Resporulation of Metarhizium anisopliae granules on soil and mortality of Tenebrio molitor: Implications for wireworm management in sweetpotato

In Australia, sweetpotato (Ipomoea batatas L.) is vulnerable to root feeding insect pests such as wireworms (e.g., Agrypnus spp.). The number of registered insecticides to control these insect pests is limited and often pest pressure, for example by wireworms, is severe close to harvest, further limiting what insecticides can be applied. Incorporating biological control agents such as entomopathogenic fungi (e.g., Metarhizium anisopliae) into integrated pest management programmes may be feasible in sweetpotato. M. anisopliae has been shown to be effective in controlling more than 200 insects and it is able to reside and grow in the rhizosphere and rhizoplane, suggesting that M. anisopliae could be a promising candidate against soil insect pests. In the study presented here, M. anisopliae was formulated into calcium alginate granules fortified with nutrients. The resporulation of the fungal granules was tested on four different soil types in the laboratory. The biocontrol efficacy of the resulting fungal growth was also examined using larval mealworms, Tenebrio molitor as a model insect in the laboratory and the glasshouse. Our results indicated that sterilised soil favoured optimal fungal resporulation, although different soil types did not have a significant effect on fungal resporulation. The resulting fungal resporulation and growth on sterilised soil caused high mortality (up to 76%) of larval mealworms in the glasshouse, whereas the fungal granules applied to non-sterile soil demonstrated poor resporulation that led to low mortality (13%) of larval mealworms. The result of this study indicates that the manipulation of microbial populations in field soil is required to enhance the fungal growth and potential insect control against wireworms in the field.     

Isolation and virulence of entomopathogenic fungi against larvae of hazelnut weevil Curculio nucum (Coleoptera,Curculionidae) and the effects of combining Metarhizium anisopliae with entomopathogenic nematodes in the laboratory

An approach to ensure effective pest biocontrol would be to select native isolates of biological control agents (BCAs). A survey to isolate entomopathogenic fungi (EPF) from a hazelnut growing area has been carried out. EPF were recovered from 133 of the 295 soil samples. The main species isolated were Metarhizium anisopliae sensu lato (36%) and Beauveria bassiana sensu lato (42.8%). With regard to controlling abiotic factors, altitude had an effect on the distribution of B. bassiana, but not on M. anisopliae. Cropping system did not have an effect on the occurrence of these EPF, while pH appeared as a predictive variable for both. In addition, we tested the virulence of six of these isolates: three M. anisopliae and three of B. bassiana against larvae of Curculio nucum L. The highest larval mortality (reaching 80%) was due to M. anisopliae (strain 34) when applied in simultaneous combination with four entomopathogenic nematode species: Steinernema carpocapsae (strain B14), Steinernema feltiae (strain D114), Steinernema. sp. (strain D122) and Heterorhabditis bacteriophora (strain DG46). The effect of nematodes was greater and no antagonistic or synergistic effects were observed.     

In vitro pathogenicity of different Metarhizium anisopliae s.l. isolates in oil formulations against Rhipicephalus microplus

The present study aimed to evaluate the in vitro pathogenicity of the Metarhizium anisopliae s.l. CG 112, CG 347, CG 32, CG 148 and CG 629 isolates formulated in vegetable or mineral oil against Rhipicephalus microplus. The bioassays were performed with R. microplus engorged females. The ticks were immersed for three minutes in oil-based formulations containing 10% oil (mineral or vegetable). The effects of the different fungal isolates were evaluated analyzing the females’ reproductive parameters (the total weight of the egg mass, hatching percentage, egg production index and nutritional index). The present study showed that all of the tested isolates and both oil formulations (vegetable or mineral oil) changed the biological parameters of the R. microplus females. However, the mineral oil formulation was more effective than the vegetable oil formulation, as the former showed a higher tick control percentage. It was concluded that there was variation in the virulence among the different M. anisopliae s.l. isolates and between the different types of oil. Moreover, that either of the isolates GC 148 and GC 629 formulated in oil confers the good potential for controlling R. microplus engorged females.     

