Beauveria bassiana sensu lato granules for management of brown planthopper, Nilaparvata lugens in rice

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1 Beauveria bassiana sensu lato granules for management of brown planthopper, Nilaparvata lugens in rice Se Jin Lee, Jeong Seon Yu, Yu-Shin Nai, Bruce L. Parker, Margaret Skinner & Jae Su Kim BioControl Journal of the International Organization for Biological Control ISSN BioControl DOI /s

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3 BioControl DOI /s Beauveria bassiana sensu lato granules for management of brown planthopper, Nilaparvata lugens in rice Se Jin Lee Jeong Seon Yu Yu-Shin Nai Bruce L. Parker Margaret Skinner Jae Su Kim Received: 30 April 2014 / Accepted: 30 October 2014 Ó International Organization for Biological Control (IOBC) 2014 Abstract Entomopathogenic fungi have potential for controlling brown planthoppers in paddy. Currently only sprayable formulations can be applied despite the fact that granular formulations may reduce physical labor during application. Herein, granules of a Beauveria bassiana sensu lato (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) isolate were produced from a millet-based solid culture. The efficacy of the granules to control brown planthoppers, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), was determined by applying them to water surrounding rice plants in the laboratory and then infesting the plants with brown planthoppers. In a spray-mediated bioassay to select the most virulent of four B. bassiana s.l. isolates, ERL836 was the most virulent and caused minimal damage to rice plants. Dropping the ERL836 granules on water provided similar control to spraying the conidia. In the laboratory ERL836-colonized millet granules were applied to the water and simultaneously infested with brown planthoppers. The granular treatment had 87.7 % control efficacy 15 days post-application and etofenprox 0.5 % granules had 94.6 % efficacy. ERL836 colonized the surface of the water and brown planthoppers underwent mycosis three and 15 days post-application. Mycelial growth on the stems of rice plants was observed using a B. bassiana s.l. mutant that expresses an enhanced green fluorescence protein. Applying millet-based ERL836 granules to water can be an efficient biological strategy to manage brown planthoppers in paddy. This method is economical and requires less work than spraying the fungi directly on rice. Keywords Entomopathogenic fungi Millet Granular formulation Beauveria bassiana sensu lato (Balsamo) vuillemin (Hypocreales: Clavicipitaceae) Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) Handling Editor: Nicolai Meyling. S. J. Lee J. S. Yu Y.-S. Nai B. L. Parker J. S. Kim (&) Department of Agricultural Biology, College of Agriculture & Life Sciences, Chonbuk National University, Jeonju , Korea jskim10@jbnu.ac.kr B. L. Parker M. Skinner Entomology Research Laboratory, University of Vermont, 661 Spear Street, Burlington, VT , USA Introduction For decades, one of the major issues in developing insecticides is how to manage pesticide-resistant insects with environmentally sound practices. Use of entomopathogenic fungi (Ascomycota: Hypocreales) can be an alternative strategy because the group has physiologically different modes of action compared to chemical pesticides. They are broad spectrum and can be used against heteropteran, lepidopteran, coleopteran and

4 S. J. Lee et al. dipteran insects (de Faria and Wraight 2007; Roberts and Hajek 1992). Most chemical pesticides used today disrupt the insect s nerve system and/or metabolic pathways including ATP synthesis and biosynthesis (Klowden 2007). Entomopathogenic fungi infect through the insect s cuticle by mechanical penetration and enzymatic degradation, followed by secretion of insecticidal secondary metabolites (Behle et al. 2006; Li et al. 2010). In addition, entomopathogenic fungi do not significantly cause adverse effects in the environment. Entomopathogenic fungi have potential for controlling brown planthoppers, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), which are serious paddy field pests in Asian countries (Matsumura 2001). Consideration has been given to the spray