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1.
An entomopathogenic fungal strain was originally isolated on artificial medium from the corpse of a pea aphid (Acyrthosiphon pisum Harris) collected at Jingzhou, China (N30°21′18.15″, E112°08′41.63″). Based on tests of the morphological, physiological and biochemical characteristics and analysis of internal transcribed spacer (ITS) sequences, it was considered to be a strain of Lecanicillium attenuatum Zare & W. Gams. Therefore, the strain was designated L. attenuatum YZU 151121. The activity of the biological agents under study was determined at 26 °C and 90% relative humidity. The number of A. pisum killed was increased by increasing the concentration of L. attenuatum. The results demonstrated that L. attenuatum YZU 151121 showed a high efficacy against 3rd-instar nymphs (LC50 = 2.91 ± 0.365 × 105 conidia/ml) and adults (LC50 = 3.12 ± 0.398 × 106 conidia/ml) after 6 days of exposure. Crude extract from this strain was tested for contact toxicity and showed high activity in 3rd-instar nymphs and adults, with LC50 values of 251.34 ± 49.54 and 315.46 ± 87.66 mg/l, respectively. In addition, crude extract at a concentration of 200 mg/l could significantly reduce fecundity in adults. These results revealed that the strain YZU 151121 may be useful in biopesticides for controlling pea aphid.  相似文献   

2.
The cherry slugworm Caliroa cerasi is a significant destructive pest of sour cherries (Prunus cerasus) in Turkey. The potential of entomopathogenic fungi for controlling C. cerasi was evaluated. The effects of exposure methods and conidial concentrations (1 × 106, 1.5 × 106, 1 × 107 and 1.5 × 107 conidia/ml) on mature larvae of C. cerasi infected by Beauveria bassiana were investigated under laboratory conditions. Larvae sprayed directly with B. bassiana conidial suspensions and larvae exposed to B. bassiana-treated leaves resulted in 100% mortality within 2.90 and 2.77 days, respectively. The median lethal time (LT50) and days to mortality were highest in the 1.0 × 107 concentrations of conidia for both direct spray and leaf exposure. The present study suggests that B. bassiana has good potential for control of the cherry slugworm, C. cerasi.  相似文献   

3.
Field trials were conducted to evaluate the efficacy of wheat bran bait formulations of Paranosema locustae and Metarhizium anisopliae for controlling grasshoppers in southeast Niger. Treatments consisted of wheat bran baits mixed with M. anisopliae, P. locustae + M. anisopliae or with P. locustae spores and P. locustae + sugar. Oedaleus senegalensis, Pyrgomorpha cognata and Acrotylus blondeli were the predominant species at the time of application representing ca. 94% of the total population. Bran application was done when O. senegalensis (ca. 75% of the population) was at its early developmental stages, with first, second and third instars accounting for 64–85%. Grasshopper population reduction, P. locustae prevalence and level of infections in the predominant species were monitored. Manual application of P. locustae and M. anisopliae formulated in wheat bran has proven to induce consistent pathogen infection in grasshopper populations. Population density over the three weeks monitoring, typically decreased by 44.7 ± 6.9%, 52.8 ± 8.4%, 73.7 ± 5.5% and 89.1 ± 1.8% in P. locustae, P. locustae + sugar, M. anisopliae and P. locustae + M. anisopliae treated plots respectively. Paranosema locustae prevalence in surviving adult grasshoppers at 28 after application was 48.1 ± 2.3%, 28.9 ± 4.8% and 27.4 ± 3.7%, with infection level of 6.2 ± 0.8 × 106, 2.3 ± 0.3 × 104 and 2.1 ± 0.3 × 103 spores mg−1 host weight in O. senegalensis, A blondeli and P. cognate respectively. Other species that each accounted for <2% of the community, namely Aiolopus thalassinus, A. simulatrix, Acorypha glaucopsis, Acrotylus patruelis, Anacridium melanorhodon, Diabolocatantops axillaris, Kraussaria angulifera and Schistocerca gregaria were found to show sign of infection. The results from this study suggest that wheat bran application of M. anisopliae and P. locustae alone or in combination, targeting early instars grasshopper could be a valuable option in grasshopper control programs.  相似文献   