Metarhizium anisopliae (Deuteromycetes: Moniliaceae) Pr1 activity: biochemical marker of fungal virulence in Rhipicephalus microplus (Acari: Ixodidae)

In the present study, the subtilisin-like protease Pr1 activity of five Metarhizium anisopliae s.l. isolates was evaluated together with their virulence against Rhipicephalus microplus females. Bioassays were performed with engorged females, and Pr1 activity was evaluated with the chromogenic substrate N-succinyl-Ala-Ala-Pro-Phe ρ-nitroanilide. All isolates were virulent to R. microplus, although the isolates CG 629, CG 148 and CG 32 caused higher mortality (P ≤ 0.05) than isolates CG 112 and CG 347 after eight days. No mortality was observed in the control group. Enzymatic assays revealed that the protease activity was greater in isolates CG 629, CG 148 or CG 32 than in isolates CG 112 or CG 347 after cultivation for 48 and 72 h. Based on these results, we suggest that the Pr1 activity may be used as a biochemical tool for screening the virulence among M. anisopliae s.l. isolates, and then selecting promising candidates for biocontrol of R. microplus ticks.     

Susceptibility of adult Aedes aegypti (Diptera: Culicidae) to infection by Metarhizium anisopliae and Beauveria bassiana: prospects for Dengue vector control

Dengue fever vectored by the mosquito Aedes aegypti is one of the most rapidly spreading insect-borne diseases, stimulating the search for alternatives to current control methods. Screening assays using a range of Metarhizium anisopliae and Beauveria bassiana isolates were performed against adult female Ae. aegypti. Four virulent isolates were selected for detailed study. Adult female mosquitoes were exposed to supports previously inoculated with fungal suspensions. Fungal isolates were suspended in Tween 80+8% vegetable oil. The isolates caused between 70 and 89% mortality as a result of fungal infection over the 7-day test period. Mean survival times varied between 3 and 5 days for treated insects, whilst control survival exceeded 40 days. The most promising isolate, M. anisopliae LPP133, based not only on virulence but facility for mass production, was used for lethal exposure time determinations. An exposure time of only 3.5 h was necessary to cause 50% mortality. Large cage trails were also carried out and mean survival time of insects exposed to fungus impregnated black cloths was significantly reduced. These results show that entomopathogenic fungi could be promising biological control agents for use against adult Ae. aegypti, by inoculating fungi onto surfaces on which the mosquitoes tend to rest. The subsequent mortality caused by the fungi could potentially reduce the populations of this insect thus reducing the incidence of Dengue.     

Susceptibility of the cactus weevil Metamasius spinolae to Beauveria bassiana and Metarhizium anisopliae under laboratory and field conditions

Aims: To evaluate different entomopathogenic fungal isolates against the cactus weevil Metamasius spinolae under laboratory and field conditions, and select an isolate to be used as a tool in the management of this insect pest. Methods and Results: Four experiments were carried out. The effect of temperature on the in vitro growth of eight isolates of entomopathogenic fungi (two Metarhizium anisopliae and six Beauveria bassiana) was assessed. The susceptibility of adult M. spinolae to the same isolates was evaluated. Using three selected isolates, the interaction between susceptibility and sex of the insect was studied. Finally, a field experiment was carried out to evaluate infection of adult M. spinolae by the same three isolates under natural abiotic conditions. Overall, growth rate was greatest at 25°C for all the isolates. In vitro growth of M. anisopliae was greater than B. bassiana. Mortality of adult M. spinolae was greater when inoculated with B. bassiana compared with isolates of M. anisopliae. Susceptibility had no interaction with the sex of the insect. The proportion of insects succumbing to infection was smaller when incubated under field conditions than when incubated under laboratory conditions. Conclusions: The experiments described here showed a complex interaction between entomopathogenic fungi and M. spinolae, and these data allows us to select isolate Bb107 as a first step towards its use in the management of this pest insect. Significance and Impact of the Study: Our results showed that entomopathogenic fungi can be used for the control of M. spinolae, which may help reduce the use of chemical insecticides and, therefore, the exposure of Opuntia ficus‐indica producers to pesticides.     

