Isolates Of Entomopathogenic Fungi Research Articles

Study on the insecticidal activity of entomopathogenic fungi for the control of the fruit fly (Anastrepha obliqua), the main pest in mango crop in Colombia

The aim of this study was to evaluate and select entomopathogenic fungi that produces insecticidal compounds for the control of adults of Anastrepha obliqua Macquart (Diptera: tephritidae) that are the main pest of mango (Mangifera indica L. Bark) in Colombia. Nine entomopathogenic fungi isolates were evaluated, five belonging to the genus Metarhizium and four belonging to the genus Beauveria. One strain of the species Metarhizium robertsii with insecticidal activity was selected. By column fractionation, an active fraction was obtained, which caused mortalities higher than 90% after 48 h of exposure. Through HPLC it was determined that the active fraction is composed of more than 22 metabolites. Identification of the metabolites by UHPLC MS/MS revealed the presence of destruxin in E, D, A and B groups (destruxin E-diol, destruxin D, destruxin D1, destruxin D2, destruxin A2, destruxin A, destruxin A3, dihydrodestruxin A, desmB, destruxin B2, destruxin B and destruxin B1). The evaluation of the insecticidal capacity of the organic fractions obtained by HPLC indicated that the extract obtained from the isolate M. robertsii had a compound with high activity on adults of A. obliqua (destruxin A) causing massive mortality of up to 100%, after 48 h of the treatment administration. Furthermore, two other compounds with medium activity were found (destruxin A2 and destruxin B), showing mortalities between 60.0 and 81.3%, respectively. The extract of the isolate MT008 of M. robertsii showed higher insecticidal activity and a potential source for the control of A. obliqua

PATHOGENICITY OF ISOLATES OF ENTOMOPATHOGENIC FUNGI TO WORKERS OF Acromyrmex heyeri (Forel, 1899) (HYMENOPTERA: FORMICIDAE)

Leaf-cutting ants stand out among the main pests of agricultural and forestry crops. Chemical control is the most used method to control these insect pests, requiring the development of techniques that are less harmful to the environment. The present study aimed at verifying the action of Beauveria bassiana (Bals.) Vuill, Cordyceps fumosorosea (Wize), and Metarhizium anisopliae (Metsch.) Sorokin isolates on the in vitro mortality of Acromyrmex heyeri (Forel). Seven isolates of entomopathogenic fungi were used: three isolates of Beauveria bassiana (IBCB 66, IBCB 170, and IBCB 632), one isolate of Cordyceps fumosorosea (IBCB 130), and three isolates of Metarhizium anisopliae (IBCB 348, IBCB 383, and IBCB 425), and five concentrations of spores (1.0×104, 1.0×105, 1.0×106, 1.0×107, and 1.0×108 spores mL-1) for each fungal isolate. The control treatment consisted of autoclaved distilled water and 0.01% Tween 40, without fungal pathogens. The experiments were carried out in a completely randomized design with five replications. Estimation of lethal concentrations of LC50 and LC90 was performed using Probit analysis. The isolates of B. bassiana, C. fumosorosea, and M. anisopliae were pathogenic to leaf-cutting ants with the five tested concentrations of spores. Higher mortality of the specimens was reached with increasing concentration. The entomopathogenic fungi evaluated in this study proved to be efficient agents for the biological control of Acromyrmex heyeri.

Field Evaluation of Promising Indigenous Entomopathogenic Fungal Isolates against Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae).

The rate of the sounds (i.e., substrate vibrations) produced by the movement and feeding activity of red palm weevil (RPW) pest infestations in a date palm tree was monitored over time after trees were separately treated with injection of entomopathogenic fungal isolates, Beauveria bassiana and Metarhizium anisopliae, or water treatment as the control. The activity sensing device included an accelerometer, an amplifier, a digital recorder, and a signal transmitter that fed the data to a computer that excluded background noise and compared the rates of bursts of movement and feeding sound impulses among treated trees and controls. Observations were made daily for two months. The rates of bursts were representative of the feeding activity of RPW. The unique spectral pattern of sound pulses was typical of the RPW larval feeding activity in the date palm. The microphone confirmed that the same unique tone was produced in each burst. Two months after fungal injection, the RPW sound signal declined, while the RPW sound signal increased in the control date palms (water injection). The mean rates of bursts produced by RPW decreased to zero after the trees were injected with B. bassiana or M. anisopliae compared with the increased rates over time in the control treatment plants.

