Isolates Of Entomopathogenic Fungi Research Articles

Efficacy of different entomopathogenic fungal isolates against chilli aphid, Myzus Persicae (Sulz.)

In recent years, microbial control of insect pests is becoming popular as insect pathogens such as bacteria, viruses, fungi and nematodes serve as potential bioagents in pest management. Among the different microbial agents, entomopathogenic fungi (EPF) are gaining importance in pest control. They can be easily mass cultured on artificial media without affecting their virulence at a cheaper cost. They are highly species specific with minimal impact on non-target organisms. The current study aimed to study the efficacy of entomopathogenic fungal isolates against aphid, Myzus Persicae (Sulz.) in chilli. Laboratory and field experiments were conducted to evaluate the pathogenicity of Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii against chilli aphid. From the study it is revealed that B. bassiana @ 108 spores ml-1 were found to be effective and found to be more superior to the other entomopathogenic fungal isolates viz., Metarhizium anisopliae and Lecanicillium lecanii against chilli aphid.

Efficacy of entomophatogenic fungi Beauveria bassiana and Cordyceps sp against Crocidolomia pavonana (FABR.) Lepidoptera: Pyralidae) as possible pest management strategy on pepper multi-cropping plantation

Black and white pepper have been considered as the most important perennial crops in some regions of Indonesia yet it took about 3-5 years before the plant start producing. One of the possible approaches to maintain the income of the farmer in the perennial plantation is multi-cropping with high-value annual crops, such as vegetables. However, many pests of vegetables already showed resistance to the common synthetic pesticide applied on the black pepper plant. Thus, it is necessary to apply another strategy for pest control, by applying entomopathogenic fungi. In this study, bioassays and field efficacy of two local isolates of entomopathogenic fungi (Beauveria bassiana and Cordyceps sp.) against one of the most insecticide-resistant pests, larvae of Crocidolomia pavonana (Fabr.) was conducted. In this study, exposure to 1 x 104 conidia mL−1 to 1 x 107 conidia mL−1 resulted in mean larval mortalities from 23.33 to 100% in two days. The probit analysis showed that the LC50 of B. bassiana was estimated at 4.26 x 104 conidia mL−1 which significantly more toxic than Cordyceps sp. (1.57 x 105 conidia mL−1) although the lethal time was similar. From the field tests, cabbage was sprayed with suspension contained 107 conidia mL−1. Means percent of mortality for all treatments was more than 75% and significantly higher (P < 0.05) than the control (tween 80). Conidia of Cordyceps sp. in palm oil cooking oil offered the most promising result against the C. pavonana.

Evaluation of Locally Isolated Entomopathogenic Fungi against Multiple Life Stages of Bactrocera zonata and Bactrocera dorsalis (Diptera: Tephritidae): Laboratory and Field Study.

Fruit flies including Bactrocera zonata and B. dorsalis (Diptera: Tephritidae) are considered major pests of orchard systems in Pakistan. This study evaluated the laboratory virulence, sub-lethal effects, horizontal transmission, greenhouse, and field-cage efficacy of locally isolated entomopathogenic fungi (EPF) against B. zonata and B. dorsalis. In virulence assays against third instars and adults, all 21 EPF isolates (Beauveria bassiana and Metarhizium anisopliae) tested were pathogenic and caused varying levels of mortality to the fruit flies. Based on the initial screening, four isolates (B. bassiana WG-21 and WG-18 and M. anisopliae WG-07 and WG-02) were selected for further study. The isolate WG-18 was the most virulent against larvae and adults of B. zonata and B. dorsalis followed by WG-21, WG-02, and WG-07. In both species, adults were more susceptible than larvae to all isolates, and pupae were the least susceptible. Isolates WG-18 and WG-21 strongly decreased female fecundity and fertility, the highest adult and larval mortality, and longest developmental time of larvae and pupae. Fungal conidia were disseminated passively from infected to healthy adults and induced significant mortality, particularly from infected males to non-infected females. In greenhouse and field-cage experiments, WG-18 and WG-21 were the most effective isolates in reducing adult emergence when applied to larvae and pupae of both fruit fly species. Our results indicate that B. bassiana isolates WG-18 and WG-21 were the most virulent against multiple life stages of B. zonata and B. dorsalis, and also exerted the strongest sub-lethal effects.

