Endophytic colonization by Beauveria bassiana increases the resistance of tomatoes against Bemisia tabaci

Kasambala Donga T., Vega F.E., Klingen I.

We investigated the ability of the fungal entomopathogen Beauveria bassiana strain GHA to endophytically colonize sugarcane (Saccharum officinarum) and its impact on plant growth. We used foliar spray, stem injection, and soil drench inoculation methods. All three inoculation methods resulted in B. bassiana colonizing sugarcane tissues. Extent of fungal colonization differed significantly with inoculation method (χ2 = 20.112, d. f. = 2, p

Swain H., Adak T., Mukherjee A.K., Mukherjee P.K., Bhattacharyya P., Behera S., Bagchi T.B., Patro R., Shasmita, Khandual A., Bag M.K., Dangar T.K., Lenka S., Jena M.

This study is the first time report of utilization of Trichoderma spp. isolated from different tree bark from Odisha state of India for rice crop health management and higher productivity. Six isolates of Trichoderma spp. were identified based on the morphological characteristics and species determination was performed by molecular assays. One of the isolated strains determined as Trichoderma erinaceum outperformed others. Trichoderma erinaceum controlled three soil borne plant pathogens i.e. Rhizoctonia solani, Sclerotium rolfsii and Sclerotium oryzae effectively under controlled condition and R. solani and Helminthosporium oryzae under filed condition. Seed treatments with the formulated isolates improved the germination rate of rice and enhanced vigour. These parameters along with higher chlorophyll content could be related to higher yield observed in two rice varieties; Karuna and Sahabhagidhan . Among the six isolates tested, Trichoderma erinaceum treatment recorded highest yield. Significantly higher expression of some stress related enzymes was observed in Trichoderma treated plants which helped in better crop growth both under biotic and abiotic stresses. These isolates helped both the varieties to accumulate more nutrients. This study proves that Trichoderma erinaceum obtained from tree bark may be incorporated in integrated rice crop management both as biocontrol agent and biofertilizer.

Su Q., Chen G., Mescher M.C., Peng Z., Xie W., Wang S., Wu Q., Liu J., Li C., Wang W., Zhang Y.

Leaf damage caused by herbivore feeding often triggers induced resistance in plants. However, some herbivores can take advantage of the resulting metabolic changes in host plants and may even manipulate plant resistance, leading to a phenomenon known as induced susceptibility. Previous work has shown that feeding by the whitefly Bemisia tabaci can reduce tomato Solanum lycopersicum resistance and that whiteflies tended to aggregate on infested plants. However, metabolomic changes in the plant and associated whitefly behavioural responses underlying this phenomenon remain poorly understood. We, therefore, investigated how B. tabaci infestation affects host physiology and the preference and performance of conspecific feeders. Bemisia tabaci adults exhibited consistent behavioural preferences for plants that experienced actual and simulated herbivory by conspecifics (consistent with observed effects on whitefly performance), but not for plants that were only mechanically wounded. Leaf volatiles and extracts of B. tabaci‐infested plants showed altered terpenoid and flavonoid profiles. Manipulative behavioural experiments indicated that suppression of the monoterpenes α‐phellandrene and α‐terpinene and of flavonoids by B. tabaci infestation influenced the foraging and oviposition preferences of conspecifics. These findings document key metabolic changes in plants exhibiting induced susceptibility and demonstrate their role in mediating herbivore foraging behaviour and aggregation on susceptible plants, thereby providing new insight into a relatively unexplored aspect of plant–herbivore interactions. A plain language summary is available for this article.

Allegrucci N., Velazquez M.S., Russo M.L., Perez E., Scorsetti A.C.

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.

