Entomopathogenic fungi (Hypocreales) for control of potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) in an area endemic for zebra chip disease of potato

Potato psyllid, Bactericera cockerelli, is a serious pest of potato and other solanaceous vegetables in the United States, Mexico, Central America, and New Zealand and is responsible for transmission of Candidatus Liberibacter solanacearum which causes a disease known as “zebra chip” (ZC). Entomopathogenic fungi could provide a viable component for an integrated pest management strategy for control of B. cockerelli and other potato pest insects. Three field trials of commercial formulations of Metarhizium anisopliae (F 52®, Novozymes Biologicals) and Isaria fumosorosea (Pfr 97®, Certis USA) and abamectin (Agri-Mek®, Syngenta, USA) were conducted in Weslaco, Texas. Rates are expressed in quantity of product delivered in 375–470 l of water/ha. F 52 applied at 0.51, 1.1, and 2.2 l/ha and Agri-Mek applied at 584 ml/ha produced reductions of B. cockerelli eggs and nymphs of 45%, 59%, 67%, and 63%, respectively. Only Agri-Mek significantly reduced plant damage. Pfr 97 at 1.1 kg/ha with and without 1% Trilogy® (neem oil, Certis, USA), and Agri-Mek at 584 ml/ha resulted in psyllid reductions of 78%, 76%, and 84%, respectively. Significantly decreased plant damage and ZC symptoms were observed for all treatments. Tuber yields for Pfr plus Trilogy and Agri-Mek were significantly higher than the control. F 52 applied at 1.1 and 2.2 l/ha and Pfr 97 at 1.1 and 2.2 kg/ha produced 62%, 62%, 66%, and 65% reduction, respectively. Tuber yield for both rates of Pfr and the high rate of F 52 were significantly higher than the control. All fungal treatments significantly reduced plant damage and ZC symptoms.     

Different host plant species modifies the susceptibility of Bactericera cockerelli to the entomopathogenic fungus Beauveria bassiana

Bactericera cockerelli (Sulc.) is a serious pest of solanaceous crops and a vector of the plant pathogen Candidatus Liberibacter psyllaurous. Entomopathogenic fungi are the most important biological control alternatives for this pest. Host plant species, however, can modify the outcomes of insect–pathogen interactions. We conducted laboratory experiments to quantify the virulence of two isolates of the entomopathogenic fungus Beauveria bassiana (Bals. [Vuill.]), BB40 and BB42, against third instar B. cockerelli nymphs maintained on chilli pepper plants. Owing to the lack of difference in virulence against B. cockerelli nymphs on chilli pepper between the two B. bassiana isolates, only BB42 was used to: compare virulence against nymphs maintained on either chilli pepper, potato or tomato; and in vivo conidia production from nymphs maintained on different host plants. Virulence of the two B. bassiana isolates against B. cockerelli nymphs was similar. Bactericera cockerelli nymphs maintained on tomato were more susceptible to B. bassiana than nymphs maintained on potato or chilli peppers. Infected nymphs maintained on chilli peppers produced the greatest number of conidia followed by infected nymphs maintained on tomato and potato. Host plant affected the susceptibility of B. cockerelli to B. bassiana isolate BB42 and subsequent conidia production. The implications of our results for microbial control of B. cockerelli by B. bassiana are discussed.     

Susceptibility of the tobacco whitefly,Bemisia tabaci (Hemiptera: Aleyrodidae) biotype Q to entomopathogenic fungi