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

Entomopathogenic fungi are regarded as effective biocontrol agents in pest management. Different fungi isolates exhibit varying degree of pathogenicity against red palm weevil [Rhynchophorus ferrugineus (Olivier)]. The pathogenicity of four native isolate from Saudi Arabia (three Beauveria bassiana named as BbSA-1, BbSA-2, BbSA-3 and one Metarhizium anisopliae regarded as MaSA-1) and three exotic isolates from Indonesia (B. bassiana coded as BbIDN-1 and M. anisopliae named as MaIDN-1 and MaIDN-2) was evaluated against red palm weevil under laboratory conditions. The isolates were applied to eggs (1 day old), larvae (3 and 35 days old), pupae (5 days old) and adults (10 days old). The average mortality rate of eggs and hatched larvae was 100% in all of the isolates except BbSA-2 and BbIDN-1, where mortality was 93.3 and 90%, respectively. The lowest mortality rate (73.3%) was recorded for BbSA-3 against 3-days-old larvae; however, all other isolates caused >80% larval mortality. Meanwhile, 93.3% mortality of 35-day-old larvae was noted for MaSA-1 isolate. The highest pupa mortality (80%) was observed for MaSA-1, while remaining isolates caused >60% mortality. The isolates BbSA-1 and MaSA-1 caused 61 and 74.3% mortality in adults, respectively. The tested fungi isolates exhibited high virulence against all life stages of red palm weevil. Local isolates had higher pathogenicity than exotic isolates. The findings of the current study suggest that entomopathogenic fungi could be used as biological control agents for the management of red palm weevil. However, field studies are needed to reach the sound conclusions and practical applications.

Efficacy of different entomopathogenic fungal isolates against four key stored-grain beetle species

The development of resistance in stored-grain insect pests can be effectively reduced by using biological control methods. Entomopathogenic fungi have been under consideration as complementary and alternative agents to synthetic insecticides. The aim of this study is to identify the pathogenic potential of four different fungal isolates of Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) (WG-47, WG-48, WG-50, WG-51) and three isolates of Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) (WG-46, WG-49, WG-52) against the adult stages of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) at 1 × 106, 1 × 107, 1 × 108 and 1 × 109 conidia/kg wheat. Mortality was found dose dependent among all the tested species. Rhyzopertha dominica was the most susceptible followed by S. granarius, T. castaneum and T. granarium. Among the different isolates B. bassiana caused higher mortality compared to M. anisopliae. The isolates WG-50 and WG-51 of B. bassiana provided maximum mortality among the different tested species and led to lower F1 individuals compared to the controls. Our study indicates that entomopathogenic fungi have an elevated potential to successfully manage the aforementioned coleopteran species on stored wheat.

Effect pesticides to entomopathogen fungi from citrus orchard in vitro

Pesticides are a group of chemicals that are intentionally applied to the environment with the aim of suppressing pests and plant diseases and protecting agricultural products. Most pesticides do not specifically target pests and diseases only during application, but also affect the products produced and human health due to the residue and the effect on non-target pests including entomopathogen. The purpose of this study was to determine the effect of pesticides applied in controlling pests and diseases of citrus plants towards the growth of entomopathogenic fungi in vitro. This test used three active ingredients of pesticides namely Mankozeb (fungicide), Profenofos and Lambda cyhalothrin (insecticides). Dosage of pesticides in the treatments were 0.25 times, 1-time, 2-times of the recommended doses and control (without pesticides). Five types of entomopathogenic fungi used were Metarhizium anisopliae, Hirsutella sp., Beauveria bassiana, Paecilomyces sp. and TB.8 (not yet identified). Each treatment with 3 replications. The size of entomopathogenic fungi showed the influence of pesticides on the growth of entomopathogenic fungi. A quarter dose of profenofos insecticide had the potential to inhibit the growth of all isolates, except M. anisopliae. All isolates did not show significant growth reductions after treated with various doses of Lambda-cyhalothrin insecticide. Mancozeb fungicide had a negative effect on the growth of all entomopathogenic fungi isolates. The highest spore density on the 21st days was Paecilomyces sp. under the Profenofos treatment. Lambda-cyhalothrin did not affect the spore productions in all entomopathogenic fungi isolates. Otherwise, spore production was not observed even at the lowest concentrations of Mancozeb treatment. Differences in the active ingredients of pesticide affected the growth and sporulation of entomopathogen.