Vega

Fungal entomopathogens have been proposed as environmentally friendly alternatives to chemical control. Unfortunately, their effectiveness continues to be limited by their susceptibility to ultraviolet (UV) light and low moisture. A relatively recent development, the use of fungal entomopathogens as endophytes, might overcome the traditional obstacles impeding the widespread adoption of fungal entomopathogens and also provide a novel alternative for management of insect pests and plant pathogens. In addition, some fungal entomopathogens could also function as biofertilizers. Eighty-five papers covering 109 individual fungal entomopathogen studies involving 12 species in six genera are reviewed. Thirty-eight plant species in 19 families were studied, with maize, common bean, and tomato being the most investigated. Of the 85 papers, 39 (46%) examined the effects of fungal entomopathogen endophytism on 33 insect species in 17 families and eight orders. Thirty-four (40%) examined plant response to endophytism, corresponding to 20 plant species. Various inoculation techniques (e.g., foliar sprays, soil drenching, seed soaking, injections, etc.) are effective in introducing fungal entomopathogens as endophytes, but colonization appears to be localized and ephemeral. The field of insect pathology will not substantially profit from dozens of additional studies attempting to introduce fungal entomopathogens into a wider array of plants, without attempting to understand the mechanisms underlying endophytism, the responses of the plant to such endophytism, and the consequent responses of insect pests and plant pathogens. This review presents several areas that should receive focused attention to increase the probability of success for making this technology an effective alternative to chemical control.

Rondot Y., Reineke A.

Fungi are important natural pathogens of arthropod pests and are successfully used as biocontrol agents in various crops. In addition to colonizing arthropods, evidence has accumulated that some entomopathogenic fungi like Beauveria bassiana can endophytically colonize a wide array of plant species. However, only limited information is currently available on the endophytic colonization of grapevines with B. bassiana and whether the fungus still maintains its pathogenic habit against insect pests. Greenhouse and field experiments were conducted to optimize endophytic establishment of the entomopathogenic fungus B. bassiana in younger, potted plants and mature grapevine plants in the vineyard. We used two different commercialized B. bassiana strains, applied either as conidial suspensions (ATCC 74040 and GHA) or as a formulated product (Naturalis®, strain ATCC 74040) on grapevine leaves. The potential of endophytic B. bassiana to provide protection against putative target pest insects like the vine mealybug Planococcus ficus was assessed in a bioassay using surface sterilized leaves. Endophytic survival of B. bassiana inside leaf tissues of seven-week-old potted plants was evident for at least 21 days after inoculation, irrespective of the inoculum used. Endophytic B. bassiana reduces infestation rate and growth of P. ficus . In the vineyard B. bassiana was detected as an endophyte in mature grapevine plants up to five weeks after last application with significant reduction of infestation with grape leafhopper, Empoasca vitis .

Schettino M., Grasso D.A., Weldegergis B.T., Castracani C., Mori A., Dicke M., Van Lenteren J.C., Van Loon J.J.

In response to herbivory by insects, various plants produce volatiles that attract enemies of the herbivores. Although ants are important components of natural and agro-ecosystems, the importance of herbivore-induced plant volatiles (HIPVs) as cues for ants for finding food sources have received little attention. We investigated responses of the ant Formica pratensis to volatiles emitted by uninfested and insect-infested cucumber (Cucumis sativus) and potato (Solanum tuberosum) plants. Cucumber plants were infested by the phloem-feeding aphid Aphis gossypii, the leaf chewer Mamestra brassicae or simultaneously by both insects. Potato plants were infested by either Aphis gossypii, by the leaf chewer Chrysodeixis chalcites or both. In olfactometer experiments, ants preferred volatile blends emitted by cucumber plants infested with M. brassicae caterpillars alone or combined with A. gossypii to volatiles of undamaged plants or plants damaged by A. gossypii only. No preference was recorded in choice tests between volatiles released by aphid-infested plants over undamaged plants. Volatiles emitted by potato plants infested by either C. chalcites or A. gossypii were preferred by ants over volatiles released by undamaged plants. Ants did not discriminate between potato plants infested with aphids and caterpillars over plants infested with aphids only. Plant headspace composition showed qualitative and/or quantitative differences between herbivore treatments. Multivariate analysis revealed clear separation between uninfested and infested plants and among herbivore treatments. The importance of HIPVs in indirect plant defence by ants is discussed in the context of the ecology of ant-plant interactions and possible roles of ants in pest management.