Endophytic Potential and Larvicidal Efficacy of Entomopathogenic Fungi against the Spotted Stem Borer, Chilo partellus

Entomopathogenic fungi (EPF) of different genera are known to have the potential to engage in fungus-plant interactions as fungal endophytes. This hidden endophytic interaction offers several advantages to host plants, such as insect pest management. Hence, this study aimed to explore the endophytic potential and virulence of EPF collections after artificial inoculation. A total of 27 EPF isolates from the genera Beauveria and Metarhizium were screened for virulence. Two inoculation methods (leaf and seed dressing) were used to study the endophytic colonisation potential of the selected isolates. There was a significant variation among the tested isolates in their ability to kill C. partellus larvae. Lower mean percentage mortality was recorded for isolates B4, DS-51-21, and B1,9 which scored 28.01%, 32.29%, and 34.58%, respectively. All the screened EPF isolates were able to colonise maize tissues after artificial inoculation, except for APPRC-34GM. The percent colonisation of maize tissues varied with strains, and delivery methods ranged from a minimum of 0% to a maximum of 53%, where the maximum was recorded by S#10H. Larval mortality after feeding maize leaves inoculated with EPF ranged from 18% to 60%. The findings of this study indicated that Beauveria spp. and Metarhizium spp. have the potential to colonise maize after artificially inoculating and translocating from the site of infection. Hence, the potential to move from the site of infection and larvicidal activity after colonisation may give the advantage to manage insect pests acting on the different parts of maize.

Potential of entomopathogenic fungi as biological control agents of Yponomeuta malinellus Zeller, 1838 (Lepidoptera: Yponomeutidae)

The apple ermine moth, Yponomeuta malinellus Zeller, 1838 (Lepidoptera Yponomeutidae), is a common pest of apple trees in Asia and Europe, and it has spread to North America. In apple growing regions of Turkey, the population of this pest may increase from time to time, requiring a separate control measure. In such cases, Turkish apple growers generally rely on synthetic insecticides to control this pest. The present study aimed to evaluate indigenous isolates of some entomopathogenic fungi (EPFs) against the pest as potential biological control agents. In the pathogenicity tests, 14 EPF isolates that belong to 4 fungal species [Beauveria bassiana (Bals.) Vuill. – 7, Clonostachys rosea (Link) Schroers – 3, Isaria farinosa (Holmsk.) Fr. – 2 and Purpureocillium lilacinum (formerly known as Paecilomyces lilacinus (Thom) Samson) (Thom) Luangsa-ard, Houbraken, Hywel-Jones & Samson – 2] were assayed against the 4th instar larvae of Y. malinellus under laboratory conditions. All the EPF isolates were tested against the pest with three different conidial suspensions (1 × 107, 1 × 108 and 1 × 109 conidia ml-1), using the spray method. The results of pathogenicity assays demonstrated that the effectiveness of the isolates increased with increasing concentration and elapsed time up to 9 days after treatment. Of the 14 isolates tested, 3 B. bassiana isolates (BbDm-1, BbDs-2 and BbKm-3) were the most pathogenic, causing mortalities between 96.7% and 100% at the highest concentration 9 days post treatment. All the results suggest that the most pathogenic above-mentioned 3 isolates of B. bassiana have a significant biocontrol potential against Y. malinellus.

