Entomopathogenic Beauveria Bassiana Research Articles

First Record of Dendrolimus pini Outbreak on Aleppo Pine in Croatia and Severe Case of Population Collapse Caused by Entomopathogen Beauveria bassiana

First Record of Dendrolimus pini Outbreak on Aleppo Pine in Croatia and Severe Case of Population Collapse Caused by Entomopathogen Beauveria bassiana

Transcriptional response of bean bug (Riptortus pedestris) upon infection with entomopathogenic fungus, Beauveria bassiana JEF-007.

Entomopathogenic Beauveria bassiana has been used as a biocontrol agent for insect pests, but its effect at the molecular level on the hosts has not been studied in detail. Herein, we performed transcriptome analysis of bean bug, Riptortus pedestris (Hemiptera: Alydidae) in response to infection with a highly virulent strain of B. bassiana JEF-007 (Bb JEF-007). Based on RNA-seq data from R. pedestris infected with Bb JEF-007 compared with non-infected bean bugs, infection was assumed to strongly activate (i) the energy production pathway by expressing dehydrogenases, (ii) metabolic pathways by expressing secreted proteins, GTPase, MBF2 transcription factor family, pigment-dispersing factor, antioxidants, and cuticle proteins, and (iii) the immune response pathway by expressing serine-threonine kinase in Toll pathway of bean bug. We have established the platform for functional studies of the genes required for an immune response against entomopathogenic fungi like B. bassiana in the bean bug, R. pedestris. Moreover, this study also paves the way for genetic modification of B. bassiana to combat with the defense mechanism of R. pedestris. © 2018 Society of Chemical Industry.

Repressed Beauveria bassiana infections in Delia antiqua due to associated microbiota.

Insects form both mutualistic and antagonistic relationships with microbes, and some antagonistic microbes have been used as biocontrol agents (BCAs) in pest management. Contextually, BCAs may be inhibited by beneficial insect symbionts, which can become potential barriers to entomopathogen-dependent pest biocontrol. Using the symbioses formed by one devastating dipteran pest, Delia antiqua, and its associated microbes as a model system, we sought to determine whether the antagonistic interaction between BCAs and microbial symbionts could affect the outcome of entomopathogen-dependent pest biocontrol. The result showed that in contrast to non-axenic D. antiqua larvae, i.e., onion maggots, axenic larvae lost resistance to the entomopathogenic Beauveria bassiana, and the re-inoculation of microbiota increased the resistance of axenic larvae to B. bassiana. Furthermore, bacteria frequently isolated from larvae, including Citrobacter freundii, Enterobacter ludwigii, Pseudomonas protegens, Serratia plymuthica, Sphingobacterium faecium and Stenotrophomonas maltophilia, suppressed B. bassiana conidia germination and hyphal growth, and the re-inoculation of specific individual bacteria enhanced the resistance of axenic larvae to B. bassiana. Bacteria associated with larvae, including C. freundii, E. ludwigii, P. protegens, S. plymuthica, S. faecium and S. maltophilia, can inhibit B. bassiana infection. Removing the microbiota can suppress larval resistance to fungal infection. © 2018 Society of Chemical Industry.

Non-host larvae negatively impact persistence of the entomopathogen Beauveria bassiana in soil.

