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PubMedDate not supplied

[The effect of entomopathogenic fungi on the activity of detoxicating enzymes of larvae of bee pyralid Galleria mellonella L. (Lepidoptera, Pyralidee) and the role of detoxicating enzymes in the formation of the insect' resistance to entomopathogenic fungi].

In the work it was shown that fungal infection of insects increased the total esterase and glutathione-S-transferase activities of hemolymph. Acid and alkaline phosphatase activity in infected larvae remained at the same level as in intact larvae. Fungi-infected bee pyralid larvae turned out to be 1.46 times more resistant to phosphoorganic insecticide malation as compared to intact larvae. On the other hand, treating insects with the inhibitors of detoxicating enzymes caused a sharp decrease in the insects' resistance to entomophathogenic fungi. The work discusses possible participation of detoxicating enzymes in the formation of the insects' resistance to entomopathogenic fungi as well as new strategies of the development and creation of complex biopreparations based on entomopathogenic microorganisms and inhibitors of detoxicating enzymes.

Animals↗

PubMed2005

Cultivation of entomopathogenic fungi for the search of antibacterial compounds.

Entomopathogenic fungi are a rich source of natural bioactive compounds. To establish cultivation conditions which facilitate the production of bioactive compounds and to select good genera among entomopathogenic fungi as the producer, 47 typical entomopathogenic fungi were tested for their ability to produce antibiotic activity. Thirty-eight strains (81%) and 30 strains (64%) of these fungi produced either anti-Bacillus compounds or anti-Staphylococcus compounds, respectively, indicating that the majority of the entomopathogenic fungi tested possessed the ability to produce antibacterial compounds. Using 9 representative strains (Aschersonia sp. HF724, Beauveria bassiana HF338, Cordyceps ramosopulvinata HF746, Metarhizium anisopliae HF293, Metarhizium flavoviride HF698, Nomuraea rileyi HF588, Paecilomyces fumosoroseus HF254, Paecilomyces tenuipes HF419, and Verticillium lecanii HF238), the cultivation conditions in liquid medium were surveyed with respect to the cultivation procedure and medium composition, particularly in terms of the presence or absence of insect-derived materials. At 26 degrees C, M. anisopliae HF293, N. rileyi HF588, and V. lecanii HF238 strains produced clear antibiotic activity against Bacillus and Saccharomyces, but only in the presence of insect-derived materials, suggesting that the production of antibacterial/antifungal compounds by entomopathogenic fungi is triggered by the presence of insect-derived materials.

Animals↗

PubMed2002

Distribution, occurrence and characterization of entomopathogenic fungi in agricultural soil in the Palestinian area.

The occurrence of entomopathogenic fungi was investigated in irrigated vegetable fields and citrus orchards soils, over a nine-month period (April-December 1999), using the Galleria bait method (GBM). Entomopathogenic fungi were found to occur in 33.6% of the soil samples studied, with positive samples yielding 70 fungal isolates, belonging to 20 species from 13 genera. Conidiobolus coronatus was the most frequent and abundant entomopathogenic species recovered, comprising 31.4% of the total number of isolates. Soil pH, soil moisture content and the geographical location had minor or no effect on the isolation of entomopathogenic fungi in the fields studied. On the other hand, organic matter content of soil, and vegetation type were found to significantly affect the occurrence of entomopathogenic fungi in soil habitats, with orchard fields yielding larger numbers of isolates than vegetable fields. Using Koch's postulates the pathogenicity of fungal isolates to Galleria larvae was found to range from 16-100% (mortality rate). Isolates of C. coronatus proved to be the most virulent isolates recovered. The effect of media and temperature on mycelial growth rate, conidial production and conidial germination of six entomopathogenic fungal species (C. coronatus, Entomophaga grylli, Erynia castrans, Hirsutella jonesii, Paecilomyces farinosus and Sporodiniella umbellata) was also studied. Mycelial growth rate, spore production and spore germination were significantly affected by media, temperature and isolates. In view of the present results, C. coronatus appears to be a good candidate for pest control in agricultural soils, as it has a wide tolerance to agricultural practices, has frequently been isolated from both vegetable and orchard fields, and is characterized by high mycelial growth rate, conidial production and conidial germination.

