those bioassays proved auspicious for the eventual utilization of the pyroclast as a bioinsecticide carrier especially since the formulation had proven to be stable for at least 18 months under a wide range of environmental conditions. The constant moisture in a closed environment within a 5°C - 40°C temperature range insures a viable state during storage. The results indicate that what would otherwise be volcanic waste may be utilized as an efficient, abundant, inexpensive, and environmentally innocuous carrier of entomopathogenic fungi.
文摘Adult corn earworm, Helicoverpa zea (Boddie), feeds on plant exudates soon after emergence from pupa in their natural habitat, and thereafter disperses to suitable host plants for reproduction. The intent of this study was to determine if EntrustTM, an organic formulation of spinosad, could be used in a behavioral-based pest management strategy to control H. zea in organic farming systems. In the laboratory, we evaluated the response of the corn earworm to Entrust mixed with sugar solution relative to ingestion, toxicity and proboscis extension. The sucrose solution served as a feeding stimulant and simulated the plant exudate. Lethal concentration of Entrust (LC50 with 95% CLs) for male corn earworm captured in pheromone-baited traps was 0.48 (0.43 - 0.53) mgL-1 for 24 h response. Mean lethal time was 2.56 ± 0.13 h with ingestion of Entrust at 50 mg·L-1. A lethal dose of Entrust at 1000 mg·L-1 inhibited neither ingestion nor proboscis extension response of the insect. A detailed study of the adult corn earworm in the laboratory relative to toxicity after ingestion of Entrust indicates that the pesticide has potential to control the insect when used in an insecticidal bait formulation as part of an attract-and- kill system. Field studies are needed to support the conclusion.
文摘Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-products as nutrient sources in culture medium, having been used, in this study, the manipueira, a by-product of the processing of the cassava flour. Fermentations were performed in flasks of Erlenmeyer of 500 mL containing 250 mL of culture media, conditioned in shaker at 180 r.p.m. and 28°C, and the media were composed by manipueira, in concentrations that varied between 400 and 1000 mL/L. The time of the process varied between 48 and 120 hours. They appraised the following parameters: cellular growth, the production of spores, the reduction of organic matter (COD analysis) and the variation of reduction sugar. Although there was a proportional cellular growth to the manipueira concentration, the production of spores was similar in all the cases, at the end of the process, in spite of the smallest speed of production of the same ones in the highest concentrations. In relation to the variation of COD, it has, also, a percentile minor of reduction in the highest concentrations. In the analysis of variation of reduction sugars, the higher concentrations are the ones that they present larger slowness in the reduction of this.
基金the National Natural Science Foundation of China(Grant No.42077136)grants from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2017075).
文摘The development of an effective and green bioinsecticide is a research hotspot.This study demonstrated the possibility of using an arsenic(As)hyperaccumulator as a bioinsecticide.When the As concentration in the Pteris vittata fronds exceeded 138 mg kg^(–1),the larva of the hawk moth(Theretra clotho)displayed apparent preference to lower-As-concentration P.vittata fronds.The As concentration in the larva body was as high as 850 mg kg^(–1).Such high concentration of As in the larva body might have been the case that T.clotho lacks a process to exclude As.The larval frass showed an As concentration of only 1%–4%of that in the larva body.The predominant As species in the larva body and frass was As(III)-SH.The percentage of As(III)-SH was slightly higher in the frass than that in the larval body.Chelation with thiols may be a universal detoxification mechanism for As in both plants and insects.In general,the adoption of P.vittata as a bioinsecticide should be feasible.However,the exact processes to achieve this goal still need further study.The mechanism of different animals to detoxify As is another interesting research topic.
