Search Results (70)

Entomopathogenic fungi (EPF) are one of the most environmentally friendly ways to control a plethora of chewing insects such as T. pityocampa, G. mellonella, and A. grisella. Bioassay of EPF on these highly damaging pests is considered important in the face of climate change in order to research alternative solutions that are capable of limiting chemical control, the overuse of which increases insects’ resistance to chemical compounds. In this study, the insecticidal virulence of Metarhizium robertsii isolates, retrieved from forest ecosystems, was tested on second-instar larvae of T. pityocampa, G. mellonella, and A. grisella. Bioassays were carried out in the laboratory, where experimental larvae were sprayed with 2 mL of a six-conidial suspension from each isolate. Mortality was recorded for 144 h after exposure. Mean mortality, lethal concentrations, sporulation percentage, and sporulation time were estimated for each isolate. Metarhizium isolates resulted in the highest mortality (89.2% for G. mellonella and 90.2% for A. grisella). Based on the LC₅₀ estimates determined by the concentration–mortality relationships for the tested fungal isolates, we demonstrated significant virulence on larvae of G. mellonella, A. grisella, and T. pityocampa. Our results indicate that entomopathogenic fungi have the potential to become a very useful tool in reducing chemical applications. Full article

Entomopathogenic fungi (EPF) are substantial biocontrol agents reducing the populations of economically important pests in numerous crops. Recent findings indicate that their role in agroecosystems is more complex and extends to affecting plant physiology and growth. This study examined the effects of Beauveria bassiana and Isaria fumosorosea, as well as Salicylic acid (SA), on physiological parameters of grapevine (Vitis vinifera cv. Sauvignon Blanc). Additionally, the impact of SA on spore germination and pathogenicity of EPF against larvae of the European grapevine moth (Lobesia botrana) was tested. Foliar application of EPF was found to increase the electron transport rate (ETR) from PSII to PSI, indicating higher photosynthetic activity compared to control plants. EPF also elevated the transpiration rate (E) and stomatal conductance (gs). In contrast, SA treatments decreased E and gs, while the high dose (10 mM) exhibited reduced Fv/Fm value, accompanied by phytotoxic spots on leaves. Spore germination of both fungi was significantly reduced only by the SA concentration of 2 mM, while 0.5 and 1 mM did not affect germination. Combination EPF and SA treatments presented the highest larval mortality of L. botrana (87.5% at 28 °C and 77.5% at 24 °C for B. bassiana and I. fumosorosea, respectively). However, SA reduced larval mycosis in most cases. Overall, the results suggest that EPF and SA can be co-applied and included in vineyard integrated strategies to support grapevine health. Full article

Chemical control using synthetic insecticides is the most widely used method for controlling the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Sub-Saharan Africa (SSA). However, the application of insecticides is not a long-term or sustainable solution. Biological control is an important pillar of integrated pest management, and entomopathogenic fungi (EPFs) are becoming increasingly important as biocontrol agents. However, no EPF biopesticides have been registered in South Africa for the control of S. frugiperda. Few studies have been conducted on the efficacy of commercial formulations of biopesticides against all S. frugiperda life stages. The objective of this study was, therefore, to assess the potential of two Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Clavicipitaceae) and two Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) based commercial biopesticides registered in South Africa against other pests, for their efficacy against S. frugiperda. The effects of these EPF formulations were evaluated on larval and prepupal mortality, moth emergence, fecundity, and longevity of the emerged moths. The results indicated that S. frugiperda second- and sixth-instar larvae were not susceptible to the biopesticides. Moth emergence, fecundity, and longevity were not significantly affected. However, prepupae were susceptible to both Metarhizium formulations, with Metarhizium anisopliae ICIPE 78 resulting in the highest mortality (56.7%). This biopesticide holds potential for the management of S. frugiperda when applied to the soil for the control of pupating larvae. Full article

