Article

Ecology of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae in temperate agroecosystems: Potential for conservation biological control

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Abstract

It is increasingly recognized that the biodiversity in agroecosystems deliver significant ecosystem services to agricultural production such as biological control of pests. Entomopathogenic fungi, specifically the anamorphic taxa Beauveria bassiana and Metarhizium anisopliae, Hypocreales (Ascomycota), are among the natural enemies of pests in agroecosystems and the fungi are candidates for future conservation biological control in temperate regions. Conservation biological control is a biological control strategy in which farming practices and environmental manipulations are adopted to enhance the living conditions for specific natural enemies of pests. However, in order to manipulate the environment for the benefit of populations of the entomopathogens, knowledge of fundamental aspects of the ecology of the fungi considered is necessary. This knowledge is still scarce despite the large bulk of recent research into inoculation and inundation biological control with these fungi. Here, we review the current knowledge of the ecology of indigenous populations of B. bassiana and M. anisopliae in agroecosystems of temperate regions, primarily Europe and North America. We suggest anamorphic life cycles of B. bassiana and M. anisopliae in these regions based on the literature of their natural occurrence and distribution in agroecosystems, population dynamics, and interactions with other organisms, environmental factors, and agronomical practices.

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... Members of the genus Metarhizium (Family: Clavicipitaceae, Order: Hypocreales), are natural enemies of insects and have been historically used as a biopesticide (Zimmermann, 1993, Zimmermann et al., 1995, Meyling and Eilenberg, 2007, Sasan, 2012. These insect pathogens have a broad host range including many species of Coleoptera, Hemiptera, Orthoptera etc. (Goettel et al., 1990, Veen, 1968, Zimmerman, 2007, Hauxwell et al., 2010. ...
... Results are also inconsistent globally: Metarhizium spp. were more frequently isolated from agricultural soils than from undisturbed or semi-disturbed habitats in Canada, Finland, the Netherlands and China , Vanninen, 1996, Steenberg, 1995, Meyling and Eilenberg, 2007. However, a study in Switzerland found that permanent grassland and field margins contained a higher density of Metarhizium species than either forest or cultivated arable land (Schneider et al. 2012). ...
... Among the entomopathogens, Metarhizium was more frequently recovered from agricultural soils than from forest or grassland habitats in Canada, Finland, the Netherlands and China , Vanninen 1996, Steenberg 1995, Meyling and Eilenberg, 2007. The persistence of Metarhizium in agricultural habitats was also observed by Hu and Leger (2002), Lingg andDonaldson (1989) andClerk (1969). ...
... Larvae of the greater wax moth, Galleria mellonella L. (Pyralidae: Lepidoptera) were used as bait for the nematodes and placed on top of the soil and the container closed with the lid. Distilled water was used to moisten the soil and to maintain humidity during the baiting process, this was done whenever the soil appeared to be a bit dry (Goble, 2009;Meyling & Eilenberg, 2007). The 2-L plastic containers were kept in a laboratory with controlled temperature of ±25°C and humidity >75% for 14 days (Meyling & Eilenberg, 2007). ...
... Distilled water was used to moisten the soil and to maintain humidity during the baiting process, this was done whenever the soil appeared to be a bit dry (Goble, 2009;Meyling & Eilenberg, 2007). The 2-L plastic containers were kept in a laboratory with controlled temperature of ±25°C and humidity >75% for 14 days (Meyling & Eilenberg, 2007). After between one to two weeks, the dead Galleria larvae that showed symptoms of EPN infection (change in colour, softness and being odour-free) were removed from the containers and rinsed with sterile water using tea sieve and a water bottle to remove organisms such as mites and scavenger nematodes from its surface (Du Preez et al., 2021;Van Zyl & Malan, 2015). ...
... In the present study, all the entomopathogens were isolated from the soil samples. Metarhizium robertsii and M. majus are known to cause virulence across a wide range of insects (Meyling & Eilenberg, 2007). The isolation of M. majus from potato soils indicates the presence of another potential species of EPF that can be tested as a biocontrol agent against L. huidobrensis. ...
Article
The potato leaf miner, Liriomyza huidobrensis (Diptera: Agromyzidae), is an important economic pest of potatoes across the world, causing substantial damage in most potato-growing areas. The use of local entomopathogens for the control of insect pests has been widely encouraged, coupled with several environmental advantages being contrasted to the effects achieved using chemical pesticides. The current study surveyed potato field soil to determine the presence of entomopathogenic nematode (EPN) and entomopathogenic fungi (EPF) species in the Sandveld region of the Western Cape province. Susceptibility of L. huidobrensis larvae and pupae to the isolated pathogens and other locally sourced isolates was evaluated. The results of the survey indicated the presence of an unknown free-living bacteria feeding insect-associated nematode species of the genus Acrobeloides, the EPN Heterorhabditis zealandica and two EPF species, Metarhizium robertsii and M. majus. All L. huidobrensis pupal (45–57%) and larval stages (52–72%) of the potato leaf miner showed susceptibility to the EPN species tested. Laboratory bioassays showed that the pupal and larval stages was the most susceptible (>72% infection) to Heterorhabditis baujardi. Liriomyza huidobrensis pupal stage showed high pathogenicity to isolates of M. robertsii (10C). Overall, all isolates of M. robertsii showed pupal pathogenicity ranging between 80% and 91%. Metarhizium robertsii outperformed Beauveria bassiana as a biocontrol agent against L. huidobrensis pupae in the laboratory. Results from this study indicate the potential of biologicals as future biocontrol agents in an integrated pest management system for potato production. KEYWORDS: Biological managementexplorationpotatopotato field soilSouth Africa
... An important base for IPM is biological control in which entomopathogenic fungi are a main tool (Inglis et al. 2001, Meyling andEilenberg 2007). For example, Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae (Metschnikoff) (Hypocreales: Clavicipitaceae), are two of the most studied fungi (Meyling and Eilenberg 2007). ...
... An important base for IPM is biological control in which entomopathogenic fungi are a main tool (Inglis et al. 2001, Meyling andEilenberg 2007). For example, Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae (Metschnikoff) (Hypocreales: Clavicipitaceae), are two of the most studied fungi (Meyling and Eilenberg 2007). Their mode of action (via cuticle) and easy in vitro reproduction encourage their popular use in pest management Pell 2003, Mascarin andJaronski 2016). ...
... Application of entomopathogenic fungi has been under the application paradigm for organosynthetic insecticides (Bateman andChapple 2001, Mora-Aguilera et al. 2017). However, microbial insecticides are living organisms that can be favored by surrounding environment (Inglis et al. 2001, Meyling andEilenberg 2007). ...
Article
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During 2016-2017, growers at San Juan de Los Planes, El Carrizal, and El Pescadero at Baja California Sur, Mexico experienced serious outbreaks of phytoplasma squash yellowing disease, causing significant economic loss, mostly from low yield and quality of squash, Cucurbita pepo L., for export. In addition, abundant beet leafhoppers, Circulifer tenellus (Baker), presumed to transmit the disease, were observed in each field. Using nested-polymerase chain reaction (PCR) amplification of the 16S rRNA gene and comparing in silico patterns, positive Western X-disease phytoplasma of the 16SrIII group was detected. Scanning electron microscopy showed phytoplasmatic particles in sieve tubes of infected plants and insects. Phytoplasma risk based on combined data of insect abundance, disease incidence, and economic threshold was analyzed to evaluate the impact of the disease over time. Only at Los Planes with 128 adult insects per trap and 75.5% incidence of disease was risk of phytoplasma high, while at El Carrizal and El Pescadero, risk was moderate. This is the first evidence of beet leafhoppers transmitting phytoplasma to squash at Baja California Sur. The information will be useful for managing disease in the region and where squash is grown worldwide.
... The nature of these symbioses can be dynamic and vary in ecological time, depending on the outcomes for host and symbiont (Aanen and Boomsma, 2005;Alizon et al., 2009). Different groups of filamentous fungi have diversified strategies of environmental exploitation (Balvanera et al., 2006;Meyling and Eilenberg, 2007;Vega et al., 2009). As a result, these strategies have driven the evolution of both partners in the symbiosis at individual, population, and community levels (Aanen and Boomsma, 2005;Samson et al., 2013;Brune, 2014;Kaltenpoth and Engl, 2014). ...
... Because of the different strategies employed to obtain nutrients, insects and fungi can share diverse habits, resulting in several ecological roles for both symbionts. This is evident for Metarhizium species (Ascomycota: Hypocreales), well known insect pathogens, and widely used in biological control (Meyling and Eilenberg, 2007;Samson et al., 2013). Several species of the genus use alternative nutritional modes by interacting with plant tissue and soil, as is the case with Metarhizium anisopliae (Meyling and Eilenberg, 2007;Vega et al., 2009;Behie and Bidochka, 2014;Chen and Zhuang, 2017;Dara, 2019). ...
... This is evident for Metarhizium species (Ascomycota: Hypocreales), well known insect pathogens, and widely used in biological control (Meyling and Eilenberg, 2007;Samson et al., 2013). Several species of the genus use alternative nutritional modes by interacting with plant tissue and soil, as is the case with Metarhizium anisopliae (Meyling and Eilenberg, 2007;Vega et al., 2009;Behie and Bidochka, 2014;Chen and Zhuang, 2017;Dara, 2019). Likewise, the hypocrealean fungal genus Trichoderma (Ascomycota: Hypocreales) is a group notable for displaying different strategies depending on their hosts (Harman et al., 2004;Samuels, 2006;Atanasova et al., 2013b). ...
Article
Symbioses between social insects and fungi can drive important processes in both. We show previously unrealised prevalence and diversity of Trichoderma species (Ascomycota: Hypocreales) in individuals of two termite species (Blattodea: Termitidae). Trichoderma is well known for producing cellulolytic and fungistatic compounds, which can be important to protect colonies against entomopathogenic fungi. We hypothesized that Trichoderma species have a positive effect on termite hosts, yet found an unexpected negative effect of Trichoderma harzianum on termite survival, the presence of Trichoderma species was not determinant for termite nutritional status. Although T. harzianum hindered growth of the entomopathogenic fungus Metarhizium anisopliae (Ascomycota: Hypocreales) in vitro, this was not registered for T. virens, suggesting they have different fungistatic roles. Despite the prevalence of Trichoderma species at the colony level being low in termites, we propose that T. harzianum has no specific ecological role that benefits higher termites and might even be a potential opportunistic parasite for termite colonies.