Potential of a combination of entomopathogenic fungal strains and a non-ionic surfactant to control the fall armyworm (Spodoptera frugiperda)

• Two entomopathogenic fungi isolates were isolated for controlling fall armyworm. • Mp -NCHU-124 and Bb -NCHU-157 showed dose-dependent effects on the FAW. • The Silwet L-77 rapidly killed FAW and tested for the EPF compatibility. • Combination with Silwet L-77 and EPF increased the mortality of FAW, reduced LT 50. • Combination with Silwet L-77 and EPF increased fungal mycosis of FAW. The fall armyworm, Spodoptera frugiperda , is an emerging invasive pest in Taiwan that feeds on a wide range of crops and causes serious damage. Herein, an entomopathogenic fungal library (EFLib) was constructed to identify potential microbes to control FAW. Twenty-eight indigenous entomopathogenic fungi (EPF) were isolated and investigated for their potential pathogenicity, with Metarhizium pinghaense ( Mp -NCHU-124) and Beauveria bassiana ( Bb -NCHU-157) exerting dose-dependent effects on the 4 th instar FAW larvae. The non-ionic surfactant Silwet L-77 rapidly killed FAW larvae after spraying at a concentration of 300 mg/kg and the toxic effect of Silwet L-77 on FAW larvae was dose-dependent. When the EPF isolates (10 6 conidia/mL) were applied to FAW larvae in combination with the non-ionic surfactant Silwet L-77 (30–90 mg/kg), the mortality rate dramatically increased and the LT 50 reduced, with increased fungal mycosis ( Mp -NCHU-124: 38% to 72% and Bb -NCHU-157: 20 to 62%), indicating the high compatibility of EPF with the non-ionic surfactant. Thus, the Silwet L-77+EPF combined formulation has potential for practical field application for FAW pest control and sustainable agriculture in the future.

DNA barcoding reveals the natural occurrence of Beauveria bassiana (Balsamo) Vuillemin in two-spotted spider mite, Tetranychus urticae Koch in Bhendi [Abelmoschus esculentus (L.) Moench] ecosystem in Coimbatore district of Tamil Nadu

BackgroundTwo-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) incidence is a major constraint in vegetable cultivation. The indiscriminate use of acaricides is causing environmental threat and also residual effect in vegetables. To develop an eco-friendly management strategy, an investigation was made to access the natural occurrence of entomopathogenic fungi (EPF) infecting mites in bhendi, India ecosystem.ResultsNatural incidence of EPF was high during the month of December. Twelve EPF isolates were isolated from the mycosed T. urticae cadavers using Potato Dextrose Agar Medium. Morphological studies confirmed that the isolated fungi were Beauveria bassiana. PCR amplification of ITS region was carried out and the results showed, amplification at 560 bp. In NCBI database, the sequence of the virulent isolates had shown 99.2, 98.7, 99.1, 97.7 and 96.8% homology with other B. bassiana isolates, confirming the occurrence of B. bassiana mycosed mites in vegetable ecosystem.ConclusionThe isolate MZ749636 (B.b-7) was found to be virulent against T. urticae causing 86% mortality of T. urticae at the conidial load of 1 × 108 conidia/ml at laboratory conditions and so it could be utilized for the eco-friendly management of T. urticae.

Molecular identification and efficacy of entomopathogenic fungi isolates against larvae of the Asian corn borer Ostrinia furnacalis (Lepidoptera: Crambidae) in Xinjiang, China

This study aimed to isolate and identify entomopathogenic fungi (EPF) from fungus-infected Ostrinia furnacalis larvae, screen their bio-efficacy against O. furnacalis, and select the most suitable virulent native EPF for biocontrol agent development. The occurrence of EPF isolated from various maize production regions in Xinjiang was investigated. Of 13,864 O. furnacalis cadavers surveyed, 536 were selected, and of 136 fungal specimens collected, 14 species were identified. Four fungal isolates were highly pathogenic to O. furnacalis: Aspergillus sp., Lecanicillium attenuatum, Beauveria bassiana and Penicillium polonicum. The Aspergillus sp. was the most abundant (42.25% distribution frequency). Bioassay results revealed that it was as pathogenic as B. bassiana (positive control), with 96.58% lethality against O. furnacalis (LC50 : 1.40 × 104 conidia ml-1 , LT50 : 3.41 days). Through morphological examination and rDNA-benA and rDNA-CaM homogeneity analyses, the isolate was identified as Aspergillus nomius. Four EPF species were highly pathogenic, with A. nomius being the most prevalent in Xinjiang. A. nomius is a potential biocontrol agent. For sustainable prevention and control of O. furnacalis infestation, identifying biocontrol agents with high virulence against O. furnacalis is crucial. The findings of this study support the development of EPF-based biocontrol approaches.

