Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was ...Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was observed by using a scanning electron microscope. The larval antennae possess six sensilla basiconica, two sensilla chaetica and one sensillum styloconicum. Larval mouthparts possess six types of sensilla： sensilla chaetica, sensilla digitiformia, sensilla epipharyngeal, sensilla basiconica, sensilla styloconica and sensilla placodea. In the adult, seven types of sensilla are found on the antennae in males and six types of sensilla （sensilla basiconica absent） occur in females. Sexual dimorphism is also found in the number and size of these sensilla on the antennae of adults. We describe for the first time the five types of sensilla on the mouthparts of the adult of P. xylostella. This study provides useful information for further research into the function of these sensilla, and better understanding the behavioral mechanisms involved in pest control.展开更多
With the long-term use of Bacillus thuringiensis （Bt） insecticide and expansion of CrylA-expressing transgenic plants, some insect pests have developed resistance to Bt in open fields, greenhouses, and in the labora...With the long-term use of Bacillus thuringiensis （Bt） insecticide and expansion of CrylA-expressing transgenic plants, some insect pests have developed resistance to Bt in open fields, greenhouses, and in the laboratory. Bt resistance is complex and there appear to be different ways for resistance development. Understanding the Bt resistance mechanisms is critical to prolong its usefulness. In this article, Bt receptors, the cadherin and aminopeptidase N （APN）, in brush border membrane vesicles （/3BMV） of Helicoverpa armigera were examined in both CrylAc-susceptible （96S） and CrylAc- resistant （LF120） strains, to compare CrylAc toxin oligomerization and pore formation in these two strains. CrylAc toxin oligomerization and pore formation in these two strains were compared. Results showed that cadherin and aminopeptidase N proteins could express normally in both susceptible and resistant 11. armigera strains. The ability to form CrylAc oligomers and ion channels on BBMVs was also not significantly different between these two strains.展开更多
The parasitoids in the genera of Encarsia and Eretmocerus （Hymenoptera： Aphelinidae） are important biological control agents of whiteflies, and some of them not only parasitize hosts but also kill them with strong ...The parasitoids in the genera of Encarsia and Eretmocerus （Hymenoptera： Aphelinidae） are important biological control agents of whiteflies, and some of them not only parasitize hosts but also kill them with strong host-feeding capacity. Two whitefly parasitoid species, Encarsia sophia and Eretmocerus melanoscutus were examined to determine if mating and host density affected their host feeding and parasitism. The whitefly host, Bemisia tabaci, was presented to these two wasp species in densities of 10, 20, 30, 40, 50 and 60 third-instar nymphs per clip cage. Mated whitefly parasitoid females fed on more hosts than unmated females under a range of host densities （under all six host densities for En. sophia; under the densities of 40 nymphs or more for Er. melanoscutus）. Meanwhile, mated females parasitized more whitefly nymphs than unmated females under all host densities for both species. With increase of host density, mated or unmated Er. melanoscutus females killed more hosts by host feeding and parasitism. Mated En. sophia females killed more hosts by host feeding with increase of host density, whereas unmated females did not parasitze whitefly nymphs at all. Our results suggest that only mated female parasitoids with host-feeding behavior should be released in crop systems to increase their bio-control efficiency.展开更多
