Entomopathogenic Fungi Research Articles

Ecology and management of the coffee berry borer (Hypothenemus hampei): the potential of biological control

AbstractCoffee is an important commodity in Latin America that is grown by smallholder farmers and large-scale coffee producers. The coffee berry borer, Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae) is a major pest of coffee that originates from West Africa and has invaded all coffee-producing regions. With climate change, the problems that this beetle poses to coffee production are expected to increase. Controlling this pest is a true challenge and chemical insecticides still are one of the main tools used, despite the environmental and human-health issues associated with this approach. To find sustainable alternatives for chemical control of the coffee berry borer, classical biological control, augmentative biological control, and integrated pest management have received extensive attention. Parasitoids, predators, entomopathogenic fungi, and nematodes have been identified and studied for their potential to manage the infestations of this major coffee pest. Conservation biological control has recently gained more attention, but its development is still in its infancy. In this review, we examine strategies for the control of the coffee berry borer in Latin America. We identify knowledge gaps for developing sustainable biological control programs, including conservation biological control within the context of farming systems, land use in the surrounding landscape, as well as the vision of coffee growers.

Biology, impact, management and potential distribution of Aromia bungii, a major threat to fruit crops around the world

AbstractAromia bungii Faldermann (Coleoptera: Cerambycidae) is an emerging invasive pest of economically important Prunus species that is native to China, Mongolia, the Russian Far East, Korea, and Vietnam. It was recently introduced to Japan, Germany, and Italy, where it is spreading and damaging crops and ornamental trees. It exhibits an adaptable lifecycle, a high reproductive output, and the larvae live concealed under the bark of infested trees, which are traits that promote its invasiveness. Detection and monitoring of A. bungii currently rely upon visual identification of infested trees that are usually already damaged, which is inefficient and not target-specific. Current control methods rely primarily upon the labour-intensive physical removal of infested trees. Although native parasitoid natural enemies of A. bungii provide control in Chinese orchards, none are appropriate for classical biological control in invaded areas due to biosafety concerns surrounding their broad host ranges. However, entomopathogenic fungi and nematodes may provide viable options for biological control in invaded ranges. Recent advancements in semiochemical baited traps may provide sustainable, target-specific, and efficacious methods to monitor and control A. bungii. There remains much to learn about the biology and control of A. bungii, and continued advancements in the study of sustainable control tools are needed for the management of this emerging pest.

Entomopathogenic fungi-based silver nanoparticles: a potential substitute of synthetic insecticides to counter behavioral and physiological immunity in Aedes aegypti mosquito (Diptera: Culicidae).

Excessive use of synthetic insecticides has resulted in environmental contamination and adverse effects on humans and other non-target organisms. Entomopathogenic fungi offer eco-friendly alternatives; however, their application for pest control requires significant advancement owing to limitations like slow killing time and effectiveness only when applied in higher amounts, whereas exposure to UV radiation, high temperature, and humidity can also reduce their viability and shelf-life. The nanoparticles synthesized using fungal extracellular extracts provide a new approach to use fungal pathogens. Our study focused on the synthesis of Metarhizium anisopliae-based silver nanoparticles (AgNPs) and evaluation of their efficiency on various physiological and behavioral parameters of the mosquito Aedes aegypti. The synthesis, size (27.6 d.nm, PDI = 0.209), zeta potential (- 24.3 mV), and shape of the AgNPs were determined through dynamic light scattering, scanning and transmission electron microscopic, and UV-visual spectroscopic analyses (432 nm). Our results showed significantly reduced survival (100% decrease in case of 3.2 and 1.8 μL/cm2 volumes, and 60% decrease in case of 0.8 μL/cm2 volume), phenoloxidase activity (t = 39.91; p = 0.0001), and gut microbiota, with increased oxidative stress and cell apoptosis in AgNPs-challenged mosquitoes. Furthermore, the AgNPs-exposed mosquitoes presented a concentration-specific decrease in flight locomotor activity (F = 17.312; p < 0.0001), whereas no significant changes in antifungal activity, self-grooming frequencies, or time spent were found. These findings enhance our understanding of mosquito responses to AgNPs exposure, and offer a more efficient mosquito control strategy using entomopathogenic fungi.