Recently, the Q biotype of tobacco whitefly has been recognized as the most hazardous strain of Bemisia tabaci worldwide because of increased resistance to some insecticide groups requiring alternative strategies for its control. We studied the susceptibility of this biotype of B. tabaci to 21 isolates of Beauveria bassiana, three isolates of Isaria fumosorosea, one isolate of I. cateni, three isolates of Lecanicillium lecanii, one isolate of L. attenuatum, and one isolate of Aschersonia aleyrodis. These isolates were evaluated on pruned eggplant seedlings, at a concentration of 10⁸ conidia/mL (deposited at 6000±586 conidia mm^?2). The mortality based on mycosis varied from 18 to 97% after 6 days. Isaria fumosorosea isolate Pf04, B. bassiana isolates Bb06, Bb12, and L. lecanii L14 were found the most effective. Furthermore, five isolates were chosen for concentration–mortality response assays and compared to B. bassiana GHA as a standard. The numbers of nymphs infected by fungi were correlated with the spore concentration. L. lecanii L14 and I. fumosorosea Pf04 had the shortest LT₅₀ at 3.5 and 3.3 days at 6000±586 conidia mm^?2. Mortality declined and LT₅₀ values were longer as the concentration of conidia was reduced. The LD₅₀ values were calculated as 87, 147, 191, 263, and 269 conidia mm^?2 for isolates L14, GHA, AS1260, Bb13, and Pf04, respectively. These results indicated that the Q biotype of sweetpotato whitefly was susceptible to the five isolates of entomopathogenic fungi and these isolates have potential to be developed as microbial pesticides for whitefly control.     

Differential susceptibility of Amblyomma maculatum and Amblyomma americanum (Acari:Ixodidea) to the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae

Nymph and adult ticks from Ambylomma americanum and Ambylomma maculatum were treated with conidia and blastospores of the entomopathogenic fungi Beauveria bassiana (90517) and Metarhizium anisopliae (20500). Fungal suspensions of conidia harvested from potato dextrose plates containing 10⁸ conidia/ml caused greater than 90% mortality in adult A. maculatum but less than 10% mortality in adult A. americanum over a 28 day time course. Similarly, infection with M. anisopliae (10⁸ conidia/ml) resulted in 60 and 15% mortality in A. maculatum and A. americanum, respectively. Nymphs of both tick species were more susceptible to fungal infection reaching mortality rates of almost 100% for A. maculatum and over 35% for A. americanum. Scanning electron microscopy of infected ticks showed rapid attachment, germination, and proliferation of fungal spores on A. maculatum cuticles, and to a much lesser extent on A. americanum cuticles. Pentane extracts of A. americanum cuticle hydrocarbons inhibited germination and hyphal growth of B. bassiana conidia, whereas no inhibition was observed using A. maculatum extracts. Significant mortality towards A. americanum was observed (>60%, 28 days) only when the ticks were treated with B. bassiana directly from the growth medium (10⁷ blastospores/ml, grown for 3–4 days in Sabouraud dextrose + 0.5% yeast extract liquid media). These results indicate tick species display differential susceptibility to the entomopathogenic fungi B. bassiana and M. anisopliae, and that the ability to overcome fungistatic compounds present in the tick epicuticle may determine the likelihood of successful infection and virulence.     

Entomogenous Fungi as Promising Biopesticides for Tick Control

When ticks were sealed in nylon tetrapacks and infected with the entomogenous fungi, Beauveria bassiana and Metarizium anisopliae and maintained in potted grass in the field, the fungal oil formulations (10⁹ conidia per ml) induced 100% mortality in larvae of Rhipicephalus appendiculatus and Amblyomma variegatum, whereas mortalities in nymphs varied between 80–100% and in adults 80–90%. The aqueous formulations (10⁹ conidia per ml) induced mortalities of 40–50% and reductions in egg hatchability of 68% (B. bassiana) and 48% (M. anisopliae) when sprayed on Boophilus decoloratus engorging on cattle. The strains of B. bassiana and M. anisopliae isolated from naturally infected ticks were also found to induce high mortalities in both R. appendiculatus and A.variegatum in tetrapacks placed in potted grass. Both aqueous and oil-based formulations were found to be effective, although the latter induced higher mortalities. These fungal strains in aqueous formulation (10⁸ conidia per ml) suppressed on-host populations of adult R. appendiculatus by 80% (B. bassiana) and 92% (M. anisopliae) when sprayed on tick-infested grass once per month for a period of 6 months. The feasibility of using entomogenous fungi for tick control in the field is discussed.     

