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1.
Larvae of mealworms Tenebrio molitor L. (Coleoptera: Tenebrionidae) have been used as animal feed, but fungal pathogens rapidly downsize the populations, resulting in economic losses. In this work, we established an effective management strategy for fungal pathogens. An entomopathogenic fungus, Beauveria bassiana, was isolated from mealworm cadavers. The bioassay of some isolates of this species at >90% relative humidity revealed that the ERL1575 isolate had the highest virulence. At 20–30% RH, ERL1575 conidia when ingested produced 80% mortality but when sprayed topically produced only <10% mortality. Mealworms that had ingested conidia were exposed to 20, 25, 30 and 35°C and high humidity (>95%) for 5 days. This experiment produced about 90% mortality except at 35°C where mortality was <20%. When 40 fungicides were assayed against ERL1575, fluazinam (1000‐fold) and mancozeb (667‐fold) significantly inhibited conidial germination and/or hyphal growth. When fluazinam and mancozeb were added to the mealworm diet of conidia‐inoculated wheat bran, most were alive 3 days post application. However, 100% mortality resulted 3 days post application in the conidia‐inoculated wheat bran without any fungicides. In conclusion, B. bassiana isolates are pathogenic at <30°C when they are ingested by mealworms but fluazinam and mancozeb can be used for management to control the pathogen in their cultures. 相似文献
2.
Conidia of Beauveria bassiana CS-1, which have the potential for the control of the diamondback moth ( Plutella xylostella), were produced by solid-state fermentation (SSF) using a packed-bed bioreactor with rice straw and wheat bran. As the packing density and the bed height were increased, the production of conidia decreased. In a packed-bed bioreactor under no aeration and no addition of polypropylene (PP) foam (control), the total average of conidia was 4.9 × 10 8 g -1. The production of conidia was affected more by the addition of PP foam as an inert support than forced aeration and was approx. 23 times higher than that of the control. The total average of conidia produced by B. bassiana was 1.1–1.2 × 10 10 g -1 .
Revisions requested 6 September 2004/2 November 2004; Revisions received 1 November 2004/8 December 2004 相似文献
3.
We established a fungal production platform by focusing on substrates of solid culture for conidial productivity and thermotolerance, and focusing on surfactants to effectively deliver fungal conidia to the Riptortus pedestris cuticles. First, to produce thermotolerant fungal conidia, 2 of each Beauveria bassiana and Metarhizium anisopliae isolates were cultured on 13 cereal substrates for 10 days. Overall, five substrates (millet, non-glutinous Italian foxtail millet, barley, glutinous Italian foxtail millet, and brown rice) produced greatest number of conidia with thermotolerant conidia. When the selected substrates were mixed with minerals, zeolite, perlite or vermiculite to reduce the amount of cereal grains, vermiculite combination showed relatively high conidial production compared to the other mineral combinations. Next, to efficiently deliver the fungal conidia to the cuticles of R. pedestris, six surfactants, CO-2.5, CO-12, LE-7, PE-61, TED-3, and siloxane were each combined with the fungal conidia. The 0.01% combination showed significantly increased insect mortality, which varied depending on isolate. Virulence tests against R. pedestris were performed with conidial suspensions of isolates to assess their virulence. As a result, isolates showed the highest virulence when a virulence test was conducted at 25°C, rather than 20°C, 30°C and 35°C. This work suggests that the combination of cereal grain substrates and vermiculite could be considered for economic conidial production with high thermotolerance, and the CO-12 surfactant is the most suitable for effective delivery to target insects, followed by the information on optimal temperature for virulence against R. pedestris. 相似文献
4.
Large amounts of conidia must be recovered to use Isaria fumosorosea as a biological control agent. Aerial conidia are mass-produced in solid substrate culture. Conidia obtained from growth on different substrates must be similar in quantity and quality (viability, purity and virulence). In the present work, several solid substrates were evaluated: rice, sorghum, sugarcane, corncob, plantain and wheat (derived from the production of Trichogramma sp.) to find alternatives that are economical and available in different regions. The highest conidia production was obtained on rice, plantain and corncob substrates, which yielded 5.33 × 10 9 conidia/g, 5.24 × 10 9 conidia/g and 4.8 × 10 9 conidia/g substrate, respectively. At concentrations of 1 × 10 7 conidia/mL, the mortality rates obtained with conidia developed on rice, plantain and corncob substrates were 98%, 97% and 88%, respectively. The lethal concentration 50 (LC 50) values of conidia obtained from rice and plantain were 7.2 × 10 4 conidia/mL and 5.1 × 10 4 conidia/mL, respectively. 相似文献
5.