4.
Tetraphleps galchanoides Ghauri (Hemiptera: Anthocoridae) nymphs were collected from hemlock woolly adelgid (HWA) Adelges tsugae Annand (Hemiptera: Adelgidae) infested Tsuga sp. in Baoxing, Sichuan, China. First and second stage nymphs collected from foliage shipped from China; were reared to adults and tested for feeding rates and host preferences. They were reared at 5, 8, 12, and 15 ± 1 °C from November to December, January to March, April, and May to June, respectively, in the quarantine laboratory at Virginia Polytechnic Institute and State University. At 8 °C, development time was 15, 20, and 40 days for the N-III, IV, and V nymphal stages, respectively. Adult males lived 83 days with a range of 21–147 days. A single adult female lived for 21 days. At 5 °C, second stage T. galchanoides nymphs consumed 0.8 HWA nymphs per day, and 2.0 HWA nymphs per day at the N-V stage. At 8 °C, consumption of HWA nymphs ranged from 1.3 to 3.4 nymphs per day for the N-III to N-V stages, respectively. Adult T. galchanoides consumed more HWA eggs than HWA adults, pine bark adelgid (PBA) Pineus strobi (Hartig) (Hemiptera: Adelgidae) adults, and eggs in no-choice tests. In choice tests with HWA eggs and PBA eggs, more HWA eggs were eaten. Adult and nymph body measurements are presented for determination of nymphal instars.  相似文献   

5.
Sporulation in Bacillus megaterium var phosphaticum (PB — 1) was induced using modified nutrient media. This modified medium induced sporulation within 36 h. After spore induction the spores were kept under refrigerated (5°C) and room temperature (32°C) for five months and survival of spores was studied at 15 days intervals by plating them in nutrient agar medium. It was observed that there was not much variation in the storage temperature (5°C & 32°C). The spore cells of Bacillus megaterium var phosphaticum (PB — 1) were observed up to five months of storage under refrigerated (5°C) and room temperature (32°C). Regeneration of spore cells into vegetative cells was studied in tap water, rice gruel, nutrient broth, sterile lignite and sterile water at different concentrations of spore inoculum. The multiplication of sporulated Bacillus megaterium var phosphaticum culture was fast and reached its maximum (29.5 × 108 cfu ml−1) in nutrient broth containing 5 per cent inoculum level.  相似文献   

6.
The cypress aphid (Cinara cupressi) is listed among the hundred most important invasive pests in the world. In Chile, it was first detected in 2003 and currently is present throughout the country. In the course of a survey of their natural enemies in Chile, three strains of entomopathogenic fungi were isolated. The isolates were identified and tested against the aphid in laboratory experiments. Two further entomopathogenic fungi (ARSEF 5126 and 5128), formulated in the mycoinsecticides Vertalec® and Mycotal®, were used as reference strains. The three Chilean isolates were identified genomically as Lecanicillium attenuatum and were pathogenic to third-instar nymphs. The isolate ARSEF 13279 yielded the lowest overall lethal concentration (LC50), 3 × 105 conidia ml?1 at four days post-inoculation, and the shortest lethal time (LT50), 3.7 days after inoculation with 106 conidia ml?1. The results indicate that the isolates have considerable potential as microbial control agents of the invasive cypress aphid.  相似文献   

7.
Ramularia collo-cygni causes leaf spots on barley (Hordeum vulgare), a disease of growing economical importance. Scanning electron microscopy was used to study the life cycle of the fungus on barley during the vegetation period and in winter. The infectious stage started with conidium germination on the surface and the penetration into the leaf via the stomatal pore where the hyphae grew within the cells that became necrotic. The conidiophores emerged through the stomatal pore. On older leaves, however, they frequently emerged apart from it and the results suggested a pushing apart of adjacent cell walls of the epidermal cells. An assessment of the amount of conidium formation of one heavily infested barley plant resulted in 4.05 × 106 conidia per plant. For the first time, conidiophores, conidium production and germination of conidia were also observed in winter on barley and on maize leaves.  相似文献   