Exposure to entomopathogenic fungus and high larval density induce a strong immune response and life‐history costs in black soldier fly, a commercially important insect

AbstractPathogen infection and conspecific density may considerably affect key life‐history traits of organisms. For naturally aggregating species, even low concentrations of pathogens or high larval densities may have detrimental effects. However, the detailed influence of these factors, particularly their interaction effect, is often overlooked in ecological and life‐history studies. To investigate the effects of conspecific density and pathogen infection on life‐history traits, we explored the influence of larval density (1 and 5 larvae cm−2, i.e., low and high density, respectively) on phenoloxidase (PO) activity, body mass, and development time of Hermetia illucens L. (Diptera: Stratiomyidae) larvae in the presence of two strains of the entomopathogenic fungus (EPF) Beauveria bassiana (Bals.‐Criv.) Vuill. We observed higher PO activity in EPF‐treated larvae than in the untreated control and a pronounced difference in PO activity between the two EPF‐strain treatments. Larvae reared at high density and treated with EPF showed higher PO activity than untreated larvae at low density. The EPF‐treated larvae and larvae reared at high density had longer larval periods than untreated larvae and larvae reared at low density, respectively. Larvae reared at high density also achieved reduced prepupal and pupal masses compared to conspecifics at low density. Interestingly, untreated larvae only achieved higher prepupal and pupal masses at low density, whereas at high density, the pattern was reversed (treated individuals had higher pupal masses). Overall, our results demonstrate that high density and fungal pathogens both induce a higher immune response compared to low density and pathogen‐free environments, but this comes with a cost of a longer larval period and reduced body mass.

Pesticidal activity of extra cellular metabolites extracted from the green muscardian fungi Metarhizium anisopliae

AbstractThe present study was undertaken to screen the pesticidal activity of extra cellular metabolites derived from entomopathogenic fungus Metarhizium anisopliae against Spodoptera litura and Aphis crassivora an important aphid pest under laboratory and pot culture condition. Fungal strain used in the study was isolated from the soil by serial dilution technique. Isolated fungal strain was mass multiplied in a liquid medium sabouraud maltose yeast extract broth under optimum condition (28°C). Culture filtrate and the collected culture derived from the medium was used for the source of metabolites. The culture filtrate was extracted with ethyl acetate, acetone and the concentrated extract was screened for pesticidal activity against Spodoptera litura and Aphis crassivora adopting leaf disc and pot culture assay respectively. Extracted metabolites showed pesticidal activity against both insect pests. However, notable effect was recorded in ethyl acetate derived metabolites. The ethyl acetate extract treatment recorded 91.2% mortality at a concentration of 100 μg against Spodoptera litura and 100% mortality at a concentration of 100 μg against Aphis crassivora. Phytotoxicity was determined by measuring the germination index (GI) of groundnut seeds by exposing it to the crude metabolites extracted in ethyl acetate and acetone. The results showed that the germination index was high on ethyl acetate extract which was recorded to be 98.0% and germination index of acetone extract was found to be 90.0%. Production of insecticidal metabolites from M. anisopliae under laboratory condition proposed the possible utilization of metabolites as an effective, safe pesticidal agent against economic important insect pests. No impact on the seedling emergence revealed non phytotoxic effect of the metabolites.

Biological and physiological effects in Bemisia tabaci feeding on tomatoes endophytically colonized by Beauveria bassiana.

Entomopathogenic fungi (EPF) treatment of plants may affect the survival and feeding preferences of herbivorous pests. However, comprehensive studies on the fitness across their entire life cycle, feeding behavior, and physiological changes in herbivores consuming EPF-treated plants within the tripartite interactions of EPF, plants, and pests are still limited. In this study, we utilized life tables, electrical penetration graph (EPG), and metabolomics to uncover the biological and physiological characteristics of Bemisia tabaci on tomato plants inoculated with Beauveria bassiana through root irrigation. Our study indicated that B. bassiana Bb252 can penetrate the entire tissue from the point of inoculation, primarily colonizing the intercellular spaces and vascular tissue. However, this colonization is temporary, lasting no more than 35 days. Moreover, the population fitness and feeding behavior of B. tabaci on tomato plants treated with B. bassiana via root irrigation were significantly affected, showing a substantial 41.4% decrease in net reproductive rate (R0), a notable reduction in watery salivation, and shortened phloem ingestion. Lastly, we observed a significant decrease in hormones and amino acids of whiteflies that fed on B. bassiana-treated tomato plants by root irrigation. Our results indicated that the endophyte, B. bassiana Bb252, reduced demographic fitness of B. tabaci by altering its hormones and amino acids levels. These findings enhance our understanding of multitrophic interactions in integrated pest management. This article is protected by copyright. All rights reserved.