Efficacy of soil isolates of entomopathogenic fungi against the bulb mite, Rhizoglyphus robini (Acari: Acaridae)

The bulb mite, Rhizoglyphus robini, is a serious pest of garlic, onion and other crops. The mite is usually found in association with dangerous fungal pathogens such as Fusarium spp. Control of this pest has relied upon the use of synthetic acaricides but chemical control of the bulb mite is difficult because it is able to develop resistance quickly. Thus, alternative control methods, e.g. biological control, need to be developed and implemented. The aim of this study was to assess efficacy of selected strains of entomopathogenic fungi (EPF) against adult females of R. robini under laboratory conditions. New EPF strains were isolated from soil samples collected in onion and garlic fields in the Czech Republic and Israel using soil elution and cultivation on selective media. Fungal species were determined using macroscopic, microscopic and molecular markers. The efficacy against R. robini females was tested in 17 isolated and 3 reference strains of EPF. Results revealed high variability among species and strains. The highest efficacy against R. robini mites was found in strains of Metarhizium anisopliae isolated from soil samples collected in the Czech Republic which caused mortality up to 99.3%, and a Metarhizium indigoticum strain from Israel causing 98.3% mortality after four days of bioassay. Isaria fumosorosea strains did not caused mortality higher than 40%. The lowest virulence was found in Beauveria spp. strains causing mortality of mites between 5 and 25%. Median lethal time (LT50) and median lethal concentration (LC50) in the three most virulent strains ranged between 2 and 4 days and between 1.01×104 and 2.36×105 spores/ml, respectively. The concentration-response models indicated that the M. indigoticum strain is more lethal than M. anisopliae strains. The present study showed that some strains of entomopathogenic fungi, especially from the genus Metarhizium, could be perspective biocontrol agents against R. robini.

Molecular characterisation and efficacy of entomopathogenic fungi against the Green shield bug Palomena prasina (L.) (Hemiptera: Pentatomidae) under laboratory conditions

ABSTRACT Green shield bug (GSB) Palomena prasina (L.) causes significant yield and quality losses in hazelnut production of Turkey. Alive and dead adults of GSB were collected from the main hazelnut cultivation areas of Turkey during 2018 and 2019. The entomopathogenic fungi (EPF) were isolated from GSB individuals and identified by DNA sequencing of the internal transcribed spacer of the rRNA. Phylogenetic analysis based on the maximum likelihood method of these sequences with reference sequences retrieved from GenBank revealed that 20 native isolates were Beauveria bassiana (6), B. pseudobassiana (1), Cordyceps confragosa (5), Akanthomyces muscarius (4), Purpureocillium lilacinum (2), Isaria fumosorosea (1), and Bionectria sp. (1). Furthermore, the isolates were tested for their efficacy against GSB adults at 1 × 108 spores mL−1 concentration under laboratory conditions. Registered bio-insecticides were applied at the same concentration to compare the efficacy of the isolates. Beauveria spp. isolates were most effective among the tested isolates with LT50 and LT90 values ranging between 3.65–6.14 and 5.26–8.25 days, respectively. These isolates caused 100% mortality in GSB adults within 6–10 days. The isolates of A. muscarius (TR-OR-1) and P. lilacinum (TR-SM-7) were highly effective and caused 100% mortality 10 and 11 days after the treatment, respectively. These results indicated that some EPF isolates obtained in this study are more promising as an alternative control agent against GSB.