Laboratory Evaluation of Temperature Effects on Germination, Radial Growth and Sporulation of Entomopathogenic Fungi and on Their Pathogenicity to Red Spider Mite, Tetranychus urticae Koch

Background: Entomopathogenic fungus (EPF) can provide safe and efficient insect pest management. Temperature, relative humidity (RH), light, air, nutritional content and host physiological condition are all elements that impact the proliferation and virulence of entomopathogenic fungus. The current study aimed to evaluate the effect of different temperatures on germination, growth, sporulation of entomopathogenic fungi and on their pathogenicity against Tetranychus urticae Koch was studied. Methods: Laboratory experiment was conducted to study the impact of temperature on germination, radial growth and sporulation of five entomopathogenic fungal isolates viz., B. bassiana (Bb 111), B. bassiana (Bb 112), B. bassiana (Bb 113), B. bassiana (Bb 114) and M. flavoviride var. minus. Virulence of five entomopathogenic fungal isolates subjected to different temperature against T. urticae also evaluated through laboratory bioassay techniques. Result: Results one valuation of entomopathogenic fungal isolates with four different temperatures at 20°C, 25°C, 30°C and 35°C showed that 25°C was optimum for germination, radial growth and sporulation. Maximum germination was recorded with the entomopathogenic isolate Beauveria bassiana (Bb 112) (95.67%) at 25°C. Interestingly, at 25°C all the B. bassiana isolates showed a radial growth of more than 50 mm with the highest recorded as 84.67 mm by B. bassiana (Bb 111). Maximum spore production was observed with B. bassiana (Bb 112) at 25°C (1.63 x 106 spores ml-1) followed by B. bassiana (Bb 111) (1.45 x 106 spores ml-1). It was also the most pathogenic against T. urticae at 25 and 30°C. The isolate Bb112 grown at 25°C caused higher mortality of 97.57 per cent against T. urticae. From the findings the isolates of B. bassiana (Bb 112) and (Bb 111) were found promising bio control agent against T. urticae with varying temperature.

Retraction: Pathogenicity of local and exotic entomopathogenic fungi isolates against different life stages of red palm weevil (Rhynchophorus ferrugineus).

Retraction: Pathogenicity of local and exotic entomopathogenic fungi isolates against different life stages of red palm weevil (Rhynchophorus ferrugineus).

Molecular Characterization of Native Entomopathogenic Fungi from Ambrosia Beetles in Hazelnut Orchards of Turkey and Evaluation of Their In Vitro Efficacy.

