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1.
The study was focused on changes in the activities of ornithine decarboxylase (ODC), lysine decarboxylase (LDC) and tyrosine decarboxylase (TyDC) in maize seedlings infested by bird cherry-oat aphid (Rhopalosiphum padi L.).Obtained results showed that the aphid infestation induced LDC activity strongly within tissues of less aphid-settled maize (Waza cv.) during the first week of the infestation in comparison to the control plants and the activity was suppressed after two weeks. However, TyDC activity fluctuated under the aphid infestation. In relation to the control, the enzyme activity was inhibited on the first day, activated after the first week and reduced again two weeks into the experiment. A significant reduction in ODC activity was also observed in seedlings of aphid-infested maize Waza cv. during the first week. In a more susceptible maize cv. (Złota Karłowa), an increase in LDC and TyDC activities in relation to the control and a simultaneous decrease in ODC activity were noted after the first day of the infestation. After one week of aphid attack, TyDC activity was induced and ODC was inhibited, whereas after two weeks ODC activity was decreased with a simultaneous increase in LDC activity in the Złota Karłowa seedlings.  相似文献   

2.
The study aimed at comparing the changes in the content of free amino acids, phenolic compounds and the activity of PAL and TAL caused by two piercing-sucking arthropods: the grape mealybug (Pseudococcus maritimus Ehrh.) and the two-spotted spider mite (Tetranychus urticae Koch) in the leaves of orchid and strawberry, respectively. The obtained results show that the amino acid content and the ratio of amino acids to phenolic compounds increased in both plant species infested by the mealybug and the mite. However, such response was weakly dependent on changes in activity of the analysed enzymes. The pest feeding affected accumulation of the phenolic compounds, since the induction of the PAL activity in mealybug-infested orchid leaves during the first 5 h of the experiment preceded the increase in phenolic compounds during the first week of insect feeding. Instead, the increased activity of TAL was accompanied by elevated levels of phenolic compounds in the leaves of strawberry infested by mites. Mechanisms of biochemical plant responses induced by infestation of the studied herbivorous arthropods are discussed.  相似文献   

3.
Pseudococcus longispinus, a notorious cosmopolitan pest species of mealybugs, known to be distributed indoors in Korea since 2002, is found to be mixed with another species, Pseudococcus orchidicola. Finding P. orchidicola as a pest of tropical plants in Korea is rather unexpected because of their main distribution in the Pacific area and South Asia. However, all the available information from morphology, molecule and advice on identification from mealybug specialists indicates this is the best match for P. orchidicola. Morphological, molecular and some biological notes on P. orchidicola are provided with some adult and nymphal images, and compared with P. longispinus. A full discussion mainly on identity and distribution of P. orchidicola is given.  相似文献   

4.
The studies concerned changes in the activities of ornithine decarboxylase (ODC), lysine decarboxylase (LDC) and tyrosine decarboxylase (TyDC) in tissues of wheat (Triticum aestivum L.) infested with bird cherry-oat aphid (Rhopalosiphum padi L.).Obtained results showed that the activities of the enzymes were stimulated in the less susceptible wheat Kontesa cv. infested by the aphids. In the case of the more susceptible Tonacja cv., on most occasions a decrease in the enzyme activities occurred. Such responses were especially clear for TyDC in both analysed cvs., and for LDC and ODC in the case of Kontesa cv. Thus it may be concluded that amino acid decarboxylation plays an important part in the biochemical defence developed in wheat tissues in response to R. padi infestation. The changes in the activities of the decarboxylases were dependent on the wheat genotype as well as the duration of the infestation.  相似文献   