Effect of passage through the plant on virulence and endophytic behavioural adaptation in the entomopathogenic fungus Beauveria bassiana

Systemic crop protection using endophytic isolates of entomopathogenic fungi is at the forefront of IPM. Nonetheless, any potential trade-offs between virulence and endophytic behaviour must be elucidated if they are to be effectively used in pest management strategies. Here we investigated endophytic adaptation in an isolate of Beauveria bassiana following successive passage through melon, tomato and cotton tissues. Plants were sprayed with a suspension of B. bassiana endophytic isolate EABb 04/01-Tip to initiate endophytic colonization. Once colonization was established, the fungus was re-isolated from the plant, applied to another plant and re-isolated again; this was repeated to achieve three passages. After each passage, a conidial suspension of each isolate was used in bioassays to evaluate both virulence against 4th instar larvae of the model insect Galleria mellonella and to quantify the extent of endophytic activity in each respective host plant species. When sprayed leaves were inspected for fungal colonization, differences in percentage tissue colonization amongst the plant species were detected after the first re-isolation. Endophytic colonization rates in melon and tomato, which varied from 70 to 100%, were higher than those observed in cotton, which ranged from 40 to 50%; endophytic colonization in cotton increased to 75–100% after the third passage. This improvement in endophytic behaviour in cotton, an apparently suboptimal plant for fungal colonization, suggests an evolutionary adaptation to localized or transient endophytic colonization, while further assays are needed. Meanwhile, when endophytic colonization of non-sprayed leaves distant from the sprayed ones was investigated, endophytic activity was evident in all three crop species suggesting that movement within plants after successive passage increased the extent of endophytic colonization from transient to systemic. The present research highlights the potential for adaptation to endophytic behaviour in crops that are less suitable for endophytic colonization. Furthermore, we demonstrated stability in virulence after multiple passages through host plants. This is a key result for the development of IPM strategies based on endophytic entomopathogenic fungi.

Sublethal concentrations of spinosad synergize the pathogenicity of fungi to larvae of Ephestia kuehniella (Lepidoptera: Pyralidae)

We evaluated the efficacy of four entomopathogenic fungi (EPF) and their compatibility with the bioinsecticide spinosad for control of Ephestia kuehniella (Zeller) under laboratory conditions. Three EPF, including Beauveria bassiana (Balsamo-Criveili) Vuillemin isolates Z1 and Iran 1395C, Lecanicillium (= Verticillium) lecanii (Zimmerman) Zare &amp; Gams, isolate Iran 229, and Purpureocillium (Paecilomyces) lilacinum (Thom) Luangs-ard, Hywel-Jones &amp; Samson, isolate Iran 1026 were tested against third and fifth larval instars of Ephestia kuehniella using a filter paper bioassay. Mortality caused by the EPF ranged from 63.3-72.5% for third instars and 50-65.5% for fifth instars, with LT50 ranging from 8.4-10.5 d and 10.1-12.9 d, respectively. The effect of spinosad at LC10 (= 26.2 ppm) on EPF spore germination was evaluated and found to be negligible, ranging from 0% for B. bassiana Z1 to 5.7% for P. lilacinum. The LC50 values for spinosad against third and fifth instar E. kuehniella larvae were 452.5 and 1446 ppm, respectively. Subsequently, spinosad at LC10 was applied to third instar E. kuehniella larvae 24 h before application of the EPFs at LC50. The addition of spinosad to applications of L. lecanii and B. bassiana Z1 and Iran1395C isolates synergized their pathogenicity to E. kuehniella larvae, whereas the effect was merely additive for P. lilacinum. Our results suggest that these EPF isolates can be used effectively in combination with spinosad for management of E. kuehniella in stored products.

Phenotypic, molecular, and virulence characterization of entomopathogenic fungi, Beauveria bassiana (Balsam) Vuillemin, and Metarhizium anisopliae (Metschn.) Sorokin from soil samples of Ethiopia for the development of mycoinsecticide