application of fungi for controlling brown planthoppers in vitro and in vivo systems. Metarhizium anisopliae var. acridum (Driver, Milner & Trueman) (Hypocreales: Clavicipitaceae), isolated from a paddy field in China, had high insecticidal activity against all stages of brown planthoppers in laboratory conditions (Geng and Zhang 2004). Metarhizium anisopliae sensu lato (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) isolates, Ma456 and Ma576 showed [50 % virulence against brown planthopper nymphs (Jin et al. 2008). Beauveria bassiana sensu lato (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) isolates and M.anisopliae s.l. Ma20 and Mf82 were virulent to the adults and eggs of N. lugens in laboratory conditions (Li et al. 2012). For maintenance of activity, in vivo passage of heterologous B. bassiana s.l. Bb2860, 2861 and 2879 through brown planthoppers enhanced their virulence (Song and Feng 2011). An emulsifiable suspension of B. bassiana s.l. SG8702 showed high virulence against N. lugens and its insecticidal activity was enhanced by the coapplication of imidacloprid as a synapse-disrupting chemical pesticide in the laboratory (Feng and Pu 2005). Entomopathogenic fungi can colonize plants as endophytes and/or epiphytes under paddy conditions, thus potentially resulting in pathogenicity to paddy pests. Some genera such as Beauveria, Isaria, Lecanicillium, Paecilomyces, Acremonium, and Cladosporium have been isolated from plants as endophytes (Vega 2008). Fungal endophytes were found in coffee, maize, potatoes, cotton, tomato, western white pine, palm, banana, cocoa, mangroves, and rice (Vega 2008). In the phyllosphere, the colonization of entomopathogenic fungi can be antagonistic against the infection of plant pathogenic fungi (Ownley et al. 2008). Most commercialized entomopathogenic fungi are available as sprayable formulations, such as wettable powders (WP) and oil- or water-based suspension concentrates (SC) (de Faria and Wraight 2007). They can be used to control brown planthoppers in paddy. About 171 entomopathogenic fungal products have been commercialized and most of these are either based on B. bassiana s.l. or M. anisopliae s.l. (33.9 %) (de Faria and Wraight 2007). Only CornGard (Mycotech Corp., USA) is listed as a granular (GR) formulation used to control lepidopteran insects (de Faria and Wraight 2007). Recently small quantities of B. bassiana s.l. GRs have been produced using a millet-based solid culture system and successfully used to control pupae of western flower thrips in soil (Skinner et al. 2012) and rice water weevils in paddy by applying the GRs on rice seedling (Kim et al. 2014a). However, little effort has been given to GR formulations for controlling brown planthoppers in paddy. We hypothesize that GR formulation of entomopathogenic fungi can accelerate conidial germination and infection due to the nutritional supply from millet and the high humidity conditions in paddy. In this work, control efficacy of the granules against brown planthoppers was investigated, and fungal colonization on the rice plants was observed using an enhanced green fluorescence protein (egfp)- expressing B. bassiana transformant. Materials and methods Fungal isolates Beauveria bassiana s.l. isolates (ERL836, ERL1170, ERL1575 and ERL1578) were provided by the Entomology Research Laboratory Worldwide Collection of Entomopathogenic Fungi, University of Vermont, Burlington, VT, USA. All the isolates were stored at Chonbuk National University as conidial suspensions in 20 % glycerol at -80 C (Forma-86C, Thermo Electron Co., MA, USA) (Humber 1997). The isolates were grown on quarter-strength Sabouraud dextrose agar ( SDA) (ph 6) in Petri dishes (60 mm diam.) in the dark at 25 ± 1 C for ten days (Humber 1997). Conidia were collected by pouring 2 ml of

