Fungal Formulations Research Articles

Using Fungal and Bacterial Bioagent Formula Antagonists to Combat Fusarium Oxysporum f. sp. Lycopersici Under Greenhouse Conditions

Objective: This study aimed to test fungal and bacterial bioagents as formula antagonists of Fusarium oxysporum f. sp. lycopersici under greenhouse conditions. Methods: The fungal and bacterial formulations' shelf life under different temperatures as well as under growth chamber and greenhouse conditions, as well as their effects on biochemical alterations involved in the induction of plant defense against the causative pathogen were investigated. Results: In-vitro antagonist screening of bacterial and fungal isolates on radial growth, reduction and inhibition percentages revealed that T. harzianum exhibited 45.6% of inhibition followed by B. pumilus with 36.7%. Among the fungal and bacterial bio-agents, the highest effect on disease incidence and efficiency against pathogenic fungus under greenhouse conditions was B. pumilus 27 and 69%, respectively followed by T. harzianum 33 and 62% when applied before pathogen inoculation. Under greenhouse conditions, the effects of bio-fungicides also affected defense enzymes like peroxidase and polyphenol oxidase. The shelf life of the wettable powder formulation of bio-agents under different temperature was very important factor and established that the most suitable temperature for long term storage is 25 ºC for both B. pumilus and T. harzianum. Conclusion: Target application of disease control techniques in tomato plants demonstrated the efficacy of B. pumilus and T. harzianum in reducing Fusarium wilt. These results pave the way for the development of bio-agents that can replace fungicides in agriculture, offering a practical substitute.

Current Leads and Marketed Formulations for an Effective Treatment of Fungal Infections.

Severe antifungal infections, especially opportunistic fungal infections, are increasing tremendously in immunocompromised patients. This is basically because more patients enduring neoplastic diseases lead to the wide use of chemotherapy, thus causing immunosuppression. Patients with HIV infection, burns, pancreatitis and neutropenia are also amenable to fungal infections. Out of a plethora of antifungal drugs applied, Amphotericin B, being a broad-spectrum antimicrobial drug, has been the gold standard treatment for a diverse variety of fungal infections since the 1950s and visceral leishmaniasis since the 1960s. However, Amphotericin B has major constraints of poor bioavailability and kidney toxicity, due to which newer antifungal compounds are being used. This article discusses fungal and parasitic diseases and formulations for treating these ailments.

Screening of Fungal Strains and Formulations of Metarhizium anisopliae to Control Phyllotreta striolata in Chinese Flowering Cabbage.

(1) Background: The cabbage flea beetle (CFB; Phyllotreta striolata) seriously damages the production of Chinese flowering cabbage (CFC; Brassica campestris L. ssp. chinensis var. utilis), which is a key leafy vegetable in South China. A large number of chemical insecticides have been sprayed to control this pest; as a result, residues and resistances are becoming an issue. It is necessary to develop biocontrol technologies to address this issue. (2) Methods: Fungal strains were selected based on bioactivity against CFB, and CFC seed pelletization with fungal conidia was subject to evaluation of control efficacy against CFB. The effective mixture of fungus and chemical insecticide was determined based on safety and joint toxicology tests. (3) Results: The screening of 103 strains from 14 genera identified the Metarhizium anisopliae strain MaGX19S02 (Ma) as the one with the highest virulence. The LC50s of Ma to CFB adult and second instar larvae on day 9 post-treatment were 3.04 × 106 and 27.2 × 106 spores/mL, respectively. In the pot test, the pelletization of CFC seeds with Ma conidia (50/25/12.5 mg in 1 g seed with 4 g fillers) demonstrated significant CFB mortalities (45-82%) 20 days after the larvae were introduced. In the field test, the seed pelletization achieved 57-81% control efficacy 14 days after sowing. Furthermore, the combination of Ma with chlorfenapyr (Chl) demonstrated a synergistic effect against CFB; based on this result, we prepared the mixture formulation of 20% Ma-Chl wettable powder (WP). The assessment of the effects of 20% Ma-Chl WP (500× diluent) against CFB revealed 93.33% mortality in the pot test and 61.3% control efficacy in the field test on day 7 post-treatment. (4) Conclusions: The findings demonstrate the potential of Ma to control CFB in the field. Seed pelletization with Ma conidia effectively controlled CFB larvae and protected CFC seedlings, wherein a mixture formulation of 20% Ma-Chl WP had substantial efficacy in controlling CFB adults. Our research provides new methods for CFB biocontrol.