Selection of promising fungal biological control agent of the western flower thrips Frankliniella occidentalis (Pergande)

Aims: Larval stages of Frankliniella occidentalis are known to be refractory to fungal infection compared with the adult stage. The objective of this study was to identify promising fungal isolate(s) for the control of larval stages of F. occidentalis. Methods and Results: Ten isolates of Metarhizium anisopliae and eight of Beauveria bassiana were screened for virulence against second‐instar larvae of F. occidentalis. Conidial production and genetic polymorphism were also investigated. Metarhizium anisopliae isolates ICIPE 7, ICIPE 20, ICIPE 69 and ICIPE 665 had the shortest LT₅₀ values of 8·0–8·9 days. ICIPE 69, ICIPE 7 and ICIPE 20 had the lowest LC₅₀ values of 1·1 × 10⁷, 2·0 × 10⁷ and 3·0 × 10⁷ conidia ml^?1, respectively. Metarhizium anisopliae isolate ICIPE 69 produced significantly more conidia than M. anisopliae isolates ICIPE 7 and ICIPE 20. Internally transcribed spacers sequences alignment showed differences in nucleotides composition, which can partly explain differences in virulence. Conclusion: These results coupled with the previous ones on virulence and field efficacy against other species of thrips make M. anisopliae isolate ICIPE 69 a good candidate. Significance and Impact of the Study: Metarhizium anisopliae isolate ICIPE 69 can be suggested for development as fungus‐based biopesticide for thrips management.     

Virulence of entomopathogenic hypocrealean fungi infecting <Emphasis Type="Italic">Anoplophora glabripennis</Emphasis>

Twenty isolates of four species of entomopathogenic hypocrealean fungi (Beauveria bassiana, Beauveria brongniartii, Isaria farinosa, and Metarhizium anisopliae) were found to be pathogenic to adults of the Asian longhorned beetle, Anoplophora glabripennis. Survival times for 50% of the beetles tested (ST₅₀) ranged from 5.0 (M. anisopliae ARSEF 7234 and B. brongniartii ARSEF 6827) to 24.5 (I. farinosa ARSEF 8411) days. Screening studies initially included strains of B. brongniartii, which is registered as a microbial control agent in Europe, Asia and South America but not in North America. At that time, we could not confirm that this fungal species is native to North America which added uncertainty regarding future registration of this species for pest control in the USA. Therefore, subsequent bioassays documented median survival times for three M. anisopliae isolates (5–6 days to death) and two of these isolates are suggested for further development because they are already registered for pest control in the USA. An erratum to this article can be found at     

Virulence of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against red palm weevil,Rhynchophorus ferrugineus (Olivier)

Nineteen different isolates of the entomopathogenic fungi Beauveria bassiana sensu lato (s.l.) and Metarhizium anisopliae s.l. (Ascomycota: Hypocreales), recovered from different soil samples (field crops, fruit orchards, vegetable fields and forests) and insect cadavers were tested against Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) at two different spore concentrations (1 × 10⁷ and 1 × 10⁸ conidia mL^?1). Three isolates of B. bassiana and two of M. anisopliae gave >88 % larval and >75 % adult mortality of R. ferrugineus on their highest dose rate respectively. More sporulating cadavers (mycosis) resulted from a high dose rate compared to low dose on both life stages of R. ferrugineus. The current study confirmed the lethal action of B. bassiana and M. anisopliae isolates with mortality levels usually directly proportional to the conidial concentration. This study further confirmed that the isolates recovered from R. ferrugineus dead cadavers gave more mortality compared to the other sources. In the virulence assay two isolates of B. bassiana caused the highest percentage of both larval and adult mortality at all exposure intervals which suggest that they may be the most promising for use in sustainable management programs aimed at microbial control in date palm orchards.     