5 B. bassiana granules for brown planthopper management 0.03 % siloxane solution (Silwet L-77 Ò ) into the dish and detaching the conidia with a sterile scraper. The numbers of conidia were counted three times per isolate at 4009 magnification through a haemocytometer. Conidia with [90 % viability were kept in a refrigerator at 4 C for 3 4 days before use. Millet-based solid culture A solid-substrate culture method was used to produce mycotized millet grains (Hua and Feng 2005). To prepare inocula for the solid cultures, a conidial suspension of each isolate was added to quarter-strength Sabouraud dextrose broth ( SDB) in a 250-ml flask. The initial conidial density was adjusted to conidia ml -1. The flasks were shaken at 150 rpm and 24 ± 2 C for three days. Millet (Panicum miliaceum L.) grains (500 g) were placed in a polyvinyl bag, soaked in 250 ml of water containing citric acid (0.4 ml l -1 ) and held at 95 C for2h.thebagwas then autoclaved at 121 C for 15 min and cooled to ambient temperature. The culture broth (5 ml) was added to the bag and thoroughly mixed. All bags were incubated for ten days at 25 ± 2 C anda16:8(l:d) photoperiod. After incubation, the bags were opened, and the contents dried at ambient temperature for about three days, until the moisture content reached \5 % (determined by a moisture analyzer [Sartorius-Omnimark, CO, USA]). All batches of mycotized millet grains were assessed for conidial concentration (g -1 ) using a haemocytometer. To determine germination of each isolate, three plates of SDA were inoculated with 0.1 ml of suspension ( conidia ml -1 ) and held in the dark at 25 C for 24 h. From each plate, 400 conidia were inspected, and those with germ tubes longer than their width were considered germinated (Kim et al. 2010). The fungal granules with [90 % germination were used in this study. Bioassay Brown planthoppers were provided by the Institute of Dongbu Farm Hannong Co., Ltd., Republic of Korea. They were reared on rice seedlings, Oryza sativa L. (Poales: Poaceae), at 28 ± 1 C and % RH in a chamber with a 16:8 (L:D) photoperiod. The rice was grown in a closed container ( cm) in an insectary (temp: 28 ± 1 C and 16:8 (L:D) photoperiod) at Chonbuk National University, Republic of Korea. Rice (variety: Chuchung) seeds were soaked in prochloraz (CAS No.: ) solution (2,0009 dilution of Spotak Ò 25 % EC, Kyoung-Nong Co., Republic of Korea) for 24 h at room temperature, transferred to fresh water, and washed daily for five days. Germinated seeds were placed on rice nursery soil (Dongbu Hannong Co., Republic of Korea) at about 250 g per tray ( cm)andkeptat30 C for three days to initiate the early growth stage of rice. The nursery soil contained peat moss (13 22 %), coco peat (10 15 %), vermiculite (40 50 %), diatomite (5 20 %), zeolite (10 15 %) and surfactants (1 %). Five rice leaves (15 * 18 cm long) were cut and placed on top of moist filter paper (Whatman No. 3) (500 ll per paper) in a Petri dish (60 mm diam.) with mesh on the top for aeration. In each dish, 15 third instar brown planthoppers collected with a manual aspirator were placed. Conidia were harvested and adjusted to conidia ml -1 using a 0.03 % siloxane solution. Etofenprox 20 % EC (CAS No , Sebero Ò, Kyung-Nong Co., Republic of Korea) was diluted 2,000-fold in distilled water as a chemical control and siloxane solution served as the negative control. Each treatment was replicated three times. The fungal suspensions and the two controls were sprayed on the brown planthoppers using a micro-sprayer (ca. 5 ml per dish) (Butt and Goettel 2000). After covering with lids the Petri dishes were kept at 28 ± 1 C, % RH and 16:8 [L:D]). The number of dead insects and signs of mycosis were recorded daily. The experiment was repeated three times using different batches of fungal conidia. Pot assay The germinated rice seeds were planted in boxes ( mm) (Cat. No.: , Hansol Tech Co., Republic of Korea) containing nursery soil (sterilized at 121 C for 30 min) and kept at 28 ± 1 Cand 16:8 (L:D) photoperiod for about ten days (until leaves were 3 * 4 cm long). The boxes were filled with sterile distilled water to about 2 cm above the soil surface to simulate field conditions. For the first experiment we investigated the efficacy of spraying leaves vs. dropping conidia on the surface of the water (pipetting conidial suspension on the water surface). Third instar brown planthoppers were transferred to the rice plants (25 nymphs box -1 ) and the fungi were applied the same day. Four treatments were tested: fungal spray on leaves, fungal dropping