Two Iron(II), α-Ketoglutarate-Dependent Enzymes Encoded by the PPZ Gene Cluster of Metarhizium majus Enable Production of 8-Hydroxyperamine.

Entomopathogenic fungus Metarhizium majus contains the nine-gene PPZ cluster, with ppzA, encoding a peramine-producing nonribosomal peptide synthetase, as the central component. In this work, the roles of two α-ketoglutarate, iron-dependent oxygenases encoded by the PPZ genes ppzC and ppzD were elucidated. PpzD was found to produce both trans-4-hydroxy-l-proline and trans-3-hydroxy-l-proline in a 13.1:1 ratio, yielding a key precursor for peramine biosynthesis. PpzC was found to act directly on peramine, yielding the novel analogue 8-hydroxyperamine.

Susceptibility of immature Telenomus remus, an egg parasitoid of Spodoptera frugiperda (J.E. Smith), to entomopathogenic fungi from South Sumatra, Indonesia

BackgroundThe fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a newly introduced pest that damages maize production in Indonesia. To control this pest in maize fields, better solution is to use the egg parasitoid, such as Telenomus remus Nixon (Hymenoptera: Scelionidae), as another better option to apply topically entomopathogenic fungi (EPF). Therefore, it is necessary to study the effect of the EPF on the egg parasitoid of T. remus. The objective of this research was to evaluate susceptibility of immature T. remus to the EPFs, Beauveria bassiana, Chaetomium sp., Curvularia lunata, Penicillium citrinum, and Metarhizium anisopliae. The EPFs (1 × 106 conidia mL−1) were sprayed topically on one-day-old mummies (immature T. remus) in post-parasitism periods.ResultsThe results showed that the cumulative percentage of T. remus adult emergence from the mummies treated with EPF on 11 days after treatment ranged 54–100% and was non-significantly different than those of control (untreated with EPF) (90.48%). Therefore, the immature stage of T. remus was not susceptible to the EPF topical application. The EPFs were harmless to the immature stage of T. remus. Percentage of aborted mummies (embryonic death) of T. remus after treated with the EPF was also non-significantly different than those of control. However, the EPFs could significantly affect developmental times of immatures stages of T. remus. The EPF also could shorten the adult longevity of the egg parasitoid.ConclusionsThe immature T. remus is less sensitive to the EPFs; B. bassiana, Chaetomium sp., C. lunata, P. citrinum, and M. anisopliae. It can be considered integrating the EPF with T. remus inundation in maize field. However, it is necessary to limit the topical application of the EPF to avoid negative effects on the adult longevity of the egg parasitoid. Thus, it needed to be further investigated that the application of the endophytic EPFs by inoculating the fungi within the plant tissue could be harmless to the egg parasitoids.

Virulence Bioassay of Entomopathogenic Fungi against Adults of Atta mexicana under Controlled Conditions