Simple SummaryTurkey is the world’s largest producer and exporter of hazelnut. Ambrosia beetle species are the most common species of pests for hazelnut in the orchards of Turkey. These beetles cause enormous economic losses by draining hazelnut branches and trees. The techniques for managing ambrosia beetles are limited. The more effective and eco-friendly alternative control methods, including the use of entomopathogenic fungi (EPF), should be included in integrated pest management programs to suppress ambrosia beetle populations. The objectives of the current study were (i) to isolate EPF from individual ambrosia beetles that were obtained from Turkey’s main hazelnut production areas; (ii) to characterize EPF isolates using DNA sequencing and iPBS profiling; and (iii) to assess the effectiveness of the isolates against three ambrosia beetle species under laboratory conditions. A total of 47 EPF isolates were obtained from beetle cadavers and classified into eight EPF species. For the first time, the primer binding site (PBS) marker system was used to successfully discriminate among the EPF species. Some isolates caused 100% mortality of the beetle species within 7 to 9 days, depending on the beetle species, demonstrating their effectiveness in managing the pests. The major EPF species in this study provided an important basis for developing bioproducts and a possible alternative approach in controlling these ambrosia beetles.Ambrosia beetles, Anisandrus dispar Fabricius, Xylosandrus germanus Blandford, and Xyleborinus saxesenii Ratzeburg (Coleoptera: Curculionidae: Scolytinae) are among the most significant hazelnut pests in Turkey. The control of these pests is difficult and expensive due to their biology. The present study aimed to isolate entomopathogenic fungi (EPF) from A. dispar, X. germanus, and X. saxesenii individuals that were obtained from the main hazelnut production areas of Turkey, characterize the EPF isolates using internal transcribed spacer (ITS)-DNA sequencing and iPBS profiling, and determine the efficacy of the isolates against A. dispar, X. germanus, and X. saxesenii under laboratory conditions. Phylogenetic analyses based on ITS revealed that the 47 native isolates were Beauveria bassiana (11), B. pseudobassiana (8), Cordyceps fumosorosea (6), Cordyceps farinosa (1), Akanthomyces lecanii (13), Purpureocillium lilacinum (3), Clonostachys rosea (2) and Metarhizium anisopliae (3). For the first time, the primer binding site (PBS) marker system, based on retrotransposons, was used to discriminate successfully among the EPF species. Some isolates of B. bassiana, B. pseudobassiana, C. fumosorosea, A. lecanii, and M. anisopliae caused 100% mortality of the beetle species within 7 to 9 days. The findings of this study indicated that some isolated entomopathogenic fungi provide an essential basis for the development of bioproducts, as well as a promising alternative method for controlling these ambrosia beetles.

Combined effects of root-associated entomopathogenic and mycorrhizal fungi on the foliar pathogen Botrytis cinerea in tomato

Many fungi live intimately associated with plants and may benefit or harm the host plant. Improved knowledge of such interactions is needed for increasing plant health and crop productivity by implementation of fungal inoculants. Co-inoculations of different beneficial fungi offer the possibility to understand complex plant–microbe interactions that may be functionally complementary for improved plant production and protection. Here, we studied the individual and combined effects of the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae with three isolates of entomopathogenic fungi (EPF), representing Metarhizium brunneum, M. robertsii and Beauveria bassiana, on protection against the foliar phytopathogen Botrytis cinerea and on plant growth. Seedlings of tomato (Solanum lycopersicum L. var. Moneymaker) were inoculated in the substrate with AMF or EPF alone and in dual combinations under greenhouse conditions. Inoculation with the different EPF isolates reduced lesion sizes of B. cinerea on inoculated tomato leaves, but only in the experimental repetition that showed highest level of disease severity. The AMF F. mosseae had no additional effect on B. cinerea lesion size in combinations with EPF. In the experimental repetition with least disease severity, the AMF treatment led to limited increase of B. cinerea lesion sizes. In general, F. mosseae caused an increase in plant biomass, and the co-inoculations of AMF and EPF did in some combinations increase plant growth. Below-ground interactions between AMF and EPF were observed, as the presence of AMF in the roots was associated with a decrease of EPF root colonization densities. However, AMF colonization rates were unaffected by EPF presence. The study indicated a functional complementarity between EPF and AMF by suppressing phytopathogens and increasing plant growth, respectively. However, it further revealed the challenge of obtaining consistent results of plant–microbe-phytopathogen interactions, which must be overcome for future implementation of beneficial fungi as inoculants in plant production.

Pathogenicity of Indigenous Entomopathogen Liquid Formulation to Paddy Bugs Nymphs (Leptocorisa acuta Thunberg)