A better understanding of the ecology of the insect pathogenic fungus, Beauveria bassiana, in soil is needed to identify reasons behind the variable efficacy often seen after field application. A transformed strain of a candidate commercial strain of B. bassiana (F418 gfp tr3), expressing the green fluorescent protein and the hygromycin B resistance gene, was used to assess the effects of the larvae of a host insect, Tenebrio molitor L. (Coleoptera: Tenebrionidae), a non-host, Costelytra zealandica (Coleoptera: Scarabaeidae) and the absence of larvae on the persistence of F418 gfp tr3 in pasteurised and non-sterile soil over 4 months. In the presence of a T. molitor larvae, F418 gfp tr3 populations increased significantly in pasteurised and non-sterile soil; however, populations increased less in non-sterile soil than in pasteurised soil. Lower populations of F418 gfp tr3 were recovered in pasteurised soil in the presence of C. zealandica larvae than in pasteurised soil without larvae. No difference was observed between F418 gfp tr3 populations in non-sterile soil with a non-host larvae or without larvae. Accompanying studies showed that F418 gfp tr3 conidia germinated and produced appressoria on live and excised cuticle of non-host (C. zealandica) larvae but infection did not occur, leading to a net loss of viable conidia in the soil. Conidia administrated orally to C. zealandica larvae were viable on recovery from faecal samples, suggesting that ingestion of the fungus by the larvae had little impact on the viable fungal population. Soil bacterial and fungal community patterns were analysed using Single-Strand Conformation Polymorphism (SSCP) and showed a correlation between changes in F418 gfp tr3 persistence in pasteurised and non-sterile soil and changes in soil communities in the presence of a host insect, non-host insect or in the absence of insect. In pasteurised soil, non-specific germination of F418 gfp tr3 conidia on the non-host larval cuticle and the presence of antagonistic bacteria introduced with the field-collected larvae are most likely responsible for the differences observed. The more complex microbial community structures in non-sterile soil could lead to fungistasis, preventing potentially antagonistic bacteria degrading conidia or inhibiting attachment and germination on the non-host larval cuticle, resulting in the observed lack of difference between non-host and no larval treatments.

Gut microbiota in an invasive bark beetle infected by a pathogenic fungus accelerates beetle mortality

Dendroctonus valens, introduced to China from North America, has caused catastrophic mortality of healthy pines and has the potential to disperse into new geographic ranges. The entomopathogen Beauveria bassiana is an environmentally friendly alternative to chemical pesticides, and it is highly lethal to D. valens. Recent studies reported that gut microbiota of insects can suppress or promote infections by B. bassiana. Although D. valens harbors an abundant gut microbiota, whether and how gut microbiota interplay with fungal entomopathogens has not been examined. Nonaxenic D. valens larvae inoculated with B. bassiana conidia died significantly faster than axenic larvae. Significant differences were found between the structures of gut bacterial communities in B. bassiana conidial suspension-inoculated and Tween 80 treated larvae, and the abundance of Erwinia sp. in the former group was significantly higher than the latter one. Reintroduction of Erwinia sp. into axenic D. valens larvae accelerated larval mortality. These observations indicate that the gut bacterial community of an invasive bark beetle is altered by entomopathogenic B. bassiana, which further accelerates beetle mortality.

Efficacy of two species of entomopathogenic fungi against the stored-grain pest, Sitophilus granarius L. (Curculionidae: Coleoptera), via oral ingestion

Sitophilus granarius is a serious stored-grain insect that can destroy the whole grain of cereal crops. The present research demonstrated that two species of entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisoplidae, killed the treated adults of S. granarius when applied via oral ingestion. Mortality of S. granarius was shown by growth and development of the ingested conidia in the insect gut causing death of infected insects. During bioassays, the fungus conidia were mixed with wheat flour then provided to the insects for feeding on the mixture for 24 h. The insects were surface-treated with a contact fungicide (Merpan®) to kill the external conidia that could penetrate the cuticle and develop to kill the infected insects. Results indicated that the most effective ratio of mixing fungus conidia with the wheat flour was 0.1:2.0 (g/g) where this ratio should contain 2.75 × 108 conidia/g of M. anisopliae mixture or 2.6 × 108 conidia/g of B. bassiana mixture. Ingested conidia of each fungus caused a first mortality of S. granarius adults after 10 and 12 days of B. bassiana and M. anisopliae treatments, respectively. They also caused 50% mortality after 2.787 and 3.047 weeks of treatments for the same fungi, respectively. The novelty of this research is in adjusting and applying a technique of disinfection of insect cuticle with a fungicide and then verifying the presence of applied fungi in the infected insects. The practical application of this method was discussed.