Shikano I., Rosa C., Tan C., Felton G.W.

It is becoming abundantly clear that the microbes associated with plants and insects can profoundly influence plant-insect interactions. Here, we focus on recent findings and propose directions for future research that involve microbe-induced changes to plant defenses and nutritive quality as well as the consequences of these changes for the behavior and fitness of insect herbivores. Insect (herbivore and parasitoid)-associated microbes can favor or improve insect fitness by suppressing plant defenses and detoxifying defensive phytochemicals. Phytopathogens can influence or manipulate insect behavior and fitness by altering plant quality and defense. Plant-beneficial microbes can promote plant growth and influence plant nutritional and phytochemical composition that can positively or negatively influence insect fitness. Lastly, we suggest that entomopathogens have the potential to influence plant defenses directly as endophytes or indirectly by altering insect physiology.

Rivera M.J., Pelz-Stelinski K.S., Martini X., Stelinski L.L.

Plants can defend themselves against herbivores through activation of defensive pathways and attraction of third-trophic-level predators and parasites. Trophic cascades that mediate interactions in the phytobiome are part of a larger dynamic including the pathogens of the plant itself, which are known to greatly influence plant defenses. As such, we investigated the impact of a phloem-limited bacterial pathogen, Candidatus Liberibacter asiaticus (CLas), in cultivated citrus rootstock on a well-studied belowground tritrophic interaction involving the attraction of an entomopathogenic nematode (EPN), Steinernema diaprepesi, to their root-feeding insect hosts, Diaprepes abbreviatus larvae. Using belowground olfactometers, we show how CLas infection interferes with this belowground interaction by similarly inducing the release of a C12 terpene, pregeijerene, and disconnecting the association of the terpene with insect presence. D. abbreviatus larvae that were not feeding but in the presence of a CLas-infected plant were more likely to be infected by EPN than those near uninfected plants. Furthermore, nonfeeding larvae associated with CLas-infected plants were just as likely to be infected by EPN as those near noninfected plants with D. abbreviatus larval damage. Larvae of two weevil species, D. abbreviatus and Pachnaeus litus, were also more attracted to plants with infection than to uninfected plants. D. abbreviatus larvae were most active when exposed to pregeijerene at a concentration of 0.1 μg/μl. We attribute this attraction to CLas-infected plants to the same signal previously thought to be a herbivore-induced plant volatile specifically induced by root-feeding insects, pregeijerene, by assessing volatiles collected from the roots of infected plants and uninfected plants with and without feeding D. abbreviatus. Synthesis. Phytopathogens can influence the structuring of soil communities extending to the third trophic level. Field populations of EPN may be less effective at host-finding using pregeijerene as a cue in citrus grove agroecosystems with high presence of CLas infection.

Shikano I.

Plants play an important role in the interactions between insect herbivores and their pathogens. Since the seminal review by Cory and Hoover (2006) on plant-mediated effects on insect–pathogen interactions, considerable progress has been made in understanding the complexity of these tritrophic interactions. Increasing interest in the areas of nutritional and ecological immunology over the last decade have revealed that plant primary and secondary metabolites can influence the outcomes of insect–pathogen interactions by altering insect immune functioning and physical barriers to pathogen entry. Some insects use plant secondary chemicals and nutrients to prevent infections (prophylactic medication) and medicate to limit the severity of infections (therapeutic medication). Recent findings suggest that there may be selectable plant traits that enhance entomopathogen efficacy, suggesting that entomopathogens could potentially impose selection pressure on plant traits that improve both pathogen and plant fitness. Moreover, plants in nature are inhabited by diverse communities of microbes, in addition to entomopathogens, some of which can trigger immune responses in insect herbivores. Plants are also shared by numerous other herbivorous arthropods with different modes of feeding that can trigger different defensive responses in plants. Some insect symbionts and gut microbes can degrade ingested defensive phytochemicals and be orally secreted onto wounded plant tissue during herbivory to alter plant defenses. Since non-entomopathogenic microbes and other arthropods are likely to influence the outcomes of plant–insect–entomopathogen interactions, I discuss a need to consider these multitrophic interactions within the greater web of species interactions.