... Several methods to isolate EPFs from the soil have been used. The traditional insect bait method uses Galleria mellonella (Lepidoptera: Pyralidae) or Tenebrio molitor (Coleoptera, Tenebrionidae) as a host (Zimmermann 1986;Meyling and Eilenberg 2007;Sharma et al. 2018). Another method used to isolate EPFs is soil dilution and cultivation on selective media (Meyling and Eilenberg 2007) or methods of molecular biology (Canfora et al. 2016). ...
... The traditional insect bait method uses Galleria mellonella (Lepidoptera: Pyralidae) or Tenebrio molitor (Coleoptera, Tenebrionidae) as a host (Zimmermann 1986;Meyling and Eilenberg 2007;Sharma et al. 2018). Another method used to isolate EPFs is soil dilution and cultivation on selective media (Meyling and Eilenberg 2007) or methods of molecular biology (Canfora et al. 2016). ...
Article
Bulb crops are attacked by various soil-dwelling pests and pathogens. Entomopathogenic (EPFs) and mycoparasitic fungi (MPFs) which are distributed in natural and agricultural soils worldwide can play an important role as natural enemies of bulb pests. The species richness and density of these fungi in onion and garlic fields have not been investigated. The aim of this study was to determine the occurrence of EPFs and MPFs in soils where these crops were grown and compared the data from sites of the Czech Republic and Israel. Methods of fungi isolation and quantification were based on elution of soil samples by water and cultivation using selective media with dodine for EPFs and cultivation using potato dextrose agar with chloramphenicol for MPFs. Entomopathogenic fungi Beauveria spp., Isaria spp., Lecanicillium spp., Metarhizium spp., Purpureocillium spp. and mycoparasitic fungi Trichoderma spp. were isolated from soil samples in both countries. The highest density was observed in the genus Metarhizium in both countries. Metarhizium spp. were most abundant in the site Mlýn Podhora in the Czech Republic. The average density of colony-forming units (CFU) per 1 mL of soil sample was 1.47 × 10 4. The lowest density was observed in the genus Beauveria in both countries, up to 5.93 × 10 2 CFU per 1 mL of soil sample. Soils in the Czech Republic contained about ten times higher number of EPFs compared to Israel. Rather higher prevalence of MPFs was also found in the Czech Republic. Possible reasons for within and between countries variability in EPFs and MPFs occurrence are discussed.
... The fungi have long been recognized as biological pesticide (myco-insecticide) with advent of genetic profiling known to colonize roots of different species [4]. The fungal species are most frequently found as soil saprophytes in agricultural fields [5]. Earlier literature has suggested that the fungi form associations with plant roots in the rhizosphere zone [6] for better survival over extended periods of time [7] which alleviated in drought stress conditions [8]. ...
... The microbial biomass estimated less than 5 per cent of propagules of total culturable bacterial population in soil in terms of AM fungi, A. chroococcum, Pseudomonas and K-mobilizers were significantly higher in rhizosphere than non-rhizospheric zone. Among different treatment combinations, the respective plate count of A. chroococcum, Pseudomonas sp. and K-mobilizers also varied between the corresponding values of 13.0 × 10 6 -25.7 × 10 6 cfu g −1 , 9.3 × 10 5 -25.8 × 10 5 cfu g −1 and 9.7 × 10 4 -19.6 × 10 4 cfu g −1 in rhizosphere and 9.9 × 10 6 -10.8 × 10 6 cfu g −1 , 7.6 × 10 5 In rhizosphere zone, acid phosphatase (AcP) activity was significantly higher in T2 (163.2) followed by T1 (149.3), T3 (139.3) ...
Conference Paper
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Biological amendments namely, Pseudomonas florescence, Azotobacter chroococcum, K-mobi-lizers and AM fungi were expedited during air-layering operation on litchi (Litchi chinensis Sonn.). Twenty-five years healthy progeny of mother plants were maintained for air layering operation. The treatments comprised of the combinations namely, T1, litchi orchard soil + sand (1:1); T2, sand + AM fungi + Azotobacter chroococcum (1:2:1); T3, sand + Pseudomonas florecence + K-mobilizer (1:1:1); T4, AM fungi + K-mobilizers (1:1); T5, P. florescence + A. chroococcum + K-mobilizer (1:1:1); T6, sand + P. Florecence (1:2); T7, uninoculated control. Treatment T2 significantly improved survival rate, plant height, stem diameter, leaf number, leaf area and total leaf chlorophylls of the saplings. Microbial biomass of A. chroococcum Pseudomonas, K-mobilizers and AM fungi were tremendously increased. Soil enzymes activity in rhizosphere was increased which indicated better P nutrition. The study indicated that biological amendments inoculation can be a promising technology to improve survival rate to produce elite litchi planting material.
... Analysing the diversity of this group would therefore seem worthwhile for identifying potential Page 2 of 12 Velavan et al. Egypt J Biol Pest Control (2021) 31:131 native isolates for control of regional pests (Meyling and Eilenberg 2007). Metarhizium species like M. anisopliae, M. flavoviridae, M. acridum and M. robertsii are well-documented due to their wide occurrence (Bischoff et al. 2009). ...
... It is essential to analyse the genetic diversity of Metarhizium in ecological studies in order to resolve the status of several species and varieties in the Metarhizium lineage, especially of several cryptic species. Such studies are important for identifying location/region specific species/isolates for exploitation in biological control (Meyling and Eilenberg 2007). As in several of the studies cited above, all the gene partitions that were analysed support the delimitation of each Metarhizium species recognized herein. ...
Article
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Background Thirty-six entomopathogenic fungi (EPF) were isolated from soil and insect cadaver samples, collected from different forest types, viz., wet evergreen, moist deciduous, dry deciduous and scrub type in South India. Partial sequences of two parsimony informative genes ITS and RPB1 were determined under a phylogenetic approach for assessing the genetic diversity. Results Twenty-seven RPB1 gene sequences and 34 sequences of ITS1, 5.8S and ITS2 regions belonging to 36 EPF were analysed for identification and characterization. Four species of Metarhizium viz., M. anisopliae, M. roberstii, M. majus and M. guizhouense were differentiated. The isolates could be grouped into four main clades of 1–5. Most of the fungi appeared to be closely related to M. anisopliae. Based on the colony characters, colour, conidial size and shape, 27 isolates were morphologically identified as M. anisopliae . Seven strains were apparently related to M. robertsii , three isolates were similar to M. majus and the remaining one was identified as M. guizhouense . Morphological studies in congruence with phylogenetic analysis resolved the species diversity. Bioassay studies showed that M. quizhouense, M. majus and M. robertsii were effective against the banana stem weevil Odoiporus longicollis . Conclusions This is the first attempt to study the diversity and occurrence of Metarhizium species in forests of South India. Wet evergreen forest of Aralam in South India was rich in EPF diversity particularly for three species namely, M. quizhouense , M. robertsii and M. anisopliae .
... after application and the retrieval of the fungus in treated soils for several months showed that our preventive application method indeed enhanced the persistence of the fungus. The fungus may have benefited from stable soil conditions in the cover crop in contrast to high soil disturbance associated with potato cultivation, as is also seen in conservation tillage regimes (Meyling and Eilenberg, 2007). In general, habitats with little human intervention, like permanent grassland or field margins, often show higher Metarhizium densities than arable fields (Botelho et al., 2019;Schneider et al., 2012). ...
... Wireworm mortality can be obstructed by other factors contributing to resistance to mycosis. These limiting factors are often related to the characteristics of the specific fungal isolate (Maistrou et al., 2020;Meyling and Eilenberg, 2007). Of particular importance is host specificity. ...
Article
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Wireworms, the larvae of click beetles (Coleoptera: Elateridae), can cause substantial losses in marketable yield of potatoes, yet control options are limited. The entomopathogenic fungus Metarhizium brunneum (Ascomycota; Hypocreales) isolate ART2825 is highly virulent against two of the most detrimental wireworm species, Agriotes obscurus L. and A. lineatus L., but field application of this isolate during potato cultivation has never succeeded. In this study, we integrated the fungus into the agricultural crop rotation prior to potato cultivation, with the aim of better adapting the application strategy to the fungus' ecological and environmental requirements. Application preceded sowing of cover crops in late summer. We hypothesized that higher temperatures and undisturbed development for several months would support the establishment of the entomopathogen and enhance biocontrol efficiency in the following season. In two subsequent seasons, we quantified (1) fungal establishment in the soil, (2) efficiency of treated soils against wireworms in vitro, and (3) levels of wireworm damage in field potatoes. Spore concentration was enhanced in treated plots and we recovered the released Metarhizium isolate from all mycosed, field-collected wireworms. Treated soils increased wireworm mortality in the laboratory, but a statistically significant reduction of potato damage was only achieved in two out of ten field trials. The application strategy shows potential for fungal enhancement and opens new avenues for biological wireworm control.
... EPF have been studied for over hundred years without reaching their full potential as effective microbial control agents (Jaber & Ownley, 2018). This is because, their performance in the field depends significantly upon abiotic factors such as temperature, humidity, UV light and rainfall (De Castro et al., 2013;Kumar et al., 2017) and are influenced by biotic factors such as multi-trophic interactions with plants, arthropods and plant pathogens (Meyling & Eilenberg, 2007;Meyling & Hajek, 2009). However, given favourable ambient conditions they can act against a variety of arthropod pest and can ensure minimal risk for non-target organism including specialist parasitoids and generalist predators (Lacey et al., 2015;Ramos Aguila et al., 2021). ...