CTL14, a recognition receptor induced in late stage larvae, modulates anti-fungal immunity in cotton bollworm Helicoverpa armigera

C-type lectin (CTL) is usually considered as pattern recognition receptors in insect innate immunity. Here we found that CTL14 of Helicoverpa armigera was only activated in the fifth instar larvae not in the second instar by entomopathogen Beauveria bassiana infection. Recombinant CTL14 protein was found to form aggregates with zymosan and B. bassiana in vitro. Immunoprecipitation studies demonstrated that CTL14 interacted with serine proteinases (SP), serine proteinase inhibitor (serpin), prophenoloxidases (PPO) and vitellogenin (Vg) in the larval hemolymph. Furthermore, depletion of CTL14 using dsRNA led to dramatic decrease in the expression level of PPO1. Additionally, CTL14 depleted H. armigera decreased the resistance to fungal challenge. Taken together, our study showed the direct involvement of CTL14 in the anti-fungal immunity of H. armigera, which further explained the stronger immune responses in the fifth instar compared to the second instar larvae.

Endophytic colonisation of tomato by the entomopathogenic fungus Beauveria bassiana: the use of different inoculation techniques and their effects on the tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae)

Abstract Fungal entomopathogens can naturally regulate populations of various insects. The entomopathogen Beauveria bassiana (Bals.-Criv.) Vuill. is also able to endophytically colonize different plants. Endophytic colonization by entomopathogens may provide a source of indirect interactions between fungi and insects and has been associated with the ability of the fungus to control insect pests. The tomato leaf miner, Tuta absoluta (Meyrick) is considered one of the most devastating pests of tomato (Solanum lycopersicum L.) and its difficult control is due to its miner habit, short life cycle, and high reproductive capacity. The aims of this study were: (i) to use three different techniques, i.e. leaf spraying, seed immersion and root dipping, for the endophytic inoculation of B. bassiana in tomato plants; and (ii) to assess the effect of B. bassiana on tomato leaf consumption and mortality of T. absoluta after inoculation. The percentage of colonization by B. bassiana was assessed 7, 14 and 28 days after inoculation. All inoculation techniques employed allowed the recovery of B. bassiana, although our results showed significant differences between techniques. Leaf spraying was the most effective, with the highest percentage of colonization recorded 7 days after inoculation. We also evaluated (i) the effect on the mortality of T. absoluta by direct contact with conidia of B. bassiana, and (ii) the effect on tomato leaf consumption and mortality by indirect contact through ingestion of inoculated plant tissues with B. bassiana. Mortality bioassays showed that B. bassiana infected T. absoluta, either by direct contact or indirectly, via ingestion of inoculated tomato leaves. Direct contact showed a higher percentage of mortality and a lower median survival time (MST) than indirect contact. Significant differences in the mortality percentages of T. absoluta after exposure with B. bassiana were found among the treatments and the control. Our results suggest that the endophytic inoculation of B. bassiana in tomato crops provides the basis for further investigation, which should focus on the virulence of the endophytic B. bassiana against T. absoluta.

Pine processionary moth (Thaumetopoea pityocampa, Lepidoptera: Thaumetopoeidae) larvae are highly susceptible to the entomopathogenic fungi Metarhizium brunneum and Beauveria bassiana