Martorana L., Foti M.C., Rondoni G., Conti E., Colazza S., Peri E.

Plants respond to insect attack by emission of volatile organic compounds, which recruit natural enemies of the attacking herbivore, constituting an indirect plant defence strategy. In this context, the egg parasitoid Trissolcus basalis is attracted by oviposition-induced plant volatiles emitted by Vicia faba plants as a consequence of feeding and oviposition by the pentatomid host Nezara viridula. However, this local tritrophic web could be affected by the recent invasion by the alien pentatomid bug Halyomorpha halys, an herbivore that shares the same environments as native pentatomid pests. Therefore, we investigated in laboratory conditions the possible impact of H. halys on the plant volatile-mediated signalling in the local tritrophic web V. faba–N. viridula–T. basalis. We found that T. basalis wasps were not attracted by volatiles induced in the plants by feeding and oviposition activities of H. halys, indicating specificity in the wasps’ response. However, the parasitoid attraction towards plant volatiles emitted as a consequence of feeding and oviposition by the associated host was disrupted when host, N. viridula, and non-associated host, H. halys, were concurrently present on the same plant, indicating that invasion by the alien herbivore interferes with established semiochemical webs. These outcomes are discussed in a context of multiple herbivory by evaluating the possible influences of alien insects on local parasitoid foraging behaviour.

Shivaramu S., Jayanthi P.D., Kempraj V., Anjinappa R., Nandagopal B., Chakravarty A.K.

Herbivore-induced plant volatiles (HIPVs) have been opined as ‘indirect or direct defenses’ of plants and are extensively studied. In contrast, HIPVs may also indicate that plant defenses have been overcome by herbivores infesting the plant; however, studies on this aspect have so far received little attention. Using the interaction of Capsicum annum (Bell pepper) with its pest Scirtothrips dorsalis (Chilli thrips) as a model system, we studied the role of HIPVs in this selected insect–plant interaction. Multiple-choice olfactometer assays with headspace volatiles collected from different growth stages of un-infested C. annum plants represented by pre-flowering (PF), flowering (FL) and fruiting stages (FR) proved FR volatiles to be highly attractive to S. dorsalis. Further, FR plants were infested with S. dorsalis adults and HIPVs released by infested plants were collected and subjected to multiple-choice olfactometer bioassays. Thrips were significantly attracted to HIPVs than to headspace volatiles of un-infested FR plants or thrips body odour. Coupled GC-EAG with S. dorsalis and HIPVs or FR plant volatile revealed specific compounds that elicited an EAG response. Individual EAG-active compounds were less attractive to thrips, however, synthetic blends of EAG-active compounds at the ratio similar to headspace samples were found to be highly attractive. However, when given a choice between synthetic blends of HIPVs and FR, thrips were significantly attracted to synthetic blend of HIPVs. Our study provides empirical data on signals HIPVs may provide to conspecific herbivores and suggests that the role of HIPVs, mostly generalized as defense, may vary based on the interaction and must be studied closely to understand their ecological functions.

Mauch-Mani B., Baccelli I., Luna E., Flors V.

Priming is an adaptive strategy that improves the defensive capacity of plants. This phenomenon is marked by an enhanced activation of induced defense mechanisms. Stimuli from pathogens, beneficial microbes, or arthropods, as well as chemicals and abiotic cues, can trigger the establishment of priming by acting as warning signals. Upon stimulus perception, changes may occur in the plant at the physiological, transcriptional, metabolic, and epigenetic levels. This phase is called the priming phase. Upon subsequent challenge, the plant effectively mounts a faster and/or stronger defense response that defines the postchallenge primed state and results in increased resistance and/or stress tolerance. Priming can be durable and maintained throughout the plant's life cycle and can even be transmitted to subsequent generations, therefore representing a type of plant immunological memory.

