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Fruit fly ground-dwelling stages (late third instar larvae, pupae, and teneral adults) are susceptible to predation from generalist ground-dwelling predators and to infection by entomopathogenic fungi (EPF). The effect of predators can be enhanced with cover crops and that of EPF by augmentative releases. However, whether these two biological control methods could be combined has not been studied under field conditions yet. Here, we studied in the field whether the enhanced activity of predators against the medfly, Ceratitis capitata, already observed in a Lolium arundinaceum ground cover could be impaired by a soil application of Metarhizium brunneum. Our results show that C. capitata adult emergence was reduced by this EPF for up to three months after fungal application, with the combination of the cover and M. brunneum being the most effective at reducing C. capitata emergence relative to bare soil (92.5% reduction). Although M. brunneum reduced the activity density of ground-dwelling predatory beetles up to 93 days after application, it showed no clear negative effects on earwigs, no effects on spiders, and a positive effect on ants up to 65 days after application. Therefore, the combined use of a ground cover of L. arundinaceum and M. brunneum against the soil-dwelling stages of C. capitata seems to work synergistically and appears as a strong and sustainable control tactic against the medfly and other fruit orchard pests. [ABSTRACT FROM AUTHOR]

One of the main negative effects of climate change on biological pest control is alteration of relationships between insect pests and their natural enemies (both entomophagous and entomopathogenic). Indeed, environmental conditions can have multiple effects on pest control success when using entomopathogenic fungi (EPF), where conidial depletion, inactivation, and loss in virulence and infectivity can all occur. Appropriate mass production and formulation strategies for EPF can partially solve these problems. However, the only strategy to guarantee high virulence and infectivity is selection of environmentally competent fungal strains that are able to persist in the host environment for the required infection period. This review examines the criteria for selection of environmentally competent EPF. While UV radiation, followed by humidity and temperature, is probably the most important propagule depletion and inactivation factors in epigeal habitats, temperature is most critical for reducing the infectivity and virulence of EPF in epigeal and hypogeal habitats. In addition, geographical origin and other biotic and abiotic factors have an important impact which may guarantee the environmental competence of selected entomopathogenic fungal strains and, therefore, farmer willingness to replace chemicals with mycoinsecticides. To achieve this, it is urgent to promote the development of microbial control solutions adapted to relatively uniform climatic zones through more simplified, targeted, and less costly EPF approval and authorization. [ABSTRACT FROM AUTHOR]

Integrated Pest Management (IPM) programs are alternatives to classical pest control through the application of chemical insecticides. IPM goal is to maintain pest populations below economically injurious levels minimizing the use of chemical insecticides. In recent years, research on insect viromes has led to the discovery of many novel viral pathogens in insect pests, some of them producing covert infections that do not cause evident symptoms. However, the impact that these viruses have on the action of natural enemies employed in IPM programs is still unknown. Spodoptera exigua iflavirus 1 (SeIV1) is an RNA virus commonly found in field populations of Spodoptera exigua. In this work, we have analysed the possible impact of those viral infections on the activity of different natural enemies used for the control of this pest. Specifically, we have studied the effects of SeIV1 on susceptibility to entomopathogenic nematodes, fungi, bacteria, and parasitoids. Infections with SeIV1 showed to be compatible with the nematode Steinernema carpocapsae as the infection did not affect the susceptibility or production of new juveniles. Moreover, they are also compatible with the fungus Metarhizium brunneum as the mortality of S. exigua larvae was not affected by the viral infection. Interestingly, infections with SeIV1 increase the susceptibility to Bacillus thuringiensis formulation and increase the mortality caused by the parasitism of Hyposoter didymator. In summary, our results show that the four natural enemies tested are not negatively affected by SeIV1 and their action remains similar or enhanced by the covert infections with this iflavirus. [ABSTRACT FROM AUTHOR]

Biocontrol with hypocrealean entomopathogenic fungi (EF) is a key tool to develop Integrated Pest Management (IPM) programs for the progressive replacement of synthetic chemical insecticides with more environmentally friendly pest control measures. These fungi stand out among entomopathogens not only for their contact mechanism of infection through the arthropod integument, but also for developing close associations with plants including the endophytic lifestyle and rhizosphere competence that can enable them to make broader contributions to IPM and crop production. Anyhow, the interaction of EF with the plants incorporates multitrophic complexity at different levels including insect pests, plants, and their natural enemies. The aim of the present review was to gather and summarize all available data on multitrophic interactions of EF. These fungi can influence both the chemical ecology of host-plant selection by insect pests and the host or prey selection by parasitoid or predators, respectively. Moreover, EF treatments are compatible with natural enemies in terms of safety and effectiveness, which could allow biocontrol strategies for their synergistic application in IPM programs. A comprehensive understanding of the impact of these multitrophic interactions in longer term, farm-level real-life biocontrol implementation studies will provide new opportunities in plant protection and production. [ABSTRACT FROM AUTHOR]