Evaluation of a guardian plant system to suppress Frankliniella occidentalis (Thysanoptera: Thripidae) in greenhouse ornamentals.

Western flower thrips (WFT), Franklinella occidentalis (Pergande), is an economically damaging pest of greenhouse ornamentals. A 'guardian plant system' (GPS) that targeted WFT was evaluated under controlled and commercial greenhouse conditions. This system used mycotized millet grains with the entomopathogenic fungus Beauveria bassiana (Balsamo-Crivelli) Vuillemin applied to soil of potted marigolds, Tagetes patula (L.), combined with the foliar-dwelling predatory mite Neoseiulus (=Amblyseius) cucumeris (Oudemans) in slow-release sachets under controlled greenhouse conditions, and with the addition of a pheromone lure under commercial settings. Significantly fewer WFT and less foliar damage on GPS was observed over the 10 and 12 weeks experimental periods compared to the untreated controls. Predatory mites were maintained up to 10 weeks with one release under controlled greenhouse conditions and 12 weeks with two releases in commercial greenhouses. In commercial greenhouses, greater numbers of WFT were found on marigolds than on crop plants within 1 m of the system. Fungal granules persisted for 12 weeks up to 2.5 × 105 CFU g-1 in the GPS soil. The use of biological control agents to suppress WFT within a GPS could be a useful IPM strategy for greenhouse production. The marigold GPS attracted WFT which were suppressed primarily through predation by foliar-dwelling predatory mites and to a lesser extent, infection from conidia produced by the granular fungal formulation in the soil. Further investigations into system deployment and fungal granular application rates and new fungal formulations are suggested to improve system efficacy. © 2023 Society of Chemical Industry.

Survival Time, Mortality Rate, and Feeding Damage of Adult Myllocerus undecimpustulatus undatus (Coleoptera: Curculionidae) Exposed to Biopesticides in Laboratory Bioassays

Survival time, percentage mortality, and feeding behavior were evaluated for adults of the weevil Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae) exposed to biopesticides by using a Petri dish plant-based bioassay system. Treatments consisted of three registered entomopathogenic fungal formulations (BotaniGard ES, PFR-97 20% WDG, and Met52 EC) and three biochemical formulations (AzaMax, Entrust, and PyGanic EC); a synthetic chemical insecticide (Sevin SL) and distilled water served as control treatments. Thirty adult M. undecimpustulatus undatus (ten per bioassay cage replicate, three replicates per treatment) were given cocoplum leaves sprayed to the point of runoff with a treatment. Survivorship of weevils was checked daily for 15 days. Five trials (15 total replicates per treatment) were performed. Survival times of weevils in all product treatments were shorter than those of weevils in the water control treatment. Percentages of beetle mortality in the Entrust and BotaniGard treatments were about two-fold higher than in the other treatments. Mean percentages of mycosis for beetles in the BotaniGard, PFR-97, and Met 52 treatments were 90%, 8%, and 5%, respectively. Weevils that consumed BotaniGard-treated leaves caused significantly more leaf damage than weevils that consumed leaves with PFR-97 or Met52. Weevils on leaves treated with Entrust, PyGanic, AzaMax, and Sevin consumed significantly less than those in the fungal and water only treatments. The high mortality rates caused by Entrust and BotaniGard suggest that populations of adult M. undecimpustulatus undatus might be well-managed using these two commercially available biopesticides. Additional testing is needed in the field to corroborate our results obtained under controlled laboratory conditions.

Native fungi from Amazon with potential for control of Aedes aegypti L. (Diptera: Culicidae).