Ambrosia beetles, known for their symbiotic relationship with fungi cultivated within the tissues of host trees, have become significant pests, particularly when they serve as vectors for pathogenic fungi such as Raffaelea lauricola. Given the regulatory and environmental constraints for chemical application as a tool for their control, entomopathogenic fungi (EPF) represent a promising pest management alternative. This review presents an overview of bioassays assessing the pathogenicity and virulence of EPF against ambrosia beetles. Most studies have been performed in vivo (artificial diet) under laboratory conditions, focusing on exotic species and testing EPF genera such as Beauveria, Metarhizium, Isaria, and Purpureocillium. However, variations in inoculation methods, environmental conditions, and fungal formulations, have led to diverse results. In addition, the complex biology of these insects, particularly their dependence on symbiotic fungi, represents significant methodological challenges. Field trials (in situ bioassays) are still scarce, and there is a need to move toward standardized protocols and more objective experimental models that consider not only insects’ behavior but also ecological factors. Bridging this gap is essential for successfully implementing EPF-based strategies to assess ambrosia beetles’ biocontrol. Full article

The use of entomopathogenic fungi (EPF), such as Cordyceps javanica, to reduce insect pest populations is gaining traction since it is an environmentally safe approach that can control many pests at different life stages. Here, we focus on the histopathology of the coffee berry borer, Hypothenemus hampei, infected by C. javanica. Morphological observation revealed that C. javanica conidia germinated within 12 h following inoculation according to light microscopic and ultrastructural levels. The fungus thoroughly penetrated the fat body and muscular tissue between 84 and 120 h post-inoculation. Transmission electron microscopy (TEM) confirmed the hyphal invasion of the cuticle at 12 h post-inoculation, with progressive tissue disruption and organelle degeneration, especially mitochondria and rough endoplasmic reticulum in adipocytes. All organelles were completely degenerated at 96 h post-inoculation. There was evidence of a connection between C. javanica activity and the coffee berry borer that might cause histopathological changes in the host defense against the pathogen, pointing to increased mortality and potential control of coffee berry borer in natural populations. Additionally, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) confirmed that apoptotic cells were slightly increased in the adipose tissue and integument of the coffee berry borer. The ability of C. javanica to fatally infect the coffee berry borer suggests that it could be deployed as a biological control agent in the field. Full article

The striped flea beetle (SFB), Phyllotreta striolata, is a significant pest of cruciferous crops. Entomopathogenic fungi (EPF) hold great promise for the integrated pest management (IPM) of the SFB. However, the lack of understanding of the different interactions between the SFB and EPF restricts the development of mycoinsecticides. This study aims to elucidate the interaction performance of the SFB with three EPF—Beauveria bassiana BbPs01 (Bb), Metarhizium robertsii MrCb01 (Mr), and Cordyceps javanica IjH6102 (Cj). The bioassay results indicated that the virulences of EPF to the SFB adults were recorded as Bb > Mr > Cj. Then, the EPF with distinct infection pathways were observed, in which Bb penetrated the SFB cuticle via germ-tubes and appressoria, Mr typically invaded using appressoria, while Cj employed germ-tubes. Moreover, the SFB with different symptoms following infection by the EPF species were recorded. Bb primarily caused SFB adults to lose their appetite, become sluggish, and die rapidly. In contrast, SFB adults infected with Mr often experienced shivering, uncoordinated movement, and slower death. Cj-infected larvae frequently displayed dendrite-like melanization originating from the spiracles, while infected adults exhibited weak shivering and slow death, which seems similar to Mr. Our findings provide novel insights into the interactions between EPF and insects and offer valuable materials for enhancing the application of mycoinsecticides in the control of the SFB. Full article

Pyrethroids are chemical insecticides used on a large scale in agriculture, horticulture, and forest protection. In order to reduce their use in IPM, alternative methods of controlling insect pests are introduced, such as the use of biopesticides based on entomopathogenic fungi (EPF). Species of the Beauveria genus are characterized by a very broad spectrum of action, which is why they are often used to produce preparations based on EPF. The aim of the study was to determine the effect of different doses of tested pyrethroids on the colony growth and metabolic activity of EPF from the Beauveria genus. In vitro, the effect of three pyrethroids (deltamethrin, λ-cyhalothrin, and α-cypermethrin) added to SDA medium at a dose 10 times lower than the recommended field dose (A), the recommended field dose (B), and 10 times higher than the recommended field dose (C) on colony growth and metabolic activity of B. bassiana and B. brongniartii was tested. The research carried out showed that pyrethroid insecticides used in the experiment showed various toxic effects towards the tested EPF of the genus Beauveria. The studies conducted showed that on the 20th day of the observation, λ-cyhalothrin used in the recommended field dose limited the growth of B. bassiana to the least extent in relation to the other tested pyrethroids. However, with respect to the fungus B. brongniartii, no toxic effect of this pyrethroid was found. Based on the results obtained, it was found that λ-cyhalothrin used in the recommended field dose and 10 times lower than recommended significantly increased the metabolic activity of B. bassiana. In relation to the B. brongniartii strain, detlamethrin used in each of the tested concentrations significantly affected its viability. Full article