Leafcutter ants (Atta spp.) are one of the mos t economically harmful pests in agriculture, considered dominant in the Neotropics and South America. Mature colonies of A. mexicana have a great economic impact on Mexico’s agriculture. Microbial agents in the form of biopesticides are an effective component of integrated pest management (IPM) strategies and may present a better alternative to synthetic insecticides. Among the fungi most used as biological insecticides there are Beauveria bassiana and Metarhizium anisopliae. The objective of this research was to evaluate the effect of the entomopathogenic fungi B. bassiana and M. anisopliae of commercial origin and a native strain of B. bassiana from México (MA-Bb1) on adults of Atta mexicana under controlled conditions. In the bioassay, five formulations and a control group were tested (B. bassiana MA-Bb1, B. bassiana MA-Bb1+ Diatomin®, B. bassiana®, M. anisopliae®, Diatomin®, and Tween 80 (0.01%). The MA-Bb1+ Diatomin® biopreparation induced the highest mortality (100%) in four-week-old A. mexicana, followed by the MA-Bb1, M. anisopliae®, and B. bassiana® biopreparations, which caused mortality of 83.33%, 73.98%, and 68.70%, respectively. Treatments containing B. bassiana and M. anisopliae were efficient in controlling A. mexicana under controlled conditions. The most efficient biological control was achieved with the B. bassiana fungus and Diatomin®, which presented the highest total death rate in A. mexicana 96 h post infection, in contrast to the control group (Tween 80), which attained the lowest speed of death in the present investigation.

Development of SCAR Markers for Genetic Authentication of Metarhizium acridum

In this study, molecular typing using Randomly Amplified Polymorphic DNA (RAPD-PCR) was conducted on 16 original isolates of Metarhizium acridum obtained from locusts (Schistocerca piceifrons ssp. piceifrons.) in Mexico (MX). The analysis included reference strains of the genus Metarhizium sourced from various geographical regions. The isolates were identified by phenotypic (macro and micromorphology) and genotypic methods (RAPD-PCR and Amplified Fragment Length Polymorphisms (AFLP), through a multidimensional analysis of principal coordinates (PCoA) and a minimum spanning network (MST). Subsequently, Sequences-Characterized Amplified Region (SCAR) markers were developed for the molecular detection of M. acridum, these markers were chosen from polymorphic patterns obtained with 14 primers via RAPD-PCR. Phenotypic and genotypic characterization identified the MX isolates as M. acridum. Of all the polymorphic patterns obtained, only OPA04 and OPA05 were chosen, which presented species-specific bands for M. acridum, and further utilized to create SCAR markers through cloning and sequencing of the specific bands. The specificity of these two markers was confirmed via Southern hybridization. The SCAR markers (Ma-160OPA-05 and Ma-151OPA-04) exhibit remarkable sensitivity, detecting down to less than 0.1 ng, as well as high specificity, as evidenced by their inability to cross-amplify or generate amplification with DNAs from other strains of Metarhizium (as Metarhizium anisopliae) or different genera of entomopathogenic fungi (Cordyceps fumosorosea and Akanthomyces lecanii). These SCAR markers yield readily detectable results, showcasing high reproducibility. They serve as a valuable tool, especially in field applications.

Morpho-molecular study of entomopathogenic fungi associated with citrus orchard pests in Northern Iran.

Entomopathogenic fungi play a significant role in regulating insect populations in nature and have potential applications in pest management strategies in different regions. Citrus spp. are among the important horticultural products in northern Iran, and the orchards are affected by different insect pests, especially mealybugs. This study aimed to isolate and identify entomopathogenic fungi associated with citrus orchard pests in northern Iran, focusing on Akanthomyces and Lecanicillium species on mealybugs. Through the samples collected from different regions within Guilan province, 12 fungal isolates were collected and identified based on the combination of morphological characteristics and molecular data. Akanthomyces lecanii, A. muscarius, Engyodontium rectidentatum, Lecanicillium aphanocladii and Lecanicillium rasoulzarei sp. nov. were identified. Of these, A. muscarius on Lepidosaphes sp., E. rectidentatum on Coccidae, and L. aphanocladii on Tetranychus urticae are reported as new fungal-host records from Iran. Moreover, a new species, Lecanicillium rasoulzarei, is illustrated, described, and compared with closely related species.