ABSTRACTThe larvae of the pine processionary moth (PPM), Thaumetopoea pityocampa, feed on the needles of pine and cedar. The urticating hairs of older instars pose a threat to human and animal health. Strains of the entomopathogenic fungi, Metarhizium brunneum (V275, ARSEF 4556) and Beauveria bassiana (KTU-24), were assayed against first to fourth instar T. pityocampa using doses ranging from 1 × 105 to 1 × 108 conidia mL−1. The three strains differed slightly in their virulence but caused 100% mortality of all instars at the highest dose. The newly emerged or first instar larvae were extremely susceptible with 100% mortality being achieved 2–4 days post inoculation with V275 at all but the lowest dose. The fourth instar larvae appeared to be less susceptible than earlier instars. There was good horizontal transmission of conidia from treated to un-inoculated larvae. However, mortality was higher in third and fourth instars and where the ratio of inoculated versus untreated larvae was high. This we presume is due to spores being more readily trapped by the urticating hairs found on third and older instar larvae. Injection of the nests offers a simple and environmentally friendly way of controlling the pest with reduced risk to operators.

Relationship between expression level of hygromycin B-resistant gene and Agrobacterium tumefaciens-mediated transformation efficiency in Beauveria bassiana JEF-007.

Agrobacterium tumefaciens-mediated transformation (AtMT) is an effective method for generation of entomopathogenic Beauveria bassiana transformants. However, some strains grow on the selective medium containing hygromycin B (HygB), which reduces the selection efficiency of the putative transformants. In this work, a relationship between HygB resistance gene promoter and AtMT efficiency was investigated to improve the transformant selection. Ten B. bassiana isolates were grown on 800μgml-1 HygB medium, but only JEF-006, -007 and -013 showed susceptibility to the antibiotics. Particularly, JEF-007 showed the most dose-dependent susceptibility. Two different Ti-Plasmids, pCeg (gpdA promoter based) and pCambia-egfp (CaMV 35S promoter based), were constructed to evaluate the promoters on the expression of HygB resistance gene (hph) at 100, 150 and 200μgml-1 HygB medium. Eightdays after the transformation, wild type, AtMT/pCeg and AtMT/pCambia-egfp colonies were observed on 100μgml-1 HygB, but significantly larger numbers of colonies were counted on AtMT/pCeg plates. At higher HygB concentration (150μgml-1 ), only AtMT/pCeg colonies were further observed, but very few colonies were observed on the wild type and AtMT/pCambia-egfp plates. Putative transformants were subjected to PCR, RT-PCR and qRT-PCR to investigate the T-DNA insertion rate and gene expression level. Consequently, >80% of colonies showed successful AtMT transformation, and the hph expression level in AtMT/pCeg colonies was higher than that of AtMT/pCambia-egfp colonies. In the HygB-susceptible B. bassianaJEF-007, gpdA promoter works better than CaMV 35S promoter in the expression of HygB resistance gene at 150μgml-1 HygB, consequently improving the selection efficiency of putative transformants. These results provide useful information for determining AtMT effectiveness in B. bassiana isolates, particularly antibiotic susceptibility and the role of promoters.

Scorpion neurotoxin AaIT-expressing Beauveria bassiana enhances the virulence against Aedes albopictus mosquitoes

To improve the insecticidal efficacy of this entomopathogen Beauveria bassiana, the fungus was genetically modified to express an insect-specific scorpion neurotoxin AaIT. The virulence of the recombinant B. bassiana strain (Bb-AaIT) against Aedes albopictus adults (which occurs via penetration through the cuticle during spore germination or by conidia ingestion), and the larvae (by conidia ingestion) was measured with bioassays. The median lethal concentration (LC50) of Bb-AaIT against A. albopictus larvae was 313.3-fold lower on day 4 and 11.3-fold lower on day 10 than that of the wild type (WT). Through conidia feeding or body contact, Bb-AaIT killed 50% of adult female mosquitoes at 3.9- or 1.9-fold reduced concentrations on day 4 and at 2.1- or 2.4-fold reduced concentrations on day 10. Compared with the results for the WT, the median lethal time (LT50) of Bb-AaIT was reduced by 28.6% at 1 × 107 conidia ml−1 and 34.3% at 1 × 106 conidia ml−1 in the larvae bioassay by conidia ingestion, while it decreased 32.3% at 1 × 107 conidia ml−1 by conidia ingestion and 24.2% at 1 × 108 conidia ml−1 by penetrating through the cuticle in the adult bioassay. All the differences were significant. Our findings indicated that Bb-AaIT had higher virulence and faster action than the WT in killing the larval and adult mosquitoes, and therefore, it is valuable for development as a commercial mosquito pesticide.