Behie S.W., Moreira C.C., Sementchoukova I., Barelli L., Zelisko P.M., Bidochka M.J.

Metarhizium robertsii is a common soil fungus that occupies a specialized ecological niche as an endophyte and an insect pathogen. Previously, we showed that the endophytic capability and insect pathogenicity of Metarhizium are coupled to provide an active method of insect-derived nitrogen transfer to a host plant via fungal mycelia. We speculated that in exchange for this insect-derived nitrogen, the plant would provide photosynthate to the fungus. By using 13CO2, we show the incorporation of 13C into photosynthate and the subsequent translocation of 13C into fungal-specific carbohydrates (trehalose and chitin) in the root/endophyte complex. We determined the amount of 13C present in root-associated fungal biomass over a 21-day period by extracting fungal carbohydrates and analysing their composition using nuclear magnetic resonance (NMR) spectroscopy. These findings are evidence that the host plant is providing photosynthate to the fungus, likely in exchange for insect-derived nitrogen in a tripartite, and symbiotic, interaction. The endophytic fungusMetarhizium robertsiiis also an insect pathogen and can facilitate transfer of insect-derived nitrogen to host plants. Here, the authors show that carbon is transferred from plant to fungus suggesting a tripartite interaction where nitrogen is exchanged for photosynthate.

Malik D., Kumar S., Sindhu S.S.

Guan J., liu J., Gou J., Xu Z., Zhou Y., Zou X.

Ghafari S., Karimi J., Cheniany M., Seifi A., Loverodge J., Butt T.M.

Paweer M.M., Namikoye E.S., Nchore S.B., Akutse K.S.

Field trials were conducted for two seasons in two experimental sites (Mwea in Kirinyaga and Ngoliba in Kiambu counties of Kenya) to assess the efficacy of fungal endophytes Hypocrea lixii F3ST1 and Trichoderma asperellum M2RT4 in the control of Trialeurodes vaporariorum vector of tomato infectious chlorosis virus (TICV) and tomato chlorosis virus (ToCV) through seeds inoculation. TICV and ToCV’s disease incidence, severity and the yield were also evaluated. All the fungal endophytes successfully colonized all the tomato plant parts, but the highest root colonization was observed in H. lixii F3ST1 compared to the T. asperellum M2RT4 in both seasons. The number of nymphs was significantly lower in the endophytically colonized tomato plants than the control treatments in all the seasons and at both sites. However, the lowest number of nymphs was recorded in H. lixii F3ST1 compared to T. asperellum M2RT4. On the other hand, the TICV and ToCV disease incidence and severity rates were lower in endophytically colonized tomato crops compared to the control plots. This could be attributed to the reduction in the virus replication and lower feeding ability of T. vaporariorum that was characterized by less excretion of honeydew causing sooty mold. However, no significant difference was observed in ToCV disease severity rates among the treatments and across the seasons. The yield was significantly higher in endophyte plots than the control treatments in both sites and across the two seasons. This study demonstrates that H. lixii F3ST1 and T. asperellum M2RT4 endophytically colonized tomato plants and conferred systemic resistance against T. vaporariorum vector, and significantly reduced the transmission of TICV and ToCV, contributing to high reduction of both diseases’ incidence and severity in the field. However, further studies are warranted to confirm these results at large scale trials.

Ren X., Xu R., Shen G., Wu S., Lei Z.