Aedes aegypti L. (Diptera: Culicidae) is the main transmitter of pathogens that cause human diseases, including dengue, chikungunya, zika and yellow fever. Faced with this problem, this study aims to select fungi with entomopathogenic potential against Ae. aegypti and develop formulations that optimize the control action of entomopathogenic fungi in the semi-field condition. 23 fungal strains native from Amazon were inoculated in Potato-Dextrose-Agar (PDA) culture medium for 14 days and then transferred by scraping to tubes containing 0.9% NaCl solution. To obtain the larvae, eggs were collected using traps in peridomestic environments for 7 days. 20 larvae of Ae. aegypti in 125 mL erlenmeyers containing 20 mL of conidial suspension at a concentration of 1x106 conidia/mL for initial selection and 1×104, 1×105, 1×106 and 1×107 conidia/mL for determination of LC50. Mortality was checked every 24 h for 5 days. The three fungi with the best virulence rates were identified using molecular techniques. The compatibility between fungi at a concentration of 1×106 conidia/mL and oily adjuvants, mineral oil and vegetable oil (andiroba, chestnut and copaiba) at concentrations of 0.1, 0.5 and 1% was evaluated. The germination capacity of 100 conidia per treatment was evaluated after incubation at 28 ºC for 24 h. To evaluate the entomopathogenic potential of the fungal formulations, conidial suspensions (1×106 conidia/mL) were added with 0.1% mineral and vegetable oil. The treatments were submitted to laboratory and semi-field conditions and mortality was verified every 24 h for 5 days. Beauveria sp. (4,458) (LC50 = 8.66× 103), Metarhizium anisopliae (4,420) (LC50 = 5.48×104) and M. anisopliae (4,910) (LC50 = 1.13×105) were significantly more effective in the larval control of Ae. aegypti, in relation to the other fungal morphospecies evaluated. Mineral oil was better compatible in all treatments evaluated. Beauveria sp. (4,458) was considerably less virulent under semi-field conditions. M. anisopliae (4,910) formulated with mineral oil increased larval mortality to 100% on the 4th day in the laboratory and on the 5th day in the semi-field. Fungal formulations developed from native Amazonian isolates represent a promising tool for the development of strategies to control Ae. aegypti.

Efficacy of Entomopathogenic Fungal Formulations against Elasmolomus pallens (Dallas) (Hemiptera: Rhyparochromidae) and Their Extracellular Enzymatic Activities.

Elasmolomus pallens are post-harvest insect pests of peanuts that are becoming resistant to chemical insecticides. In this, we study evaluated the effect of conidial formulations on entomopathogenic fungi against E. pallens to reduce the adverse effects. Fungal conidia were formulated and applied on sterile filter papers at varying concentrations (1 × 104–1 × 108 conidia mL−1) inside plastic containers. The test insects were exposed and maintained in a relative humidity of 80 ± 10% for 10 d at room temperature (25 ± 2 °C). Mortality was recorded every 24 h. Dose–response bioassay (LC50 and LC90) values for Aspergillus flavus formulated in oil were 1.95 × 106 and 3.66 × 109 conidia/mL, whereas formulations in Tween 80 had 9.36 × 107 and 6.50 × 109 conidia/mL. However, oil-formulated Metarhizium anisopliae had 3.92 × 106 and 2.57 × 108 conidia/mL, with 6.85 × 106 and 5.37 × 108, for formulations in Tween 80. A. flavus had LT50 values of 3.3 and 6.6 days, whereas M. anisopliae had LT50 values of 3.6 and 5.7 d. Maximum protease, chitinase, and lipase activities of 2.51, 0.98, and 3.22 U/mL, respectively, were recorded for A. flavus, whereas values of 2.43, 0.93, and 3.46 were recorded for M. anisopliae. The investigated pathogens demonstrate potential against E. pallens; therefore, their applicability under field conditions requires further investigation.

Fungal-Based Biopesticide Formulations to Control Nymphs and Adults of the Desert Locust, Schistocerca gregaria Forskål (Orthoptera: Acrididae): A Laboratory and Field Cage Study

This is the first field study in which we have tested the efficacy of four different entomopathogenic fungal (EPF) formulations together in single study—i.e., Green Muscle, Green Guard, Metarhizium anisopliae, and an isolate of Beauveria bassiana (isolate WG-11)—against nymphs and adults of the desert locust, Schistocerca gregaria Forskål (Orthoptera: Acrididae). We conducted several different studies: (a) lethal bioassay against the 3rd, 5th, and adult stages under laboratory conditions; (b) sublethal effects on the reproduction, diet consumption, fecal production, and weight gain; (c) a greenhouse trial; and (d) a field cage trial. Under laboratory conditions, all EPF formulations caused significant mortality, and the highest efficacy was observed with Green Muscle, followed by Green Guard, B. bassiana, and M. anisopliae. Susceptibility was found to be greatest in 3rd-instar nymphs, followed by 5th instars, and then adults. Along with lethal effects, sublethal doses of EPF reduced the number of egg pods per female, total eggs per pod, and egg hatching, while extending nymphal developmental time and reducing adult longevity; again, Green Muscle performed better. Sublethal doses not only retarded reproduction, but also caused behavioral changes, including reductions in food consumption, fecal production, and weight gain. All EPF formulations not only produced significant mortality in laboratory conditions, but also performed very well under the greenhouse and field conditions. The maximum mortality against 3rd-instar (81.7% and 74.0%), 5th-instar (73.3% and 65.1%), and adult locusts (67.5% and 58.9%) was observed when using Green Muscle under greenhouse and field trials, respectively. The current study showed that all of the EPF formulations have the potential to reduce pest populations, and could be used in the integrated pest management program.