A survey for natural entomopathogenic fungi of the Chagas disease vector Triatoma infestans was conducted in five provinces of Argentina since 2001. Nymphs (1.5%) and adults (3.3%) infected with a strain of the fungus Beauveria bassiana were found at Dean Funes, Córdoba province, Argentina. Field collected insects that died in the laboratory were maintained in moist chambers and incubated at 22 °C. Beauveria bassiana from infected insects was cultured on SDAY media. Pathogenicity tests were conducted with a conidial suspension (1 × 10 7 conidia/ml) of this isolate on T. infestans adults. A mortality rate of 100% was obtained at 15 days post-infection. This is the first record of natural infection of T. infestans by B. bassiana. 相似文献
6.
Twelve fungal strains including Lecanicillium muscarium (Petch.) Zare and Gams, Isaria farinosa (Holmsk.) Fr., Fusarium sp., Beauveria bassiana Sensu Lato and Beauveria sp. were isolated from larvae and adults of D. micans. In addition, virulence of these isolates against this pest was determined. Conidia suspensions of 1×10 6 conidia mL –1 were applied to larvae and adults. The highest mortality and mycosis for larvae were obtained from isolate ARSEF 9271 ( Beauveria bassiana) with 90% mortality and mycosis within 10 days. ARSEF 9271 also produced 93% mortality and mycosis in adults. On the other hand, the highest mortality and mycosis for adults were obtained with isolate ARSEF 9272 ( Beauveria sp.), with 100% mortality and 80% mycosis within 10 days. These results indicate that isolates ARSEF 9271 and ARSEF 9272 seem to be the most promising potential fungal biocontrol agents against D. micans. 相似文献
7.
Beauveria bassiana s.l. is a cosmopolitan fungus used in the control of different species of arthropods. The current study explored the virulence for ticks, proteolytic and lipolytic activities of 10 Brazilian B. bassiana s.l. isolates. For this purpose, Rhipicephalus microplus biological parameters was evaluated after immersion of the engorged females in fungal suspension (10 8 conidia mL ?1) and the enzymatic activities were performed posteriorly the fungal growth in minimal medium. After the biological assays, five isolates changed all parameters analysed with highest efficacy of approximately 61% (CG 206) and 66% (CG 481). However, we observed that the most virulent isolates did not show the highest enzymatic activities. Interestingly, CG 500, considered an isolate of intermediate efficacy, demonstrated higher enzymatic activities than the other isolates in four of five analyses (total protease, Pr1, Pr2 and lipase; p?.05). Based on these data, it seems reasonable to suggest that these enzymatic activities should not be used as markers of virulence for these fungal isolates. It is noteworthy that complementary studies regarding chitinase analyses, gene expression, production of toxins and hydrophobicity of conidia can be used in the selection of pathogenic isolates. 相似文献
8.
This study determined the pathogenicity and virulence of Beauveria bassiana and Metarhizium anisopliae to eggs of the chinch bug Blissus antillus (Hemiptera: Lygaeidae). Eggs were inoculated under laboratory conditions by immersion in concentrations of 1 × 10 4 and 5 × 10 6 conidia/ml. Inoculated eggs were kept under controlled conditions. Evaluations were carried out daily for 20 days. M. anisopliae isolates were highly virulent to eggs, even at 1 × 10 4 conidia/ml. All B. bassiana isolates tested were considered to be of low virulence or avirulent. The most virulent isolate tested was ESALQ 818 ( M. anisopliae), which caused 96.7% infection, when eggs were immersed in suspensions of 1 × 10 4 conidia/ml. Conidial production on infected eggs was observed to be highest for M. anisopliae isolate CG144, with a mean value of 11.6 × 10 5 conidia/ml/egg. Infection of Blissus eggs oviposited on plant stems was greater when M. anisopliae isolate CG144 was formulated in mineral oil (63.5% mortality) than when formulated in Tween 80 (27.1% mortality). 相似文献
9.