Inoculating plants with entomopathogenic fungi can improve plant resistance to pests and promote growth, suggesting that this approach is a sustainable method for controlling insect pests. Two Beauveria bassiana isolates (GZGY-1-3 and XJWLMQ-32) were inoculated via three different methods (foliar, soil and seed treatments) to assess the endophytic colonization and plant growth of bean (Phaseolus vulgaris) plants at 7, 14 and 21 days post-inoculation (DPI). Western flower thrips (WFT), Frankliniella occidentalis Pergande, feeding on B. bassiana-inoculated bean leaves was carried out by foliar spraying. A two-sex life table study was generated to determine the effect of feeding on B. bassiana-inoculated bean plants on the development and fecundity of WFT. Results showed that both isolates endophytically colonized leaves, stems and roots via the three inoculation methods, and the colonization rates from bean plants varied with the inoculation methods and decreased as the DPI increased. Root weight, plant weight and leaf numbers of bean were promoted after both B. bassiana isolates inoculation. Plant growth was strongly promoted by the XJWLMQ-32 isolate. The inoculated plants could deter feeding by WFT, and the life table study results showed that feeding on the inoculated plants resulted in a slow development rate (r = 0.15 d-1, λ = 1.16 d-1) and low fecundity (F = 27.62 eggs per female) in WFT. This study highlights that B. bassiana can endophytically colonize P. vulgaris and promote plant growth and that this plant–microbe symbiosis can deter WFT feeding and inhibit population growth.

Pec M., Salazar-Mendoza P., Magalhães D.M., Delalibera I., Bento J.M.

Biswas C., Dey P., R. T., Ramesh Babu V., Alam N.M., Mandal A.K.

Papantzikos V., Mantzoukas S., Eliopoulos P.A., Servis D., Bitivanos S., Patakioutas G.

In this study, the bioinsecticidal action of a commercial formulation with Beauveria bassiana was evaluated on the new sucking pest in Greece: Halyomorpha halys, of the kiwifruit. Additionally, the biostimulant potential of the same formulation was studied on kiwi growth. The application was performed in three different ways in a commercial field of kiwi crop A. deliciosa “Hayward” field in Arta, Greece: (i) trunk spray, (ii) root injection, and (iii) trunk inoculation. During the 2 years seasons of the experiment, weekly measurements of the H. halys population were determined. The insect is sucking plants nutrients; therefore, the total chlorophyll content in the leaves of the treatments was recorded weekly. In addition, the percentage of infested kiwifruits was estimated at the end of the experiment. Moreover, to study the biostimulant potential of the formulation, growth measurements on stems and leaves were performed during the experiment. Finally, at the kiwi harvest point, the fruit biomass, dimensions, and weight were obtained, and the leaves’ proline content was evaluated. The results encourage us to further study this EPF formulation as the bioinsecticidal effect was noted by the reduction in H. halys population, and biostimulant action was perceived by the higher plant biomass.

Li Y., Yan S., Jiang D.

This study evaluated the effects of cadmium (Cd) exposure on the passive and active lethal efficiency of Beauveria bassiana (Bb) to Lymantria dispar larvae and analyzed the corresponding mechanism from mycelial vegetative growth, fungal and host nutrient competition, and fungal spore performance. The results showed that the passive lethal efficiency of Bb to Cd-exposed L. dispar larvae was significantly higher than that of larvae not exposed to Cd. After Bb infection, the fungal biomass in living larvae and the mycelium encapsulation index of dead larvae were significantly decreased under Cd exposure. Cd exposure damaged the mycelial structure, as well as inhibited the mycelial growth and sporulation quantity. A total of 15 and 39 differentially accumulated mycotoxin metabolites were identified in Bb mycelia treated with low Cd and high Cd, respectively, and the contents of these differentially accumulated mycotoxins in the low Cd and high Cd treatment groups were overall lower than those in the control group. Nutrient content and energy metabolism-related gene expression were significantly decreased in Cd-exposed larvae, both before and after Bb infection. Trehalose supplementation alleviated the nutritional deficiency of larvae under the combined treatment of Cd and Bb and decreased the larval susceptibility to Bb. Compared with untreated Bb, the lethal efficiency of low Cd-exposed Bb to larvae increased significantly, while high Cd-exposed Bb was significantly less lethal to larvae. Cd exposure promoted at low concentrations but inhibited the hydrophobicity and adhesion of spores at higher concentrations. Spore germination rate and stress resistance of Bb decreased significantly under the treatment of both Cd concentrations. Taken together, heavy metals can be regarded as an abiotic environmental factor that directly affects the lethal efficiency of Bb to insect pests.