8.
Axenic cultivation of biocontrol fungus Trichoderma viride was conducted on a synthetic medium and different wastewaters and wastewater sludges in shake flasks to search for a suitable raw material resulting in higher biocontrol activity. Soluble starch based synthetic medium, dewatered municipal sludge, cheese industry wastewater sludge, pre-treated and untreated pulp and paper industry wastewater and slaughter house wastewater (SHW) were tested for T. viride conidia and protease enzyme production. The maximum conidia production followed the order, soluble starch medium (>109 c.f.u./mL), untreated pulp and paper industry wastewater (4.9 × 107 c.f.u./mL) > cheese industry wastewater (1.88 × 107 c.f.u./mL) ≈ SHW (1.63 × 107 c.f.u./mL) > dewatered municipal sludge (3.5 × 106 c.f.u./mL) > pre-treated pulp and paper industry wastewater (1.55 × 106 c.f.u./mL). The protease activity of T. viride was particularly higher in slaughterhouse wastewater (2.14 IU/mL) and dewatered municipal sludge (1.94 IU/mL). The entomotoxicity of soluble starch based synthetic medium was lower (≈6090 SBU/μL) in contrast to other raw materials. The entomotoxicity inversely decreased with carbon to nitrogen ratio in the growth medium and the conidia concentration and protease activity also contributed to the entomotoxicity. The residual c.f.u./g formulation of T. viride conidia were up to approximately, 90% after 1 month at 4 ± 1 °C and about 70% after 6 months at 25 ± 1 °C. Thus, production of T. viride conidia would help in marketability of low cost biopesticide from the sludge and safe reduction of pollution load.  相似文献   

9.
Alligatorweed, (Alternanthera philoxeroides (Mart.) Griseb.), an aquatic and wetland plant native to South America, is an aggressive weed in many parts of the world. Its ability to compete with other native plants and to impede waterways has made it a serious threat to aquatic ecosystems. Although biological control with insects has been fairly successful in aquatic habitats, there is a need for additional agents to manage the weed in upland sites. Accordingly, in a survey in Brazil in 1997 a fungus, Nimbya (=Alternaria) alternantherae (Holcomb and Antonopoulus) Simmons and Alcorn, was discovered and confirmed to be highly damaging to alligatorweed. Studies were conducted to determine the potential of this fungus for controlling this weed. Several isolates from Brazil, USA, and Puerto Rico were compared and no differences in virulence were observed, although a lower dew requirement was demonstrated for the Brazilian isolates. Conidia were more effective than mycelial suspension, and inoculum concentrations of 1×105 and 1×106 conidia per ml provided significant levels of control of the weed in greenhouse and field experiments, respectively. In a host-range study, N. alternantherae infected 6 plant species from a total of 42 species belonging to 23 families. N. alternantherae has the potential to be an effective mycoherbicide for alligatorweed.  相似文献   

10.
Bacillus thuringiensis HD-73 was transformed with the endochitinase gene chiA74 under the control of a strong promoter (pcytA) and a 5′ mRNA stabilizing (STAB-SD) sequence (HD-73-pEBchiA74). Expression levels were compared with those observed from the wild type strain (HD-73) and the recombinant HD-73 strain expressing chiA74 under the control of its native promoter (HD-73-pEHchiA74). The chitinolytic activity of HD-73-pEBchiA74 was markedly elevated, being ~58- and 362-fold higher than, respectively, HD-73-pEHchiA74 and parental HD-73, representing the highest levels of chitinase expression in recombinant B. thuringiensis reported to date. Parasporal crystals measured under transmission electron microscopy showed that HD-73 produced crystals of 1.235 (±0.214) and 1.356 (±0.247) μm in length when the bacterium was grown in respectively, NBS and NBS with glucose. Otherwise, HD-73-pEBchiA74 synthesized crystals of 1.250 (±0.222) and 1.139 (±0.202) μm in length when cultivated in NBS and NBS with glucose, respectively, values that showed a diminution of ~10 and 20% compared with crystals produced by HD-73-pEHchiA74 grown under the same conditions. Comparison of viable spore counts per ml showed that HD-73-pEBchiA74 produced fewest viable spores (1.5 × 109, 1.3 × 109), compared to HD-73-pEHchiA74 (4.9 × 109, 5.3 × 109) and HD-73 (6.8 × 109, 8.8 × 109) when grown in NBS and NBS supplemented with glucose, respectively. No change in cellular protease activity was observed despite the overproduction of the chitinase.  相似文献   

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