Unveiling a Novel Role of Cdc42 in Pyruvate Metabolism Pathway to Mediate Insecticidal Activity of Beauveria bassiana.

The small GTPase Cdc42 acts as a molecular switch essential for cell cycles and polar growth in model yeast, but has not been explored in Beaurveria bassiana, an insect-pathogenic fungus serving as a main source of fungal formulations against arthropod pests. Here, we show the indispensability of Cdc42 for fungal insecticidal activity. Deletion of cdc42 in B. bassiana resulted in a great loss of virulence to Galleria mellonella, a model insect, via normal cuticle infection as well as defects in conidial germination, radial growth, aerial conidiation, and conidial tolerance to heat and UVB irradiation. The deleted mutant’s hyphae formed fewer or more septa and produced unicellular blastospores with disturbed cell cycles under submerged-culture conditions. Transcriptomic analysis revealed differential expression of 746 genes and dysregulation of pyruvate metabolism and related pathways, which were validated by marked changes in intracellular pyruvate content, ATP content, related enzyme activities, and in extracellular beauvericin content and Pr1 protease activity vital for fungal virulence. These findings uncover a novel role for Cdc42 in the pathways of pyruvate metabolism and the pyruvate-involved tricarboxylic acid cycle (TCA cycle) and a linkage of the novel role with its indispensability for the biological control potential of B. bassiana against arthropod pests.

The Multilateral Efficacy of Chitosan and Trichoderma on Sugar Beet

The majority of all fungal formulations contain Trichoderma spp., making them effective biological control agents for agriculture. Chitosan, one of the most effective natural biopolymers, was also reported as a plant resistance enhancer and as a biocide against a variety of plant pathogens. An in vitro three-way interaction assay of T. atroviride, chitosan, and important plant pathogens (such as Cercospora beticola and Fusarium oxysporum) revealed a synergistic effect on fungistasis. Furthermore, chitosan coating on Beta vulgaris ssp. vulgaris seeds positively affected the onset and efficiency of germination. We show that priming with T. atroviride spores or chitosan leads to the induced expression of a pathogenesis-related gene (PR-3), but only supplementation of chitosan led to significant upregulation of phytoalexin synthesis (PAL) and oxidative stress-related genes (GST) as a defense response. Repeated foliar application of either agent promoted growth, triggered defense reactions, and reduced incidence of Cercospora leaf spot (CLS) disease in B. vulgaris. Our data suggest that both agents are excellent candidates to replace or assist common fungicides in use. Chitosan triggered the systemic resistance and had a biocidal effect, while T. atroviride mainly induced stress-related defense genes in B. vulgaris. We assume that both agents act synergistically across different signaling pathways, which could be of high relevance for their combinatorial and thus beneficial application on field.

Efficacy of focal applications of a mycoinsecticide to control Aedes aegypti in Central Brazil.

Entomopathogenic fungi can achieve important innovative outcomes for integrated mosquito control especially of Aedes aegypti, the key vector of arboviruses to humans in the tropics and subtropics. This study sought to design and to develop a simple dissemination device to attract and to infect gravid A. aegypti adults with a granular formulation of the ascomycete Metarhizium humberi IP 46, and to validate this device in the laboratory as well as in semi-field and field conditions. Hydrogel (polyacrylamide potassium polyacrylate) was confirmed to be a suitable substitute for water used in the device that attracted gravid females under field conditions. Females laid eggs on black polyethylene terephthalate carpet fixed in the device that also proved to be a suitable substrate for a granular formulation of fungal microsclerotia and/or conidia. The plastic device (29.5cm high) was divided into a lower closed compartment with a water reservoir and an upper, laterally open but covered compartment with continuously hydrated gel and the fungal formulation attached to the carpet. The uppermost compartment permitted free circulation of mosquito adults. The device attracted both male and female A. aegypti. The fungal formulations of IP 46 propagules tested in the device were effective against adults in laboratory, semi-field, and field settings. Findings in the laboratory, semi-field, and especially in field conditions strengthen the value and utility of this innovative device for focal applications of a mycoinsecticide against this important mosquito vector.Key points• Low-cost and simple disseminating device for focal control of Aedes aegypti.• Granulized Metarhizium humberi IP 46 and hydrogel yield extended control.• Findings in field tests strengthen benefit of the device for focal application.