Animals↗

PubMed2006

Endophytic colonization of date palm (Phoenix dactylifera L.) leaves by entomopathogenic fungi.

Light and scanning electron microscopy together with fungal isolation techniques were used to detect entomopathogenic fungi within young and adult date palm (Phoenix dactylifera) petioles and to assess fungal survival in leaf tissues. The entomopathogenic fungi Beauveria bassiana, Lecanicillium dimorphum and Lecanicillium c.f. psalliotae survived inside leaf tissues at least 30 days after inoculation. Entomopathogenic fungi colonized inoculated petioles endophytically and were recovered up to 3cm from the inoculation site. Fungi were detected inside the parenchyma and sparsely within vascular tissue using microscopy techniques. Our results show that the entomopathogenic fungi used in this study survived and colonized date palm tissues in bioassays both under laboratory and field experimental conditions with no evidence of significant damage.

Arecaceae↗

PubMed1997

Entomopathogenous fungi degrade epicuticular hydrocarbons of Triatoma infestans.

Studies were undertaken to analyze the ability of entomopathogenous fungi to degrade insect hydrocarbons. Strains of Beauveria bassiana and Metarhizium anisopliae pathogenic to the blood-sucking bug Triatoma infestans were grown on hydrocarbon and non-hydrocarbon insect lipid extracts and on synthetic hydrocarbon-enriched media as the sole carbon source. Entomopathogenous fungi were shown to utilize hydrocarbons as the only carbon source for their growth. Insect-derived hydrocarbons served more efficiently as metabolic fuel rather than synthetic compounds of similar structure. [3H]n-Pentacosane, [11,12-3H]3,11-dimethylnonacosane, and [14C]n-hexadecane were catabolized into different amounts of polar lipids, free fatty acids, and acylglycerols. In experiments using the branched alkane, labeled hydrocarbons of different chain length than the precursor were also synthesized. Evidence of complete catabolism was obtained by a significant release of 14CO2 from [1-14C]n-hexadecane. 14CO2 production might be used as a simple method to compare hydrocarbon utilization by fungal strains. These data demonstrate that entomopathogenous fungi are able to transform a variety of hydrocarbon structures into different lipid products, part of which may be subsequently utilized for energy production and for the biosynthesis of cellular components. These data are the first evidence of hydrocarbon catabolism and synthesis in entomopathogenous fungi.

Alkanes↗

PubMed1989

Glossina morsitans morsitans: mortalities caused in adults by experimental infection with entomopathogenic fungi.

Various strains of the entomopathogenic fungi: Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus and P. farinosus were found to be pathogenic for adult tsetse, Glossina morsitans morsitans but B. bassiana and M. anisopliae were the most pathogenic, often causing mortalities of up to 100%. Dose-mortality relationships were demonstrated for both B. bassiana and M. anisopliae and male tsetse were observed to be more susceptible to infection than females. Pure cultures of B. bassiana and M. anisopliae were isolated from haemolymph and fat body of tsetse previously exposed to fungal spores and hyphal fragments were often observed floating freely in the haemolymph. No increase in abortions was observed in female pregnant tsetse infected with B. bassiana and M. anisopliae and pupae produced by the infected females showed no increase in pupal mortality. Furthermore, when larvae were heavily dusted with spores of B. bassiana and M. anisopliae prior to pupation and incubation, no increase was observed in pupal mortality suggesting lack of fungal infection.

Animals↗

PubMed2006

Pathogenicity of three formulations of entomopathogenic fungi for control of adult Haematobia irritans (Diptera: Muscidae).