... According toMohandoss and Suryanarayanan (2009) andSchulz et al. (2015) EPF established as endophytes in planta must deal with more than one competitor (multipartite interactions among bacteria and fungi naturally occurring) endophyte, that secrete antifungal and antibacterial metabolites to restrain invaders as well host defence-related functions.Wang et al. (2015) stated that in-vitro co-culture bacteria secreted metabolites that inhibit fungal growth, these also might be the reason for the gradually decreased colonization rate sustenance of B. bassiana BB-16 in C. limon over time. As well, colonization rate sustenance might depend on the type of host species, type of tissues, strain and EPF species among biotic and abiotic factors(Brownbridge et al., 2012;De Castro et al., 2013;Meyling & Eilenberg, 2007;Meyling & Hajek, 2009;Vega, 2018). Moreover, when dealing with trees (different to herbaceous, annual plants), endophytes might face challenges during its establishment, because they have a larger biomass, longevity and complex anatomy, making more difficulty of reaching their vascular tissues by the EPF(Cazorla & Mercado-Blanco, 2016).Even thought, on the other hand, the persistence of endophytic B. bassiana BB-16 in C. limon leaves and stems within the 30-dpi significantly contribute in minimizing D. citri development and suppressing its progeny fitness as it can be appreciated in below discussed points because of the different variations in the values of the various population parameters measured. ...
Article
In response to mitigating the negative impacts of synthetic insecticides in controlling Diaphorina citri, the main vector of Huanglongbing, we assessed the effects of endophytically colonized Citrus limon seedlings by Beauveria bassiana BB‐16 on the population fitness of D. citri using the age‐stage two‐sex life‐table theory. The mean fecundity (F) and reproductive rate (R0) of the F1 generation of D. citri reared on endophytically colonized plants (F = 121.7; R0 = 30.43) were significantly lower than the endophyte‐free plants (F = 438; R0 = 197.1). In addition, the values of finite rate of increase (λ) and intrinsic rate of increase (r) on endophytically colonized plants (λ = 1.0927 day−1; r = 0.0887 day−1), were significantly lower than the endophytes free plants (λ = 1.1528 day−1; r = 0.1422 day−1). Moreover, the pre‐adult survival rate (sa) on endophytically colonized plants (sa = 37.5%) was significantly lower than the endophyte‐free plants (sa = 75%). Our results demonstrate that B. bassiana BB‐16 established as endophyte in C. limon under controlled conditions, reduced the population fitness of D. citri progeny and highlight the potential of integrating this entomopathogenic fungus as endophyte for sustainable management of D. citri and other citrus pests in citrus orchards.
... While these endpoints may be sufficient for chemical substances that degrade over time, they are not sufficient to evaluate the effects of biological agents. EPF propagate through infected hosts, build up their populations, and promote further secondary infections (Meyling and Eilenberg 2007). For example, it has been proposed that further persistence of M. brunneum in soil correlates with the occurrence of its host insect, Diabrotica virgifera virgifera (Pilz et al. 2011). ...
Article
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Purpose The successful implementation of a plant protection product depends on its effectiveness against a target species and its safety for the environment. Risk assessment schemes have therefore been devised to facilitate classification and regulation. These guidelines, however, are directed towards chemical substances and are in many cases less suitable for the assessment of products employing microorganisms. Methods In this study, we developed a protocol for non-target testing of soil-applied entomopathogenic fungi for the biocontrol of insect pests. Using the predatory mite Gaeolaelaps (Hypoaspis) aculeifer as a non-target model organism, our protocol evaluates the lethal and sublethal effects of the fungus in recommended and ten-fold field concentrations. Results The proposed protocol considers fungal biology when setting test duration, endpoints, and quality control measures. To assess its practicability, we performed a trial with Metarhizium brunneum ART2825 as a representative entomopathogenic fungus. The biocontrol agent was able to infect a susceptible host and reproduce, showing that potential hazards can be detected using our approach. No hazard was detected for the non-target species, with no statistically significant differences in 5-week survival and reproductive output between treated and untreated groups. Conclusion Based on our results, the protocol is deemed appropriate for the detection of non-target effects. Subject to further validation, our approach could thus provide the basis for standardized protocols for the evaluation of the environmental safety of biocontrol organisms.
... Our data suggest that M. brunneum BIPESCO 5 is more persistent when applied in Tyrol. Meyling and Eilenberg [46] summarized that Metarhizium is more common in exposed and regularly disturbed soil but cannot extensively proliferate. In addition, different tillage systems lead to very variable soil densities. ...
Article
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Inundative mass application of Metarhizium brunneum BIPESCO 5 (Hypocreales, Clavicipitaceae) is used for the biological control of Diabrotica v. virgifera (Coleoptera, Chrysomelidae). Long-term field trials were performed in three Austrian maize fields—with different cultivation techniques and infestation rates—in order to evaluate the efficacy of the treatment to control the pest larvae. In addition, the indigenous Metarhizium spp. population structure was assessed to compare the different field sites with BIPESCO 5 mass application. Annual application of the product Granmet-PTM (Metarhizium colonized barley kernels) significantly increased the density of Metarhizium spp. in the treated soil above the upper natural background level of 1000 colony forming units per gram dry weight soil. Although a decrease in the pest population over time was not achieved in heavily infested areas, less damage occurred in treated field sites in comparison to control sites. The Metarhizium population structure was significantly different between the treated field sites. Results showed that inundative mass application should be repeated regularly to achieve good persistence of the biological control agent, and indicated that despite intensive applications, indigenous populations of Metarhizium spp. can coexist in these habitats. To date, crop rotation remains the method of choice for pest reduction in Europe, however continuous and preventive application of M. brunneum may also present an alternative for the successful biological control of Diabrotica.
... Beauveria bassiana is becoming increasingly popular to protect crop yields from losses due to pest infestation. B. bassiana is a well-known entomopathogenic fungus that can parasitize more than 700 different kinds of insects [7]. Isolates of B. bassiana can antagonize a variety of soil and foliar plants pathogens [8] while they are in symbiosis with many plant species. ...
Article
Aims: To study the response of groundnut (Arachis hypogaea L.) to vermicompost enriched with biofertilizers, bioagents and micronutrients. Study Design: Field experiment was conducted at Junagadh (Gujarat) with ten treatments comprising of vermicompost enriched with biofertilizers, bioagents and micronutrients viz., Absolute Control (T1), 100% Recommended dose of fertilizers (T2), Vermicompost 2 t/ha (T3), Vermicompost 2 t/ha + Biofertilizers (Rhizobium Bradyrhizobium japonicum + Phosphate Solubilizing Bacteria Bacillus subtilis + Potash Solubilizing Bacteria Frateuria aurantia each at 2 L/ha) (T4), Vermicompost 2 t/ha + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha (T5), Vermicompost 2 t/ha + Beauveria bassiana 3 kg/ha (T6), Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha (T7), Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T8), Vermicompost 2 t/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T9) and Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha (T10) in Randomized Block Design with three replications. Place and Duration of the Study: Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh (Gujarat) during kharif seasons of 2019 and 2020. Methodology: Five plants were selected randomly from each net experimental plot and tagged. Growth parameters viz., plant height, number of branches, SPAD meter reading and number of root nodules, and yield attributes viz., number of mature pods per plant and pods weight per plant were recorded from that tagged plants and their average was considered for final record. Pod yield and haulm yield were recorded from net plot size of each experiment plot and converted in to hectare base. Shelling percentage was counted on the basis of 150 g pod sample taken randomly from net plot produce. Results: The results indicated that the highest plant height (35.64 cm), number of branches per plant (8.11), number of root nodules per plant (154.5) at 45 days after sowing (DAS), dry weight of root nodules per plant at 45 DAS (0.982 g), Soil Plant Analysis Development (SPAD) meter reading at 45 DAS (39.09), number of mature pods per plant (18.40), pod weight per plant (15.37 g), 100-kernel weight (44.08 g) and shelling percentage (73.16%) with the highest pod yield (2.305 t/ha) and haulm yield (3.889 t/ha) were achieved by application of Vermicompost 2 t/ha + Biofertilizers (Rhizobium + Phosphate Solubilizing Bacteria + Potash Solubilizing Bacteria each 2 L/ha) + Trichoderma harzianum 3 kg/ha + Pseudomonas fluorescens 3 L/ha + Beauveria bassiana 3 kg/ha + Micronutrients (Fe + Zn + Cu + Mn) Grade-V at 40 kg/ha, which is considered the more effective application among all treatments improves growth, pod and haulm yield of groundnut under clay soil conditions.
... Entomopathogenic fungi have potential to adapt to different environmental and climatic conditions 14 and present low toxicity to vertebrates. 15 The endophytic relationship between entomopathogenic fungi and oil palms is an alternative to pest control decreasing the dependence of chemical insecticides. ...
Article
BACKGROUND The potential of Beauveria bassiana and Metarhizium anisopliae isolates obtained from naturally infected oil palm pests was evaluated to control Demotispa neivai as an alternative for organophosphate insecticide use in oil palm crops in Latin America. Two B. bassiana (Bb-0018 and Bb-0025) and two M. anisopliae (Ma-0002 and Ma-0003) isolates were tested against D. neivai adults for hydrophobicity, virulence, survival, adhesion to host cuticle, and mortality in semi-field conditions. RESULTS Concentration–mortality bioassays demonstrate that isolates had lethal effect on D. neivai adults with Bb-0025 (LC50 = 3.45 × 10⁷ conidia mL–1) and Bb-0018 (LC50 = 3.75 × 10⁷ conidia mL–1) being the most effective followed by Ma-0003 (LC50 = 3.38 × 10⁸ conidia mL–1) and Ma-0002 (5.33 × 10⁸ conidia mL–1). Adult survival was 99% without exposure to fungal isolates, decreasing to 21.65% in insects exposed to Ma-0002, 19.41% with Ma-0003, 20.13% with Bb-0018, and 0.17% with Bb-0025. Mortality of D. neivai adults caused by the entomopathogenic fungal isolates was similar in both laboratory and semi-field conditions. Also, vegetative growth of the entomopathogenic fungal isolates was found in infected D. neivai adults in the field. CONCLUSION Our data suggest that the tested entomopathogenic fungal isolates are effective against D. neivai with potential to be used as biological control agents contributing to decrease the use of chemical insecticides to control this oil palm pest. This article is protected by copyright. All rights reserved.