Molecular basis and regulatory mechanisms underlying fungal insecticides' resistance to solar ultraviolet irradiation.

Resistance to solar ultraviolet (UV) irradiation is crucial for field-persistent control efficacies of fungal formulations against arthropod pests, because their active ingredients are formulated conidia very sensitive to solar UV wavelengths. This review seeks to summarize advances in studies aiming to quantify, understand and improve conidial UV resistance. One focus of studies has been on the many sets of genes that have been revealed in the postgenomic era to contribute to or mediate UV resistance in the insect pathogens serving as main sources of fungal insecticides. Such genetic studies have unveiled the broad basis of UV-resistant molecules including cytosolic solutes, cell wall components, various antioxidant enzymes, and numerous effectors and signaling proteins, that function in developmental, biosynthetic and stress-responsive pathways. Another focus has been on the molecular basis and regulatory mechanisms underlying photorepair of UV-induced DNA lesions and photoreactivation of UV-impaired conidia. Studies have shed light upon a photoprotective mechanism depending on not only one or two photorepair-required photolyases, but also two white collar proteins and other partners that play similar or more important roles in photorepair via interactions with photolyases. Research hotspots are suggested to explore a regulatory network of fungal photoprotection and to improve the development and application strategies of UV-resistant fungal insecticides. © 2021 Society of Chemical Industry.

Innovative granular formulation of Metarhizium robertsii microsclerotia and blastospores for cattle tick control

The tick Rhipicephalus microplus poses a serious threat to the cattle industry, resulting in economic losses aggravated by tick resistance to chemical acaricides. Strains of Metarhizium spp., a well-known group of entomopathogenic fungi, can contribute to managing this ectoparasite. We explored two novel granular, microsclerotia- or blastospores-based formulations of Metarhizium robertsii for R. microplus control under semi-field conditions. Fungal persistence in soil was also observed for 336 days. The experiment used pots of Urochloa decumbens cv. Basilisk grass, treated with 0.25 or 0.5 mg of granular formulation/cm2 (25 or 50 kg/ha) applied to the soil surface prior to transferring engorged tick females onto the treated soil. The fungal granules yielded more conidia with subsequent sporulation under controlled indoor conditions than in the outdoor environment, where the levels of fungus rapidly declined over time. Metarhizium-root colonization ranged from 25 to 66.7% depending on the propagule and rate. Fungal formulations significantly reduced the number of tick larvae during the humid season, reaching at least 64.8% relative efficacy. Microsclerotia or blastospores-granular formulations of M. robertsii can reduce the impact of R. microplus, and thus prove to be a promising tool in the control of ticks.

Compatibility of Entomopathogenic Fungi with Neonicotinoids for the Management of Brown Plant Hopper of Rice, Nilaparvata lugens stal. (Delphacidae: Hemiptera)

Background: Rice is the staple food of Indians and it is attacked by more than 100 species of insects. Among all, brown planthopper (BPH), Nilaparvata lugens (Stal) (Hemiptera: Delphacidae) is one of the major sucking insects, which can cause appreciable damage by sucking sap on other hand transmitting viral diseases. Farming community using several insecticides for managing the BPH. However, continuous use of these insecticides causes health hazards and environmental pollution and also leads to development of insecticide resistance. Keeping this view in mind, the present investigation has been planned with combined use of fungal formulations and commonly used neonicotinoid insecticides in rice eco system for managing BPH. Methods: This experiment was carried out in two parts, one is studied the compatibility between neonicotinoids (Thiamethoxam 25 SG and Dinotefuran 20 SG) and entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii =Verticillium lecanii) by following the standard poison food technique. Second one is after studied the compatibility between neonicotinoids and entomopathogenic fungal agents, inhibitory studies were conducted under glasshouse conditions.Result: The study revealed that two tested insecticides affected the radial growth of fungi partially at all the three concentrations (0.5RC, RC and 1.5RC). At recommended concentration (RC), dinotefuran 20 SG @0.4 g/l was found to be slightly harmful to all three fungi (20% - 35% reduction of the growth of the fungus) and thiamethoxam 25 SG @ 0.25g/l appeared to be slightly harmful to B. bassiana and M. anisopliae and moderately harmful to L. lecanii (35-50% reduction of the growth of the fungus). Thiamethoxam 25SG alone recorded 65.0% mortality of BPH and when mixed with B. bassiana and M. anisopliae gave 86.25% and 81.25% mortality of BPH respectively under glass house conditions. Similarly, Dinotefuron 20 SG alone could gave 98.75% mortality of BPH.