The striped flea beetle (SFB), Phyllotreta striolata, is a major pest of Brassicaceae crops, causing substantial yield losses worldwide. Effective biocontrol strategies, particularly the development of mycoinsecticides, require the identification of virulent entomopathogenic fungi (EPF) and the establishment of reliable bioassay systems. However, establishing reliable bioassay systems for SFB has been particularly challenging, especially for larval stages due to their recalcitrant rearing requirements. This study aimed to establish a standardized bioassay protocol to evaluate EPF efficacy against SFB. A specialized larval collection apparatus was developed, and the virulence of three EPF strains (Beauveria bassiana BbPs01, Metarhizium robertii MrCb01, and Cordyceps javanica IjH6102) was assessed against both adult and larval stages using a radish slice-based rearing system. Intriguingly, BbPs01 and MrCb01 exhibited significantly higher LT₅₀ values in larvae than in adults, contrary to the typical pattern of greater larval susceptibility observed in most insect systems. We hypothesized that isothiocyanate—specifically sulforaphane, a compound abundant in radish tissues—exerts fungistatic effects that impair fungal growth and virulence. Follow-up experiments confirmed that radish-derived sulforaphane inhibited fungal activity. Through alternative host plant screening, Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis) was identified as an optimal larval diet that minimally interferes with EPF bioactivity, enabling reliable virulence assessments. This study presents critical methodological advancements for SFB biocontrol research, providing a robust framework for standardized larval bioassay and novel insights into plant secondary metabolite interactions with entomopathogens. The optimized system supports the development of targeted mycoinsecticides and contributes to a deeper understanding of tri-trophic interactions in crucifer pest management. Full article

Entomopathogenic fungi (EPFs) can influence plant–insect interactions through complex molecular and chemical mechanisms. This study investigates how EPF treatment of tomato plants modulates volatile organic compound (VOC) emissions and subsequent trophic interactions between tomato plants, the herbivorous pest Phthorimaea absoluta, and the parasitic wasp, Trichogramma chilonis. Our results demonstrate that EPF-treated plants exhibited reduced attractiveness to adult P. absoluta moths, which were actively repelled by EPF-induced VOCs. Conversely, these same plants showed enhanced recruitment of the parasitoid T. chilonis, which demonstrated positive chemotaxis toward the modified VOC profile. Chemical analysis revealed significantly elevated emissions of key VOCs in EPF-treated plants, particularly (E)-β-Caryophyllene, β-phellandrene, and α-Phellandrene. This increase is correlated with enhanced production of defense-related phytohormones, including JA, SA, and JA-Ile, which may regulate VOC biosynthesis pathways. Behavioral response studies using synthetic VOCs and electroantennogram (EAG) measurements confirmed that these EPF-induced VOCs elicited strong olfactory responses in both insect species. To summarize, EPF treatment reshapes multitrophic interactions by strategically modulating plant VOC emissions and activating defense signaling pathways in tomato plants, providing new insights for potential applications in sustainable pest management strategies. Full article

Greece’s olive oil production is significantly affected by the olive fruit fly Bactrocera oleae (Diptera: Tephritidae), and its presence is perceived when it is too late to act for damage recovery. In this work, some unexplored entomopathogenic fungi (EPFs) were studied for their efficacy on olive fruit fly pupae in soil samples. Olive grove soil samples were collected to evaluate the effect of EPFs in their natural environment. The parameters that were analyzed to evaluate the performance of EPFs on B. oleae included the adult survival time, pupa hatch time, and the presence of mycelium on B. oleae pupae and dead adults. The efficacy of some EPFs was highlighted by the mycelium present on dead B. oleae adults after treating pupae with fungal isolates on the soil substrate. The results showed that for the soil substrate, external fungal growth was observed in dead adults with A. contaminans, A. keveii, A. flavus P. lilacinum, and T. annesophieae (100%). Remarkably, the lowest male proportion for soil and non-soil substrates was for A. flavus (0.41–0.42) for the first time, for A. keveii (0.36), and for P. citreosulfuratum (0.41) on the soil-only substrate in contrast to the control treatment (0.5 for both substrates). Given the high infestation caused by the olive fruit flies in Greece, the results of the study emphasize to use of incorporating certain EPF-based biopesticides into integrated pest management (IPM) programs. Full article