5.
To improve natural suppression of the obscure mealybug, Pseudococcus viburni (Signoret), the parasitoids Pseudaphycus flavidulus (Brèthes) and Leptomastix epona (Walker) (Hymenoptera: Encyrtidae) of Chilean origin were released in California's Central Coast vineyards from 1997 to 1999. A survey for parasitoids of P. viburni was conducted in the Edna Valley appellation wine grape region from 2005 to 2007, 6–8 years after classical biological control releases were discontinued. Two survey methods were used. First, field collections of obscure mealybugs from commercial vineyard blocks (2005–2007) and, second, placement of “sentinel mealybugs” on potted (1 L) grape vines (2006 only). From both survey methods, P. flavidulus was recovered, albeit levels of parasitism were low (less than 0.6%). We also placed longtailed mealybug, Pseudococcus longispinus (Targioni Tozzetti), on potted plants concurrent with placement of sentinel obscure mealybugs in the vineyard in order to measure parasitoid activity on this closely-related mealybug species. No P. flavidulus were recovered from P. longispinus. Other encyrtid parasitoids reared from either P. viburni or P. longispinus were Anagyrus pseudococci (Girault), Leptomastix dactylopii Howard, Leptomastidea abnormis (Girault), Coccidoxenoides perminutus Girault, and Tetracnemoidea peregrina (Compere). A hyperparasitoid, Chaetocerus sp., was also reared. The data are discussed with respect to biological control of vineyard mealybugs and newly developed controls for the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). Because Pseudaphycus species reared from mealybugs are superficially very similar a taxonomic key and discussion of host relationships for selected Pseudaphycus species are provided.  相似文献   

6.
Abstract 1. The Argentine ant, Linepithema humile, tends honeydew‐excreting homopterans and can disrupt the activity of their natural enemies. This mutualism is often cited for increases in homopteran densities; however, the ant’s impact on natural enemies may be only one of several effects of ant tending that alters insect densities. To test for the variable impacts of ants, mealybug and natural enemy densities were monitored on ant‐tended and ant‐excluded vines in two California vineyard regions. 2. Ant tending increased densities of the obscure mealybug, Pseudococcus viburni, and lowered densities of its encyrtid parasitoids Pseudaphycus flavidulus and Leptomastix epona. Differences in parasitoid recovery rates suggest that P. flavidulus was better able to forage on ant‐tended vines than L. epona. 3. Densities of a coccinellid predator, Cryptolaemus montrouzieri, were higher on ant‐tended vines, where there were more mealybugs. Together with behavioural observations, the results showed that this predator can forage in patches of ant‐tended mealybugs, and that it effectively mimics mealybugs to avoid disturbance by ants. 4. Ant tending increased densities of the grape mealybug, Pseudococcus maritimus, by increasing the number of surviving first‐instar mealybugs. Parasitoids were nearly absent from the vineyard infested with P. maritimus. Therefore, ants improved either mealybug habitat or fitness. 5. There was no difference in mealybug distribution or seasonal development patterns on ant‐tended and ant‐excluded vines, indicating that ants did not move mealybugs to better feeding locations or create a spatial refuge from natural enemies. 6. Results showed that while Argentine ants were clearly associated with increased mealybug densities, it is not a simple matter of disrupting natural enemies. Instead, ant tending includes benefits independent of the effect on natural enemies. Moreover, the effects on different natural enemy species varied, as some species thrive in the presence of ants.  相似文献   

7.
We performed “no‐choice” tests to study the host range of the parasitoid Allotropa burrelli (Muesebeck) (Hymenoptera: Platygastridae) for use against the Comstock mealybug, Pseudococcus comstocki (Kuwana) (Hemiptera: Pseudococcidae), in Southern France. We tested three Pseudococcidae species as potential non‐target hosts: two species from the same genus (Pseudococcus longispinus and Pseudococcus viburni) and Planococcus citri. Allotropa burrelli did not parasitize any of the non‐target mealybug species tested. No attempt of oviposition was recorded for the three species tested during the first 20 min of parasitoid release and no parasitism occurred in 6–8 hr of exposure of the mealybugs to the parasitoid.  相似文献   