Fitness and efficacy of Encarsia sophia （Girault ＆ Dodd） （Hymenoptera： Aphelinidae） as a biological control agent was compared on two species of whitefly （Hemiptera： Aleyrodidae） hosts, the relatively smaller...Fitness and efficacy of Encarsia sophia （Girault ＆ Dodd） （Hymenoptera： Aphelinidae） as a biological control agent was compared on two species of whitefly （Hemiptera： Aleyrodidae） hosts, the relatively smaller sweetpotato whitefly, Bemisia tabaci （Gennadius） biotype ＇B＇, and the larger greenhouse whitefly, Trialeurodes vaporariorum （Westwood）. Significant differences were observed on green bean （Phaseolus vulgaris L.） in the laboratory at 27 ± 2℃, 55% 4- 5% RH, and a photoperiod of 14 ： 10 h （L ： D）. Adult parasitoids emerging from T. vaporariorum were larger than those emerging from B. tabaci, and almost all biological parameters of E. sophia parasitizing the larger host species were superior except for the developmental times of the parasitoids that were similar when para- sitizing the two host species. Furthermore, parasitoids emerging from T. vaporariorum parasitized more of these hosts than did parasitoids emerging from B. tabaci. We conclude that E. sophia reared from larger hosts had better fitness than from smaller hosts. Those from either host also preferred the larger host for oviposition but were just as effective on smaller hosts. Therefore, larger hosts tended to produce better parasitoids than smaller hosts.展开更多
The impacts of potato psyllid （Bactericera cockerelli） feeding on potato foliage on the free amino acids （FAAs） composition in potato leaf and tubers were determined under greenhouse conditions. The free amino aci...The impacts of potato psyllid （Bactericera cockerelli） feeding on potato foliage on the free amino acids （FAAs） composition in potato leaf and tubers were determined under greenhouse conditions. The free amino acids in plant extracts were separated by high-performance liquid chromatography, and in both leaf and tuber samples, at least 17 FAAs were detected. Psyllid feeding significantly changed the levels of several FAAs in both leaf and tuber samples. The concentration of leucine increased 1.5-fold, whereas that of serine and proline increased 2- and 3-fold, respectively. In contrast, the concentrations ofglutamic acid, aspartic acid and lyscine were significantly reduced by 42.0%, 52.1% and 27.5%, respectively. There were also significant changes in the levels of FAAs in the Zebra chip （ZC） infected tubers compared with the healthy tubers, and the levels of six of the FAAs increased, and the levels of nine of the FAAs decreased. The results from this study indicate that potato psyllid causes major changes in free amino acid composition of plant tissues, and this change in plant metabolism may contribute to the plant stress as indicated by increased levels of proline in the leaves and hence promoting the development of plant diseases such as ZC disease.展开更多
A recombinant Helicoverpa armigera nucleopolyhedrovirus （HearNPV） ex- pressing the insect-selective neurotoxin （RjAalTjO from Cuban scorpion Rhopalurus junceus was constructed by replacing the UDP-glucosyltransfera...A recombinant Helicoverpa armigera nucleopolyhedrovirus （HearNPV） ex- pressing the insect-selective neurotoxin （RjAalTjO from Cuban scorpion Rhopalurus junceus was constructed by replacing the UDP-glucosyltransferase gene （egt） using ）^- red homologous recombination system. Another egt deleted control HearNPV was con- structed in a similar way by inserting egfp gene into the egt locus. One-step viral growth curve and viral DNA replication curve analysis confirmed that the recombination did not affect the viral growth and DNA replication in host cells. There is no discernable differ- ence in occlusion-body morphogenesis between RjAalTf-HearNPV,, Egfp-HearNPV and HZ8-HearNPV, which was confirmed by transmission electron microscopy analysis. How- ever, the insecticidal activity of RjAal 7f-HearNPV is enhanced against the third instar H. armigera larvae according to the bioassay on virulence comparison. There is a dramatic reduction （56.9%） in median lethal dose （LD50） and also a reduction （13.4%） in median sur- vival time （ST50） for the recombinant RjAalTf-HearNPV compared to the HZ8-HearNPV, but only a 27.5% reduction in LD50 and 10.1% reduction in ST50 value when Egfp- HearNPV is compared with HZ8-HearNPV. The daily diet consumption analysis showed that the RjAal 7f-HearNPV was able to inhibit the infected larvae feeding compared with the egt minus HearNPV. These results demonstrated that this novel recombinant RjAa17f- HearNPV could improve the insecticidal effect against its host insects and RjAa17fcould be a considerable candidate for other recombinant baculovirus constructions.展开更多