Pure culture of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> LHL07 reprograms soybean to higher growth and mitigates salt stress

Little is known about the role of endophytic fungi against abiotic stresses and isoflavonoids (IF) contents of soybean. In current study, we investigated the role of fungal endophytes on the growth of soybean under salt stress conditions. Pure cultures of nine endophytic fungi were isolated from the roots of field-grown soybean plants, and their culture filtrates were screened on Waito-C and Dongjin-byeo rice cultivars; for identification of plant growth promoting fungal strains. It was observed that fungal isolate GMC-2B significantly promoted the growth of both Waito-C and Dongjin-byeo. GMC-2B was later identified as a new strain of Metarhizium anisopliae LHL07 on the basis of 18S rDNA sequences and phylogenetic analysis. Metarhizium anisopliae LHL07 inoculated soybean plants recorded significantly higher shoot length, shoot fresh and dry biomass, chlorophyll contents, transpiration rate, photosynthetic rate and leaf area; under sodium chloride induced salt stress as compared to non-inoculated control plants. An elevated proline and reduced superoxide dismutase and malondialdehyde contents in M. anisopliae LHL07 inoculated soybean plants demonstrated mitigation of salt induced oxidative stress. Furthermore, reduced abscisic acid and elevated jasmonic acid contents in soybean plants confirmed that lesser stress was convened to M. anisopliae inoculated-plants under salinity stress. We also assessed the role of M. anisopliae interaction on IF biosynthesis of soybean, and found significantly higher IF contents in M. anisopliae inoculated soybean plants. In conclusion, endophytic fungal interactions with soybean can be beneficial to improve soybean quality and quantity under salt affected agricultural systems.     

Laboratory evaluation of entomopathogenic fungi against the white grubs,Holotrichia oblita and Anomala corpulenta (Coleoptera: Scarabaeidae) from the field of peanut,Arachis hypogaea

We evaluated the pathogenicity of nine isolates of entomopathogenic fungi, including six isolates of Metarhizium anisopliae, one of Beauveria bassiana, and two of Beauveria brongniartii, against eggs and various larval instars of two scarab-beetle species, Holotrichia oblita and Anomala corpulenta, under laboratory conditions. The fungal isolates differed in pathogenicity. Generally, the isolates were more pathogenic to A. corpulenta than to H. oblita. Some of the isolates prevented egg hatching and caused larval death. Isolates M2-2 and Br5-8 caused 39 and 27% egg mortality, respectively, and produced 23 and 24% viewable fungal-infection rates in H. oblita. Three isolates had no significant effect on egg hatchability. Three isolates (Br5-8, Br232818, and M200614) caused about 40% mortality in H. oblita first instars. In A. corpulenta, all isolates except M200614 caused more than 60% egg mortality, and M2-2, Br232818 and Br5-8 caused egg-infection rates greater than 50%. M2-2 caused 47% infection and 100% mortality in first-instar larvae of A. corpulenta, while Br5-8 and Br232818 yielded over 80% mortality of the larvae. The three most virulent isolates, M2-2, Br232818 and Br5-8, were selected for further bioassays against second- and third-instar larvae. In addition, seven graduated concentrations of a Br5-8 conidial suspension were assayed against H. oblita second instars. Larval mortality was positively correlated with fungal dosage, and the LC₅₀ was 4.49×10⁶ conidia/mL. These three virulent isolates may be used to prevent H. oblita and A. corpulenta larval infestations in field crops.     

Effect of entomopathogenic fungi upon adults of Stomoxys calcitrans and Musca domestica (Diptera: Muscidae)

The pathogenicity and virulence of 10 isolates of entomopathogenic fungi from the soil of lodging pens of dairy production units in Aguascalientes, Mexico, on adults of Stomoxys calcitrans and Musca domestica were determined. All isolates were pathogenic when exposed by aspersion to a concentration of 1×10⁸ conidia/ml, causing between 20.3 and 91.7% mortality in S. calcitrans and between 31 and 91.7% in M. domestica at 7 days post-exposure; in S. calcitrans isolates of Beauveria bassiana (Bb114) and Metarhizium anisopliae (Ma135), sensu lato, were the most noteworthy as mortality reached above 90% with an LC₅₀ of 3.5×10⁵ conidia/ml for Bb114, while for Ma135 reached 1.6×10⁴ conidia/ml. In M. domestica Ma134 and Ma135 showed mortality above 90% with an LC₅₀ of 4.3×10⁴ and 1.4×10⁵ conidia/ml, respectively.     