Strains IMI 330189 of Metarhizium acridum (Driver & Milner) J.F. Bisch., Rehner & Humber (Hypocreales: Clavicipitaceae) and EABb 90/2-Dm of Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) are a promising biocontrol tool of Dociostaurus maroccanus (Thunberg) (Orthoptera: Acrididae), although the effects of thermoregulation and Moroccan locust-fever on the infection process of these fungi remain unknown. In vitro experiments, measuring conidial germination and hyphal growth either at constant or at fluctuating temperatures simulating thermoregulatory conditions, indicated that strain IMI 330189 had greater fitness at temperatures above 27 °C and the strain EABb 90/2-Dm was better adapted to the temperature range of 10-25 °C. These effects were mirrored in vivo, where locust thermoregulation caused a marked reduction in the virulence of EABb 90/2-Dm in comparison to no thermoregulation conditions (average survival time: 6.10 vs. 15.83 days; mortality: 100% vs. 73.7%) but only a moderate reduction in the virulence of IMI 330189 (average survival time: 4.57 vs. 8.26 days; mortality: 100% vs. 100%). Thermal gradient experiments revealed that the strain IMI 330189 induced behavioral fever in D. maroccanus (preferred temperatures approximately 4 °C above the uninfected control), although it only led to a slight reduction in virulence. Strain EABb 90/2-Dm did not induce such a clear behavioral response. Under the temperature conditions of the main breeding areas of the Moroccan locust, strain IMI 330189 is likely a better candidate for use in biocontrol, although strain EABb 90/2-Dm could be also a good alternative in more temperate environments either as a stand-alone one or in mixed combinations of the two fungal strains, potentially providing more effective control over a broader range of temperatures. [ABSTRACT FROM AUTHOR]

Background and aims: Entomopathogenic mitosporic ascomycetes Beauveria, Metarhizium and Isaria sp. are commonly used for pest control but can also serve other, lesser known functions such as increasing nutrient bioavailability or promote plant growth. The objective of this work was to identify the doses of entomopathogenic fungi (EF) to be applied to soil in order to modify iron (Fe) uptake by plants and promote their growth. Methods: We used an in vitro assay to assess the ability of Beauveria bassiana, Metarhizium brunneum and Isaria farinosa to mobilize Fe from nine Fe oxides differing in composition, particle size and crystallinity, including ferrihydrite, hematite, goethite and magnetite. We also conducted an in vivo assay by applying five different doses (viz., 0, 5 × 10, 5 × 10, 5 × 10 and 5 × 10 conidia ml) of a conidial suspension of M. brunneum to the surface of a calcareous soil, which induced Fe chlorosis and a non-calcareous soil which did not induce chlorosis to explore the ability of the fungus on improving Fe nutrition and plant growth of sorghum and sunflower plants. Results: In the in vitro assay, all three EF increased Fe availability differently depending on particle size and crystallinity, and I. farinosa and B. bassiana increased the pH of the culture medium, whereas M. brunneum did not produce a great effect. In the in vivo assay, the highest dose (5 × 10 conidia ml) of M. brunneum alleviated Fe chlorosis symptoms of sorghum plants grown in the calcareous soil, and the two highest doses (5 × 10 and 5 × 10 conidia ml) increased plant height and inflorescence production of sunflower grown in both soils. Conclusions: The observed benefits of EF on plant growth and nutrition provide support for more sustainable and cost-effective use of these biocontrol agents. [ABSTRACT FROM AUTHOR]

An analytical strategy based on a hybrid quadrupole-Orbitrap mass spectrometry was proposed for the simultaneous screening of known destruxins and characterization of potential members of this class of secondary metabolites, in order to evaluate the metabolite production of entomopathogenic fungi used as biocontrol agents. Initially, the fragmentation pathway of the known and commercially available destruxin A was established combining high resolution mass spectrometry (HRMS) and multiple stage MS data in order to obtain the strategy for the characterization of other destruxins for which reference standards were not available. Nineteen known destruxins including A, B, C, D, Ed, F, A, B, Ed, A, B, D, A, DesmA, DesmB, DesmC, DesmB, and two chloro-derivatives (Cl and E chlorohydrin) were unequivocally identified in Metarhizium brunneum using the proposed strategy. In addition, four unknown destruxins, namely C, Ed, G, and G, were structurally elucidated and characterized for the first time in this fungal strain. [ABSTRACT FROM AUTHOR]