Entomopathogenicity of beauveria bassiana and metarhizium anisopliae to the cowpea aphid,aphis craccivora koch (homoptera: Aphididae)

The pathogenicity of four isolates each of the entomopathogenic fungi, Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. to apterous adult Aphis craccivora Koch was evaluated in the laboratory at 4 concentrations of conidia. All fungi isolates tested were found to be pathogenic to the insect but their virulence varied among species and isolates within species. Three isolates, B. bassiana CPD 11 and M. anisopliae CPD 4 and 5 caused significantly higher mortality than the other isolates at the various concentrations tested causing mortality of between 58–91%, 64 to 93% and 66–100%, respectively, at 7 days post treatment. At the highest concentration of 1 × 10⁸conidiaml^‐1, these isolates produced the shortest LT₅₀s of 3.5, 3.6 and 3.4 days, respectively. Their LC₅₀s were 6.8 × 10⁵, 3.1 × 10⁵ and 2.7 × 10⁵ conidia ml^‐1, respectively. The results indicate that these isolates are promising candidates for the control of the cowpea aphid but their pathogenicity to various aphid non‐target beneficial organisms within the cowpea agroecosystem warrant further investigation before initiating field control.     

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.     

Use of entomopathogenic fungi combined with biorational insecticides to control Dichroplus maculipennis (Orthoptera: Acrididae: Melanoplinae) under semi-field conditions

Grasshoppers are among the invertebrate herbivores that cause most economic losses in grasslands throughout Argentina’s Pampas and parts of Patagonia. Chemical insecticides remain the sole option for grasshopper control in this area, despite being of significant environmental concern. Our aim was to evaluate the efficacy of combinations between three entomopathogenic fungi strains (Beauveria bassiana LPSc 1067 and LPSc1082), and Metarhizium anisopliae (LPSc 907), two biorational insecticides (luphenuron and methoxyfenozide), and a new synthetic chemical pesticide (rynaxypyr) in the control of the pest grasshopper Dichroplus maculipennis under field cage conditions. Fungal strains used were adjusted to 1 × 10⁸, 1 × 10⁶ and 1 × 10⁴ conidia/ml. Insecticides were tested at three concentrations: the average concentration recommended for application in the field (100%), 50% of that level and finally 25%. Combinations of the insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to D. maculipennis nymphs than any of the individual agents used alone. The three insecticides tested did not negatively affect the isolates of the two species of entomopathogenic fungi employed.     

Behavioral and electrophysiological responses of Coptotermes formosanus Shiraki towards entomopathogenic fungal volatiles

Termites adjust their response to entomopathogenic fungi according to the profile of fungal volatile organic compounds (VOCs). This study demonstrates the pathogenicity of Metarhizium anisopliae, Beauveria bassiana and Isaria fumosorosea (=Paecilomyces fumosoroseus) towards the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Using no-choice assays, M. anisopliae was found to be highly virulent (LT₅₀ 3.10 d) when compared to B. bassiana (LT₅₀ 6.62 d) and I. fumosorosea (LT₅₀ 12.39 d). Also using choice assays, the foraging behavior of C. formosanus was determined in the presence of pathogenic fungi. The highly pathogenic fungi (M. anisopliae) elicited a repellent response, causing most of the termites to forage in a safe zone farthest from the fungal source. This repellency resulted in relatively low mortality similar to the controls. The repellency of M. anisopliae conidia can be used to protect human belongings and timber from termites. While I. fumosorosea cultures were not repellent to C. formosanus workers, the termites were highly susceptible to infection. Electroantennographic responses of workers showed approximately 47% and 78% lower level of response to conidia of B. bassiana and I. fumosorosea, respectively, as compared to M. anisopliae. The VOC profile of repellent cultures of M. anisopliae mainly consisted of paraffins (60.97%), while the major proportion of the I. fumosorosea profile consisted of branched and cyclic alkanes (84.41%). From the above findings, we conclude that the incorporation of I. fumosorosea may increase the control potential of bait.     