Fungal entomopathogens are the most effective biocontrol agents against insect pests in the natural ecosystem. This study was conducted for phenotypic, molecular, and virulence characterization of locally isolated entomopathogenic fungi from soil samples of six localities in Ethiopia. Entomopathogenic fungi were isolated from 120 soil samples with the galleria baiting method. A total of 65 (54.2%) entomopathogenic fungal isolates belongs to Beauveria spp and Metarhizium spp were identified based on cultural and morphological features. All isolates were pre-screened based on germination, vegetative growth rate, and spore production as fungal in-vitro virulence determinates. Isolate AAUKB-11 displayed the peak germination of 99.67% and isolate AAUMFB-77 achieved the highest radial growth rate of 3.43 mm day−1 with the highest sporulation 4.60 × 108spores/ml. The phylogenetic analysis of ITS-rDNA confirmed that 7 isolates were identified as B. bassiana and 5 isolates were categorized into M. anisopliae. Selected B. bassiana and M. anisopliae strains were evaluated for their pathogenicity efficiency against G. mellonella larvae and caused 86.67%–100% mortality. The mortality rates of G. mellonella larvae peaked at 100% with 4(33.33%) isolates from B. bassiana and 2(16.67%) isolates from M. anisopliae after 10 days of treatments. The high virulent isolate, B. bassiana AAUMB-29 displayed the least LT50 value of 2.36 days followed by isolate B. bassiana AAUMFB-77 with LT50 of 2.53 days. Future studies should be needed to focus on the evaluation of high virulent isolates against other potential insect pests to assess their vigorous role as favorable biological control agents.

List of natural fungal pathogens infecting bark beetles and lepidopteran forest pests from Bulgaria

Information about fungal infections detected in different bark beetles and lepidopteran forest pests in Bulgaria is presented. Eighteen species of entomopathogenic fungal species and numerous isolates of orders Hypocreales, Eurotiales и Entomophthorales have been reported from 12 bark beetles and 10 moths within a sixty years period. The results from conducted laboratory and field bioassays with several isolates of entomopathogenic fungi against bark beetles and the gypsy moth were summarized.

Simple method to detect and to isolate entomopathogenic fungi (Hypocreales) from mosquito larvae

Entomopathogenic fungi are important agents for mosquito vector control. We report on the utility of a simple method to detect fungi on living larvae of Aedes aegypti that had been exposed to a fungal entomopathogen. Four species of the hypocrealean genera Metarhizium, Beauveria, Tolypocladium and Culicinomyces, known for their larvicidal activity against mosquito species, were tested. Living larvae previously exposed to a suspension of different conidial concentrations were set directly into the surface water film on non-nutritive agar supplemented with chloramphenicol, thiabendazole and crystal violet and then incubated. Except for C. clavisporus ARSEF 964 (which developed and produced conidia mostly inside the cadaver rather than on its surface in the present study), this method favored external fungal development and conidiogenesis on larvae of different instars after death. The dead larva on the water agar represents the unique and specific source of nutrition for the fungus that killed it. The technique facilitates the detection and posterior isolation of entomopathogenic fungi, and offers a compact, convenient, and rapid means to survey larval mosquito populations for fungal pathogens at the field.

Selecting native entomopathogenic fungi against Cosmopolites sordidus (Germar) in the laboratory

The objective of this study was to select native isolates of entomopathogenic fungi against adult Cosmopolites sordidus in laboratory conditions. Four isolates of Beauveria bassiana, two isolates of Metarhizium anisopliae, and two isolates of Paecilomyces lilacinus were tested against C. sordidus. The entomopathogenic fungi that resulted in mortality rates over 50% were M. anisopliae (MA-CsCha and MA-Carabid) and B. bassiana (BB-CsCha and BB-CsLp). The most virulent isolates were MA-CsCha, BB-CsCha, and MA-Carabid with median lethal times (LT50) of 4.82, 5.4, and 5.79 days, respectively. In conclusion, the MA-CsCha, BB-CsCha, MA-Carabid, and BB-CsLp isolates are viable candidates to be tested in banana fields.