6 S. J. Lee et al. on water surface, chemical control, and negative control. Conidial suspensions of conidia ml -1 (5 ml box -1 ) were sprayed with a micro-sprayer or pipetted on the water surface. Etofenprox spray (20 % EC) served as a chemical positive control, and siloxane solution served as a negative control. After the treatments, the boxes were covered with lids, where mesh for aeration was mounted, and held at * 28 C. The number of dead insects, percentage of plant damage (based on the number of leaves with blight (symptom of browning and death of plant tissues)) and mycosis were recorded daily. Each day mycosed insects were removed from the boxes. Each treatment was replicated three times and the entire experiment was repeated three times. Next we investigated the efficacy of ERL836 granules. Rice in boxes was infested with rice planthoppers as above and the following treatments used: mycotized millet ERL836 granules were applied to the water surface at 1 g box -1, etofenprox 0.5 % granules at g box -1 (the chemical positive control) were applied similarly and an untreated negative control. After the treatment the boxes were covered and held at the same conditions as described above, followed by the same observations, i.e. mortality, mycosis and plant damage as above. Each treatment was replicated three times and the entire experiment was repeated three times. Observation of fungal colonization To determine where the brown planthoppers were infected by the fungal inoculum, a B. bassiana s. l. mutant (Bb-egfp-#3) that was generated by the fungal transformation of B. bassiana s. l. ERL1170 and expresses enhanced green fluorescence protein (egfp) (Kim et al. 2013) was used. The egfp gene is expressed under control of the gpda promoter, and the mutant has a phosphinothricin (PPT)-resistant bar gene as a selection marker. The Bb-egfp-#3 mutant was cultured on Czapek s solution agar containing 600 lg ml -1 phosphinothricin. The Bb-egfp-#3 mutant was cultured on millet granules as described above, and applied to the water in the box containing the rice plants. Rice in boxes was infested with third instar brown planthoppers (25 box -1 ) and egfp-expressing fungal granules were applied on the surface of water in the box at 1 g box -1 (the same day of infestation). Fungal colonization of the rice was observed daily under fluorescence microscopy (AM4113T-GFBW Dino-Lite Premier, AnMo Electronics Corp., New Taipei City, Taiwan) by daily picking up one box from several replicated boxes (15 boxes per treatment). Rice plants were taken out of the box 15 days after the treatment and placed on a glass plate for microscopic observation. Data analysis The data sets across the experimental repeats were similar in terms of average and thus pooled in the analyses. The percentage of live brown planthoppers and plant damage data were arc-sine transformed and analyzed using an analysis of variance (ANOVA) followed by Tukey s honestly significant difference (HSD) for multiple comparisons. All analyses were conducted using SPSS ver (SPSS Inc., 2009) at the 0.05 (a) level of significance. Results Fungal virulence In the bioassay, the positive control, etofenprox 20 % EC treatment gave the highest mortality, and it was followed by ERL836 treatment, which had the highest efficacy of the tested isolates seven days after treatment (F 5,36 = 131.4, p \ 0.001) (Table 1). Some ERL836-treated nymphs had mycelial growth on the surface of the nymphs followed by death seven days post-application. Table 1 Percentage of live brown planthoppers seven days after the spray of B. bassiana s.l. isolates against third instar brown planthoppers in Petri dish conditions at 5 ml ( conidia ml -1 ) per dish Treatment Application rate % live N. lugens (± SE) Untreated control 90.1 ± 4.9 d ERL conidia ml ± 6.7 b ERL conidia ml ± 17.3 c ERL conidia ml ± 2.9 d ERL conidia ml ±1 6.9 d Etofenprox 20 % EC 2,000 9 (0.5 g l -1 ) 3.1 ± 1.7 a Means followed by similar letters are not significantly different according to Tukey s HSD (a = 0.05)