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.     

Virulence of Hypocreales fungi to pecan aphids (Hemiptera: Aphididae) in the laboratory

There is need for efficacious biocontrol agents for aphids in commercial orchards. As a preliminary step to this end we determined the virulence of several Hypocreales fungi to pecan aphids. In the first experiment we tested the virulence of Isaria fumosorosea (ARSEF 3581) blastospores to three pecan aphids Monellia caryella, Melanocallis caryaefoliae, and Monelliopsis pecanis under laboratory conditions. Rates of 1 × 10⁷ or 1 × 10⁸ spores per ml were applied in 2 ml via a spray tower to 90 mm Petri dishes containing 10 aphids each. Mortality and mycosis were determined after 24, 48 and 72 h. Treatment effects were observed by 48 h post-application, and by 72 h the higher application rate caused >90% mortality and mycosis in M. caryella and M. caryaefoliae, whereas <70% was observed in M. pecanis.We conducted two subsequent experiments (Experiments 2 and 3), using the same methodology, to compare the virulence of several Hypocreales species and strains against the aphid of primary economic concern to most pecan growers, M. caryaefoliae. In Experiment 2, we compared blastospores and conidia of two I. fumosorosea strains (ARSEF 3581 and ATCC 20874 [= strain 97]). The blastospores of ARSEF 3581 and conidia of ATCC 20874 showed higher virulence than other treatments and thus were included in Experiment 3, which also compared the virulence of conidia of Beauveria bassiana (GHA strain) and Metarhizium anisopliae (F52 strain). Results in Experiment 3 indicated the highest virulence in I. fumosorosea 3581 blastospores and M. anisopliae (F52) followed by I. fumosorosea (20874) conidia. The detection of pathogenicity to pecan aphids establishes the potential for commercial usage and additional study. Results reported here will narrow treatments to test in future greenhouse and field trials.     

Influence of substrate and relative humidity on the efficacy of three entomopathogenic fungi for the hide beetle,Dermestes maculatus (Coleoptera,Dermestidae)

Dermestes maculatus De Geer (Coleoptera: Dermestidae) is a carrion feeder that is also a pest of poultry houses, museums, silkworm culture, and many stored foods. The Hypocreales, Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff), and Isaria fumosorosea Wize, were tested for efficacy against D. maculatus larvae on concrete, plastic, leather, and wood surfaces. Only wood had a significant negative effect on efficacy, and B. bassiana was the most efficacious species. The conidia of all three species lost viability quickly on wood with various responses on the other surfaces. When beetle larvae were exposed to deposited B. bassiana and incubated at 43, 56, 75, or 82% relative humidity, mortality was greatest at the lowest humidity suggesting enhancement of fungal infection by desiccation stress. The results indicate that entomopathogenic Hypocreales, especially B. bassiana, may be useful for control of hide beetles when applied at a low dose to surfaces that do not impact the viability of conidia.     

Lethal effects of Gliocladium virens,Beauveria bassiana and Metarhizium anisopliae on the malaria vector Anopheles albimanus (Diptera: Culicidae)