Yerli entomopatojenik fungus izolatları ile üç ticari entomopatojenik fungus ürününün Sitophilus oryzae L. ve Tribolium confusum du Val üzerindeki etkinlikleri

In the present study, a total of 17 indigenous entomopathogenic fungal (EPF) isolates (Beauveria bassiana (Bals.) Vuill. – 14, Clonostachys rosea (Link) Schroers – 2, Isaria farinosa (Holmsk.) Fr. – 1) obtained from soil samples collected from Antalya province (southwestern part of Turkey) and three commercial EPF products [i.e. Priority® (Paecilomyces fumosoroseus), Nibortem® (Verticillium lecanii) and Nostalgist® (Beauveria bassiana)] were evaluated for their efficacy against the 7–10-day-old adults of Sitophilus oryzae L. (Coleoptera: Curculionidae) and Tribolium confusum du Val. (Col.: Tenebrionidae) under laboratory conditions. All the isolates and products were tested at 1 × 107 conidia/ml suspensions against the both insect species. The results from the single-dose pathogenicity assays showed that three B. bassiana isolates (BbDm-1, BbKp-1 and BbMp-1) caused mortalities 96.7%, 100% and 93.3% in S. oryzae, and 100%, 100% and 96.7% in T. confusum, respectively, 14 days after inoculation whereas all three commercial products achieved mortalities ranging from 56.7% and 63.3% in S. oryzae and from 56.7% and 66.7% in T. confurusum. In addition, the results from molecular phylogenetic analyses based on the ITS region sequence indicated that the three effective B. bassiana isolates (BbDm-1, BbKp-1 and BbMp-1) showed a high similarity (99%) with other B. bassiana isolates in GenBank. Overall results suggest that these three B. bassiana isolates have potential for management of S. oryzae and T. confusum.

Isolate-Specific Effect of Entomopathogenic Endophytic Fungi on Population Growth of Two-Spotted Spider Mite (Tetranychus urticae Koch) and Levels of Steroidal Glycoalkaloids in Tomato.

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 15days 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.

Entomopathogenic Fungi Biomass Production and Extracellular Biosynthesis of Silver Nanoparticles for Bioinsecticide Action

Entomopathogenic fungi are microbial agents of insect control in nature. They have been used as biologic strategies to manage insect invasion; however, the challenge is to maintain their shelf life and viability when exposed to high temperatures, ultraviolet radiation, and humidity. Synthesized silver nanoparticles (AgNPs) from fungal extracellular enzymes are an alternative using these microorganisms to obtain nanoparticles with insecticidal action. The present study evaluates the biomass production and the potential to synthesize silver nanoparticles using entomopathogenic fungi isolates. Sixteen isolates of entomopathogenic fungi were used in this study. The fungi pathogenicity and virulence were evaluated using the insect model Tenebrio molitor, at a concentration of 5 × 106 conidia/mL. The fungal biomass was produced in a liquid medium, dried, and weighed. The synthesis of silver nanoparticles was performed with aqueous extracts of the entomopathogenic fungi and silver nitrate solution (1 mM), following characterization by a UV/vis spectrophotometer, mean size, and polydispersity index. The results showed a significant variation in pathogenicity, virulence, and biomass production among the evaluated fungi isolates; however, only one of the isolates did not have the potential to synthesize silver nanoparticles. Pearson’s correlation showed significant correlation values only between virulence × biosynthesis potential and biomass production × biosynthesis potential, both with negative values, indicating an inverse correlation. Thus, AgNPs with entomopathogenic fungus extract can produce an innovative bioinsecticide product using a green production process.

Biodiversity and pathogenicity of entomopathogenic fungi associated with the lesser spruce sawfly, Pristiphora abietina

AbstractOutbreaks of lesser spruce sawfly, Pristiphora abietina (Christ) (Hymenoptera: Tenthredinidae), on conifers regularly occur in Turkey and other European countries. Chemical pesticides have been used to contain outbreaks, but those may damage the forest and disturb natural enemies. To minimize the use of chemical pesticides in the management of this forest pest, we identified the entomopathogenic fungi (EPF) that naturally occur on P. abietina and tested their efficacy against the pest under laboratory and semi‐field conditions. Using morphological and molecular techniques, 13 EPF isolates were obtained from the pest and identified as Beauveria bassiana (Bals.‐Criv.) Vuill., Beauveria pseudobassiana S.A. Rehner &amp; Humber, and Lecanicillium muscarium (Petch.) Zare &amp; W. Gams. A laboratory screening test at 106 conidia ml−1 showed that all isolates caused 59‐100% mortality after 14 days. Further experiments were performed with the three most effective isolates, all belonging to B. bassiana. For these isolates, an increase in conidia dose increased pest mortality. Also, the ability of horizontal transmission in the pest population was shown. All three isolates were effective in killing P. abietina on spruce under semi‐field conditions. These data will contribute to the development of an integrated pest management program for P. abietina based on microbial biological control.