... Historically, with only asexual stages known, they were classed within the Deuteromycetes, the Fungi Imperfecti. However, as molecular tools have allowed their association with known sexual stages, they have been reclassified, with Beauveria species placed within the genus Cordyceps and Metarhizium species in Metacordyceps (Meyling and Eilenberg 2007), but their original nomenclature was retained. In general, fungi get their nutrition from the products from which they imbibe following the release of degradative enzymes into their environment (Chandler 2017). ...
Article
Bubonic plague is a lethal bacterial disease of great historical importance. The plague organism, Yersinia pestis, is primarily transmitted by fleas (Siphonaptera). In natural settings, where its range expands, Y. pestis resides in association with wild rodents and their fleas (sylvatic plague). While chemical insecticides are used against plague vector fleas, biological approaches have not been as critically evaluated. Benign and cost-effective control methods are sorely needed, particularly where imperiled species are at risk. Here we explore the potential of two representative insect pathogenic fungi, Beauveria bassiana Vuillemin 1912 (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae Metschnikoff 1879 (Hypocreales: Clavicipitaceae), each already used commercially worldwide in large-scale agricultural applications, as candidate biopesticides for application against fleas. We review the life cycles, flea virulence, commercial production, and field application of these fungi, and ecological and safety considerations. Pathogenic fungi infections among natural flea populations suggest that conditions within at least some rodent burrows are favorable, and laboratory studies demonstrate lethality of these fungi to at least some representative flea species. Continued study and advancements with these fungi, under appropriate safety measures, may allow for effective biocontrol of plague vector fleas to protect imperiled species, decrease plague outbreaks in key rodent species, and limit plague in humans.
... EPF species are mostly isolated from the soil, which protects them from the damaging solar radiation (Meyling and Eilenberg 2007). It has been noted that certain species of Beauveria and Metarhizium can infect and kill insects in soil and also EPF interact with roots of plant for their growth and survival which predominately relies on insects for carbon and not on soil (Inglis et al. 2001). ...
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Background: Apprehensions about the safety and the environment regarding the insecticidal application against insect infestations have directed our attention toward advancement of biological mediators so that they are assimilated into the concept of integrated pest management stratagems to develop a more practical approach for the management of insect pests. Management of insect pests by making use of biological approaches (such as fungal entomopathogens (EPF) or others which are antagonistic to insect population) provides a substitute approach which reduces the continuous use of chemical amalgams against insect pests. Main body: The present review provides a framework of the present status of information on EPF as it identifies with their current use as biological control of pest infestations. To utilize a variety of biological control methodologies against insect hosts, it is essential to improve our comprehension of the ecology of EPF and also their role in nature. This article may assist us with understanding the virulence and the virulence factors related with EPF and present the latest developments and accomplishments in the significant field. We focus on recent instances of studies that show the overall patterns in interactions among insect pests and EPF prompting the advancement of epizootics. Also, we sum up the topical discoveries on current status of mycoinsecticides and propose future research needs. Conclusions: As the current mechanism of fungal pathogenesis on insects is moderately slow and needs improvement, there is likewise the requirement for additional comprehension of the interactions among entomopathogens and insect pests so as to grow soundly planned procedures by identifying potential targets and via the improvement of fungal strains for improving the adequacy of these organisms in field applications.
... They are gaining acceptance in Integrated Pest Management (IPM) systems, where they can serve as effective and environmental safety biological control agents of a great variety of crop pests (Zimmermann, 2007;Lacey and Shapiro-Ilan, 2008;Lacey et al., 2015;Quesada-Moraga, 2020). Besides their main habitats, soil and insect cadavers, they have recently been found to establish interesting plant associations (Meyling and Eilenberg, 2007;Vega et al., 2009;Quesada-Moraga, 2020). They can be found in the phylloplane, rhizosphere and as endophytes (Meyling and Eilenberg, 2006;Vega et al., 2008;Hu and Bidochka, 2019;Quesada-Moraga, 2020). ...
Article
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Entomopathogenic fungi are gaining acceptance in Integrated Pest Management (IPM) systems as effective and environmental safety biological control agents to protect a great variety of crops against pest insects. Many of these insect-pathogenic fungi can establish themselves as endophytes and thereby may induce the plant immune system. The activation of plant defenses by the fungal endophytic colonization can have a direct impact on herbivores and plant pathogens. An integral component of many plant defense responses is also the release of volatile organic compounds, which may serve as an indirect defense by attracting the natural enemies of herbivores. Here we investigated the effect of endophytic colonization by the entomopathogenic fungus Beauveria bassiana on the volatile emission by melon and cotton plants, either unharmed or after being damaged by sap-sucking aphids or leaf chewing caterpillars. We found that when the plants are colonized by B. bassiana they emit a different blend of volatile compounds compared to uncolonized control plants. Some of the emitted compounds have been reported previously to be released in response to herbivory and have been implicated in natural enemy attraction. Several of the compounds are also known to have antimicrobial properties. Therefore, endophytic colonization by B. bassiana might help to not only direct control insect pests but also increase the resistance of plants against agronomically important pests and phytopathogens.
... It is estimated that arthropod pests cause about 35% of crop loss in agriculture directly or by transmitting phytopathogens (van der Goes van Naters and Carlson 2006) and the use of biologicalbased control strategies have gained increasing interest to mitigate environmental impact. Entomopathogenic fungi (EPF) in the order Hypocreales (Ascomycota), particularly the genera Beauveria (Cordycipitaceae) and Metarhizium (Clavicipitaceae) are widely distributed taxa with potential as biological control agents for pest management (Castro et al. 2018;Meyling and Eilenberg 2007). However, despite showing pathogenic potential against several arthropod pests, these fungi have some caveats due to sensitivity to various biotic and abiotic factors (Lacey et al. 2015; Hajek 2010) that enforces a need for innovation in application methods to ensure their reliability and efficiency. ...
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Entomopathogenic fungi (EPF) can be experimentally established in several plant species as endophytes. Ecological effects of EPF inoculations on plant growth and plant-herbivore interactions have been demonstrated, potentially by altering plant physiological responses. However, the role of these responses in plant-fungus-herbivore tripartite interactions has not been well elucidated. Steroidal glycoalkaloids (SGAs) are plant specialized metabolites with bioactive properties against arthropod herbivores. Here, the effects of seed treatments by three EPF isolates, representing Beauveria bassiana, Metarhizium brunneum, and M. robertsii, on population growth of two-spotted spider mites (Tetranychus urticae Koch) were evaluated on tomato (Solanum lycopersicum). The levels of two SGAs, α-tomatine and dehydrotomatine, were determined in tomato leaves by LC-MS with and without T. urticae infestations after EPF inoculations. Interestingly, the population growth of T. urticae was significantly highest with M. brunneum and lowest with M. robertsii and B. bassiana at 15 days after infestation. Overall there was a significant negative correlation between SGAs content and the number of T. urticae. The levels of SGAs were significantly induced by T. urticae presence in all treatments, while only M. robertsii showed significantly higher levels of SGAs than M. brunneum and control in one of two experiments. Contrastingly, the effects on SGAs accumulation and population growth of T. urticae did not directly correlate with EPF endophytic colonization patterns of the inoculated plants. This study suggests a link between ecological effects and physiological responses mediated by EPF inoculations and T. urticae infestation with potential implications for plant protection.
... The main pathway by which B. bassiana infects insects is integument infection. The fungal spores must adhere to the cuticle of the insects, germinate, and produce germ tubes and hyphae; then, they penetrate into the insect integument and infect 3,34 . In this study, by using SEM, it was observed that the spores of B. bassiana may adhere to the epidermis of E. fetida and are often attached at the intersegmental furrows, annulus on the segments, and grid-like structures between the annuli and around the stomata. ...
Article
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Beauveria bassiana is one of the most widely studied and used entomopathogenic fungus as biopesticide. In the biological control of pests, B. bassiana will persist in the soil after application, and will inevitably contact with earthworms, especially the epigeic earthworm species. So, what are the effects of earthworm and its epidermal mucus on the activity of B. bassiana? We employed the epigeic earthworm Eisenia fetida, B. bassiana TST05 strain, and the insect Atrijuglans hetaohei mature larvae to study the impact of earthworm epidermal mucus on the vitality and pathogenicity of B. bassiana to insect. Methods included scanning electron microscope observation, detection of spore germination, fungal extracellular enzyme activity, and infection testing to A. hetaohei. The results showed that the B. bassiana spores may attach to the cuticle of E. fetida but they could be covered by the epidermal mucus and became rough and shrunken. After treatment with the epidermal mucus, the spore germination and extracellular enzymes of B. bassiana was significantly inhibited. Inoculation of A. hetaohei larvae with a mixture of B. bassiana and mucus showed that the mucus could reduce the pathogenicity of B. bassiana to the insect, resulting in a slower disease course and lower mortality. It was concluded that the epidermal mucus of the earthworm E. fetida can inhibit the activity of B. bassiana, as well as the infectivity and pathogenicity of fungus to target insects. However, after treatment with epidermal mucus the surviving B. bassiana still had certain infectivity to insects. This is of great significance for the application of B. bassiana in biological control of pests.
... These entomopathogenic fungi have a worldwide distribution and have been extensively studied due to their virulence, broad host range, ease of mass production, and relative safety to the environment (Aw and Hue 2017). Metarhizium anisopliae s.l. has been isolated from soils of tropical and temperature regions across the globe in addition to numerous different arthropod hosts(Meyling and Eilenberg 2007;). Over 200 insect species from more than seven orders (including the Blattaria, Orthoptera, Coleoptera, Hemiptera, Diptera, Hymenoptera and Lepidoptera) as well as some groups in the Arachnida are known to be infected by M. anisopliae s.l.(Chandler et al. 2000;Webster and Weber 2007; Zimmerman 2007; Aw and Hue 2017). ...