Powder formulations of three species of entomopathogenic fungi were evaluated for their pathogenic effect upon adult horn flies, Hematobia irritans (L.) (Diptera: Muscidae). Flies were treated with conidia and blastospores of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill. (strain GHA), Metarhizium anisopliae (Metschnikoff) Sorokin (strain ESCI), and Paecilomyces fimosoroseus (Wize) Brown & Smith (strain ARSEF 3581) in the laboratory. At 4 d postexposure, flies treated with B. bassiana had an average of 98.4% mortality versus 43.5% from treatment with M. anisopliae and 13.0% from treatment with P. fiimosoroseus. At 7 d postexposure, flies treated with B. bassiana had an average of 100.0% mortality compared with 73.0% from treatment with M. anisopliae and 33.3% from treatment with P.fumosoroseus. Mean lethal time (LT50) was 2.70, 4.98, and 7.97 d for B. bassiana, M. anisopliae, and P. fiumosoroseus, respectively. Entomopathogenic fungi such as B. bassiana and M. anisopliae may have the potential for controlling populations of horn flies. These studies indicate that B. bassiana and M. anisopliae were not only pathogenic to adult horn flies, but they caused mortality in a short time.

Animals↗

PubMed1995

Entomopathogenic fungi associated with Ixodes ricinus ticks.

The objective of this study was to demonstrate the occurrence of entomopathogenic fungi on Ixodes ricinus ticks in relation to the tick stage, engorgement and season. Ticks were collected from the vegetation, from small rodents and from deer. All entomopathogenic fungi found belonged to the Hyphomycetes. Paecilomyces farinosus and Verticillium lecanii were the predominant species. Other species, found only on engorged females were: Beauveria bassiana, B. brongniartii, P. fumosoroseus and V. aranearum. Eight out of 1833 ticks collected from the vegetation and three out of 269 engorged nymphs were infected with fungi. Thirty-three out of 149 engorged females were infected, whereas males and engorged larvae were not infected. Throughout the season, a significantly higher proportion of ticks collected in autumn were infected. Entomopathogenic fungi may have a significant impact on the size of the I. ricinus population, since females were the most frequently infected stage.

Animals↗

PubMed2004

Diversity of entomopathogenic fungi near leaf-cutting ant nests in a neotropical forest, with particular reference to Metarhizium anisopliae var. anisopliae.

We investigated the prevalence of entomopathogenic fungi associated with leaf-cutting ant colonies in a small area of tropical forest in Panama. There was a high abundance of Metarhizium anisopliae var. anisopliae near the colonies. Beauveria bassiana was also detected in the soil, Aspergillus flavus in dump material, and six Camponotus atriceps ants were found infected with Cordyceps sp. Based on a partial sequence of the IGS region, almost all of the M. anisopliae var. anisopliae isolates fell within one of the three main clades of M. anisopliae var. anisopliae, but with there still being considerable diversity within this clade. The vast majority of leaf-cutting ants collected were not infected by any entomopathogenic fungi. While leaf-cutting ants at this site must, therefore, regularly come into contact with a diversity of entomopathogenic fungi, they do not appear to be normally infected by them.

Animals↗

PubMed2003

Study of temperature-growth interactions of entomopathogenic fungi with potential for control of Varroa destructor (Acari: Mesostigmata) using a nonlinear model of poikilotherm development.