Persistence and virulence of promising entomopathogenic fungal isolates for use in citrus orchards in South Africa

Thaumatotibia leucotreta (Meyrick) (1912) (Lepidoptera: Tortricidae) is a key economic pest of citrus in South Africa. Although a variety of control options are available, none currently registered target the soil-dwelling life stages of the pest. Three fungal isolates, two Metarhizium anisopliae sensu lato Metschnikoff (Sorokin) isolates (G 11 3 L6 and FCM Ar 23 B3) and one Beauveria bassiana sensu lato Balsamo (Vuillemin) isolate (G Ar 17 B3) have been identified as showing the greatest potential against T. leucotreta soil-dwelling life stages. Since environmental persistence is an important factor in the success of entomopathogenic fungi against soil pests, the isolates, along with two commercial isolates (B. bassiana Eco-Bb® and M. anisopliae ICIPE 69), were subjected to a six-month field persistence trial. Every month after burial of the fungal isolates, inside net bags, in orchard soil, the number of colony forming units (CFUs) per gram of soil was measured and the viability of the conidia was assessed using bioassays. All isolates investigated were capable of persisting in the soil for the duration of the trial period and in addition, were capable of initiating infection in T. leucotreta late fifth instar larvae and subsequent pupae. However, with the exception of the commercial isolates which showed some correlation, no correlation was found between the number of CFUs recorded and percentage T. leucotreta mycosis. Persistence of entomopathogenic fungi in the field is affected by a series of factors, and although the effect of these factors was not measured, the data have provided preliminary evidence towards the persistence capability of these candidate biopesticides against T. leucotreta.     

Evaluation of Metarhizium anisopliae strains as potential biocontrol agents of the tick Rhipicephalus (Boophilus) microplus and the cotton stainer Dysdercus peruvianus

The negative aspects of traditional pest control have led to the investigation of alternative methods such as biological control. Metarhizium anisopliae, well known as an entomopathogenic fungus capable of actively invading and killing its hosts and thus a candidate biopesticide, is here tested against two agricultural pests of economic/social importance and also evaluated for its chitinolytic secretion and capacity to grow and sporulate at different temperatures. None of the isolates was able to grow below 4 °C or above 37 °C. Chitinolytic activity under artificial growth conditions revealed that Rhipicephalus (Boophilus) microplus cuticle induces N-acetyl-β-d-glucosaminidase and endochitinase activities more efficiently than Dysdercus peruvianus cuticle and that glucose did not repress those activities. Bioassays were carried out with R. microplus females and fourth instar D. peruvianus. Six isolates of M. anisopliae were pathogenic to the engorged female cattle ticks. E6, GC47 and CG97 were the most virulent isolates for both arthropod models although differences were seen among them. M. anisopliae strains caused 90–100 % mortality on the fourth post-infection day in R. microplus. D. peruvianus females were more sensitive to fungal infection than males, and the most virulent strains caused 50 % mortality on the third to fourth day post-infection. Our studies suggest that M. anisopliae strain CG47 is a candidate for commercial pesticide formulations due to its capacity to kill both hosts and its ability to sporulate at higher temperatures.     