A new fungal entomopathogen has potency as a biocontrol agent of longhorn beetle larva, Osphranteria coerulescencs

A new fungal entomopathogen has potency as a biocontrol agent of longhorn beetle larva, Osphranteria coerulescencs

Implementation of Omics Approaches in Unravelling the Potency of Cordyceps militaris in Drug Discovery

Abstract:: Natural products have long garnered the interest of scientific communities as they have proven to be an effective therapeutic resource that paved the path for medicinal research and drug development. Among them, Cordyceps militaris is an entomopathogenic caterpillar fungus with a renowned history of being utilized as a medicinal remedy for centuries in Eastern civilizations. The number of pharmacological functions reported by this specific fungus resulted in continuous efforts to unravel new effective bioactive compounds and their corresponding mechanism of action. As time progresses, computational techniques become the forefront of genomic and proteomic analysis, besides acting as a platform for integrating various up-to-date multidisciplinary data sources. This review briefly introduces Cordyceps militaris alongside the latest known biologically active compounds and their respective therapeutic potential. The need to implement computational applications to cope with the continuous phytochemical evolution of Cordyceps militaris will be illustrated. Moreover, many databases, mathematical algorithms, or sourcing tools that could benefit data visualization, dissemination, and interpretation aligned to fungal-based research are enumerated, in addition to describing some of the broad discoveries relative to Cordyceps militaris in the past. In conclusion, using advanced computational technology may be the foundation to leverage natural product discovery about Cordyceps militaris and contribute to future mass production of this fungus for commercial purposes in the world pharmaceutical industry.

Thermal ecology shapes disease outcomes of entomopathogenic fungi infecting warm-adapted insects

The thermal environment is a critical determinant of outcomes in host-pathogen interactions, yet the complexities of this relationship remain underexplored in many ecological systems. We examined the Thermal Mismatch Hypothesis (TMH) by measuring phenotypic variation in individual thermal performance profiles using a model system of two species of entomopathogenic fungi (EPF) that differ in their ecological niche, Metarhizium brunneum and M. flavoviride, and a warm-adapted model host, the mealworm Tenebrio molitor. We conducted experiments across ecologically relevant temperatures to determine the thermal performance curves for growth and virulence, measured as % survival, identify critical thresholds for these measures, and elucidate interactive host-pathogen effects. Both EPF species and the host exhibited a shared growth optima at 28 °C, while the host’s growth response was moderated in sublethal pathogen infections that depended on fungus identity and temperature. However, variances in virulence patterns were different between pathogens. The fungus M. brunneum exhibited a broader optimal temperature range (23–28 °C) for virulence than M. flavoviride, which displayed a multiphasic virulence-temperature relationship with distinct peaks at 18 and 28 °C. Contrary to predictions of the TMH, both EPF displayed peak virulence at the host's optimal temperature (28 °C). The thermal profile for M. brunneum aligned more closely with that of T. molitor than that for M. flavoviride. Moreover, the individual thermal profile of M. flavoviride closely paralleled its virulence thermal profile, whereas the virulence thermal profile of M. brunneum did not track with its individual thermal performance. This suggests an indirect, midrange (23 °C) effect, where M. brunneum virulence exceeded growth. These findings suggest that the evolutionary histories and ecological adaptations of these EPF species have produced distinct thermal niches during the host interaction. This study contributes to our understanding of thermal ecology in host-pathogen interactions, underpinning the ecological and evolutionary factors that shape infection outcomes in entomopathogenic fungi. The study has ecological implications for insect population dynamics in the face of a changing climate, as well as practically for the use of these organisms in biological control.

Interaction of beauvericin in combination with antibiotics against methicillin-resistant Staphylococcus aureus and Salmonella typhimurium

Multidrug resistance in bacteria is a major challenge worldwide, increasing both mortality by infections and costs for the health systems. Therefore, it is of utmost importance to find new drugs against resistant bacteria. Beauvericin (BEA) is a mycotoxin produced by entomopathogenic and other fungi of the genus Fusarium. Our work determines the effect of BEA combined with antibiotics, which has not been previously explored. The combination analysis included different antibiotics against non-methicillin-resistant Staphylococcus aureus (NT-MRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Salmonella typhimurium. BEA showed a synergy effect with oxacillin with a fractional inhibitory concentration index (FICI) = 0.373 and an additive effect in combination with lincomycin (FICI = 0.507) against MRSA. In contrast, it was an antagonist when combined with ciprofloxacin against S. typhimurium. We propose BEA as a molecule with the potential for the development of new therapies in combination with current antibiotics against multidrug-resistant bacteria.

Effects of an entomopathogenic fungus on the reproductive potential of Drosophila males.