7 B. bassiana granules for brown planthopper management Table 2 Percentage of live brown planthoppers and damaged rice plants in the pot assay 15 days after the application of B. bassiana s.l. ERL836 by spraying leaves and dropping on water at 5 ml ( conidia ml -1 ) per rice planting box ( mm) Treatment Application rate % live N. lugens (± SE) % rice plant damage (± SE) Untreated control 91.7 ± 7.6 c 86.7 ± 5.8 c ERL836 spray conidia ml ± 5.1 b 20.1 ± 7.7 b ERL836 dropping conidia ml ± 2.9 b 21.7 ± 6.4 b Etofenprox 20 % EC 2,000 9 (0.5 g l -1 ) 6.3 ± 2.9 a 5.1 ± 3.8 a Means followed by similar letters in the same column are not significantly different according to Tukey s HSD (a = 0.05) Table 3 Percentage of live brown planthoppers and damaged rice plants in the pot assay 15 days after the application of B. bassiana s.l. ERL836 millet granules (* conidia g -1 ) on the surface water at 1 g per rice planting box ( mm) Treatment Application rate Granular application and control efficacy When the treatments of spray and dropping of ERL836 were compared, both treatments had survival rates of %, which was significantly lower than the untreated control (F 3,24 = 179.0, p \ 0.001) (Table 2). There was no significant difference in control efficacy between the two application methods. After applying ERL836 granules to water, 11.7 % of the brown planthopper population was alive at 15 days posttreatment, which was higher than the chemical control but lower than the untreated control (F 2,18 = 161.1, p \ 0.001) (Table 3). Treatment of ERL836 granules caused no damage to the rice plants (F 2,18 = 155.8, p \ 0.001). Fungal colonization % live N. lugens (± SE) % rice plant damage (± SE) Untreated 95.1 ± 3.6 c 96.7 ± 2.9 c control ERL836 GR 1.0 g box ± 5.3 b 13.3 ± 4.4 b Etofenprox 0.5 % GR g box ± 1.3 a 6.7 ± 2.1 a Means followed by similar letters in the same column are not significantly different according to Tukey s HSD (a = 0.05) Growth of applied fungus and mycelial mass was first observed on the water surface three days after treatment, and mycotized brown planthoppers were observed 15 days after treatment. At 15 days, mycelial growth was observed on the stems of rice plants (Fig. 1a). When plants were treated with the egfpexpressing mutant, strong fluorescence was observed on the stems of rice plants and near the rice seeds (Fig. 1b). Green fluorescence was observed up to 3 cm above the seeds. Discussion Beauveria bassiana s. l. ERL836 had the highest virulence against brown planthoppers in laboratory conditions, followed by B. bassiana ERL1170. The other two B. bassiana s.l. isolates, ERL1575 and ERL1578 did not show any significant control activity. Some B. bassiana s.l. isolates were proven to be virulent against brown planthoppers (Feng and Pu 2005; Li et al. 2012; Song and Feng 2011). Recently we found that ERL836 also had high virulence against nymphs and adults of bean bug, Riptortus pedestris F. (Heteroptera: Alydidae) (Kim et al. 2014b). This B. bassiana s.l. isolate may appear to have a broad spectrum of activity. Little difference of control efficacy between spray and surface treatment (dropping; pipetting conidial suspension on the water surface) was observed 15 days post-application. Some conidia from spray treatment might pass through the leaves and arrived on the rice water in the boxes although it would be very small in quantity. Interestingly, the dropping of ERL836 conidia on the rice water showed similar control effect as foliar spray. Consideration needs be given to the rice stems as they are the main habitat of brown planthoppers. Some conidia which were

8 Author's personal copy S. J. Lee et al. Fig. 1 Fungal colonization of rice. a Mycelial growth of ERL836 on the stems of rice plants, and b observation of green fluorescence on the stems of plants treated with millet granules containing an egfp-expressing B. bassiana s.l. mutant 15 days after the treatments. The fungal granules were applied on the surface of water in the box at 1 g box-1 and the boxes were kept at 28 ± 1 C and 16:8 (L:D) photoperiod. Arrows indicate fluorescence on the rice stems dropped near the rice stems could germinate and move up the rice stems via capillary action of the water. The upward movement of water from the surface might accelerate ERL836 colonization on the stems. In this work, the experiment was conducted at high humidity by covering the rice planting boxes with lids, thus