Thesis
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This thesis is about the discovery of Metarhizium isolates from lone star ticks (Amblyomma americanum) in northwest Arkansas and the evaluation of these isolates' pathogenicity to lone star ticks in a lab assays.
... Soil inhabiting EPF plays a major role in managing many soilassociated insect populations and pervasive element of many terrestrial ecosystems (Quesada Moraga et al., 2007;Meyling and Eilenberg, 2007). The same fungal isolates perform the role as a potential biocontrol agent under cultivated agro-systems (Meyling and Eilenberg, 2006). ...
Article
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Ecological consideration is of key importance in finding fungi and other entomopathogens for managing insect pests. The probability of finding entomopathogenic fungi is increased by knowing the soil characteristics supporting fungal survival and diversity. Many opportunistic fungi are closely associated with EPF in soil. Diversity and occurrence of fungi were carried out from soil samples (145) and dead insects (225) collected from natural and cultivated areas of south Punjab. The relative research for the presence and abundance of EPF in samples of soils collected from cultivated to non-cultivated hilly lands show that fruit orchid can be considered as a richer in these fungal species. The EPF was mainly isolated from the collected (225) insect cadavers belonging to six insect orders out of which only 94 were positive for any category of fungus isolated. Insects from Coleoptera were reported with maximum occurrence (44.68%) for harboring any kind of the fungus followed by Lepidoptera (36.17%). Aspergillus niger (27.50%) was the most occurring taxa among all isolates, while Fusarium oxysporium was dominantly occurring specie (17.02%). It can be concluded that orchard soils that are least disturbed (tillage, weeding, etc) and supplied with ample moisture should be preferred for sampling in order to isolate the entomopathogens. Furthermore, insect cadavers from coleoptera and lepidoptera should be preferred for collection for the sake of entomopathogenic fungi.
... Similar to the distribution features of diverse insect species, fungal parasites are largely cosmopolitan and sympatrically distributed in different ecosystems [3]. For example, it has been reported that the propagules of the ascomycete Metarhizium and Beauveria species could reach up to 10 6 CFUs (colony forming units) per gram of soil [4][5][6]. It is therefore conceivable that the multiple species or strain spores of fungal parasites can land on individual insect hosts to theoretically trigger co-infections. ...
Article
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Fungal entomopathogens are largely facultative parasites and play an important role in controlling the density of insect populations in nature. A few species of these fungi have been used for biocontrol of insect pests. The pattern of the entomopathogen competition for insect individuals is still elusive. Here, we report the empirical competition for hosts or niches between the inter- and intra-species of the entomopathogens Metarhizium robertsii and Beauveria bassiana. It was found that the synergistic effect of coinfection on virulence increase was not evident, and the insects were largely killed and mycosed by M. robertsii independent of its initial co-inoculation dosage and infection order. For example, >90% dead insects were mycosed by M. robertsii even after immersion in a spore suspension with a mixture ratio of 9:1 for B. bassiana versus M. robertsii. The results thus support the pattern of competitive exclusion between insect pathogenic fungi that occurred from outside to inside the insect hosts. Even being inferior to compete for insects, B. bassiana could outcompete M. robertsii during co-culturing in liquid medium. It was also found that the one-sided mycosis of insects occurred during coinfection with different genotypic strains of either fungi. However, parasexual recombination was evident to take place between the compatible strains after coinfection. The data of this study can help explain the phenomena of the exclusive mycosis of insect individuals, but co-occurrence of entomopathogens in the fields, and suggest that the synergistic effect is questionable regarding the mixed use of fungal parasites for insect pest control.
... For example, herbivorous insects are often regulated by predators (Vidal and Murphy, 2018) or parasitoids (Anderson et al., 2019). Such knowledge is also widely utilized in biological control of insect pests in agriculture (Meyling and Eilenberg, 2007). However, the diversity, commonness and distribution of natural enemies of plant diseases and whether these natural enemies have the potential to reduce disease levels is less known both for natural and agricultural systems. ...
Article
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While top‐down control plays an important role in shaping both natural and agricultural food webs, we lack insights into how top‐down control effects vary across spatial scales. We used a multi‐scale survey of top‐down control of coffee pests and diseases by arboreal ants to examine if colony location creates a small‐scale mosaic in top‐down control around trees and if the strength of that control varies between sites at the landscape scale. We investigated pest and disease levels on coffee shrubs at different distances from shade trees with and without a Crematogaster spp. ant colony in 59 sites along a coffee management intensity gradient in southwestern Ethiopia. Within sites, ants significantly suppressed herbivory and coffee leaf rust at distances less than 10 meters from nesting trees. Top‐down control varied between sites, with stronger top‐down control of free‐feeding herbivory near ant colonies at sites with lower management intensity and stronger top‐down control of a skeletonizer at sites with higher canopy cover. We conclude that the strength of top‐down control by ants is highly heterogeneous across spatial scales, as a consequence of the biology of the predator at the small scale and herbivore density or changes in herbivore‐ant interactions at the landscape scale.
... Both species require arthropod hosts to develop the mitosporic conidia; they quiesce in conidial stage in the soil prior to infecting a host. Insects are considered to be the most important sources of organic matter for both species (Meyling and Eilenberg, 2007). Pathogenic features of these entomopathogens are very complex and various. ...
Article
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The insecticidal efficacy of the experimental bioinoculants (Natur Nova, Natur Agro Hungary Ltd., Hungary) containing Beauveria bassiana (Bals.-Criv). Vuill. and Metarhizium anisopliae Metschnikoff against stored product pests modelled by granary weevil, Sitophilus granarius L. was evaluated on wheat in laboratory tests. In order to comparability, two applications were also set up: one purely ash-treated grain treatment against wireworms and a soil-injected one. Our results confirmed that some biopesticides can exert unexpected effect on non-target arthropods. However, the examined biopesticides were as empirically effected against the target arthropods regarding wireworms. Nevertheless, the application exempt from ash of the examined bioinoculants Natur Nova containing B. bassiana and M. anisopliae were not suitable for the elimination of the stored product pests modelled by S. granarius. In contrast, the putative plant protection effect of these biopesticides was observed in the course of applying the agents in the recommended environment and pest species as well as when applying them with ash carrier.
... Acaropathogenic (APFs) and entomopathogenic fungi (EPFs) are common in nature, have a cosmopolitan distribution and cause natural epizootics in populations of insects, mites or other arthropods [55,56]. Fungal pathogens are a permanent component of mite natural habitats [57]. ...
Article
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Mites of the genus Rhizoglyphus (Acari: Acaridae) are serious pests of plants belonging to the orders Liliales and Asparagales such as onions, garlic, lilies, and tulips. Their control by synthetic pesticides is becoming problematic as a result of resistance development in these mites and environmental and health issues. New pest control methods thus need to be developed. This review provides an overview of studies related to bulb mite management. Entomopathogenic fungi and generalist predatory mites are prospective agents for biological control of these pests while entomopathogenic nematodes and the metabolites of their symbiotic bacteria seems to be less effective. There are, however, many more organisms in the soil that might play important roles in biological control of bulb mites as well as other soil pests of these bulbous plants. Therefore, a holistic approach based on the understanding of food webs in the soil environment and their ecological services is essential for developing effective control of bulb mites. For the rehabilitation and conservation of soil biodiversity supporting these ecosystem services, emphasis must be placed on sustainable soil management (e.g., ensuring green coverage, minimal soil disturbance and high content of organic matter).
... The genus Beauveria contains cosmopolitan entomopathogenic fungi that are found in a variety of different insect hosts and are widely used as biological control agents for the protection of crops, with the best known species of the genus being the Beauveria bassiana [1][2][3]. Apart from its entomopathogenic role, B. bassiana is also known to produce a multitude of natural products and active metabolites, with protective properties against inflammation related disorders, such as asthma [4,5]. ...
Article
In the present work the entomopathogenic fungus B. bassiana lipids were studied against the potent pro-inflammatory and thrombotic mediators implicated in several disorders, platelet-activating factor (PAF) and thrombin. Bioactivities of lipid extracts from B. bassiana cells and culture supernatants and of their lipid fractions separated by a one-step HPLC-analysis ere assessed against the PAF/Thrombin-induced aggregation of washed rabbit platelets. Lipid extracts from both cell-biomass and supernatant inhibited strongly PAF/Thrombin-activities and platelet-aggregation, exhibiting higher specificity against PAF. Similarly, HPLC-derived lipid-fractions of phenolics/glycolipids, Sphingomyelins and Phosphatidylcholines (PC) showed strong anti-PAF potency. PC PAF-like molecules exhibited the strongest antagonistic anti-PAF effects, while in higher amounts they agonistically inhibited PAF-activities. Some bioactive lipids with strong anti-PAF effects are exo-cellularly secreted in the culture media during fungal growth, while others are not. The presence of such lipid bioactives in B. bassiana with strong anti-inflammatory and anti-thrombotic properties, provide new perspectives and putative future applications for this entomopathogenic fungus.
... These rare species show some aspect of morphology, ecology or specialised behaviour. 52, 53 Mohammed et al. 54 demonstrated that the Rashad ant fauna is characterised by a large proportion of rare ants (45% of the species occur in less than 5% of the samples), compared to the Australian savannah (where 27% of the species are rare). This makes the advance of agrosystems over native areas even more worrying, because rare species are the most vulnerable to extinction due to their low density and limited ability to persist in disturbed environments. ...