While mortality is often the primary focus of pathogen virulence, non-lethal consequences, particularly for male reproductive fitness, are less understood; however, they are essential for understanding how sexual selection contributes to promoting resistance. We investigated how the fungal pathogen Metarhizium brunneum affects mating ability, fertility, and seminal fluid protein (SFP) expression of male Drosophila melanogaster paired with highly receptive virgin females in non-competitive settings. Depending on sex and dose, there was a 3-6-day incubation period after infection, followed by an abrupt onset of mortality. Meanwhile, the immune response was strongly induced already 38 h after infection and continued to increase as infection progressed. Latency to mate somewhat increased during the incubation period compared to sham-treated males, but even on Day 5 post infection >90% of infected males mated within 2 h. During the incubation period, M. brunneum infection reduced male reproductive potential (the number of offspring sired without mate limitation) by 11%, with no clear increase over time. Approaching the end of the incubation period, infected males had lower ability to convert number of mating opportunities into number of offspring. After repeated mating, infected males had lower SFP expression than sham controls, more so in males that mated with few mates 24 h earlier. Overall, despite strong activation of the immune response, males' mating ability and fertility remained surprisingly little affected by the fungal infection, even shortly before the onset of mortality. This suggests that the selection for resistance acts mainly through mortality, and the scope for fertility selection to enhance resistance in non-competing settings is rather limited.

Industrial attractiveness of entomopathogenic Fusarium as biopesticide against melon thrips, Thrips palmi

AbstractMelon thrips, Thrips palmi (Thysanoptera: Thripidae), is a serious insect pest in crop productions, and synthetic chemicals are frequently used to control them. However, this practice causes residual issue in nature and makes melon thrips acquire strong resistance. To overcome these problems, a group of entomopathogenic fungi could be used as an alternative for controlling melon thrips. In this work, a total of 100 fungal isolates from soil in four different regions of Korea were isolated and subjected to virulence assays against melon thrips. Twenty‐five highly virulent fungal isolates, which showed 100% mortality 6 days after treatment, were determined. Liquid‐cultured filtrates of the selected isolates were further used to investigate their insecticidal activity against melon thrips, and of the 25 selected isolates finally seven isolates including Metarhizium spp. and Fusarium spp. showed high insecticidal activity in a dose‐dependent manner. Under a thermal stress at 121°C, culture filtrates of the seven isolates still kept their insecticidal activities. When liquid‐cultured spores were exposed to 45°C, spores of Fusarium isolates were resistant to the thermal stress, but those of Metarhizium isolates were susceptible to the stress. The culture filtrates of Fusarium isolates did not show any phytotoxicity to the tomato plants, followed by no phytotoxicity of liquid‐cultured spores, although mycotoxins need to be further clearly characterized. This work suggests that entomopathogenic Fusarium isolates are competitive in virulence against melon thrips and production of insecticidal metabolites compared to Metarhizium, and particularly attractive in sporal resistance against thermal stress, significantly stronger than Metarhizium.

Pathogenicity, infection process, physiological and biochemical effects of Metarhizium rileyi against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) larvae

BackgroundMetarhizium rileyi is an important entomopathogenic fungus which has a wide range of host pests. In this work, the virulence of M. rileyi EFNL-08 against 3rd instar larvae of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was quantified. Additionally, the infection process and aspects of the host immunological response were described in the laboratory.ResultsBioassay results proved that M. rileyi was highly virulent to 3rd instar S. frugiperda larvae with 98.33% mortality at 1 × 108 conidia/ml. Scanning electron microscopy was used to monitor morphological aspects of the infection process. When hyphal bodies (Hbs) of M. rileyi were injected into the hemocoel of host, they were not recognized by the host’s immune system as invaders. There were nonsignificant differences in the hemocytes and phenoloxidase activity between the infected and control larvae at the initial 30 h, indicating that fungus successfully avoids the attack from the immune system. However, it inhibited the enzyme activity at the latest stage when Hbs reached a high density. After infection with M. rileyi, the activity of glutathione-S-transferase (GST) of S. frugiperda larvae presented a significant upward trend, while the activity of acetylcholinesterase (AchE) initially increased, followed by a decrease, and eventually stabilized. However, the activity of both detoxification enzymes in the control group showed slight fluctuations in the initial stage, and then stabilized at a low level.ConclusionObtained results provided new insights into the virulence and potential physiological responses of M. rileyi. This provides ideas for further development of novel and efficient entomopathogenic fungi (EPF) for pest control.