Entomopathogenic Beauveria bassiana granules to control soil-dwelling stage of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae)

The western flower thrip, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is recognized as a serious pest worldwide, but overuse of chemical pesticides results in environmental pollution and insect resistance. Herein we report the biocontrol of soil-dwelling stages of western flower thrips using entomopathogenic Beauveria bassiana granules. Using a B. bassiana isolate expressing enhanced green fluorescent protein (Bb-egfp), we confirmed that Bb-egfp was highly virulent to the thrips and colonized the soil, which allowed soil-dwelling pupae to come in contact with the colonized fungal mass. In a glasshouse trial, granules of BbERL836 and BbERL1578 isolates were applied to the soil surface of tomatoes growing in pots and female F. occidentalis were released on tomato plants three days after the fungal application. Populations reductions between 75 and 90% were observed in the treatments of BbERL836 and BbERL1578 at 20 and 40 days after application (chemical control: 85% reduction). In the field trial with cucumbers, the two ERL soil treatments showed ca. 90% control efficacy, similar to that of spinetorm, a semi-synthetic insecticide (85% efficacy). This study shows that using entomopathogenic B. bassiana granules to kill soil-dwelling stages of thrips is an effective strategy to manage F. occidentalis populations in tomato and cucumber.

First record of entomopathogenic Beauveria bassiana (Ascomycota: Hypocreales) on pleasing fungus beetle Episcapha quadrimacula (Coleoptera: Erotylidae) in Malaysia

The presence of entomopathogenic <em>Beauveria bassiana</em> on Pleasing Fungus Beetle <em>Episcapha quadrimacula</em> has been reported on fruiting bodies of <em>Ganoderma boninense</em> for the first time in Malaysia.

Toxicity and efficacy of novel biopesticides for organic management of cucumber beetles on Galia muskmelons

Spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vittata) cucumber beetles are significant pests of cucurbits, and organic management options are limited. Beetle feeding results in aesthetic damage and reduction in marketable yields as well as transmission of bacterial wilt resulting in plant mortality. Biopesticides are formulated from naturally occurring organisms such as fungi and bacteria that are pathogenic or toxic to insect pests and may be used in organic production systems. These products are thought to have lower risk to non-target organisms including mammals and beneficial insects. This research examined the potential of novel microbial products and fungal organisms to reduce cucumber beetle damage on melons. Laboratory bioassays were performed to evaluate the efficacy of a bacterial extract of Chromobacterium subtsugae and two common strains of entomopathogenic fungi, Beauveria bassiana and Isaria fumosorosea, on cucumber beetles in a controlled environment. Trials were performed against adult beetles in organic field experiments on muskmelon (Cucumis melo L. cv. reticulatus Ser.). Prior to testing in the field, anti-feedant effects were observed when beetles were exposed to leaves with Chromobacterium subtsugae and Beauveria bassiana in the laboratory. However, in field applications, we did not observe a reduction in beetle populations below the economic threshold levels, and subsequently, there was no yield increase compared to the control. Additional research is needed to improve biopesticide efficacy through formulation and timing of delivery, determine efficacy on multiple life stages of the pest, and understand interactions of microbial biopesticides in the environment and potential for non-target impacts in organic systems.