8.
Polyamines (PAs) are involved in plant response to abiotic and biotic stresses, however, their role in biochemical insect-plant interactions is not clear. Therefore, we compared the involvement of polyamines and key enzymes of their biosynthesis in gall formation process. The present study had used galls on oak leaves caused by asexual generation (♀♀) of three Cynipidae species, namely Cynips quercusfolii L., Neuroterus numismalis (Fourc.) and N. quercusbaccarum L., as a model. The obtained results indicate that gall formation on oak leaves affected amine content, but intensity of the changes in their levels were strongly dependent on the insect species. Nevertheless the downward trend was dominant among those changes. Changes in the activity of lysine decarboxylase (LDC), tyrosine decarboxylase (TyDC) and ornithine decarboxylase (ODC) usually corresponded with the direction of changes in polyamine contents. Several cases of divergence between changes in amine levels and the rate of their biosynthesis may suggest the involvement of other regulation mechanisms such as: arginine decarboxylase (ADC) and S-adenosylmethionine decarboxylase (SAMDC) as well as amine oxidases involved in its catabolic pathways. Thus, the future studies on biochemical mechanism of regulation of PAs accumulation during galls formation should be focused on importance of these enzymes.  相似文献   

9.
The obscure mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) is recorded for the first time from Colombia based on specimens collected on Opuntia cylindrica (Lam.) DC., Mammillaria sp. (Cactaceae), Escallonia paniculata (Ruiz & Pav.), Roem. & Schult. (Escalloniaceae), Ficus carica L. (Moraceae), Coffea arabica L. (Rubiaceae), Citrus sp. (Rutaceae), Cestrum nocturnum L. and Solanum betaceum Cavanilles (Solanaceae). Multiple methods were used to identify P. viburni because it belongs to the “Pseudococcus maritimus” complex, a group composed of more than 60 species with high variation in morphological characteristics. The specimens were identified based on the morphology and morphometric analysis of third-instar nymphs and adult females. This morphological identification was corroborated by data on geographical distribution, plant hosts and a molecular identification using two different loci, CO1 (mtDNA) and the 28S ribosomal gene (nuclear genome). An updated list of species of Pseudococcus Westwood recorded from Colombia and information on morphological variation found in the studied specimens from Brazil and Colombia are provided.  相似文献   

10.
From 2013 to 2018, surveys were conducted in counties not previously surveyed in order to determine species of mealybugs present in the cocoa orchard in Côte d'Ivoire as well as their abundance according to the age of cocoa trees. Immature and mature cocoa trees were inspected to hand‐height in 5 and 29 counties infected with Cacao swollen shoot virus (CSSV). In each cocoa farm, mealybugs were searched for on fruits, leaves, flowers, twigs and trunks. Mealybug species were identified, and colonies were counted. Five mealybug species were identified on immature cocoa trees: Ferrisia virgata, Formicococcus njalensis, Planococcus citri, Planococcus kenyae and Pseudococcus longispinus. In addition to these species, four species, Dysmicoccus brevipes, Maconellicoccus hirsutus, Phenacoccus hargreavesi and Pseudococcus jackbeardsleyi were identified on mature cocoa trees. On immature cocoa trees, Fo. Njalensis, Pl. citri and Ps. longispinus comprised were, respectively, 35%, 33% and 19% of colonies, respectively. On mature cocoa trees, Fo. Njalensis and Pl. citri comprised 63.2% and 21.0%, and others species 15.8%. Nevertheless, the abundance of mealybug species varied according to the age of cocoa trees. The preferred organs of mealybugs were pods (74.1%) followed by twigs (13.4%) and flowers (7.4%). Previously, the mealybug Paracoccus burnerae (Brain) was found on Theobroma cacao, which is the first record for this species in Côte d'Ivoire and on this host‐plant.  相似文献   