基金supported by the China Postdoctoral Science Foundation (2013M542388)the Postdoctoral Scientific Research Project in Shaanxi Province,China+1 种基金the Fundamental Research Funds for the Central Universities of China (2014YB087)the Agricultural Science and Technology Innovation in Shaanxi Province,China (2016NY-058)
文摘Plutella xylostella （L.） （Plutellidae） is an important agricultural pest throughout the world. In this study, the morphology of antennal and mouthpart sensilla in the larvae and adults of P. xylostella （L.） was observed by using a scanning electron microscope. The larval antennae possess six sensilla basiconica, two sensilla chaetica and one sensillum styloconicum. Larval mouthparts possess six types of sensilla： sensilla chaetica, sensilla digitiformia, sensilla epipharyngeal, sensilla basiconica, sensilla styloconica and sensilla placodea. In the adult, seven types of sensilla are found on the antennae in males and six types of sensilla （sensilla basiconica absent） occur in females. Sexual dimorphism is also found in the number and size of these sensilla on the antennae of adults. We describe for the first time the five types of sensilla on the mouthparts of the adult of P. xylostella. This study provides useful information for further research into the function of these sensilla, and better understanding the behavioral mechanisms involved in pest control.
基金supported by the National Basic Research Program of China (31071693)
文摘With the long-term use of Bacillus thuringiensis （Bt） insecticide and expansion of CrylA-expressing transgenic plants, some insect pests have developed resistance to Bt in open fields, greenhouses, and in the laboratory. Bt resistance is complex and there appear to be different ways for resistance development. Understanding the Bt resistance mechanisms is critical to prolong its usefulness. In this article, Bt receptors, the cadherin and aminopeptidase N （APN）, in brush border membrane vesicles （/3BMV） of Helicoverpa armigera were examined in both CrylAc-susceptible （96S） and CrylAc- resistant （LF120） strains, to compare CrylAc toxin oligomerization and pore formation in these two strains. CrylAc toxin oligomerization and pore formation in these two strains were compared. Results showed that cadherin and aminopeptidase N proteins could express normally in both susceptible and resistant 11. armigera strains. The ability to form CrylAc oligomers and ion channels on BBMVs was also not significantly different between these two strains.
基金We appreciate the assistance of Y.-M. Zhang and Texas AgriLife Research, Texas A＆M University Sys- tem during this study. The research was financially supported by the National Natural Science Foundation of China （30930062）, the National Basic Research and Development Program of China （2006CB102005-3 and 2009CB 119200） and the Fund for Modem Agro-industry Technology Research System （nycytx-004）.
文摘The parasitoids in the genera of Encarsia and Eretmocerus （Hymenoptera： Aphelinidae） are important biological control agents of whiteflies, and some of them not only parasitize hosts but also kill them with strong host-feeding capacity. Two whitefly parasitoid species, Encarsia sophia and Eretmocerus melanoscutus were examined to determine if mating and host density affected their host feeding and parasitism. The whitefly host, Bemisia tabaci, was presented to these two wasp species in densities of 10, 20, 30, 40, 50 and 60 third-instar nymphs per clip cage. Mated whitefly parasitoid females fed on more hosts than unmated females under a range of host densities （under all six host densities for En. sophia; under the densities of 40 nymphs or more for Er. melanoscutus）. Meanwhile, mated females parasitized more whitefly nymphs than unmated females under all host densities for both species. With increase of host density, mated or unmated Er. melanoscutus females killed more hosts by host feeding and parasitism. Mated En. sophia females killed more hosts by host feeding with increase of host density, whereas unmated females did not parasitze whitefly nymphs at all. Our results suggest that only mated female parasitoids with host-feeding behavior should be released in crop systems to increase their bio-control efficiency.