Molecular characterization and the effectiveness of native entomopathogenic Beauveria bassiana strains against adults of Mediterranean fruit fly (Ceratitis capitata)

Molecular characterization of locally isolated Beauveria bassiana (Cordycipitaceae, Hypocreales) strains and their pathogenicity against Ceratitis capitata (Diptera: Tephritidae) adults are herein reported for the first time. Molecular identification based on the phylogenetic analyses of ITS-rDNA and combined data of TEF1 and Bloc, revealed that all fungal strains were conclusively assigned to B. bassiana clade. Interestingly, Maximum parsimony based-phylogeny analysis of the combined TEF1 and Bloc sequences detected additional genotypes among the sub-clades than ITS-rDNA analysis. Genetic diversity among strains was performed using random amplified polymorphic DNA (RAPD) markers. RAPD genotyping segregated all the strains into three clusters and characterized the 15 strains with different genotypes. RAPD-PCR clustering analysis showed that B. bassiana strains were relatively separated according to geographical origin. Molecular analyses using nuclear genes (TEF1 and Bloc) and RAPD markers suggest that B. bassiana is an aggregate of species, rather than a single species. Under laboratory conditions, B. bassiana strains were highly pathogenic to C. capitata adults with mortality rate in the range of 71.67–91.67%. Based on the Average of Survival Time (AST) and median lethal times (LT50) values, fungal strains were able to reduce significantly lifespan of flies compared to controls. Further experiments under field conditions are required to evaluate the real contribution of these fungal strains as promising biological control agents against C. capitata adults in Morocco.

Isolation and Assessment of Stability of Six Formulations of Entomopathogenic Beauveria bassiana.

Beauveria bassiana is the most widely studied and exploited entomopathogen. The development of a suitable formulation for B. bassiana is a critical component in aiding the entomopathogen germinate and infect the host. In addition to being economical to produce, having high residual activity, it is also important that the formulation is easy to handle, stable during storage, and convenient to mix and apply and be consistently effective in controlling the target pest.In this chapter we describe preparation of experimental formulations of conidia of B. bassiana. The formulations are prepared with barley, rice, wheat bran, clay, kaolin, and peat. The protocol for assessing the stability of the formulations of B. bassiana is also described.

The entomopathogen Beauveria bassiana has epiphytic and endophytic activity against the tomato leaf miner Tuta absoluta

AbstractThe recent introduction and rapid spread of the tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) throughout Europe, Africa and the Middle East poses a severe threat to future cultivation of tomato and other Solanaceae. Among the best practicable means for effective and sustainable control of this invasive insect pest are entomopathogenic fungi, which can either prevent a further spread of this insect to new areas or keep population densities below an economic threshold level. Here, we report on the efficacy of a commercially available mycoinsecticide based on the entomopathogen Beauveria bassiana (Bals.) Vuill. (Ascomycota: Hypocreales) against all four larval stages of T. absoluta. In bioassays, high mortality rates and significantly reduced longevity of larvae were obvious when larvae had fed for a period of around 15 days on leaves with B. bassiana propagules present on the surface as an epiphyte with mortality values corrected for variance in control mortality of 90–100%. In addition, a second mode of action of B. bassiana against T. absoluta larvae was evident in bioassays in the form of an endophytic establishment of this fungus in treated tomato plants. Longevity of T. absoluta L4 larvae was significantly lower in individuals which had fed on surface‐sterilized tomato leaves obtained from plants treated 18 days before the bioassay with a B. bassiana suspension compared to larvae feeding on control plants treated with water. Corrected mortality reached values between 30% and 50% for all larval instars. Growth of tomato plants was not inhibited due to colonization by endophytic B. bassiana and a weak systemic translocation of fungal propagules in non‐treated leaves was evident in the assays. Accordingly, entomopathogenic fungi like B. bassiana express different modes of action again target insect pests, which is of particular relevance for the design of efficient management strategies for invasive pests like T. absoluta.

Rearing tomato whitefly and field evaluation of modified and unmodified conidia of Beauveria bassiana, Isaria farinosa, Metarhizium anisopliae and low rates of chlorpyrifos under tropical conditions.