The small poplar longhorn beetle, Saperda populnea is an important pest of Lombardy poplars ( Populus nigra L.) in Turkey. A survey for natural entomopathogenic fungi of S. populnea larvae was made in Erzurum, Turkey, during the period 2004–2005. Larvae (13.5%) infected with a strain of the fungus Beauveria bassiana were found. The pathogenicity of B. bassiana strain 46 was conducted with different concentrations of conidia (10 6, 10 7 and 10 8 conidia/ml) of this isolate on S. populnea larvae. The lowest concentration (10 6 conidia/ml) caused about 56% mortality within 6 days. One hundred percent mortality was achieved after median lethal time
(LT 50) of 4.6 and 4.4 days for 10 7 and 10 8 conidia/ml, respectively. There were no significant differences between median lethal times. This is the first record of natural
infection of S. populnea larvae by B. bassiana. 相似文献
10.
Two isolates of Beauveria bassiana, wild type ( wt) and its mutant type ( mt) were compared in terms of growth patterns on culture plates containing media based on wheat bran, grasshopper exoskeletons,
colloidal chitin or Sabouraud-dextrose agar (SDA). Germination for the mt isolate was up to 33% faster in all media. Influence of media on virulence was determined against larvae and adults of Tenebrio molitor. Mortality higher than 90% was reached for adults after 6 days using conidia from all media. For larvae, a mortality of 80%
was reached after 11 days with conidia collected from SDA medium and between 15 and 35% with conidia from other media. In
SDA medium, conidial yield was almost ten times higher for the mt isolate compared to the wt isolate; however, virulence traits were similar against either larvae or adults. These results may influence commercial preparations
of entomopathogenic fungi based on conidia. 相似文献
11.
Spore productivity in six entomopathogenic fungal strains isolated from insect cadavers at four locations in Chiang Mai province was evaluated in five cereal grains: white-rice, wheat, rye, corn and sorghum. According to sequence analysis of the internal transcribed spacer regions of these isolates, they were closely related to Beauveria bassiana (2 isolates), Metarhizium flavoviride (1 isolate), Metarhizium anisopliae (1 isolate), Paecilomyces lilacinus (1 isolate) and Isaria tenuipes (1 isolate). Among all fungal isolates, the maximum amount of spores (530.0?×?10 9 conidia/g) was yielded P. lilacinus CMUCDMT02 on sorghum grain followed by white-rice (399.3?×?10 9 conidia/g). Moreover, the highest number of spore in M. flavoviride was 102.8?×?10 9 conidia/g sorghum whereas white-rice yielded the greatest amount of spore for B. bassiana CMUCDMF03 (141.0?×?10 9 conidia/g) after 60?days incubation. The fungal growth rate was found highest in corn for all strains and rye showed the lowest with the exception of P. lilacinus CMUCDMT02 among the tested grains. Spore viability was over 80?% for all isolates that had been inoculated for 60?days. Fungal conidia suspension of P. lilacinus obtained highest virulence against Bactrocera spp. at a concentration of 1?×?10 6 spore/ml. The strains isolated, exhibited good production of conidia suggesting a promising strategy for the mass production of inoculum as biocontrol agents with low production cost. 相似文献
12.
Exploratory activities were done in Syria, Turkey, Iran, Uzbekistan, Kazakhstan, The Kyrghyz Republic, and Russia to locate entomopathogenic fungi of Eurygaster integriceps. Isolates from the entomopathogenic genera Beauveria, Paecilomyces, and Verticillium were collected. Beauveria bassiana was the most commonly recovered species. Thirty-one isolates of the 221 recovered were examined at 20, 25, 30, and 35 °C for 20 days for growth and sporulation. Growth and sporulation were generally highest at 25 °C. None of the isolates grew at 35 °C, and at 30 °C growth was retarded with no conidia being produced. Single- and multiple-concentration bioassays were conducted on greenhouse-grown wheat plants and in pine litter to evaluate virulence of fungi from several sources to E. integriceps. When tested at a single concentration, mortality after 15 days ranged from 66 to >95% in the litter assays and 50 to 91% in the plant assays. There was a distinct concentration response for most of the isolates tested in the multiple-concentration assay, particularly in the in-litter environment. In litter, mortality tended to develop earlier than in on-plant assays. Several isolates of B. bassiana and one Metarhizium anisopliae displayed consistently high virulence against E. integriceps and were more virulent than two commercial strains. Our results demonstrate the potential of entomopathogenic fungi for management of E. integriceps in overwintering sites and in wheat fields. 相似文献
13.