11.
In order to understand better non-target effect and potential uses, the host specificity of two parasitoid species (Anagyrus sp. nov. nr. sinope Noyes & Menezes and Leptomastix dactylopii Howard) (both Hymenoptera: Encyrtidae) for six mealybug species [Ferrisia virgata (Cockerell), Phenacoccus madeirensis Green, Phenacoccus solani Ferris, Planococcus citri (Risso),Pseudococcus longispinus (Targioni-Tozzetti) and Pseudococcus viburni (Signoret)] (all Hemiptera: Pseudococcidae) was studied through behavioral observations and laboratory rearing. The selected mealybug species represent major subfamilies and tribes of Pseudococcidae. Except for F. virgata, all mealybug species induced examinations by Anagyrus sp. nov. nr. sinope and L. dactylopii. Anagyrus sp. nov. nr. sinope was specific to P. madeirensis, which was the only mealybug species selected for oviposition and suitable for complete development of the parasitoid. No encapsulation of Anagyrus sp. nov. nr. sinope in P. madeirensis was observed. Leptomastix dactylopii accepted multiple species for oviposition, with the ranking of species preference as P. citri > P. viburni > P. longispinus > P. solani > P. madeirensis. Only P. citri, P. longispinus and P. viburni supported the development of L. dactylopii. Parasitoids developing in P. longispinus and P. viburni suffered from high encapsulation rates, while no encapsulation was observed when developing in P. citri. The results of this study suggest that Anagyrus sp. nov. nr. sinope is highly host specific. Leptomastix dactylopii, on the other hand, has a wider host range. The use of Anagyrus sp. nov. nr. sinope in a mealybug biological control program is limited to P. madeirensis and L. dactylopii to P. citri. The results presented in this study also lead us to question the accuracy of the reported host range of L. dactylopii, which include all six mealybug species tested.  相似文献   

12.
The sex pheromone of the citrus mealybug (Pseudococcus cryptus), [(1R,3R)-3-isopropenyl-2,2-dimethylcyclobutyl]methyl 3-methyl-3-butenoate, was synthesized from (+)-α-pinene in five operational steps in a 43% overall yield. The synthetic pheromone was identical with the natural pheromone in 1H-NMR and mass spectroscopic properties, and showed almost the same pheromonal activity as the natural pheromone.  相似文献   

13.
The activity of ornithine decarboxylase (ODC) is increased 20 fold in leaves of Nicotiana tabacum cv. Xanthi n.c. following infection with tobacco mosaic virus at 20°. The activity reaches its maximum when localized necrotic lesions appear. There is little or no increase in plants kept at 32° when infection is systemic. However, if the infected plants are transferred to 20°, a marked and rapid increase in ODC activity occurs in the upper leaves, which collapse seven to nine hours after the transfer. ODC activity therefore parallels the activity of phenylalanine ammonia lyase during the hypersensitive reaction. Tyrosine decarboxylase was found to be activated in the same conditions. By contrast no increase in arginine decarboxylase activity could be detected. Temperature has a much greater effect on the polyamine and tyramine content of Xanthi n.c. leaves than does infection with TMV.  相似文献   

14.
《Journal of Asia》2020,23(1):152-158
Combinatory effect of ethyl formate (EF) and phosphine (PH3) fumigation against Pseudococcus longispinus and P. orchidicola was evaluated on 13 foliage nursery plants. Treatment with the combination of EF at 16 mg/L and PH3 at 0.1 mg/L for 4 h resulted in 100% fumigant activity against both adults and nymphs of P. longispinus and P. orchidicola in a 12 L desiccator. The combination treatment showed higher efficacy towards adults than towards nymphs for both mealybug species, although it was reversed for P. orchidicola when EF was treated alone. The combination treatment showed higher fumigant activity than the single EF or PH3 treatment. In larger fumigation chambers (0.65 m3 and 10 m3), 100% fumigant activity was observed with the combination of EF at 20 g/m3 and PH3 at 1 g/m3 against both mealybug species regardless of location inside chambers. The highest sorption rates for each fumigant were 24.4% for PH3-treated Hoya carnosa and 75.4% for EF-treated Philodendron selloum. Except P. selloum, all other species tested exhibited significant leaf damage one week after the combination treatment. Two species, Echeveria 'Perle von Nürnberg' and Heteropanax fragrans showed 100% leaf damage and died 5 months later without any new leaf formation. However, other 10 species were able to recover the treatment damage after 5 months. Treatment of these two plants with EF seems unfeasible. This study suggests that the combination of EF and PH3 can be used for controlling P. longispinus and P. orchidicola in some foliage nursery plants.  相似文献   