Article
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The ecological consequences of biodiversity loss are usually the reduction of ecosystem functions. These responses, however, differ depending on the type of land-use change and the ecological setting. We investigated the impact of land-use type and ecosystem functions on the ant assemblage of Rashad District, Sudan. We analysed the effects of three different land uses (soy monoculture, pasture and organic production of vegetables) on the ant community by assessing ant composition in 176 different locations. The collection sites were conventional soy monoculture, pastures, organic agriculture, and native vegetation such as Campo, Kubos, and forests. We recorded 264 ant species on the soil surface of the Rashad District, where 342 to 354 species were thought to exist. Pastures and organic agriculture areas have 61% and 56% of the native myrmecofauna, respectively, while conventional soy monoculture areas are home to only 17% of native ant species. Forest areas present a unique community, and soy monoculture areas have the strongest pattern of biotic homogenisation. We also detected that rare species (of low frequency) were the chief promoters of richness in the Rashad District, and the most threatened with local extinction, due to their low density and low occurrence in agrosystems. Overall, we found that agricultural expansion reduces ant diversity, particularly in soybean crops, and can affect ecosystem functions. To mitigate the reduction in the ant assemblage, we recommend the conservation of multiple natural habitats.
... Metarhizium species have been widely studied and used as a sustainable mycoinsecticide for the biological control of a wide range of insect pests (Meyling and Eilenberg, 2007;Zimmermann, 2007). It has been reported that some Metarhizium species not only participate in the control of insect pests, but they are also capable of colonizing the plant rhizosphere (Wyrebek et al., 2011;Sasan and Bidochka, 2012;Bamisile et al., 2018;Vega, 2018;Nishi and Sato, 2019). ...
Article
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Species of the entomopathogenic fungi Metarhizium are used worldwide as biocontrol agents. Recently, other lifestyles have been associated with some Metarhizium species, which include their role as saprophytes, endophytes, and plant growth promoters. Herein, the effect of three Metarhizium anisopliae strains on the growth of Arabidopsis thaliana plantlets was evaluated using an in vitro split system. Arabidopsis fresh weight and total chlorophyll content significantly increased 7 days post-inoculation with the three Metarhizium anisopliae strains evaluated. The primary root length was promoted by all fungal strains without physical contact, whereas in direct contact primary root growth was inhibited. Volatile organic compounds identification revealed that during the interaction of Arabidopsis with Ma-20 and Ma-25 strains only β-caryophyllene was produced, whereas in the Arabidopsis-Ma-28 interaction o-cymene was mainly emitted. The plant growth promoting effect induced by Metarhizium anisopliae strains was also achieved in Arabidopsis, tomato and maize plants grown in soil pots. Our results showed that three Metarhizium anisopliae strains were able to increase plant fresh weight, opening promising perspectives for field production, with the advantages of insect biocontrol and plant growth promotion induced by this species of fungus.
... M. persicae and S. frugiperda are naturally infected by many species of EPF, some of which are very effective biocontrol agents (Firake and Behere 2020). The occurrence of such EPF naturally in an environment or agro-ecosystem indicates their potential role as biotic factors regulating insect pest populations in the field (Meyling and Eilenberg 2007). ...
Article
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Different biogeographic strains and isolates of entomopathogenic fungi vary in their genetic, enzy-matic and pathogenic characteristics, this study assessed the virulence of 2 indigenous strains of Beauveria bassiana(Balsam) Vuillemin and Metarhizium anisopliae (Metschn.) Sorokin (Ascomycota, Hypocreales: Clavicipitaceae), isolated from naturally infected insect cadavers, against the 3rd instar nymphs of Myzus persicae (Sulzer) (Hemiptera: Aphidi-dae) and 3rd instar larvae of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) using leaf-dip and larval-dip methods, respectively.
... Entomopathogenic fungi are components of terrestrial ecosystems involved in the dynamics of arthropod populations in natural and agricultural ecosystems [12]. About 1000 fungal species have the ability to penetrate invertebrate exoskeleton and trigger immune response [13]. ...
Article
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Infectious keratitis and sclerokeratitis caused by filamentous fungi prevail in agricultural regions with tropical and subtropical climates and are related mostly to mild abrasive corneal trauma especially after vegetable matter related injury. Biotechnological advances have introduced biological control agents in agriculture such as fungal-based biocontrol agents that use Beauveria and Metarhizium species as bioinsecticides. Keratitis and sclerokeratitis are the most frequent pathologies associated to Beauveria and Metarhizium infection that are the main entomopathogenic fungi used in biological control, although other clinical cases such as sinus, skin lesions, and disseminated infections have been reported. Search of publications was carried out using the databases: Scopus, Pubmed, ScienceDirect, MedLine Scielo. A total of 30 articles were retrieved from 1984 – 2021. From these, 17 keratitis and one sclerokeratitis clinical cases were related to Beauveria infection, while Metarhizium was linked to 13 keratitis cases and two sclerokeratitis clinical cases. Female sex predominated in both Metarhizium and Beauveria clinical cases, there was no significant difference in sclerokeratitis / keratitis by sex. Contact lenses use was a factor reported in 66.6% cases of infection with Metarhizium and 22.2% with Beauveria. The review of clinical cases of keratitis and sclerokeratitis related to Beauveria and Metarhizium suggests the need to consider entomopathogenic fungi in ocular pathologies and the risk that imply the misuse of contact lenses and agricultural/gardening activities.
... Globally, fungi of the genus Beauveria or Isaria (Cordycipitaceae) and Metarhizium (Clavicipitaceae) are a common component of soil microbiota. The density of diasporas of these fungi in the soil may exceed 1000 CFU·g -1 [7,8]. Extensive research carried out by Medo and Cagan [9] in Slovakia showed the presence of EPF in many case of soil samples and the dominance of Metarhizium anisopliae (present in 37% of trials), Beauveria bassiana (36%) and Isaria fumosorosea (9%) species. ...
Article
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Soil samples from 76 sites in southeastern Poland were collected and the presence of entomopathogenic fungi (EPF) was evaluated by the bait larvae method. EPF were detected on the average in 43.5% of samples. The soil usage method (forest, agricultural crop, garden, seminatural habitat), the date of sampling (spring, summer, autumn) and physico-chemical properties of the soil significantly differentiated the total mortality of larvae and the occurrence of EPF and their species composition. Soils of seminatural habitats and agricultural crops had significantly higher level of total mortality of larvae compared to the soils of gardens and forests. The total mortality of larvae in the soil was the highest at autumn. The share of EPF in soils due to the usage methods can be determined in a decreasing sequence: garden, agricultural crops, seminatural habitats, forest. In the soils of agricultural crops I. fumosorosea dominated and in the soils of gardens, forests and semina-tural habitats B. bassiana. The share of M. anispoliae sensu lato in soils was rather similar. In the samples obtained in the summer, EPF dominate, and in the samples collected in spring and autumn, other factors dominated mortality of larvae. The species composition of EPF in the soil collected in spring and summer was similar. In the samples taken in autumn, B. bas-siana species dominated.
... M. persicae and S. frugiperda are naturally infected by many species of EPF, some of which are very effective biocontrol agents (Firake and Behere 2020). The occurrence of such EPF naturally in an environment or agro-ecosystem indicates their potential role as biotic factors regulating insect pest populations in the field (Meyling and Eilenberg 2007). ...
Article
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Background: As diferent biogeographic strains and isolates of entomopathogenic fungi vary in their genetic, enzy�matic and pathogenic characteristics, this study assessed the virulence of 2 indigenous strains of Beauveria bassiana (Balsam) Vuillemin and Metarhizium anisopliae (Metschn.) Sorokin (Ascomycota, Hypocreales: Clavicipitaceae), isolated from naturally infected insect cadavers, against the 3rd instar nymphs of Myzus persicae (Sulzer) (Hemiptera: Aphidi�dae) and 3rd instar larvae of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) using leaf-dip and larval-dip methods, respectively. Results: Both fungal isolates exhibited considerable pathogenicity against M. persicae and S. frugiperda. Mortality in all bioassays was conidial concentration and exposure time dependent and increased signifcantly along with both factors (R2=0.86–0.99 for B. bassiana and 0.82–0.94 for M. anisopliae). Moreover, M. anisopliae isolate appeared more virulent to S. frugiperda larvae than B. bassiana isolate, while the later fungal isolate was more lethal to M. persicae nymphs than the former one. At the highest conidial concentration (1.0× 109 conidia/ml), M. anisopliae caused maxi�mum mean mortality of S. frugiperda (88%) and M. persicae (65%) and B. bassiana exhibited maximum mean mortality of S. frugiperda (76%) and M. persicae (94%). Moreover, probit regression analyses showed LT50 values for M. persicae of 4.57 and 6.86 days at 1.0× 109 conidia/ml for the isolates of B. bassiana and M. anisopliae, respectively, while LC50 values were 7.75× 106 and 8.70× 107 conidia/ml after 10th day of application, for the isolates of B. bassiana and M. anisopliae, respectively, against M. persicae. Similarly, LT50 values for S. frugiperda were 7.75 and 7.03 days for 1.0× 109 conidia/ml concentration and LC50 values were 2.84× 107 and 8.84× 105 conidia/ml at 10th day data for the isolates of B. bassiana and M. anisopliae, respectively. Conclusion: Overall study results demonstrated the efectiveness of B. bassiana and M. anisopliae against M. persi�cae and S. frugiperda, respectively. However, feld evaluations of these indigenously isolated promising fungal strains against these insect pests
... [50][51][52][53]. Both are natural enemies of a wide range of insects and arachnids particularly in agriculture, however less is known about their relevance in forest ecosystems [54,59]. In this work we showed morphologically and phylogenetically that an isolate of B. bassiana obtained from a bark beetle corpses was capable of acting as an entomopathogenic agent on P. mexicanus, killing the insects in only six days. ...
... ), as well as Cordyceps farinosa (Holmsk.) Kepler, B. Shrestha & Spatafora (= Isaria farinosa, Paecilomyces farinosus), are frequently isolated from temperate soils(Meyling and Eilenberg 2007;Masoudi et al. 2020). Our records of entomopathogens are very similar to those byMasoudi et al. (2020) for forests and reforested parkland, and presumably artificial grasslands in China, with the noteworthy absence in our study of the rhizospheric, endophytic PARBH clade. ...
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... These microorganisms have attracted significant attention for their use in biological control programs of insect pests in a diverse ecosystem (Lacey et al., 2015;Strasser et al., 2010). Among the EPF, Metarhizium anisopliae is the most studied fungus, along with Beauveria bassiana (Balsamo) Vuillemin, in terms of commercial production (Goettel et al., 2005;Meyling and Eilenberg, 2007). Several microbial pesticides have been formulated from different species of EPFs worldwide (Fang et al., 2014). ...