Construction and Selection of an Entomopathogenic Fungal Library From Soil Samples for Controlling Spodoptera litura

Chemical pesticides have been used for pest control for many decades, but they cause serious problems, including insecticide resistance, secondary pest resurgence, and negative environmental impacts. Therefore, sustainable alternatives to chemical pesticides are necessary for pest control. Entomopathogenic fungi (EPF) are natural epizootic pathogens of insects, and some of them have been used as microbial biocontrol agents. Herein, we attempted to construct an entomopathogenic fungal library (EFLib) via the “Tenebrio molitor pathogenicity-based fungal collection method (TmPC)” to select EPF for control of the serious agricultural pest Spodoptera litura. A total of 172 soil samples were collected in northern and central Taiwan for the EFLib construction. The isolation efficiency of TmPC was 64.02%. The EFLib consisted of 101 isolates and was designated as the National Chung Hsing University (NCHU) EFLib. Among these isolates, 26 showed high virulence (mortality = 100%) to T. molitor larvae. Based on the results of molecular identification, the highly virulent isolates belonged to seven genera, including Beauveria, Clonostachys, Fusarium, Cordyceps, Penicillium, Purpureocillium, and Metarhizium. To evaluate the potential of these isolates for Spodoptera litura control, 12 isolates were selected for pathogenicity screening against S. litura larvae. A total of six EPF isolates belonging to the genera Beauveria and Metarhizium showed rapid eradication of the S. litura larvae. To rank the potential of these fungal strains for pest management, the six isolates were subjected to thermotolerance and conidial production assays, and a novel effective conidia number (ECN) formula was applied. The results indicated that the ECN index of Beauveria australis (NCHU-113) was much higher than that of Metarhizium isolates. However, among the Metarhizium isolates, NCHU-95 showed the highest ECN index. Altogether, NCHU-69 and NCHU-113 should be further tested in field trials. To our knowledge, this is the first attempt to integrate pathogenicity or virulence and ECN data into EPF screening and ranking, providing a baseline for mass selection of potential EPF strains for further applications.

Entomopathogenic Fungal Screening against Two Spotted Spider Mites, Tetranychus urticae Koch in Tomato and Broad Mite, Polyphagotarsonemus latus (Banks) in Chilli

Background: Entomopathogenic fungi are microorganisms that specifically infect and often kill insects and other arthropods. Most are non-pathogenic to plants and relatively non-toxic to humans and animals. Use of fungal entomopathogens can be an alternative to insecticides and could help in bio-intensive pest management. The current study aimed to study the pathogenicity of entomopathogenic fungal isolates against two Spotted Spider Mites, Tetranychus urticae Koch in tomato and broad Mite, Polyphagotarsonemus latus (Banks) in chilli. Methods: An extensive survey for the natural occurrence of entomopathogenic fungi on insects and mites was made in different agro climatic regions of Tamil Nadu during 2013 and 2014. Survey revealed the occurrence of two entomopathogenic fungi viz., Beauveria bassiana (Balsamo) Vuillemin and Metarhizium flavoviride Gams and Rozsypal var. minus. Laboratory experiment was conducted to evaluate the pathogenicity of fourteen isolates of Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii against Tetranychus urticae and Polyphagotarsonemus latus. Result: In opposition to T. urticae, the Beauveria bassiana isolate Bb 112 showed the highest toxicity of all the other isolates tested, with low LC50 value of 0.6 x106 spores ml-1 and LT50 of 92.60h. Against P. latus, Bb 112 had high virulence with low LC50 value of 0.3x106 spores ml-1 and LT50 value of 92.32h. Hence, there is potential for use of entomopathogenic fungi in the field conditions as an alternate control method in combating the insect pests and other arthropod pests since they are considered natural mortality agents and are environmentally safe.