The whitefly ( Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a serious pest of a wide range of economically important agricultural and ornamental crops in all agro-ecological regions in the world. This study evaluated the efficacy of conidia of entomopathogenic Beauveria bassiana (BB 315), Isaria farinosa (ARSEF 5081) and Metarhizium anisopliae (Ma 275.86DC), against whitefly ( Bemisia tabaci ) under tropical climate. Two forms of conidia: (a) modified conidia (conidia with improved ecological competence), and (b) unmodified conidia of the three isolates were subjected to heat treatment (45°C) for 5 days. Germination rates of these conidia before and after their exposure to heat were compared at 25 °C on Sabouraud Dextrose Agar (SDA, aw= 0.995) to assess resilience to heat stress. Further, assessment of germination potentials of conidia was conducted at three aw levels (0.995, 0.98 and 0.96: corresponding to different levels of water availability). Thereafter, they were tested against B. tabaci infestation on tomato plants and insect densities after the treatments were compared with the effect of low rate chlorpyrifos. The conidia germinated differently on SDA at the three a w levels and the rate of germination of modified conidia of each isolate was significantly higher at 0.98 a w (F 2, 16 =0.31, P=0.001). Modified conidia of B. bassiana appeared more tolerant to temperature stress. All the isolates significantly reduced pest incidencerelative to control after 14 days and there was no significant difference (P>0.05) between the effect of modified and unmodified conidia against B. tabaci in the field. The level of control achieved using the conidia of the three fungal isolates was comparable with the chlorpyrifos treatment. Key Words : Bemisia tabaci, entomopathogen, water activity

Effectiveness of Beauveria bassiana Native Isolates in the Biological Control of the Med-iterranean Fruit Fly (Ceratitis capitata)

The effectiveness of native entomopathogenic Beauveria bassiana isolates in the biological control of the Mediterranean fruit fly (Ceratitis capitata) was evaluated under laboratory and field condi- tions. Local isolates (P. Bv32, P. Bv39, P. Bv41, P. Bv51, and P. Bv52) of the fungus B. bassiana in- duced higher adult mortalities (77%, 65%, 65%, 65%, and 58%, respectively) than a control against the Mediterranean fruit fly under laboratory conditions. Adult mortality increased by increasing the conidial concentrations. In addition, the lethal time (LT50) for killing adult C. capitata ranged from 3.91 to 5.60 days, and the logged lethal concentration (LC50) ranged from 3.80 to 10.50, de- pending on the isolate. Furthermore, the contact application method induced significantly higher mortality than feeding alone, compared with the control. In addition, spraying peaches with a co- nidial suspension of the isolates P. Bv32 and P. Bv39 significantly reduced infestation by the fruit fly, compared with the control. The isolates grew well at a temperature range of 25˚C - 30˚C; ger- mination of the conidia occurred at 15˚C - 30˚C, and sporulation occurred at 20˚C - 25˚C. High Mediterranean fruit fly mortalities were induced at 15˚C - 30˚C, with significant differences among the isolates. However, the isolates failed to grow, germinate, or sporulate above 35˚C or below 10˚C. Under field conditions, a formula of the bioinsecticide containing the isolate P. Bv32 of B. bassiana significantly reduced peach infestation with Medfly maggots by 25% compared with the control, and by 30% when combined with a low dose of the commercial insecticide Confidor®.

Endophytic colonisation of tobacco, corn, wheat and soybeans by the fungal entomopathogen Beauveria bassiana (Ascomycota, Hypocreales)

We demonstrate the effectiveness of three inoculation methods (foliar spray, seed immersion and root immersion) in establishing fungal the entomopathogen Beauveria bassiana as an endophyte in tobacco, corn, wheat and soybean. Colonisation of leaves by B. bassiana was assessed 7, 14, 21 and 28 days post-inoculation. There were significant differences (p < 0.001) in endophytic colonisation among the different inoculation techniques.