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... Microbial control (MC) using entomopathogenic fungus is an ecologically favorable, human innocuous, and long-term pest control strategy (Zimmermann, 2007). Entomopathogenic fungi are a viable pest management strategy in organic and conventional farming systems (Lomer et al., 2001;Meyling & Eilenberg, 2007;Flores et al., 2013). ...
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... For instance, EPF Beauveria, Metarhizium, Isaria, Lecanicillium, and Hirsutella are the key genera, which have been exploited at remarkable levels (Sharma and Sharma 2021). These are generally common habitants of the soil ecosystem, which protects them from harmful solar radiation (Meyling and Eilenberg 2007). Moreover, it has been noted that EPF interacts positively with plant roots and enhances their growth and survival longevity primarily relies on the insect for carbon and not on soil (Inglis et al. 2001). ...
Chapter
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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.
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El género Metarhizium está constituido por diversas especies, las cuales presentan una amplia distribución geográfica y es considerado uno de los mejores agentes de control biológico de insectos plagas. Objetivo. Determinar la diversidad genética de aislamientos de Metarhizium aislados de insectos y agroecosistemas mediante marcadores del ADN polimórfico amplificado al azar. Metodología. Para el aislamiento de Metarhizium se recolectaron suelos de diferentes agroecosistemas (limón mexicano, toronja, caña de azúcar, mango), de insectos Diatraea saccharalis (Lepidóptera: Crambidae), Diatraea magnifactella (Lepidoptera: Crambidae), Schistocerca piceifrons piceifrons (Orthoptera: Acrididae), Macrodactylus murinus (Coleoptera: Scarabaeidae), Spodoptera frugiperda (Lepidoptera: Noctuidae) y del acaro Boophilus microplus (Acari: Ixodidae), estos se analizaron mediante marcadores RAPD. Resultados. Los marcadores RAPD fueron altamente informativos y polimórficos. El dendrograma generado estuvo conformado por cuatro grupos (A, B, C y D); el grupo A se conformó por 11 aislados de agroecosistemas, uno de D. magnifactella y dos de D. saccharalis. En el grupo B uno de D. saccharalis y uno de agroecosistema de limón. En cambio en el grupo C estuvieron los aislados de B. microplus y uno de suelo. Mientras que el grupo D estuvo conformado por los aislados de S. frugiperda, M. murinus y S. piceifrons. Implicaciones. La determinación de la diversidad genética entre aislados de Metarhizium obtenidos de insectos y agroecosistemas, genera una aportación sobre el hábitat que permitirá desarrollar estrategias para llevar a cabo un adecuado control biológico de insectos plaga. Conclusión. Los análisis mediante los marcadores RAPD indicaron la existencia de una diversidad genética entre los aislados de Metarhizium colectados de diferentes insectos y agroecosistemas. Palabras clave: Marcadores RAPD, hongos entomopatógenos, caracterización molecular.
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The fungus, Beauveria bassiana (Bals.) Vuil., is one of the most important entomopathogenic fungi worldwide. It can be found in a variety of natural and agricultural habitats, and it has recently demonstrated the ability to live endophytically within plants. The present study was conducted to compare the ability of local isolates of the fungus B. bassiana to colonize cucumber plants under greenhouse conditions, using two inoculation methods: seed dusting and seedling drench. Ten different isolates of B. bassiana: B83, B100, B157, B186, B195, B202, B203, B221, B239, and B240 were used. Colonization of the upper plant parts (leaf, petiole, and stem) was calculated after 30 and 60 days of treatment. Other fungal genera present inside the plant were also determined. The results show that all isolates used had the ability to grow systemically and colonize cucumber plants under greenhouse conditions in both treatments. The isolates, B100, B195, and B240, were the most well-established in the plant. Depending on the fungal isolate and the plant part, colonization varied from 0 to 100%. The colonization was highest in the leaf followed by the petiole, and the stem. Moreover, the fungus B. bassiana survived inside cucumber for at least 60 days under greenhouse conditions. Additionally, various genera of fungi were isolated from the cucumber, of which, the genus, Aspergillus, was the most frequent, followed by the genus, Penicillium, with frequency reached 30.7 and 29.5 %, respectively, 60 days post-treatment.
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This book presents topics on the development, improvement and commercialization of fungi for the biological control of pests, weeds and diseases which are of economic importance. Common themes such as production, formulation and application of technologies, biosafety, risk assessment and registration requirements are all covered. The book attempts to bring together scientists, industry and government agencies involved in all aspects of fungal biological control agents for the first time.
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Effects of temperature on growth on a semisynthetic medium of 65 isolates of Beauveria bassiana from different geoclimatic and host origins were determined. The isolates were grouped according to the climate of their geographic origin, distinguishing between cool and warm regions; according to their host origin, distinguishing between isolates from acridids or from soil associated with acridid populations; and according to host order. In general, B. bassiana grew at a wide temperature range from 8 to 35 C. A well defined maximum thermal threshold occurred at temperatures of >35-37 C for 50 isolates; >32-35 C for 12; and >30-32 C for 1 isolate. The lower temperature threshold for all isolates tested was below 8 C. Relative growth rate, calculated from the maximum growth rate for each isolate, was significantly affected by temperature and isolate. Optimal temperatures were generally between 25 and 28 C with several isolates exhibiting optimal growth at temperatures as low as 20 or as high as 30 C. Relative growth rates were not very useful in distinguishing differences among many of the isolates at the near-optimal temperatures. In contrast, the ability to distinguish differences in relative growth rates among isolates increased progressively as temperatures increased above 28 C or decreased below 20 C. There were no apparent relationships between relative growth rates and climatic origin. In comparisons of acridid-associated isolates, relative growth rates were higher for the insect isolates at 8 C and for the, African soil isolates at 35 C. At the other temperatures, no clear relationships were apparent. When comparisons were made according to host order, there were significant differences in relative growth rates according to host order at 8, 11, 30, and 32 C but not at the other temperatures. Since temperature growth responses varied considerably among isolates, with some having wide ranges of temperature optima while others were much more restricted, strain selection according to thermal requirements may be warranted when choosing a strain for development as a microbial control agent.
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The effect of simulated rain at two intensities (26.7 or 112.7 mm h-1) and durations (30 or 60 min) on the persistence of Beauveria bassiana conidia applied in water on leaves of alfalfa leaves of alfalfa (Medicago sativa) or wheat (Triticum aestivum) was investigated. Initial populations of conidia on the leaves of both crops were similar, and ranged from 1.7 105 to 3.5 105 colony-forming units cm-2. The simulated rain reduced the concentration of conidia on leaves by 28-61%. Although there was a slight effect due to rain intensity for alfalfa, there was no influence of either rain duration or crop type on the retention of B. bassiana conidia.
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The suppression of agricultural pests has often been proposed as an important service of natural enemy diversity, but few experiments have tested this assertion. In this study we present empirical evidence that increasing the richness of a particular guild of natural enemies can reduce the density of a widespread group of herbivorous pests and, in turn, increase the yield of an economically important crop. We performed an experiment in large field enclosures where we manipulated the presence/absence of three of the most important natural enemies (the coccinellid beetle Harmonia axyridis, the damsel bug Nabis sp., and the parasitic wasp Aphidius ervi) of pea aphids (Acyrthosiphon pisum) that feed on alfalfa (Medicago sativa). When all three enemy species were together, the population density of the pea aphid was suppressed more than could be predicted from the summed impact of each enemy species alone. As crop yield was negatively related to pea aphid density, there was a concomitant non-additive increase in the production of alfalfa in enclosures containing the more diverse enemy guild. This trophic cascade appeared to be influenced by an indirect interaction involving a second herbivore inhabiting the system – the cowpea aphid, Aphis craccivora. Data suggest that high relative densities of cowpea aphids inhibited parasitism of pea aphids by the specialist parasitoid, A. ervi. Therefore, when natural enemies were together and densities of cowpea aphids were reduced by generalist predators, parasitism of pea aphids increased. This interaction modification is similar to other types of indirect interactions among enemy species (e.g. predator–predator facilitation) that can enhance the suppression of agricultural pests. Results of our study, and those of others performed in agroecosystems, complement the broader debate over how biodiversity influences ecosystem functioning by specifically focusing on systems that produce goods of immediate relevance to human society.
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The effects of mulching with organic materials on yield and damage by brassica root maggots (Delia floralis and D. radicum) in cauliflower, were studied in field experiments for 3 years. Mulching with grass-clippings consistently resulted in increased yield and reduced damage by root maggots, as measured by wilting symptoms and root damage. During one of these years, the effects of mulching with grass-clippings on root fly population dynamics was also studied. Mulching did not reduce egg-laying but resulted in increased egg-predation. The number of D. floralis pupae per plant was not reduced by mulching, probably because of higher larval mortality owing to competition in unmulched plots. Mulching decreased the rate of parasitization by Aleochara bilineata (Staphylinidae), resulting in a higher number of healthy pupae per plant in grass-mulched plots, and these healthy pupae were heavier. All these effects were most pronounced when the mulch material completely covered the ground, even close to the stems of the plants.
Chapter
The chapter discusses the ecological/epizootiological basis for environmental manipulations, reviews research on this approach and the criteria to choose insect/entomopathogen systems for research and implementation. Research on environmental manipulation is focused on four areas. The first is improved transport from the pathogen reservoir, usually the soil, to a site such as a leaf surface where the insect host can come into contact with the entomopathogen. The second area is improvement in persistence of the entomopathogen at the site where it contacts the insect host. The third area is overall growth of the entomopathogen population, which depends on transmission and persistence as well as other factors. The fourth area is activation of latent infections. Many resource (crop)/pest systems include one or more entomopathogens that occur naturally and occasionally cause epizootics. Environmental manipulation has certain advantages over the approaches to microbial control that require environmental release of pathogen units because certain requirements for those approaches have caused major problems in implementation. The requirements for other approaches that are of little or no concern in environmental manipulation include market size (host specificity), cost of pathogen production, patentability, registration, persistence in storage, formulation, screening for efficacious species or strains, and habitat stability.