The banana pseudostem weevil (BPW), Odoiporus longicollis (Oliver), is one of the most destructive pests of bananas that is seriously affecting the yield and quality of bananas. We isolated pathogens from banana pseudostem weevils in Xishuangbanna and Dongchuan, Yunnan, China, and explored their biological characteristics. The pathogenicity of the strains was verified through laboratory and greenhouse inoculation experiments. The results showed that four strains of fungi were identified and confirmed as Beauveria caledonica (Bc) via ITS-rDNA sequencing. Optimal in vitro culture conditions were found to be a photoperiod of 24 h light, 25 °C temperature, and 18 days on potato dextrose agar (PDA) medium with insect meal. Under these conditions, the Cs-1 strain achieved a colony diameter of 65.17 ± 0.74 mm and spore production of 1.24 × 10⁸ cfu/cm². The Cs-1 strain had the shortest lethal time (LT₅₀) of 9.36 days at an inoculum of 1.00 × 10⁹ cfu/mL, with a lethality of 86.67% after 20 days. The Cs-3 strain showed 77.78% lethality at 1.00 × 10⁸ cfu/mL after 20 days. Despite variations in virulence, lethality did not correlate with major cuticle-degrading enzymes. The Cs-3 strain demonstrated effective biocontrol in greenhouse tests. Banana plants suffered significant damage without Bc-treated BPW, while the treated plantlets thrived. The mortality rate reached 82.78% after 35 days. This study marks the first identification of these entomopathogenic fungi (EPF) in Yunnan, China, highlighting B. caledonica’s potential for biocontrol application. Full article

Concerns about the environmental and health risks of synthetic insecticides are driving the search for alternative pest control methods. Leaf-cutting ants (LCAs), one of the most significant pests in the neotropics, cause substantial economic damage to agriculture and present challenges for control due to their complex biology and ecology. While chemical control remains the primary strategy, its intensive use has negative environmental impacts, promotes pest resistance, and endangers non-target species, including plants, animals, and humans. This review describes the biology of LCAs, examines traditional control methods and suggests alternative strategies such as the use of entomopathogenic fungi (EPFs) combined with sublethal doses of insecticides, plant essential oils (EOs), and RNAi techniques. Here, we emphasize the need to address LCA management sustainably by investigating the biology and ecology at both the “colony” and “individual” levels. Colony-level factors include morphology, life cycle, behavior, division of labor, and nest structure, while individual-level mechanisms involve sensory, biochemical, and behavioral adaptations for garden sterilization and decontamination. This review also highlights the potential of sublethal insecticide doses combined with EPFs to induce behavioral changes and worker mortality, and it details the mode of action of EOs and the use of RNAi as promising control strategies. The integration of biological and chemical approaches could offer sustainable alternatives to synthetic insecticides. Full article

This study addresses the agricultural impact of the grasshopper Sphenarium purpurascens and evaluates the efficacy of entomopathogenic fungi (EPF), Beauveria bassiana, and Metarhizium robertsii, formulated in vegetable oil emulsions as sustainable pest control agents. The losses caused by S. purpurascens at different developmental stages (N4, N5, and adult) were assessed in five economically significant crops (Medicago sativa, Zea mays, Helianthus sp., Cynodon dactylon, and Cucurbita pepo), revealing a marked preference for Helianthus sp. and C. pepo, with consumption rates reaching 0.92 g/48 h during N4 and N5 stages, while adults showed preference for M. sativa (1.18 g/48 h) and Z. mays (1.15 g/48 h). The viability of EPF in oil emulsions (20% and 40% concentrations) was evaluated, demonstrating that formulations with Azadirachta indica and Moringa oleifera maintained over 99% fungal viability compared to the control absolute with distilled water (DW). The effectiveness of EPF against S. purpurascens adults was tested, with EPF on M. robertsii combined with Persea americana achieving 100% mortality within 72 h. Finally, the pathogenicity and dispersion of EPF in oil emulsions were evaluated, demonstrating that, at 240 h, the B. bassiana + A. indica strain (with three inoculated insects) achieved 100% mortality. It was observed that the number of inoculated adults directly influenced the mortality of S. purpurascens. These findings highlight the potential of EPF as a sustainable pest management strategy, emphasizing the need for further field trials to optimize its application and mitigate agricultural losses caused by S. purpurascens. Full article