Fungal entomopathogens, especially Beauveria bassiana, are often studied within the context of their use in biological pest control; however, there is limited knowledge of their distributions in host plants and soil ecosystem. We examined the distribution of B. bassiana and its influence on rice plants and paddy soils. B. bassiana could only be detected on the foliar surfaces of rice plants within 15 days under Bb-4 (7.5 × 10 4 conidia/mL) and Bb-7 (7.5 × 10 7 conidia/mL) treatments. The endophytic colonization of B. bassiana could not be found in stems, roots, or seeds of rice plants under Bb-4 and Bb-7 treatments. The fungus was found only in the leaves of rice plants under Bb-4 and Bb-7 treatments at 15 days after inoculation. Moreover, B. bassiana was absent from paddy soils under Bb-4 and Bb-7 treatments at all times. Enzyme activity (urease and phosphatase) in the paddy soils of Bb-4 and Bb-7 treatments showed no significant difference from the control. It is possible that B. bassiana was not able to colonize paddy soil. Detailed understanding of distribution and ecological interactions of B. bassiana is helpful for understanding and predicting the effects of fungal entomopathogens on host populations, and the interactions among fungal entomopathogens and other organisms in the community. 相似文献
14.
The pathogenicity of four isolates each of the entomopathogenic fungi, Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. to apterous adult Aphis craccivora Koch was evaluated in the laboratory at 4 concentrations of conidia. All fungi isolates tested were found to be pathogenic to the insect but their virulence varied among species and isolates within species. Three isolates, B. bassiana CPD 11 and M. anisopliae CPD 4 and 5 caused significantly higher mortality than the other isolates at the various concentrations tested causing mortality of between 58–91%, 64 to 93% and 66–100%, respectively, at 7 days post treatment. At the highest concentration of 1 × 10 8conidiaml ‐1, these isolates produced the shortest LT 50s of 3.5, 3.6 and 3.4 days, respectively. Their LC 50s were 6.8 × 10 5, 3.1 × 10 5 and 2.7 × 10 5 conidia ml ‐1, respectively. The results indicate that these isolates are promising candidates for the control of the cowpea aphid but their pathogenicity to various aphid non‐target beneficial organisms within the cowpea agroecosystem warrant further investigation before initiating field control. 相似文献
15.
Three Metarhizium anisopliae and three Beauveria bassiana isolates were cultivated in media containing casamino acids, soybean flour or sunflower seed flour and were shaken for three days. M. anisopliae presented similar yields of around 10 6 submerged spores/ml without significant differences among them, whereas B. bassiana produced yields of around 10 8 spores/ml, of which GHA strain produced more submerged spores in the casamino acids medium. The other two strains showed no significant difference in the production of submerged spores in the three media used. Differences in mortality on Aedes aegypti larvae were observed with the submerged spores of Metarhizium depending on isolate and medium used. M. anisopliae 2157 caused significantly higher mortality (40%) when cultivated in casamino acids medium. It presented an LC 50 of 8.93 × 10 5 submerged spores/ml water against mosquito larvae five days after application, whereas it caused 27% mortality in Ae. aegypti adults 10 days after application. In conclusion, fungal nutrition affected virulence of some isolates of M. anisopliae against Ae. aegypti larvae while such an effect was not noted for B. bassiana isolates. 相似文献
16.
Beauveria bassiana (Hypocreales: Cordycipitaceae) is an entomopathogenic fungus that has shown promising results as a biocontrol agent of ticks. Locally isolated B. bassiana are better acclimatised to the natural conditions of their geographical origin; therefore, they are essential in developing effective biocontrol agents for ticks. The current study aimed to isolate native strains of B. bassiana that are pathogenic to Rhipicephalus microplus ticks. The virulence of the isolates was tested against R. microplus larvae using a formulation containing 15% avocado oil, 0.05% adjuvant and 108 conidia mL?1. The two best strains were further evaluated for various biological parameters on adult engorged female ticks. Breakthru® or Ballista® (adjuvant) was mixed with the formulation to compare their effect on the isolates' virulence. In total 61 entomopathogenic fungi were isolated from the 360 greater wax moth larvae, Galleria mellonella (Lepidoptera: Pyralidae) used. The virulence test identified Bb-40 and Bb-41 to be the most virulent isolates against R. microplus larvae with mortalities of 91 and 93% and LT50 values of 5.8 and 6.2 days, respectively. Compared to the control, both strains significantly affected all the measured biological parameters. The type of adjuvant also considerably affected the susceptibility of ticks to the fungi. In conclusion, the two isolates combined with adjuvants can be used as a biocontrol agent to control R. microplus. 相似文献
17.