AIMS: To investigate the thermal biology of entomopathogenic fungi being examined as potential microbial control agents of Varroa destructor, an ectoparasite of the European honey bee Apis mellifera. METHODS AND RESULTS: Colony extension rates were measured at three temperatures (20, 30 and 35 degrees C) for 41 isolates of entomopathogenic fungi. All of the isolates grew at 20 and 30 degrees C but only 11 isolates grew at 35 degrees C. Twenty-two isolates were then selected on the basis of appreciable growth at 30-35 degrees C (the temperature range found within honey bee colonies) and/or infectivity to V. destructor, and their colony extension rates were measured at 10 temperatures (12.5-35 degrees C). This data were then fitted to Schoolfield et al. [J Theor Biol (1981)88:719-731] re-formulation of the Sharpe and DeMichele [J Theor Biol (1977)64:649-670] model of poikilotherm development. Overall, this model accounted for 87.6-93.9% of the data variance. Eleven isolates exhibited growth above 35 degrees C. The optimum temperatures for extension rate ranged from 22.9 to 31.2 degrees C. Only three isolates exhibited temperature optima above 30 degrees C. The super-optimum temperatures (temperature above the optimum at which the colony extension rate was 10% of the maximum rate) ranged from 31.9 to 43.2 degrees C. CONCLUSIONS: The thermal requirements of the isolates examined against V. destructor are well matched to the temperatures in the broodless areas of honey bee colonies, and a proportion of isolates, should also be able to function within drone brood areas. SIGNIFICANCE AND IMPACT OF THE STUDY: Potential exists for the control of V. destructor with entomopathogenic fungi in honey bee colonies. The methods employed in this study could be utilized in the selection of isolates for microbial control prior to screening for infectivity and could help in predicting the activity of a fungal control agent of V. destructor under fluctuating temperature conditions.

Acari↗

PubMed2004

Pathogenicity of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae to Ixodidae tick species Dermacentor variabilis, Rhipicephalus sanguineus, and Ixodes scapularis.

Nymphal and adult ticks from three different tick species, Dermacentor variabilis Say, Ixodes scapularis Say, and Rhipicephalus sanguineus Latrielle, were treated with conidia and blastospores of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae Metschnikoff. Dose-response experiments indicated that a critical concentration of fungal spores is required for infection and mortality. Over a 28-d time course, fungal suspensions of either B. bassiana or M. anisopliae at 10(8) conidia/ml resulted in 50-70% mortality in adult I. scapularis and R. sanguineus, but <20% mortality in D. variabilis ticks. R. sanguineus nymphs were highly susceptible to both entomopathogenic fungi, displaying >60% mortality within 14 d postinfection and >90% mortality within 21-28 d postinfection. D. variabilis nymphs also were more susceptible than their corresponding adults, displaying mortalities ranging from 20 to 40% 28 d postinfection. I. scapularis nymphs, however, seemed to be slightly less susceptible than adults (45% mortality, 28 d postinfection). The addition of nutrients to fungal cell suspensions did not have any noticeable effects on mortality toward any of the tick species tested. Significant mortality against D. variabilis adults (approximately 65%) was noted only when B. bassiana fungal cells with growth media carryover were used as the inoculum against the ticks. Entomopathogenic fungi such as B. bassiana and M. anisopliae may have the potential for controlling populations of I. scapularis and R. sanguineus, and under certain conditions D. variabilis. Our results indicate that inoculum conditions can greatly affect successful virulence and subsequent mortality.

Animals↗

PubMed1995

Cuticle degrading proteases from insect moulting fluid and culture filtrates of entomopathogenic fungi.

Insects degrade their own cuticle during moulting, a process which is catalysed by a complex mixture of enzymes. Entomopathogenic fungi infect the insect host by penetration of the cuticle, utilizing enzymatic and/or physical mechanisms. Protein is a major component of insect cuticle and a major recyclable resource for the insect and, therefore, represents a significant barrier to the invading fungus. To this end, both insects and entomopathogenic fungi produce a variety of cuticle degrading proteases. The aim of this paper is to review these proteases and to highlight their similarities, with particular reference to the tobacco hornworm, Manduca sexta, and the entomopathogenic fungus, Metarhizium anisopliae.

Animals↗

PubMed2001

Pathogenicity of four strains of entomopathogenic fungi against the bovine tick Boophilus microplus.