Xu G., Li C., Gui W., Xu M., Lu J., Qian M., Zhang Y., Yang G.

AbstractBACKGROUNDPiriformospora indica is an endophytic fungus that can promote the growth and confer the resistance against diverse stresses in host plants by root colonization. However, the effects of P. indica colonization on improving plant resistance to insect pests are still less explored. The brown planthopper (BPH) Nilaparvata lugens is a serious monophagous pest that causes extensive damage to rice plants. Here, we aimed to evaluate the effects of P. indica colonization on rice resistance against BPH.RESULTSThe colonization of P. indica in the rice roots resisted the damage from BPH. The age‐stage, two‐sex life table analyses showed that feeding on P. indica‐colonized rice plants affected BPH's female adult longevity, oviposition period, fecundity, population parameters and population size. BPH female adults feeding on P. indica‐colonized plants excreted less honeydew. P. indica colonization remarkably increased the duration of np, N2, and N3 waveform, as well as the occurrences of N1 and N2, and decreased the duration of N4‐b for BPH on rice plants. Meanwhile, the weight of BPH on the colonized plants was significantly lower than the control. In addition, the feeding and oviposition preferences of BPH to P. indica‐colonized plants were reduced. qRT‐RCR analyses revealed that P. indica colonization induced the expressions of jasmonic acid (JA)‐ and salicylic acid (SA)‐related genes in rice plants.CONCLUSIONP. indica colonization can reduce BPH performance on rice plants with potentially inhibitory effects on population growth. Collectively, these results support the potential for endophytically colonized P. indica as an effective strategy to improve insect resistance of crops.This article is protected by copyright. All rights reserved.

Campagnani M.O., Auad A.M., Maurício R.M., Madureira A.P., Cangussú M.A., Rosa L.H., Pereira M.F., Muniz M., Souza S.R., Silva N.B., Silva A.C., Campos W.G.

Pests in pastures have compromised the production of biomass for feeding livestock herds. Many strategies have been applied to sustainably solve this problem. One viable and innovative technique is the delivery of entomopathogenic fungi through endophytes. Therefore, this study aimed to (i) evaluate the endophytic capacity of two entomopathogenic fungi, Fusarium multiceps UFMGCB 11443 and Metarhizium anisopliae UFMGCB 11444, in Urochloa brizantha [(Hochst. ex A. Rich.) Stapf] (Poaceae) cultivar ‘Marundu’) via foliar inoculation or seed treatment, and (ii) measure their efficiency in controlling Mahanarva spectabilis Distant, 1909 (Hemiptera: Cercopidae) in U. brizantha. In the greenhouse, the fungi colonized the tissues of U. brizantha plants when inoculated via foliar spraying or seed treatment. The fungi F. multiceps and M. anisopliae caused 88% and 97.1% epizootic effects via seed inoculation, respectively, and 100% epizootic effects via foliar inoculation. In the field, the lowest fungal dose of 0.5 kg/ha had the same effect as a fourfold greater dose, with a >86% decrease in insect pest infestation observed. In summary, the fungi F. multiceps and M. anisopliae have endophytic effects and can effectively control M. spectabilis in U. brizantha pastures.

Wang X., Yuan Q., He L., Wang Z., Li G., Wang Z., Liu H.

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

Wakil W., Boukouvala M.C., Kavallieratos N.G., Naeem A., Ghazanfar M.U., Alhewairini S.S.