Entomopathogenic fungi (EPF)-based biopesticides have attracted growing interest in pest management as alternatives to neurotoxic insecticides. Their potential was evaluated against various pests, including the broad bean weevil (Bruchus rufimanus Boheman 1833), a significant threat to faba bean (Vicia faba L.) crops. This study examined the entomotoxic effects and sublethal impacts (on oviposition) of three fungal strains under laboratory conditions: Beauveria bassiana (GHA), Metarhizium brunneum (USDA 4556), and M. brunneum (V275) on B. rufimanus adults. Subsequently, a large-scale field trial assessed the efficacy of B. bassiana (GHA) against B. rufimanus infestations using conventional anti-drift and dropleg spraying methods. The laboratory LT₅₀ values ranged from four days for B. bassiana to eight days for M. brunneum (V275). The mortality rates recorded after ten days ranged from 86.6% for M. brunneum (V275) to 96.6% for B. bassiana (GHA). The inhibition of oviposition rates ranged from 12% for M. brunneum (USDA 4556) to 36% for B. bassiana (GHA). Field trials showed that the dropleg nozzles targeted faba bean pods, the oviposition sites of B. rufimanus, more effectively than the anti-drift nozzles. However, both fungal and chemical treatments applied via dropleg nozzles offered limited protection, reducing the infestation rates by 7% and 14%, respectively, with only a 3% improvement over anti-drift nozzles. This suggests that the large-scale spraying of chemical or fungal agents, including B. bassiana GHA, is not an optimal IPM strategy for managing B. rufimanus in faba beans. These laboratory and field results highlight the potential of EPF for managing B. rufimanus. However, the limitations of spray-applied plant protection methods underscore the need to redirect research toward more targeted strategies, such as attract-and-infect or endophytic EPF approaches. Full article

Environmentally sound insect pest management strategies require continuous isolation and identification of effective biocontrol agents from different ecosystems. The quest for fungal isolates that are adapted to high temperatures is particularly significant, as they hold the potential to produce mycoinsecticides that are highly effective in semiarid and arid areas. This study aimed to collect new virulent isolates of entomopathogenic fungi (EPF) from Kazakhstan that show promise for controlling Colorado potato beetle (CPB) populations under arid conditions. Local isolates could be adapted to abiotic and biotic factors in the environment in which they survive. The findings of this study should provide insights into the species of EPF that inhabit a specific arid region of Kazakhstan, examining their traits in the regional climate, soil composition, and biological diversity. Throughout 2023–2024, a series of soil samples was collected from diverse locations within the Turkestan region of southern Kazakhstan for the isolation of EPF. The isolation of EPF was conducted using susceptible larvae of Tenebrio molitor (Coleoptera: Tenebrionidae), a host that does not have specificity for particular species of EPF. Using this insect bait, 41 pure cultures of EPF were isolated from soils in the arid zone of Kazakhstan. Polymerase chain reaction analysis based on the TEF1-α locus showed that all the isolates were indistinguishable from Beauveria bassiana ARSEF 2860 species. However, analysis of the ITS locus revealed two cryptic species: B. bassiana and B. pseudobassiana. For laboratory evaluation of biological activity EPF, the second and third instars of CPB were collected from potato fields in southern Kazakhstan and placed in plastic containers. Test CPB larvae were treated with conidia suspensions at 1 × 10⁷ spores/mL and survival was recorded daily for 3 weeks. The results of the bioassays revealed that all the new Kazakhstan isolates were pathogenic to larvae CPB and caused complete mortality by the end of the 11-day. These results showed that new isolates of EPF were highly virulent against larvae CPB. Full article