The purpose of this study was to determine the effectiveness of bio insecticide liquid formulations made from indigenous entomopathogens against paddy bugs nymphs. The study used a non-factorial Complete Randomized Design with 9 treatments and 1 control with five replications. The treatments studied consisted of E0: Control, E1: Beauveria sp Pky isolate + coconut water (CW), E2: Metarhizium sp isolate Jjt + AK, E3: Beauveria sp isolate Jts + CW, E4: Metarhizium sp isolate Lcc + CW, E5: Beauveria sp Pky isolate + shrimp shell extract (SSE), E6: Metarhizium sp isolate Jjt + SSE, E7: Beauveria sp isolate Jts + SSE, E8: Metarhizium sp isolate Lcc + SSE, E9: Synthetic insecticide b a Carbamate (Dharmabas 500 EC 2 ml L-1). The result showed that liquid bioinsecticide formulations were effective against mortality, infected nymphs and nymph death time. All entomopathogenic fungi isolates were able to cause infections in paddy bugs nymphs of 68% - 84%. Beauveria sp Pky isolate and Metarhizium sp isolate Jjt caused nymph mortality of 72% - 84% and the effectivity did not differ from insecticide b.a. Carbamate. Conidia viability of all entomopathogenic isolates in liquid media within 24 hours reached more than 80%. The fastest time to death of paddy bugs nymph occurred at 5.44 days ( Metarhizium sp. isolate) and 5.92 days (Beauveria sp. isolate) in coconut water media. Metarhizium sp. and Beauveria sp. in the medium of coconut water or shrimp shell extract has a very high potential to be developed as a bio insecticide, but it still needs to be further tested for its effectiveness in field conditions.Keywords: indigenous entomopathogen, coconut water, shrimp shell extract, paddy bugs nymph

Infectivity of Entomopathogenic Fungal Isolates Against Tarnished Plant Bug Lygus lineolaris (Hemiptera: Miridae).

Twelve isolates of entomopathogenic fungi belonging to Metarhizium robertsii, M. pinghaense, M. brunneum, Beauveria bassiana, and Isaria fumosorosea were screened against tarnished plant bug. All isolates were pathogenic, causing mortality from 28.8 ± 3.4 to 96.3 ± 2.7%. The LT50 values ranged from 2.7 to 6.0 d while the LT90 values varied between 6.6 and 15.0 d. Metarhizium robertsii isolate CPD6 (will be under the trade name NoVil) was among the isolates that caused high mortality within shorter times and was selected for study on developmental stages and greenhouse trial. The third-, fourth-, and fifth-instar nymphs, and adults were inoculated with 106, 107, and 108 conidia per ml of NoVil. All the stages were susceptible to fungal infection. However, third and fourth instars were the most susceptible with no significant differences in mortality across the three concentrations. On the other hand, mortality was dose-dependent with fifth-instar nymph and adult stages. The LT50 and LT90 values were also dose-dependent, with higher concentrations having shorter lethal-time values as compared to the lower concentrations. In the greenhouse, pepper plants were sprayed with NoVil and chemical insecticide Flonicamid (as industrial standard), before releasing adult tarnished plant bug. Mortality of 37.3, 75.5, and 76.3% was recorded in the control, NoVil, and Flonicamid, respectively. This study has identified NoVil as a potential mycoinsecticide candidate for the control of tarnished plant bug under greenhouse conditions. Further field testing on juvenile and adults is needed to evaluate the potential for in-field control.

Efficacy of single and combined applications of entomopathogenic fungi and nematodes against the pupae of colorado potato beetle (Leptinotarsa decemlineata [Say]), (Coleoptera: Chrysomelidae)

BackgroundThe lethal effects of different entomopathogenic fungi (EPF) and nematodes (EPN) on the pupae of the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) were investigated in a two-step study when used separately or together. In the first step, Nostalgist (Beauveria bassiana strain Bb-1, Agrobest Co.), Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae), Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) (Bioglobal Co.), 2 Turkish isolates of Beauveria bassiana BIM-001 and BY2 were applied separately to the pupal stage of pest in the soil. In the experiments, 3 different concentrations (150, 200, and 250 million infective juveniles (IJs)/100 l water) of EPN and a single concentration (1x108 spores/ml for and maximum recommended field dose 1 × 108 CFU/ml) of EPF were used. In the second step, BIM-001 and BY2 isolates of B. bassiana were combined with both EPN species; S. feltiae + B. bassiana BIM-001, S. feltiae + B. bassiana BY2, H. bacteriophora + B. bassiana BIM-001, H. bacteriophora +B. bassiana BY2 were applied to pupae. At this stage, 150 million IJs/100 l water which was the maximum recommended field concentration for EPN and 1 × 108 spores/ml for local EPF isolates were used.ResultsAccording to the study results, pupae deaths were significantly higher in Nostalgist (74%) than those of B. bassiana BIM-001, B. bassiana BY2, S. feltiae, and H. bacteriophora (P<0.05). While both EPN caused higher mortality than B. bassiana BY2, B. bassiana BIM-001 had the highest mortality rates. The combination of S. feltiae + B. bassiana BIM-001 at the highest mortality rate (80%) was found statistically different and significant from other EPF + EPN treatments on pupae. Moreover, there were non-statistical differences between the other EPF and EPN combinations.ConclusionIt was found that the combined use of EPF and EPN was more effective on the pupae of L. decemlineata than a single application. According to the results of the study, it may be promising to use EPN and EPF together for the control of the Colorado Potato Beetle pupae.