Can we manage alien invasive insects without altering native soil faunal communities? A field trial on Popillia japonica

Biological and integrated pest control are key assets to environmentally friendly management of cropland. Use of entomopathogens against target pests is common, yet the effects of such released organisms on native, non-target invertebrates are currently poorly known. This is particularly true for relatively inconspicuous components of agroecosystems such as soil biological biota. Popillia japonica, a polyphagous alien invasive scarab beetle native to Japan, is now present in Europe where huge efforts are being conducted to control the pest and slow its spread. In particular, entomopathogenic nematodes and fungi have been used for larval control. Here we test the effects of those agents on both P. japonica larvae and non-target soil biota by comparing soil arthropod assemblages before and after treatment of field plots in an irrigated perennial meadow.Application of an indigenous strain of the nematode Heterorhabditis bacteriophora resulted in significant reduction in numbers of P. japonica larvae. In contrast, an indigenous strain of the entomopathogenic fungus Metarhizium robertsii failed to provide significant control. We found no evident effect on non-target edaphic arthropods under either treatment in comparison to untreated control plots. Some taxa, namely Collembola and Acarina, showed a disproportionate increase in treated plots, suggesting that some changes may occur in the long term, at least in particular arthropod groups. Our results suggest the selected strain of H. bacteriophora is an excellent candidate for managing P. japonica larvae with minimal adverse impact on non-target species and ecosystem functioning.

Enzyme production by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and their application in the control of nematodes (Haemonchus spp. and Meloidogyne incognita) in vitro

Brazil is affected by the infection of gastrointestinal nematodes (Haemonchus spp.) because it causes subclinical diseases in small ruminants that directly affect weight and milk production and, in turn, generate a health risk for the animals. In the same way root-knot nematodes (Meloidogyne incognita) is a serious disease, which parasitize the roots of tomato plants causing damage such as poor nutrient absorption leading to significant yield losses. In order to minimize the economic impact of these nematodes, it is important to establish new control strategies. Beauveria bassiana and Metarhizium anisopliae are two main mycoinsecticides used to control many orders of insects, such as Lepidoptera and Hemiptera. These fungi have the ability to produce extracellular enzymes, which play an important role to control in the pest infection process. The aim of this study was to evaluate the production of proteases and chitinases by the entomopathogenic fungi B. bassiana and M. anisopliae on different solid and liquid culture media and their application in vitro to the control of Haemonchus spp and Meloidogyne incognita. To achieve this goal, enzymes were produced under solid and liquid fermentation conditions to determine the highest chitinolytic and proteolytic activity of commercial two strain of B. bassiana (IBCB 66 and ESALQ PL63) and M. anisopliae (IBCB 425 and ESALQ E9) in liquid media: SDY broth, YPG culture medium, synthetic, and soluble starch with yeast extract. The solid media tested were: rice supplemented with whey and chrysalis flour mixed with rice. In addition, the nematicidal action of their extracts (containing concentrated enzymes and without fungal cells) was measured. The results showed that the best culture medium (p< 0.01) for protease was solid serum rice medium, with a value for M. anisopliae IBCB 425 of 52 U/mg, and for B. bassiana ESALQ PL63 the value was 36 U/mg, compared to all the tested media. On the other hand, for chitinase of M. anisopliae strain IBCB 425, the activity value was close to 0.60 U/mg. In contrast, for B. bassiana isolate ESALQ PL63, SDY medium was the best inducer for chitinase production, with a value of 0.90 U/mg. Regarding the nematicidal activity of the crude extracts, the reduction percentages were 58% for ESALQ PL63 and 100% for IBCB 425 in the case of animal parasites. For plant parasites, the reduction percentages were 19% for ESALQ PL63 and 71% for IBCB 425. Thus, the use of enzyme-rich crude extracts presents promising control options for pest control.