OBJECTIVE: To evaluate the pathogenicity of 4 strains of the entomopathogenic fungi Metarhizium flavoviride var flavoviride and Metarhizium anisopliae var anisopliae in vitro against the bovine tick Boophilus microplus. SAMPLE POPULATION: 300 B. microplus females were used for each series of 5 conidial suspensions of the 4 fungal strains; a control group of 60 females was treated with sterilized water. PROCEDURE: For each fungal strain, sporulating cultures were used to produce conidial suspensions containing 10(4), 10(5), 10(6), 10(7), and 10(8) conidia/ml. A bioassay was performed by immersing B. microplus females in conidial suspensions; the procedure was repeated with a new group of 60 females for each dilution (a total of 300). A control group was immersed in the same volume of sterilized distilled water. Ticks were maintained at 27 C and 80% relative humidity for 7 days, and the following variables were evaluated: weight before egging, egging weight, percentage eclosion, reproductive efficiency, and percentage control. RESULTS: A low index of eclosion was found in the treated groups, with a progressive decrease in percentage eclosion (control = 100%) with increased conidial concentration. The highest level of effectiveness of biocontrol was detected in groups treated with concentrations of 10(7) and 10(8) conidia/ml. CONCLUSIONS AND CLINICAL RELEVANCE: Strains of the entomopathogenic fungi M. anisopliae var anisopliae and M. flavoviride var flavoviride were effective as biological control agents against B. microplus, with M. flavoviride strain CG-291 being the most effective. The pathogenicity of these strains and the development of an application method for this fungus for control of ticks may result in improved animal productivity and a reduction in environmental pollution through the use of fewer chemical insecticides.

Animals↗

PubMed2004

Entomopathogenic fungi from 'El Eden' Ecological Reserve, Quintana Roo, Mexico.

Entomopathogenic fungi were isolated and identified from insects collected from the tropical forest and an agricultural area at El Eden Ecological Reserve, Quintana Roo, Mexico. These fungi were studied to determine their potential as biological control agents of greenhouse Trialeurodes vaporariorum (Homoptera: Aleyrodidae), and to contribute to the knowledge of biodiversity of this area. No pest insects were observed in the tropical forest. In contrast, all insects collected in the agricultural area were considered important pests by the local farmers, with the whitefly, as the most relevant, plentiful in Cucurbitaceae plants. From approximately 3400 collected insects in three different surveys, different anamorphic Ascomycetes were recovered. One isolate of Aspergillus sp., two of Penicillium sp., three of Paecilomyces marquandii, and three of Verticillium sp. out of 308 insects (2.9%) from three insect orders, Hymenoptera, Diptera and Isoptera in the tropical forest. In contrast, a higher number of fungal isolates were recovered from the agricultural area: three isolates from Aspergillus parasiticus, 100 of Fusarium moniliforme, one of Aschersonia sp., and 246 of Fusarium oxysporum out of 3100 insects (11.3%) from three insect orders, Homoptera, Coleoptera and Lepidoptera. The results of this study show Fusarium moniliforme and F oxysporum as highly virulent to infected insects in the agricultural area, with 100 and 246 isolates respectively, out of 350 infected insects of 3100 studied specimens. Laboratory whitefly nymph bioassays with isolates Ed29a of F. moniliforme, Ed322 of F. oxysporum, and Ed22 of P marquandii showed 96 to 97.5% insect mortality with no significant differences (P < 0.05) among them. F. oxysporum Ed322 produced no mortality when inoculated on tomato, bean, squash and maize seedlings (with and without injuries) compared to the 100% mortality caused by phytopathogenic strains, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. radicis lycopersici.

Animals↗

PubMed1999

Preliminary survey for entomopathogenic fungi associated with Ixodes scapularis (Acari: Ixodidae) in southern New York and New England, USA.

Free-living larval, nymphal, and adult Ixodes scapularis Say were collected from scattered locales in southern New England and New York to determine infection rates with entomopathogenic fungi. Infection rates of larvae, nymphs, males, and females were 0% (571), 0% (272), 0% (57), and 4.3% (47), respectively. Two entomopathogenic fungi were isolated from field-collected I. scapularis females from Fire Island, NY. Isolates were identified as Verticillium lecanii (Zimmermann) Viegas and Verticillium sp. (a member of the Verticillium lecanii species complex).