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Aspects of the phenology and growth characteristics of stinging nettle are described which could be important for insects. Six habitat categories were contrasted by selecting nettle patches in shaded and unshaded conditions on clay, peat and sandy soils. The efficiency of suction sampling for Hemiptera (except aphids) and Coleoptera was examined and compared with the searching of cut-stem samples. Suction sampling was used to build up a general phenological picture of adult insects in preparation for an intensive study of one site and a comparison of nineteen sites in contrasting habitats. The life histories and habitat preferences of fourteen Heteroptera, five Homoptera and seven Coleoptera are described, including monophagous and polyphagous plant feeders and a few predatory species common on nettle in East Anglia. Several gaps in the information still remain and these are pointed out. The repuirements of the phytophagous species are discussed in relation to the successful exploitation of nettle by so many species. The comparison of insect faunas in different habitats in this study provides a basis for comparing other sites with respect to regional, climatic and biotic factors.
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This paper reviews two aspects of agricultural biodiversity. 1. The ways in which agricultural biodiversity may be increased to favour pest management are examined. At the simplest level, the structure within a monoculture may be altered by changing management practices to benefit natural enemies. At the other extreme, annual and perennial non-crop vegetation may be integrated with cropping, and biodiversity increased at the landscape level. 2. The existence of a hierarchy for the types of benefits of increased biodiversity is discussed. Vegetational diversity can lead to suppression of pests via 'top-down' enhancement of natural enemy populations and by resource concentration and other 'bottom-up' effects acting directly on pests. Whilst such low-input pest management mechanisms are attractive in their own right, other (non-pest management related) benefits may simultaneously apply. These range from short-term benefits in crop yield or quality, longer term benefits for sustainability of the farming system and, ultimately, broad societal benefits including aesthetics, recreation and the conservation of flora and fauna. Examples are given of such multi-function agricultural biodiversity.
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The influence of three formulations (water, oil, and a 5% oil emulsion) and two canopy positions (top and middle) on the persistence of conidia of Beauveria bassiana on phylloplanes of alfalfa (Medicago sativa) and crested wheatgrass (Agropyron cristatum) was investigated. Penetration into the canopy and coverage of leaves by conidia in oil applied with an ultralow volume (ULV) applicator was equal to that of conidia formulated in water-Tween or the oil emulsion applied at high volumes. Numbers of B. bassiana recovered from the top of the canopy immediately following application ranged from 8.3 × 103 to 1.2 × 105 colony-forming units (cfu)/cm2 for alfalfa and 5.1 × 103 to 3.5 × 104 cfu/cm3 for wheatgrass. In alfalfa, but not wheatgrass, the canopy influenced penetration of conidia as evidenced by the significant effect of sampling height. Conidia were relatively short lived on leaves at the top of the canopy in both crops and, by 4 days, conidial populations were reduced by more than 75%. At the middle of the canopy, conidia persisted longer on phylloplanes of both crops. This observation was more pronounced in alfalfa than in wheatgrass; at 16 days populations were reduced by more than 99% on wheatgrass leaves and by 28 to 85% on alfalfa leaves. Formulation had no obvious effect on the persistence of conidia. Mortality of grasshopper nymphs (Melanoplus sanguinipes) fed leaves sprayed with conidia from the top of the canopy corresponded to the conidial population data. Immediately after application of conidia, nymph mortality attributed to B. bassiana ranged from 31 to 58%, whereas mortality of nymphs fed leaves 2 days postapplication of conidia ranged from 0 to 5.5%. Methods to increase the persistence of conidia are required if plant surfaces are targeted in a strategy to control grasshoppers with B.bassiana.
Article
By baiting soil samples with larvae of Galleria mellonella detailed surveys of the occurrences of entomopathogenic fungi were conducted over two consecutive years in the soil of an organically farmed field (17.1ha) and the associated hedgerow. Samples were collected at specific points (at distances of 25m) based on Geographical Information Systems (GIS) and sample point coordinates were relocated by Global Positioning System (GPS). In the agricultural field soil Beauveria bassiana was the most common fungus while Paecilomyces fumosoroseus was most common in soil from the hedgerow. Significant clustering of B. bassiana in the agricultural field was found in one of the two years. High and low densities of B. bassiana were subsequently confirmed within selected areas by reducing distances between sample points. The results demonstrated the suitability of the sampling method for identifying distribution patterns of soil borne entomopathogenic fungi and the importance of large sample sizes to describe local biodiversity of the fungi in the soil environment.
Article
1 Pandora neoaphidis is an important aphid-specific fungal pathogen in temperate agroecosystems. Laboratory studies were carried out to obtain baseline data on factors that may affect its performance in conservation biological control.2 Virulence of P. neoaphidis was assessed in dose–response bioassays against Microlophium carnosum on nettle, Uroleucon jaceae on knapweed, Acyrthosiphon pisum on bean and bird's-foot trefoil Lotus corniculatus, and Metopolophium dirhodum on barley and Yorkshire fog Holcus lanatus. The most susceptible aphid was A. pisum feeding on bean with an LD50 of 19 conidia per mm2, whereas U. jaceae had an LD50 of 104 conidia per mm2 and was least susceptible to infection.3 The presence of foraging adult ladybirds, Coccinella septempunctata, increased transmission of P. neoaphidis from infected cadavers to apterae of M. carnosum, U. jacea, and A. pisum by 7–30% at the largest cadaver density tested. Adult coccinellids that had previously foraged on nettle, knapweed, bean or bird's-foot trefoil transfered conidia to A. pisum on bean and induced infections in 2–13% of aphids.4 Conidia of P. neoaphidis dispersed passively in the airstream from sporulating M. carnosum cadavers on nettle plants and initiated infections in A. pisum colonies feeding on bean (4–33%) or M. dirhodum on barley (3%) located within 1.0 m of the nettle source.5 The results suggest that M. carnosum and A. pisum may be more useful as reservoirs for P. neoaphidis in noncrop and crop areas than U. jaceae or M. dirhodum, and infection and dispersal between habitats could be enhanced in the presence of coccinellids.
Article
The influence of rain on removal of Beauveria bassiana conidia from potato (Solanum tuberosum) leaves and Colorado potato beetle (Leptinotarsa decemlineata) larvae was investigated. In the first experiment, substrates were exposed to simulated rain of varying intensities (25, 77, and 89 mm/h) and durations (0, 15, 30, 45, and 60 min). Substantial numbers of colony-forming units (CFU) were removed from leaves (89 to 95%) and from larvae (34 to 70%) by rain exposure, and the majority of CFU were removed within the first 15 min of exposure. Rain intensity had a minimal effect on conidial persistence on both leaves and larvae, but more CFU were removed from larvae exposed to the highest rain intensity treatment. Conspicuous clumping of conidia was observed on the cuticles of both leaves and larvae following application. After rain exposure, conidial clumping was less conspicuous. In a second experiment, the influence of six formulations on the persistence of conidia exposed to rain was investigated. Treatments consisted of a water control, sunflower oil, a wettable powder, and four oil emulsions applied at two rates. Formulation significantly affected removal of CFU from potato leaves but not Colorado potato beetle larvae. Conidia applied in sunflower oil were not removed from potato leaves by exposure to 39 mm of rain in 30 min. In contrast, conidial persistence during this period was substantially reduced for conidia applied in water, a wettable powder containing clay, and an oil emulsion formulation applied at a low volume rate (2.3 liters of oil in 281 liters of water/ha). Although simulated rain removed substantial quantities of B. bassiana CFU from leaves and to a lesser extent from Colorado potato beetle larvae, a substantial number of the conidia applied in water remained after exposure to relatively high intensity rains. Evidence suggested that conidia in direct contact with the cuticle of leaves and larvae were less prone to be removed by rain than conidia in aggregates and thus not in contact with the cuticle, and emulsifiable oil formulations may be used to enhance conidial retention on foilage.
Article
When Spodoptera exigua pupae were buried for 10 days at 24°C in nonsterile soil inoculated with Beauveria bassiana conidia, 1 × 107 conidia/cm3 of soil was the lowest conidial density to produce disease in pupae and adults. At water potentials of −37 and −200 bars (24°C), adult emergence was reduced when 3.2 × 107 or 1 × 108 conidia/cm3 was used in Yolo fine sandy loam (YFSL) and Staten peaty muck (peat). In these dry soils, adult emergence was as low as 6% at 1 × 108 conidia/cm3. At water potentials of −0.3, −2, and −15 bars, a concentration of 1 × 108 conidia/cm3 was necessary to reduce adult emergence. In these treatments, 18 to 62% of the pupae eclosed to the adult stage. Thus, adult emergence was greater at water potentials from −0.3 to −15 bars that at −37 and −200 bars. Also at −0.3 and −2 bars, adult emergence was greater in peat than in YFSL. Uninoculated control soils had 85–94% adult emergence. Adult emergence increased as the temperature decreased from 25° to 8°C. At 8°C, adult emergence was the same in inoculated and uninoculated soil. Clay-coating of conidia, to increase conidial longevity, did not influence S. exigua mortality.
Article
A method for baiting soil samples with Delia floralis larvae was developed, and a systematic survey was conducted on soils from northern Norway for insect pathogenic fungi, using D. floralis and Galleria mellonella larvae as bait. The occurrence of insect pathogenic fungi in soils from arable fields and adjacent field margins of conventionally and organically managed farms was compared. The study showed a significantly higher occurrence of insect pathogenic fungi in soils from arable fields of organically managed farms. No significant differences in the occurrence of insect pathogenic fungi were, however, found between the field margins of the two cropping systems. Fungal species identified in the study were Beauveria bassiana, Fusarium merismoides, Metarhizium anisopliae and Tolypocladium cylindrosporum.T. cylindrosporum was found more frequently when using D. floralis as the bait insect than when using G. mellonella.