文摘Fitness and efficacy of Encarsia sophia （Girault ＆ Dodd） （Hymenoptera： Aphelinidae） as a biological control agent was compared on two species of whitefly （Hemiptera： Aleyrodidae） hosts, the relatively smaller sweetpotato whitefly, Bemisia tabaci （Gennadius） biotype ＇B＇, and the larger greenhouse whitefly, Trialeurodes vaporariorum （Westwood）. Significant differences were observed on green bean （Phaseolus vulgaris L.） in the laboratory at 27 ± 2℃, 55% 4- 5% RH, and a photoperiod of 14 ： 10 h （L ： D）. Adult parasitoids emerging from T. vaporariorum were larger than those emerging from B. tabaci, and almost all biological parameters of E. sophia parasitizing the larger host species were superior except for the developmental times of the parasitoids that were similar when para- sitizing the two host species. Furthermore, parasitoids emerging from T. vaporariorum parasitized more of these hosts than did parasitoids emerging from B. tabaci. We conclude that E. sophia reared from larger hosts had better fitness than from smaller hosts. Those from either host also preferred the larger host for oviposition but were just as effective on smaller hosts. Therefore, larger hosts tended to produce better parasitoids than smaller hosts.
文摘The impacts of potato psyllid （Bactericera cockerelli） feeding on potato foliage on the free amino acids （FAAs） composition in potato leaf and tubers were determined under greenhouse conditions. The free amino acids in plant extracts were separated by high-performance liquid chromatography, and in both leaf and tuber samples, at least 17 FAAs were detected. Psyllid feeding significantly changed the levels of several FAAs in both leaf and tuber samples. The concentration of leucine increased 1.5-fold, whereas that of serine and proline increased 2- and 3-fold, respectively. In contrast, the concentrations ofglutamic acid, aspartic acid and lyscine were significantly reduced by 42.0%, 52.1% and 27.5%, respectively. There were also significant changes in the levels of FAAs in the Zebra chip （ZC） infected tubers compared with the healthy tubers, and the levels of six of the FAAs increased, and the levels of nine of the FAAs decreased. The results from this study indicate that potato psyllid causes major changes in free amino acid composition of plant tissues, and this change in plant metabolism may contribute to the plant stress as indicated by increased levels of proline in the leaves and hence promoting the development of plant diseases such as ZC disease.
文摘A recombinant Helicoverpa armigera nucleopolyhedrovirus （HearNPV） ex- pressing the insect-selective neurotoxin （RjAalTjO from Cuban scorpion Rhopalurus junceus was constructed by replacing the UDP-glucosyltransferase gene （egt） using ）^- red homologous recombination system. Another egt deleted control HearNPV was con- structed in a similar way by inserting egfp gene into the egt locus. One-step viral growth curve and viral DNA replication curve analysis confirmed that the recombination did not affect the viral growth and DNA replication in host cells. There is no discernable differ- ence in occlusion-body morphogenesis between RjAalTf-HearNPV,, Egfp-HearNPV and HZ8-HearNPV, which was confirmed by transmission electron microscopy analysis. How- ever, the insecticidal activity of RjAal 7f-HearNPV is enhanced against the third instar H. armigera larvae according to the bioassay on virulence comparison. There is a dramatic reduction （56.9%） in median lethal dose （LD50） and also a reduction （13.4%） in median sur- vival time （ST50） for the recombinant RjAalTf-HearNPV compared to the HZ8-HearNPV, but only a 27.5% reduction in LD50 and 10.1% reduction in ST50 value when Egfp- HearNPV is compared with HZ8-HearNPV. The daily diet consumption analysis showed that the RjAal 7f-HearNPV was able to inhibit the infected larvae feeding compared with the egt minus HearNPV. These results demonstrated that this novel recombinant RjAa17f- HearNPV could improve the insecticidal effect against its host insects and RjAa17fcould be a considerable candidate for other recombinant baculovirus constructions.