Animals↗

PubMed2004

A proposed role for the cuticular fatty amides of Liposcelis bostrychophila (Psocoptera: Liposcelidae) in preventing adhesion of entomopathogenic fungi with dry-conidia.

Maximum challenge exposure of Liposcelis bostrychophila to Beauveria bassiana, Paecilomyces fumosoroseus, Aspergillus parasiticus or Metarhizium anisopliae resulted in no more than 16% mortality. We investigated several of L. bostrychophila's cuticular lipids for possible contributions to its tolerance for entomopathogenic fungi. Saturated C14 and C16 fatty acids did not reduce the germination rates of B. bassiana or M. anisopliae conidia. Saturated C6 to C12 fatty acids that have not been identified in L. bostrychophila cuticular extracts significantly reduced germination, but the reduction was mitigated by the presence of stearamide. Cis-6-hexadecenal did not affect germination rates. Mycelial growth of either fungal species did not occur in the presence of caprylic acid, was reduced by the presence of lauric acid, and was not significantly affected by palmitic acid. Liposcelis bostrychophila is the only insect for which fatty acid amides have been identified as cuticular components. Stearamide, its major fatty amide, did not reduce germination of B. bassiana or M. anisopliae conidia or growth of their mycelia. Adhesion of conidia to stearamide preparations did not differ significantly from adhesion to the cuticle of L. bostrychophila. Pretreatment of a beetle known to be fungus-susceptible, larval Oryzaephilus surinamensis, with stearamide significantly decreased adhesion of B. bassiana or M. anisopliae conidia to their cuticles. This evidence indicates that cuticular fatty amides may contribute to L. bostrychophila's tolerance for entomopathogenic fungi by decreasing hydrophobicity and static charge, thereby reducing conidial adhesion.

Amides↗

PubMed2003

Cytotoxicity against insect cells of entomopathogenic fungi of the genera Hypocrella (anamorph Aschersonia): possible agents for biological control.

Extracts from entomopathogenic fungi of the genus Hypocrella (7 species) and its anamorph Aschersonia (11 species) were screened for cytotoxicity to Sf9 and C6/36 insect cells and L929, BHK(21)C13 and HepG2 mammalian cells. Cytotoxic extracts to insect cells (ID50's < or = 10 microg ml(-1)) but not to mammalian cells (ID50's > or = 10 microg ml(-1)) conformed to the criteria of the project and were considered 'lead' extracts for further investigation. 'Leads' were found in two of the Hypocrella species: H. discoidea, and H. tamurai and in three of the Aschersonia species: A. samoensis, A. badia, and A. tamurai. Bioassay-guided fractionation of the cell extract of the fungus A. samoensis BCC 1393 led to the identification of two known anthraquinone dimers, (+)rugulosin (1) and skyrin (2) which showed selective toxicity towards insect cells. (+)Rugulosin (1) and skyrin (2) exhibited strong cytotoxic activity against the insect cell line Sf9 with respective ID50 values of 1.2 and 9.6 microg ml(-1), but showed weak activity toward mammalian cells. This first report of (+)rugulosin (1) and skyrin (2) in A. samoensis is confirmed and demonstrated in another four strains of A. samoensis isolated in Thailand. The preferential cytotoxicity against Sf9 insect cells gives evidence that these insect-pathogenic fungi of the Hypocrella/Aschersonia group might be useful as an agent for pest control.

Aedes↗

PubMed2002

The susceptibility of different species and stages of ticks to entomopathogenic fungi.

Boophilus annulatus, Hyalomma excavatum and Rhipicephalus sanguineus ticks were shown to be susceptible to different entomopathogenic fungi under laboratory conditions. Comparative results of bioassays using five different fungal species showed that some strains of Metarhizium anisopliae are highly pathogenic against various tick stages tested. In contrast to to their activity against insects, fungi also affected tick eggs. All tested tick stages including those feeding on a host were found to be susceptible to these fungi, except for adult H. excalatimn ticks, which were relatively resistant.

Animals↗