the spray and the dropping showed similar control efficacy. However in paddy fields, sprayed conidia against brown planthoppers might suffer from unfavorable conditions, such as low RH. Dropping of ERL836 in paddy fields may have higher control efficacy than sprays due to fungal germination and colonization. ERL836 GR formulation had high control efficacy, nearly equal to the chemical insecticide, etofenprox GR in the pot assay. On the rice water, ERL836 conidia from the granules could germinate and colonize on the rice plants, followed by infection of brown planthoppers. This GR application has many advantages when compared to the current spray application in horticulture (Skinner et al. 2012) and paddy (Kim et al. 2014a). First, relatively less physical labor is required in the GR application rather than spray. Secondly, millet in the granules serves as a nutritional supply for hyphal growth and colonization. Additionally the use of millet can increase the fungal thermotolerance (Kim et al. 2010), followed by long term stability. However, there are some limitations to the use of granules in paddy as mentioned by Kim et al. (2014a). Of importance is that most B. bassiana conidia are hydrophobic (Kim et al. 2010), so it takes time for the granules to absorb water. Incorporation of suitable surfactants with the granules is recommended (Burges 1998). The timing of applying the fungus to rice water in the field is important and should be investigated. Timing possibly affects the control efficacy against planthoppers in the paddy fields. Brown planthoppers are mainly present in July and August, when rice plants grow high and begin to produce grains (Matsumura 2001). The lower part of the growing rice plants (main habitat of rice planthoppers) receives little sunlight and thus high humidity can be expected. If fungal granules are applied to paddy water one or two weeks earlier, successful fungal colonization and effective control efficacy can be expected. Thus, small brown planthopper nymphs and adults can be infected during feeding. Secondly, in the fields fungicides are commonly used, so the control efficacy of ERL836 may be lower due to possible antagonistic effects (St. Leger and Screen 2001; Wraight et al. 2001). Recently

9 B. bassiana granules for brown planthopper management Kim et al. (2014a) found that, of the forty fungicides, only fluazinam and mancozeb significantly inhibited the growth of B. bassiana s.l. in in vitro assays. Studies are needed to determine the effects of chemical fungicides on the control efficacy of ERL836 granules under field conditions. After the GR application in this work, hyphal growth of ERL836 on the rice stems was observed. Similarly in the spray-mediated assay, some sprayed conidia, which were not attached to the insects, could be colonized on the rice plants. It is unknown whether the fungus grew epiphytically or endophytically. However there are some reports about endophytic B. bassiana s.l. isolates in rice (Jia et al. 2013; Tian et al. 2004; Vega 2008). If ERL836 has endophytic colonization in rice plants, it may be effective in controlling plant-pathogenic fungi, such as Rhizoctonia solani Kühn (Cantharellales: Ceratobasidiaceae), Magnaporthe oryzae (Hebert) Barr (Magnaporthales: Magnaporthaceae), and Fusarium moniliforme (Sawada) Wollenw (Hypocreales: Nectriaceae) (Griffin et al. 2005, 2006; Ownley et al. 2008). In conclusion, GR application of B. bassiana s.l. ERL836 showed high control efficacy against brown planthoppers in the pot assays, nearly equal to the use of a chemical insecticide, and fungal colonization on the rice stems was confirmed. This work suggests that applying millet-based ERL836 granules to water can be an effective and efficient biological strategy to manage brown planthoppers in paddy. This method is economical and requires less work than spraying the fungi directly on rice. Acknowledgments We are grateful to Drs. Myoung Eul Jai and Shin Taek Soo (Dongbu Farm Hannong Co., Korea) for providing the laboratory population of brown planthoppers. This work was carried out with the support of Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ009147) Rural Development Administration, Republic of Korea. References Behle RW, Garcia-Gutierrez C, Tamez-Guerra P, McGuire MR, Jackson MA (2006) Pathogenecity of blastospores and conidia of Paecilomyces fumosoroseus against larvae of the Mexican bean beetle, Epilachna varivestis mulsant. Southwest Entomol 31: Burges HD (1998) Formulation of mycoinsecticides. In: Burges HD (ed) Formulation of microbial biopesticides: beneficial microorganisms, nematodes and seed treatment. Kluwer Academic, Dordrecht, The Netherlands, pp Butt TM, Goettel MS (2000) Bioassay of entomopathogenic fungi. In: Navon A, Ascher KRS (eds) Bioassays of entomopathogenic microbes and nematodes. 