Pathogenicity of Entomopathogenic Fungi Fusarium beomiforme against Rhipicephalus microplus Tick Infestation in Cattle

Background: Tick infestation in cattle is commonly controlled using chemical acaricides producing acaricidal resistance, environmental pollution and hazards to human health. Biological control of ticks using entomopathogenic fungi can be an alternative to chemical acaricides and can be used in conjunction with chemical control in integrated pest management. Methods: The isolation of entomopathogenic fungi was carried out from naturally infected ticks in Durg district of Chhattisgarh. The species confirmation of fungal isolates was conducted by Polymerase chain reaction (PCR) using ITS gene as a molecular marker. In vitro efficacy of entomopathogenic fungi at various concentrations against engorged (adult) female ticks and unfed (Nymphs), egg laying capacity and egg hatchability of treated Rhipicephalus microplus was assessed in laboratory. Result: The entomopathogenic fungi isolated from naturally infected ticks was confirmed as Fusarium beomiforme by morpho- molecular analysis. The efficacy of F. beomiforme against adult female and nymphs of R. microplus at the concentration of n x 108 spores ml-1 showed 100% mortality. The 100% reduction of egg laying capacity of treated female ticks and no hatchability of eggs treated with F. beomiforme at the concentration of n x 107 spores ml-1 and n x 108 spores ml-1 was observed.

Compatibility levels of fipronil with entomopathogenic fungi

The present study evaluated the compatibility of the insecticide fipronil with entomopathogenic fungi, in vitro. The compatibility betwee fipronil and entomopathogenic fungi was based on vegetative growth and sporulation of seven isolates of fungi. The studied isolates were three from Beauveria bassiana, one from Cordyceps fumosorosea, and three from Metarhizium anisopliae, and four concentrations of fipronil (0.2, 0.4, 0.6, and 0.8 g L-1), added in PDA (potato-dextrose-agar) culture medium. After 15 days, the colony diameter was measured and the spores were recorded. There was a reduction in the vegetative growth of the isolates at concentration of 0.8 g L-1 of fipronil. For the isolates of B. bassiana and M. anisopliae, there was a decrease in spore production when added the concentrations above 0.4 g L-1 of fipronil; and for C. fumosorosea, spore production decreased when fipronil concentrations were greater than 0.6 g L-1. The insecticide fipronil was classified as “compatible” in terms of toxicity in vitro for tested fungi isolates depending on its concentration. The combination of the insecticide fipronil with the entomopathogenic fungi isolates tested is possible at concentrations below 0.6 g L-1.

Virulence of native isolates of entomopathogenic fungi (Hypocreales) against the “sweetpotato whitefly” Bemisia tabaci (Hemiptera: Aleyrodidae), including the effects of temperature and fungicides