Tetranychus urticae is an important pest of tomato crops globally, affecting plant yield and growth. Beauveria bassiana and Metarhizium robertsii have the potential to control T. urticae. We investigated the influence of two B. bassiana (i.e., WG-12 and WG-19) isolates and one M. robertsii (WG-02) isolate when colonizing different plant organs (leaves, stems, and roots) and their influence on the growth of tomato plants, through foliar, root-dipping, and seed-soaking application techniques. We also examined the acaricidal activity of the three isolates against T. urticae (female adults), spraying tomato leaf discs with each isolate separately. After 28 days, WG-12 and WG-19 colonized 97 and 91% of the leaves after foliar inoculation, whereas WG-02 exhibited the lowest leaf colonization (76%). The height of the tomato plants, the root length, the number of leaves, and the weight of the biomass above and below the ground were enhanced significantly after inoculation with WG-02 vs. B. bassiana isolates and control. The complete mortality of T. urticae was caused by WG-12 and WG-02 after 10 days, whereas WG-19 killed 94% of the adults. For the effective management of T. urticae, we propose the application of the WG-02 isolate since it provides complete protection and promotes the growth of tomato plants.

Komagata Y., Sekine T., Oe T., Kakui S., Yamanaka S.

Abstract Background Implementing pest and disease control techniques that have low environmental impact is important for sustainable agriculture. Microbial biopesticides are an effective approach due to their low environmental impact and low risk of resistance development. Because it is not usually possible to control multiple pests and diseases with a single microbial biopesticide, it is essential to investigate the potential for combining microbial biopesticides with varying control spectrums effectively. Many biopesticides have antimicrobial activity and may therefore interact negatively in combination. Results This study demonstrated that a mixture of Beauveria bassiana and Bacillus subtilis formulations proved potential for simultaneous control of greenhouse whitefly (Trialeurodes vaporariorum Westwood) and tomato powdery mildew (Oidium neolycopersici). Three greenhouse experiments were conducted to assess the efficacy of mixed and single-use treatments. A laboratory experiment comparing the insecticidal effect of each treatment was also conducted. In all greenhouse experiments, the combined treatment controlled the greenhouse whitefly (78.9–88.3%) and tomato powdery mildew (47.2–81.0%) compared to untreated controls, which was as well as each treatment alone. In some greenhouse and laboratory experiments, the mixed treatment showed an approximately 1.32 to 1.78 times higher insecticidal effect compared to single-use treatments. Regarding the control efficacy against the pest and disease, negative effects of microbial agents on each other were not observed. Conclusions These results demonstrated the effectiveness of concurrent use of two microbial pesticides examined on dual control of pest and disease and showed potential for improved control of certain pests. The knowledge of this work could suggest the possibility of more environmentally friendly pest control systems with the use of microbial pesticides.

Batool R., Xuelian G., Hui D., Xiuzhen L., Umer M.J., Rwomushana I., Ali A., Attia K.A., Jingfei G., Zhenying W.

AbstractSeed priming with beneficial endophytic fungi is an emerging sustainable strategy for enhancing plant resistance against insect pests. This study examined the effects of Beauvaria bassiana Bb20091317 and Metarhizium rileyi MrCDTLJ1 fungal colonization on maize growth, defence signalling, benzoxazinoid levels and gene expression. The colonization did not adversely affect plant growth but reduced larval weights of Spodoptera frugiperda. Maize leaves treated with M. rileyi exhibited higher levels of jasmonic acid, jasmonoyl‐Isoleucine, salicylic acid, and indole acetic acid compared to control. B. bassiana and M. rileyi accelerated phytohormone increase upon S. frugiperda herbivory. Gene expression analysis revealed modulation of benzoxazinoid biosynthesis genes. We further elucidated the immune regulatory role of the transcription factor zmWRKY36 using virus‐induced gene silencing (VIGS) in maize. zmWRKY36 positively regulates maize immunity against S. frugiperda, likely by interacting with defense‐related proteins. Transient overexpression of zmWRKY36 in tobacco‐induced cell death, while silencing in maize reduced chitin‐triggered reactive oxygen species burst, confirming its immune function. Overall, B. bassiana and M. rileyi successfully colonized maize, impacting larval growth, defense signalling, and zmWRKY36‐mediated resistance. This sheds light on maize‐endophyte‐insect interactions for sustainable plant protection.