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10 S. J. Lee et al. and reasons for their successes using entomopathogenic fungi. Biocon Sci Technol 20: Li M, Lin H, Li S, Chen P, Jin L, Yang J (2012) Virulence of entomopathogenic fungi to adults and eggs of Nilaparvata lugens Stal (Homopera: Delphacidae). Afri J Agricul Res 7: Matsumura M (2001) The current status of occurrence and forecasting system of rice planthoppers in Japan. J Asia- Pac Entomol 4: Ownley BH, Griffin MR, Klingeman WE, Gwinn KD, Moulton JK, Pereira RM (2008) Beauveria bassiana: endophytic colonization and plant disease control. J Invertebr Pathol 98: Roberts DW, Hajek AE (1992) Entomopathogenic fungi as bioinsecticides. In: Leatham GF (ed) Frontiers of industrial mycology. Chapman and Hall, New York, USA, pp Skinner M, Gouli S, Frank CE, Parker BL, Kim JS (2012) Management of Frankliniella occidentalis (Thysanoptera: Thripidae) with granular formulations of entomopathogenic fungi. Biol Control 63: Song TT, Feng MG (2011) In vivo passages of heterologous Beauveria bassiana isolates improve conidial surface properties and pathogenicity to Nilaparvata lugens (Homoptera: Delphacidae). J Invertebr Pathol 106: St. Leger RJ, Screen SE (2001) Prospects for strain improvement of fungal pathogens of insects and weeds. In: Butt TM, Jackson C, Magan N (eds) Fungi as biocontrol agents. CABI Publishing, Wallingford, UK, pp Tian XL, Cao LX, Tan HM, Zeng QG, Jia YY, Han WQ, Zhou SN (2004) Study on the communities of endophytic fungi and endophytic actinomycetes from rice and their antipathogenic activities in vitro. World J Microbiol Biotechnol 20: Vega FE (2008) Insect pathology and fungal endophytes. J Invertebr Pathol 98: Wraight SP, Jackson MA, DeKock SL (2001) Production, stabilization and formulation of fungal biocontrol agents. In: Butt T, Jackson C, Magan N (eds) Fungal biocontrol agents: progress, problems, and potential. CAB International, Wallingford, UK, pp Se Jin Lee is a PhD student in Insect Microbiology and Biotechnology Laboratory of Chonbuk National University, Korea. She is studying insect pathology and biological control, particularly focusing on entomopathogenic fungi. Jeong Seon Yu is a MD student in Insect Microbiology and Biotechnology Laboratory of Chonbuk National University, Korea. She is studying mass production of entomopathogenic fungi solid substrates and the application of fungal granules to target pests in agricultural practice. Yu Shin Nai is a research professor in Insect Microbiology and Biotechnology Laboratory of Chonbuk National University, Korea. His work focuses on insect pathology, fungal genomics, and expression of foreign genes in entomopathogenic fungi to improve the fungal biological activity. Bruce L. Parker is a professor in Entomology Research Laboratory of University of Vermont, USA and adjunct professor of Chonbuk National University. His research group focuses on the integrated pest management and entomopathogenic fungal thermotolerance and formulation. Margaret Skinner is a research professor in Entomology Research Laboratory of University of Vermont, USA. Her research group focuses on the integrated pest management and entomopathogenic fungal thermotolerance and formulation. She has a strong relationship with local farmers in the USA by providing information of biological control. Jae Su Kim is a professor in Insect Microbiology and Biotechnology Laboratory of Chonbuk National University, Korea. His main interest is biological control of agricultural pests using entomopathogenic fungi and functional genomics of some important isolates.