Hypocrella, Moelleriella and related species in the Hypocreales (Ascomycota, Sordariomycetes) cause epizootics of whiteflies and scale insects in nature. However, studies on their host specificity, virulence, infection cycles, optimal development under laboratory conditions, and compatibility with other control methods, are unexplored for most species. Under laboratory conditions, the virulence of several isolates of field-collected hypocrealean fungi (Hypocrella, Moelleriella, Regiocrella, and Verticillium) was determined on Bemisia tabaci eggs and 4th instar nymphs. In addition to virulence, the effect of temperature and two commercial fungicides on growth rates and germination of the isolates was evaluated. None of the isolates infected the eggs, while M. libera, M. ochracea, and M. turbinata caused high nymphal mortality. Moelleriella libera was the most virulent isolate. At all temperatures, M. libera, Regiocrella sp. (P17H20), and Verticillium cf. pseudohemipterigenum had the highest germination and growth rates. The optimal growth temperature depended on the isolate, but at 23 °C and 25 °C, the probability of spore germination was higher for most isolates. Finally, the fungicides azoxystrobin and chlorothalonil inhibited growth rates and conidial germination at 24 and 48 h of exposure. This research produces vital knowledge on the virulence and infection cycles of poorly studied native species of entomopathogenic fungi. In addition, the results provide information on the optimal temperature for development in laboratory conditions and susceptibility to fungicides, which could contribute to future biological control strategies.

Identification and evaluation of isolated entomopathogenic fungus from Egyptian soil against the black cutworm larvae of Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

BackgroundThe black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is considered as one of the most destructive pests of many field crops in Egypt. Entomopathogenic fungi (EPF) have long been accepted as relatively safe alternatives to chemical insecticides. In the past decades, many researchers have compared the effective local isolates of EPF to the formulated product of the same fungus and reported that local isolates were more efficient than formulations when used against target insects.ResultsThe present study discussed the pathogenic activity of local isolate after scientific characterization. Two insect species [Galleria mellonella L. and Agrotis ipsilon (Hufn.)] were used in this evaluation. The fungus was isolated from soil samples by trapping method, and fourth-instar larvae of Galleria were used to evaluate the pathogenicity of the isolate. The isolate was identified as Beauveria bassiana. Different levels of the fungus development depending on the test temperatures (20, 25, 30, 35 and 40 °C) were tested. Optimal growth of the isolate fungus was recorded at 25 °C. The corrected mortality rate for fourth-instar larvae of G. mellonella treated with the isolate spores at 6.4 × 105 spores/ml was (96%) after 10 days, while the mortality of last instar larvae of A. ipsilon was (48 and 100%) at the concentrations of 9.2 × 104 and 2.9 × 106 spores/ml, respectively, after 14 days compared to (24%) in the control. Both pupation and the sex ratio in adults were affected at different levels according to the concentration. The effect was also very clear in the increased rates of malformation in adults.ConclusionThe EPF, B. bassiana, isolated from the soil, was highly effective against G. mellonella larvae in storage and A. ipsilon larvae in soil; therefore, it could be recommended as an alternative control agent for chemical pesticides.

Entomopathogenic Fungi in the Soils of China and Their Bioactivity against Striped Flea Beetles Phyllotretastriolata

The present research aims to explore the occurrence and diversity of entomopathogenic fungi (EPF) in cultivated and uncultivated lands from different provinces of China and to search for EPF against Phyllotreta striolata. In this study, first, the EPF biodiversity from the soil of four provinces (Hunan, Hubei, Henan and Hebei) was surveyed. There were 302 fungal isolates obtained from 226 soil samples collected from croplands (114), arbor (79), grasslands (97) and fallow land (12); 188 EPF isolates were identified as 11 genera. The data indicate that Hubei Province has the greatest EPF diversity, with a Shannon Evenness Index (SHEI) value of 0.88. Here, the grassland, arbor and cropland had an EPF diversity with SHEI values of 0.81, 0.86 and 0.76, respectively, while the fallow land had the highest SHEI value of 1.00, which suggests that cultivation by humans affected the count and richness of soil fungi: the less human activity, the more kinds of fungi found. Finally, the pathogenicity of 47 fungal strains against the adult P. striolata was determined. Isaria javanica (IsjaHN3002) had the highest mortality. In conclusion, this study reports the EPF distribution and biodiversity in the soil from four provinces in China, showing that the amount and type of fungi in the soil varied by region and vegetation and that soil was one of the resources for acquiring EPF. The potential of I. javanica as a biocontrol must be studied further.