An isolate of Bipolaris eleusines was investigated as a potential candidate for biocontrol of barnyardgrass and additional weeds in paddy rice fields and for safety to selected crop species under greenhouse conditions. Barnyardgrass appeared more susceptible at the three-leaf stage than older plants, and disease severity increased as the fungal inoculum increased from 1 × 10 5 to 1 × 10 7 conidia/ml when sprayed till run-off. The high application rate caused 73% mortality of barnyardgrass, relative to the non-treated control, but increasing application rate to >1 × 10 7 conidia/ml did not enhance efficacy ( P >.05). This B. eleusines isolate showed no pathogenicity to rice ( Oryza sativa spp. indica, O. sativa spp. japonica and an O. sativa hybrid), corn, wheat or any dicot crop species tested while causing slight infection on sorghum and barley. We conclude that B. eleusines, with high efficacy against barnyardgrass and demonstrated safety to rice, is a promising mycoherbicide candidate worthy of further evaluation and development for control of barnyardgrass in paddy rice fields. 相似文献
18.
The quality of Beauveria bassiana conidia directly affects the virulence against insects. In this study, continuous subculturing of B. bassiana on both rice grains and potato dextrose agar (PDA) resulted in 55 and 49 % conidial yield reduction after 12 passages and 68 and 60 % virulence reduction after 20 and 12 passages at four d post-inoculation, respectively. The passage through Tenebrio molitor and Spodoptera exigua restored the virulence of rice and PDA subcultures, respectively. To explore the molecular mechanisms underlying the conidial quality and the decline of virulence after multiple subculturing, we investigated the conidial proteomic changes. Successive subculturing markedly increased the protein levels in oxidative stress response, autophagy, amino acid homeostasis, and apoptosis, but decreased the protein levels in DNA repair, ribosome biogenesis, energy metabolism, and virulence. The nitro blue tetrazolium assay verified that the late subculture's colony and conidia had a higher oxidative stress level than the early subculture. A 2A-type protein phosphatase and a Pleckstrin homology domain protein Slm1, effector proteins of the target of rapamycin (TOR) complex 1 and 2, respectively, were dramatically increased in the late subculture. These results suggest that TOR signalling might be associated with ageing in B. bassiana late subculture, in turn affecting its physiological characteristics and virulence. 相似文献
19.
The larvae of the pine processionary moth (PPM), Thaumetopoea pityocampa, feed on the needles of pine and cedar. The urticating hairs of older instars pose a threat to human and animal health. Strains of the entomopathogenic fungi, Metarhizium brunneum (V275, ARSEF 4556) and Beauveria bassiana (KTU-24), were assayed against first to fourth instar T. pityocampa using doses ranging from 1?×?10 5 to 1?×?10 8 conidia mL ?1. The three strains differed slightly in their virulence but caused 100% mortality of all instars at the highest dose. The newly emerged or first instar larvae were extremely susceptible with 100% mortality being achieved 2–4 days post inoculation with V275 at all but the lowest dose. The fourth instar larvae appeared to be less susceptible than earlier instars. There was good horizontal transmission of conidia from treated to un-inoculated larvae. However, mortality was higher in third and fourth instars and where the ratio of inoculated versus untreated larvae was high. This we presume is due to spores being more readily trapped by the urticating hairs found on third and older instar larvae. Injection of the nests offers a simple and environmentally friendly way of controlling the pest with reduced risk to operators. 相似文献
20.
The strawberry bud weevil, Anthonomus signatus (Say) (Coleoptera: Curculionidae) is a serious pest of strawberry crops in Canada. The results of previous laboratory screening and bioassay experiments showed that A. signatus adults were susceptible to several isolates of Beauveria bassiana (Balsmo) Vuillemin. Based on these results, the INRS-IP and INRS-CFL isolates were selected for field trails. Using a randomized block design with four replicates, three applications of the INRS-IP and INRS-CFL isolates were applied at a rate of 1×10 13 conidia/ha at 7-day intervals. The multiple applications of B. bassiana triggered a significant reduction of A. signatus adult populations in strawberries. Twenty-four days after the first application, a significant difference was observed between the mean numbers of surviving adults in all B. bassiana-treated plots compared to control plots. During the field experiment, the persistence of insecticidal activity and the viability of B. bassiana conidia were also monitored. Results showed the presence of viable and infective conidia on strawberry foliage up to 6 days after each application. Moreover, the multiple applications of B. bassiana at a rate of 1×10 13 conidia/ha resulted in a significant reduction of damaged strawberry fruits compared with control plots, where fruit loss was caused by A. signatus feeding and egg laying. 相似文献
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