Characterization of Mycoviruses and Analyses of Chitinase Secretion in the Biocontrol Fungus <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis>

Metarhizium anisopliae is the best-characterized entomopathogen and is used to control insect pests in sugar cane plantations in Brazil on a commercial scale. We have previously reported the infection of some M. anisopliae strains by dsRNA mycoviruses. Here we describe the purification and characterization of the viruses (MaV-A1, MaV-M5, MaV-RJ) in terms of dsRNA content, capsid proteins, electron microscopy, Western blot, and hybridization patterns. One spontaneous mutant lost some of the high molecular weight dsRNA components and showed significant alterations in colony morphology and spore production, suggesting that viral genes interfere with fungal phenotype. A comparison between dsRNA mycovirus-free and infected M. anisopliae isolates showed that virus-free isolates have increased endochitinase secretion. By comparing the following parameters: the buoyant density in CsCl of the presumed virions; the number and estimated molecular weight of the dsRNA components and the molecular mass of the capsid proteins to other mycoviruses previously described, we suggest the inclusion of MaV-A1 and MaV-M5 in the family Totiviridae and MaV-RJ in the family Partitiviridae. Received: 25 September 2001 / Accepted: 1 February 2002     

Selection of virulent isolates of entomopathogenic hyphomycetes against Clavigralla tomentosicollis Stål. and evaluation in cage experiment using three cowpea varieties

The virulence of 8 isolates of entomopathogenic hyphomycetes against adult and 5th instar nymph of Clavigralla tomentosicollis was evaluated in the laboratory at 4 different concentrations of inoculum. At all concentrations, Beauveria bassiana CPD 9 and Metarhizium anisopliae CPD 5 caused the highest mortality in adult bug ranging from 58 to 97% and 53 to 100%, respectively at 7 days post inoculation. The same isolates had the shortest LT₅₀ (3.5 and 4.1 days, respectively) and the lowest LC₅₀ (1.8 × 10⁵ and 9.8 × 10⁴ conidia ml^-1 values in adult insects. In nymphs, M. anisopliae CPD 5 was the most virulent isolate causing mortality of between 43 to 92% with the shortest LT₅₀ of 2.7 days and the lowest LC₅₀of 4.6 × 10⁵ conidia ml^-1 which however did not differ significant from LC₅₀ observed in B. bassiana CPD 9 isolate at 5 days post inoculation. A significant reduction in feeding in both developmental stages treated with fungi was observed at 2 days after treatment with the greatest reduction occurring in insects treated with B. bassiana CPD 9 and M. anisoplia CPD 5. In adult insects treated with these isolates, some bugs ceased feeding 24 h before death. When these two isolates were compared in caged experiment with an untreated control using a susceptible, tolerant and moderately resistant variety of cowpea, percentage pod and seed damage were significantly lower in fungal treated cages than in the control cages on all varieties tested. Grain yield per plant was also significantly higher in fungal treated cages than in the control cages on all varieties. The performance of M. anisopliae CPD 5 was however superior to B. bassiana CPD 9. Application of the fungi on moderately resistant variety of cowpea was found to enhance the performance of the pathogen. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pathogenicity of Beauveria bassiana and Metarhizium anisopliae to the tobacco spider mite Tetranychus evansi

Seventeen isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and two isolates of Beauveria bassiana (Balsamo) Vuillemin were evaluated for their pathogenicity against the tobacco spider mite, Tetranychus evansi Baker & Pritchard. In the laboratory all the fungal isolates were pathogenic to the adult female mites, causing mortality between 22.1 and 82.6%. Isolates causing more than 70% mortality were subjected to dose–response mortality bioassays. The lethal concentration causing 50% mortality (LC₅₀) values ranged between 0.7×10⁷ and 2.5×10⁷ conidia ml⁻¹. The lethal time to 50% mortality (LT₅₀) values of the most active isolates of B. bassiana and M. anisopliae strains varied between 4.6 and 5.8 days. Potted tomato plants were artificially infested with T. evansi and treated with B. bassiana isolate GPK and M. anisopliae isolate ICIPE78. Both fungal isolates reduced the population density of mites as compared to untreated controls. However, conidia formulated in oil outperformed the ones formulated in water. This study demonstrates the prospects of pathogenic fungi for the management of T. evansi.     