15.
Mealybugs (Hemiptera: Pseudococcidae) are pests constraining the international trade of Brazilian table grapes. They damage grapes by transmitting viruses and toxins, causing defoliation, chlorosis, and vigor losses and favoring the development of sooty mold. Difficulties in mealybug identification remain an obstacle to the adequate management of these pests. In this study, our primary aim was to identify the principal mealybug species infesting the major table grape-producing regions in Brazil, by morphological and molecular characterization. Our secondary aim was to develop a rapid identification kit based on species-specific Polymerase Chain Reactions, to facilitate the routine identification of the most common pest species. We surveyed 40 sites infested with mealybugs and identified 17 species: Dysmicoccus brevipes (Cockerell), Dysmicoccus sylvarum Williams and Granara de Willink, Dysmicoccus texensis (Tinsley), Ferrisia cristinae Kaydan and Gullan, Ferrisia meridionalis Williams, Ferrisia terani Williams and Granara de Willink, Phenacoccus baccharidis Williams, Phenacoccus parvus Morrison, Phenacoccus solenopsis Tinsley, Planococcus citri (Risso), Pseudococcus viburni (Signoret), Pseudococcus cryptus Hempel, four taxa closely related each of to Pseudococcus viburni, Pseudococcus sociabilis Hambleton, Pseudococcus maritimus (Ehrhorn) and Pseudococcus meridionalis Prado, and one specimen from the genus Pseudococcus Westwood. The PCR method developed effectively identified five mealybug species of economic interest on grape in Brazil: D. brevipes, Pl. citri, Ps. viburni, Ph. solenopsis and Planococcus ficus (Signoret). Nevertheless, it is not possible to assure that this procedure is reliable for taxa that have not been sampled already and might be very closely related to the target species.  相似文献   

16.
Lysine decarboxylase (LDC; EC 4.1.1.18) of Selenomonas ruminantium is a constitutive enzyme and is involved in the synthesis of cadaverine, which is an essential constituent of the peptidoglycan for normal cell growth. We purified the S. ruminantium LDC by an improved method including hydrophobic chromatography and studied the fine characteristics of the enzyme. Kinetic study of LDC showed that S. ruminanitum LDC decarboxylated both L-lysine and L-ornithine with similar K m and the decarboxylase activities towards both substrates were competitively and irreversibly inhibited by DL-α-difluoromethylornithine, which is a specific inhibitor of ornithine decarboxylase (EC 4.1.1.17). We also showed a drastic descent of LDC activity owing to the degradation of LDC at entry into the stationary phase of cell growth.  相似文献   