Background and aims: Entomopathogenic fungi are known for their insecticidal properties but possess other, lesser known attributes as plant growth promoters and nutrient bioavailability improvers. In this work, their effect on iron availability and ability to alleviate iron chlorosis symptoms were examined. Methods: Three strains of common entomopathogenic fungi ( Beauveria bassiana, Isaria farinosa and Metarhizium brunneum) were studied in an in an in vitro experiment involving three iron oxides of different nature. Then, lupin, sorghum, wheat and sunflower pot-grown on three calcareous soils with a low iron availability and one non-calcareous sandy soil with a high iron availability, were studied. Metarhizium brunneum was applied to the soil surface to compare with untreated soils. Results: Metarhizium brunneum EAMb 01/58-Su was the most efficient strain in dissolving iron from iron oxides in the in vitro experiment; also, it increased leaf chlorophyll content in sorghum and wheat, plant height in wheat, and flower production in sunflower grown on two of the three calcareous soils. However, the fungus decreased dry weight in wheat and sunflower production in plants grown on the sandy soil. No effect on lupin plants -the most sensitive to iron chlorosis- was observed. Conclusions: M. brunneum alleviated iron chlorosis symptoms in sorghum, wheat and sunflower grown on calcareous soils but had a negative effect on two of the four plant species grown on the sandy soil. These encouraging results with calcareous soils suggest giving priority to this soil dwelling pest control strategy in such conditions to take advantage of this new added value. [ABSTRACT FROM AUTHOR]

Capillary electrophoresis (CE) with ultraviolet (UV) detection has been evaluated in this work as a valuable tool to use in the risk assessment of fungal biocontrol agents, that are entomopathogenic fungus used nowadays as an alternative to chemical insecticides. Compared to HPLC-UV methods, which are frequently used in this scientific field, the method proposed using CE-UV provided faster analyses, with low cost reagents, reduced solvent consumption and generated low levels of residues. Specifically, the secretion of destruxin (dtx) A by BIPESCO5, EAMa 01/58-Su and ART2825 strains from fungus Metarhizium brunneum, over 18 days in different conditions, was monitored. The recent interest in this metabolite resides in the fact that it could be a risk to human health and the environment. Results showed that BIPESCO5 and EAMa 01/58-Su strains cultivated in a complete culture medium produced dtx A at levels that could be directly analyzed by CE (BIPESCO5, which produced the highest dtx A concentration at day 9). However, for a minimal culture medium, a preconcentration step was necessary prior to the determination of this metabolite by CE-UV. C18 and HLB cartridges were successfully used to improve the sensitivity of the CE method when necessary. In addition, dtx A was not detected in ART2825 strain in any culture medium. All these results were in agreement with the values found in the literature using HPLC. [ABSTRACT FROM AUTHOR]

This study delves into the compatible use of a parasitoid with multifunctional endophytic Entomopathogenic Ascomycetes (EA) in IPM under greenhouse conditions. The parasitoid Hyposoter didymator was evaluated against Spodoptera littoralis in a multitrophic system with melon plants that were endophytically colonized by one of three EA strains (Metarhizium brunneum [one] or Beauveria bassiana [two]). In the first scenario, plants were inoculated by three different methods, and after infestation with noctuid larvae, the parasitoid was released at a 1:20 ratio. Microbiological and molecular techniques allowed the identification of progressive colonization throughout the whole plant life cycle, and for B. bassiana, approximately 20% of seeds from new fruits were colonized. The parasitoid was shown to be compatible with all strains and application methods, with total mortality rates ranging from 11.1 to 77.8%. Significant lethal and sublethal effects, a decrease in pupal weight and mortality of pupae showing abnormalities and an extension of the immature developmental times were observed for different strain–application method combinations. Additionally, the fungal treatments improved crop growth, as revealed by the significant gains in plant weight. In a second scenario (by inoculating plants with the fungi only by leaf spraying), and after infestation with noctuid larvae, the parasitoid was released at a 1:10 ratio, which revealed the remote fungal effect from the inoculation point and confirmed the compatibility of the parasitoid-EA-based strategy. These findings underscore the compatible use of a parasitoid with endophytic EA for S. littoralis control that can additionally exploit their multifunctionality for sustainable crop production. [ABSTRACT FROM AUTHOR]