Image analysis-based quantification of fungal sporulation by automatic conidia counting and gray value correlation

The present work describes a new computer-assisted image analysis method for the rapid, simple, objective and reproducible quantification of actively discharged fungal spores which can serve as a manual for laboratories working in this context. The method can be used with conventional laboratory equipment by using bright field microscopes, standard scanners and the open-source software ImageJ. Compared to other conidia quantification methods by computer-assisted image analysis, the presented method bears a higher potential to be applied for large-scale sample quantities. The key to make quantification faster is the calculation of the linear relationship between the gray value and the automatically counted number of conidia that has only to be performed once in the beginning of analysis. Afterwards, the gray value is used as single parameter for quantification. The fast, easy and objective determination of sporulation capacity enables facilitated quality control of fungal formulations designed for biological pest control.•Rapid, simple, objective and reproducible quantification of fungal sporulation suitable for large-scale sample quantities.•Requires conventional laboratory equipment and open-source software without technical or computational expertise.•The number of automatically counted conidia can be correlated with the gray value and after initial calculation of a linear fit, the gray value can be applied as single quantification parameter.

Predatory effects of the fungus Arthrobotrys cladodes on sheep gastrointestinal nematodes

ABSTRACT The biological control of gastrointestinal nematodes of animals using nematophagous fungi is considered a promising approach. The objective of this study was to evaluate the effectiveness of Arthrobotrys cladodes (CG 719) isolates in vitro and after passage through the gastrointestinal tract of sheep. In experiment 1, the in vitro predatory capacity of A. cladodes against gastrointestinal nematodes in sheep was evaluated. Petri dishes containing fungi cultured on water agar medium were inoculated with 2,000 infective larvae of sheep gastrointestinal nematodes. Experiment 2 involved treatment and control groups comprising six sheep each. The animals in the treatment group received single 10 g doses of pellets containing fungal formulations, and fecal samples were collected after 12, 24, 36, 48, 60, and 72 h. In experiment 1, a larval reduction of 72.3% was observed at 7 days after the larval inoculation. In both assays of experiment 2, larval reductions were significant (p < 0.01). In assay A, this fungus was able to pass throught the gastrointestinal tract of sheep, with a larval reduction of 83.5%. In assay B, proportion of larvae recovered from coprocultures was reduced by 72.4%. Thus, we concluded that pelleted formulations of A. cladodes were effective against gastrointestinal nematodes in vitro and after passage through the gastrointestinal tract of sheep.

Auto-dissemination of commercially available fungal pathogens in a laboratory assay for management of the brown dog tick Rhipicephalus sanguineus.

Rhipicephalus sanguineus is a canine tick that infests dogs throughout the world and is frequently found in homes and dog kennels. Management of this tick species is complicated by the presence of resistance to commonly utilized acaricides. Fungal formulations could provide a valuable alternative tool for management and are especially relevant indoors where detrimental environmental effects on fungal spores are of less concern. Two commercially available fungal formulations, one containing Metarhizium anisopliae and the other containing Beauveria bassiana, were compared for time to death and sporulation in nymphal ticks exposed for 60 min in treated filter paper packets. Beauveria bassiana exposure killed ticks faster than M. anisopliae exposure and B. bassiana was more likely to sporulate on tick cadavers than M. anisopliae. To determine whether infected ticks could disseminate fungus to their conspecifics, ticks were marked and treated with fungus before being placed with untreated ticks. Fungus was successfully transmitted from treated to untreated ticks. Mortality of ticks exposed to B. bassiana-exposed conspecifics occurred sooner than for those exposed to M. anisopliae-exposed conspecifics, indicating faster dissemination in the former. Therefore, although both formulations resulted in decreased longevity of ticks compared with the controls, the B. bassiana formulation holds the most promise for direct or indirect application with respect to brown dog tick management.