Entomopathogenic fungi disturbed the larval growth and feeding performance of Ocinara varians (Lepidoptera: Bombycidae) larvae

Abstract Feeding experiments using three strains of entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea were conducted with newly moulted 3rd–5th instar Ocinara varians Walker larvae in the laboratory. The mortality of larvae immersed individually in spore suspension (1 × 10⁷ spores/mL) of all the strains was ≥ 80% except 5th instar larvae treated with M. anisopliae which transformed into pupae, but did not result in adult emergence. The growth (total body mass), consumption, relative consumption rate and relative growth rate, were reduced at all three larval stages, while developmental time was extended in infected larvae with concurrent significant increase in approximate digestibility in infected larvae. Conversion of digested food (ECD) and ingested food (ECI) values declined in infected larvae as compared to the healthy larvae (control). The 5th instar larvae treated with M. anisopliae showed higher ECD and ECI values than control. Based on mortality and growth inhibition it can be suggested that all the studied fungal strains have a high potential for biocontrol and could be developed into biocontrol agents against O. varians.     

Effects of Entomopathogenic fungi and Bacillus thuringiensis‐based biopesticides on Spoladea recurvalis (Lepidoptera: Crambidae)

Spoladea recurvalis (Fabricius) is one of the most devastating pests of amaranths causing severe yield losses of 60%–100% to the crop. Unfortunately use of chemical pesticides is the most common control strategy that vegetable farmers rely on to control the pest. However, it is not effective and harmful to environmental and human health. Aiming to provide more environmentally friendly alternatives, this study evaluated the effects of various entomopathogenic fungal isolates and commercial based Bacillus thuringiensis Subsp. kurstaki product Halt^®, on the pest. Twenty‐four entomopathogenic fungal (EPF) isolates from three genera (14 Metarhizium anisopliae, 9 Beauveria bassiana and 1 lsaria fumosorosea) were screened in the laboratory to assess their pathogenicity against second instar larvae of S. recurvalis. Only M. anisopliae ICIPE 30 reached a moderate threshold, causing 58.3% larval mortality. All the 11 isolates (8 M. anisopliae, 2 B. bassiana and 1 l. fumosorosea) tested against adult S. recurvalis were pathogenic, with M. anisopliae ICIPE 30 and B. bassiana ICIPE 725 causing the highest mortality of 92% and 83%, respectively. Metarhizium anisopliae ICIPE 30 had the shortest LT₅₀ value of 4.8 days. Bacillus thuringiensis Subsp. kurstaki product Halt^® caused <50% mortality on S. recurvalis larvae. A consecutive application of M. anisopliae ICIPE 30 and Bt did not cause a significant increase in larval mortality compared to separate applications of both products. Results of this study suggest that M. anisopliae ICIPE 30 was the most potent candidate and could be used in an autodissemination approach for management of adult S. recurvalis.     

Infection of Blissus antillus (Hemiptera: Lygaeidae) Eggs by the Entomopathogenic Fungi Metarhizium anisopliae and Beauveria bassiana

This study determined the pathogenicity and virulence of Beauveria bassiana and Metarhizium anisopliae to eggs of the chinch bug Blissus antillus (Hemiptera: Lygaeidae). Eggs were inoculated under laboratory conditions by immersion in concentrations of 1 × 10⁴ and 5 × 10⁶ conidia/ml. Inoculated eggs were kept under controlled conditions. Evaluations were carried out daily for 20 days. M. anisopliae isolates were highly virulent to eggs, even at 1 × 10⁴ conidia/ml. All B. bassiana isolates tested were considered to be of low virulence or avirulent. The most virulent isolate tested was ESALQ 818 (M. anisopliae), which caused 96.7% infection, when eggs were immersed in suspensions of 1 × 10⁴ conidia/ml. Conidial production on infected eggs was observed to be highest for M. anisopliae isolate CG144, with a mean value of 11.6 × 10⁵ conidia/ml/egg. Infection of Blissus eggs oviposited on plant stems was greater when M. anisopliae isolate CG144 was formulated in mineral oil (63.5% mortality) than when formulated in Tween 80 (27.1% mortality).