17.
Polyamines are fundamental molecules of life, and their deep evolutionary history is reflected in extensive biosynthetic diversification. The polyamines putrescine, agmatine, and cadaverine are produced by pyridoxal 5′-phosphate-dependent L-ornithine, L-arginine, and L-lysine decarboxylases (ODC, ADC, LDC), respectively, from both the alanine racemase (AR) and aspartate aminotransferase (AAT) folds. Two homologous forms of AAT-fold decarboxylase are present in bacteria: an ancestral form and a derived, acid-inducible extended form containing an N-terminal fusion to the receiver-like domain of a bacterial response regulator. Only ADC was known from the ancestral form and limited to the Firmicutes phylum, whereas extended forms of ADC, ODC, and LDC are present in Proteobacteria and Firmicutes. Here, we report the discovery of ancestral form ODC, LDC, and bifunctional O/LDC and extend the phylogenetic diversity of functionally characterized ancestral ADC, ODC, and LDC to include phyla Fusobacteria, Caldiserica, Nitrospirae, and Euryarchaeota. Using purified recombinant enzymes, we show that these ancestral forms have a nascent ability to decarboxylate kinetically less preferred amino acid substrates with low efficiency, and that product inhibition primarily affects preferred substrates. We also note a correlation between the presence of ancestral ODC and ornithine/arginine auxotrophy and link this with a known symbiotic dependence on exogenous ornithine produced by species using the arginine deiminase system. Finally, we show that ADC, ODC, and LDC activities emerged independently, in parallel, in the homologous AAT-fold ancestral and extended forms. The emergence of the same ODC, ADC, and LDC activities in the nonhomologous AR-fold suggests that polyamine biosynthesis may be inevitable.  相似文献   

18.
The roles of ornithine decarboxylase, lysine decarboxylase and tyrosine decarboxylase in biochemical interactions of two cultivars of winter triticale (Triticosecale), Tornado and Witon, and bird cherry-oat aphid (Rhopalosiphum padi L.) were determined. Results showed the resistant Witon had higher lysine decarboxylase activity than the susceptible Tornado. There was a significant negative correlation between the density of R. padi populations and lysine decarboxylase activity. Such correlations did not occur for the other decarboxylases. Aphid feeding induced a decrease of lysine decarboxylase activity within both cultivars after one week of infestation and increased its activity after two weeks in the moderately resistant Witon. Ornithine decarboxylase activity was induced in tissues of the susceptible Tornado and inhibited in Witon after two weeks of infestation. Aphid infestations did not change tyrosine decarboxylase activity in Witon, whereas in Tornado it decreased in activity after one day of aphid feeding and then increased after two weeks. It was concluded that of the three enzymes studied, lysine decarboxylase was the most important in the response of winter triticale to infestation by R. padi.  相似文献   

19.
Ornithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines. ODC-antizyme inhibitors (AZINs) are homologous proteins of ODC, devoid of enzymatic activity but acting as regulators of polyamine levels. The last paralogue gene recently incorporated into the ODC/AZINs family is the murine Gm853, which is located in the same chromosome as AZIN2, and whose biochemical function is still unknown. By means of transfection assays of HEK293T cells with a plasmid containing the coding region of Gm853, we show here that unlike ODC, GM853 was a stable protein that was not able to decarboxylate l-ornithine or l-lysine and that did not act as an antizyme inhibitor. However, GM853 showed leucine decarboxylase activity, an enzymatic activity never described in animal cells, and by acting on l-leucine (Km = 7.03 × 10? 3 M) it produced isopentylamine, an aliphatic monoamine with unknown function. The other physiological branched-chain amino acids, l-valine and l-isoleucine were poor substrates of the enzyme. Gm853 expression was mainly detected in the kidney, and as Odc, it was stimulated by testosterone. The conservation of Gm853 orthologues in different mammalian species, including primates, underlines the possible biological significance of this new enzyme. In this study, we describe for the first time a mammalian enzyme with leucine decarboxylase activity, therefore proposing that the gene Gm853 and its protein product should be named as leucine decarboxylase (Ldc, LDC).  相似文献   

20.
The impact of native natural enemies on populations of the grape mealybug,Pseudococcus maritimus (Ehrhorn) in apple and pear orchards was assessed using a combination of techniques, including exclusion cages, limb-banding, and visual inspection of shoots and fruits. The complex of native natural enemies (which included two encyrtid parasitoids, (Pseudaphycus websteri Timberlake andMayridia species), a coccinellid beetle (Hyperaspis lateralis Mulsant), and a chamaemyiid fly (Leucopis verticalis Malloch), provided reasonably good control in orchards that had not been treated with insecticides for one to two years. However, surveys indicated that most of these species were absent from orchards regularly sprayed with pesticides.  相似文献   

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