Interaction of Tomato Genotypes and Arbuscular Mycorrhizal Fungi under Reduced Irrigation

Climate change is increasing drought events and decreasing water availability. Tomato is commonly transplanted to an open field after seedling production in a nursery, requiring large volumes of water. Arbuscular mycorrhizal (AM) fungi help plants cope with drought stress; however, their effects depend on plant genotype and environmental conditions. In this study, we assessed the interactions among different tomato seedling genotypes and two AM fungi, Funneliformis mosseae and Rhizophagus intraradices, under two water regimes, full and reduced. Our results showed that F. mosseae was more effective than R. intraradices in the mitigation of drought stress both in old and modern genotypes. However, seedlings inoculated with R. intraradices recorded the highest values of leaf area. ‘Pearson’ and ‘Everton’ genotypes inoculated with F. mosseae recorded the highest values of root, leaf, and total dry weights under reduced and full irrigation regimes, respectively. In addition, ‘Pearson’ and ‘H3402’ genotypes inoculated with F. mosseae under a reduced irrigation regime displayed high values of water use efficiency. Our results highlight the importance of using AM fungi to mitigate drought stress in nursery production of tomato seedlings. However, the development of ad hoc AM fungal formulations, which consider genotype x AM fungi interactions, is fundamental for achieving the best agronomic performances.

Current status and perspectives of fungal entomopathogens used for microbial control of arthropod pests in Brazil.

Entomopathogenic fungi play a central role in Brazil's biopesticide market. Approximately 50% of registered microbial biopesticides comprise mycoinsecticides and/or mycoacaricides consisting of hypocrealean fungi, with most based on Metarhizium anisopliae sensu stricto (s. str.) and Beauveria bassiana s. str. These fungi are mainly used to control spittlebugs in sugarcane fields and whiteflies in row crops, respectively, with annual applications surpassing three million hectares. Research also emphasizes the potential of fungal entomopathogens to manage arthropod vectors of human diseases. Most registered fungal formulations comprise wettable powders or technical (non-formulated) products, with relatively few new developments in formulation technology. Despite the large area treated with mycoinsecticides (i.e., approx. 2 million ha of sugarcane treated with M. anisopliae and 1.5 million ha of soybean treated with B. bassiana), their market share remains small compared with the chemical insecticide market. Nevertheless, several major agricultural companies are investing in fungus-based products with the aim at achieving more sustainable IPM programs for major pests in both organic and conventional crops. Government and private research groups are pursuing innovative technologies for mass production, formulation, product stability and quality control, which will support cost-effective commercial mycoinsecticides. Here, we summarize the status of mycoinsecticides currently available in Brazil and discuss future prospects.

Evaluation of Two Entomopathogenic Fungi for Control of Culex quinquefasciatus (Diptera: Culicidae) in Underground Storm Drains in the Coachella Valley, California, United States.

Commercially available formulations of two entomopathogenic fungi, Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Clavicipitaceae) and Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae), were assessed for control of Culex quinquefasciatus Say (Diptera: Culicidae) in underground storm drain systems (USDS) in the Coachella Valley of southern California. Each of three treatments, the two fungi or a water control, was applied to 1 m2 of vertical wall at eight USDS sites in spring and autumn of 2015. Fungal infectivity and lethality were assessed at 1 d and 1, 2, and 4 wk post-application. Overnight bioassays using adult lab-reared female mosquitoes were carried out on the treated USDS wall areas and then mosquitoes were held in the laboratory for up to 21 d to allow fungal infections to be expressed. Postmortem fungal sporulation was assessed up to 2 wk at 100% humidity. Mosquito-fungal interactions also were assessed in bioassays of the three treatments on filter paper exposed to USDS conditions during autumn. Metarhizium anisopliae killed mosquitoes faster than B. bassiana; nevertheless, both freshly applied formulations caused greater than 80% mortality. Fungal persistence declined significantly after 1 wk under USDS conditions, but some infectivity persisted for more than 4 wk. Beauveria bassiana was more effective against Cx. qinquefasciatus in the spring, while M. anisopliae was more effective in the cooler conditions during autumn. USDS environmental conditions (e.g., temperature, relative humidity, standing water) influenced fungal-related mortality and infection of Cx. quinquefasciatus. The utility of these fungal formulations for mosquito abatement in the Coachella Valley and implications for fungal control agents in USDS environments are discussed.