Control of Anopheles albimanus, the main vector of malaria on the coast of the State of Chiapas, is based mainly on application of chemical insecticides, which has resulted in resistance to most registered insecticides. Strategies for biological control may provide sustainable alternatives. We report on the lethal effects of a native isolate of Gliocladium virens on An. albimanus larvae and adults, compared to that of strains of Beauveria bassiana and Metarhizium anisopliae. Conidial suspensions of G. virens, B. bassiana and M. anisopliae cultured on Sabouraud agar were tested in bioassays with An. albimanus larvae and adults. Mosquito larvae were more susceptible to all fungi, compared to adults. On early and late instar larvae, M. anisopliae showed the most pathogenic effect (LC₅₀ of 1.4×10⁵ conidia/mL in early instars; 1.1×10⁵ conidia/mL in late instars), followed by G. virens (LC₅₀ of 3.3×10⁵ conidia/mL in early instars and 3.5×10⁶ conidia/mL in late instars). Metarhizium anisopliae sensu lato and the native G. virens could be considered good choices for An. albimanus control in southern Mexico.     

Host plant influences pathogenicity of Beauveria bassiana to Bemisia tabaci and its sporulation on cadavers

Laboratory bioassays were conducted to determine host plant effect on pathogenicity of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuill. (Ascomycota: Hypocreales) to the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Fourth instar B. tabaci reared on cucumber, tomato, melon, green pepper, potato, eggplant, marrow, cabbage, bean or cotton, were treated with 1 × 10⁷ conidia/ml B. bassiana EABb 93/14-Tp isolate. Mortality caused by B. bassiana significantly increased with time and it was significantly affected by the host plant on which the nymphs were reared. Mean mortality of nymphs 8 days after inoculation ranged between 52.3±7.3 for nymphs reared on cotton and 91.8±5.8 for nymphs reared on cucumber. Average survival times of nymphs treated with the fungal suspensions were also significantly influenced by the host plant, with a mean of 4.7±0.1 days for nymphs reared on cucumber, 6.6±0.2 days for cotton and 6.9±0.1 days for green pepper. The production of newly formed conidia was also affected by host plant and varied from 111000±8600 conidia/cadaver for nymphs reared on cotton to 597000±28000 conidia/cadaver for those reared on melon.     

Screening of entomopathogenic fungi against the European spruce bark beetle,Dendroctonus micans (Coleoptera: Scolytidae)

The European spruce bark beetle, Dendroctonus micans Kugelann (Coleoptera: Scolytidae), is one of the most serious destructive pests of oriental spruce (Picea orientalis L.). In order to find an effective biocontrol agent against this pest, we determined the effectiveness of entomopathogenic fungi against D. micans. Virulence of nine highly pathogenic strains including Beauveria bassiana (2), Beauveria cf. bassiana (2), Metarhizium anisopliae (2), Metarhizium sp. (1), Isaria fumosorosea (1) and Evlachovaea sp. (1) was evaluated on D. micans larvae and adults under laboratory conditions. Mortality values for both larvae and adults ranged from 83 to 100% and from 23 to 100%, respectively. Larvae were more susceptible to fungi than adults (P<0.05). Based on screening tests, B. cf. bassiana isolate KTU-53 was found the most effective isolate. LC₅₀ values were calculated as 1.77×10⁴ and 2.65×10⁴ conidia mL^?1 for isolate KTU-53 against larvae and adults, respectively. Consequently, B. cf. bassiana isolate KTU-53 appears to be the most promising microbial control agent for biocontrol of D. micans.     

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.     

Toxicity of non-ionic surfactants and interactions with fungal entomopathogens toward Bemisia tabaci biotype B

Several non-ionic surfactants can be used to enhance insecticidal performance of various bio-based products and agrochemicals. In this study, we describe the toxicity of four commercial non-ionic surfactants against immature Bemisia tabaci (Gennadius) biotype B whiteflies along with their spreading ability. Results revealed that trisiloxane-based surfactants (Break-thru^® and Silwet^® L-77) exhibited the highest toxicity to 1st–2nd (early) and 3rd–4th (late) instar nymphs as well as the greatest wetting performance. We also investigated whether sub-lethal concentrations of Break-thru^® and Silwet^® L-77 improved the insecticidal efficacy of the fungal entomopathogens Beauveria bassiana (Balsamo) Vuillemin (strain CG1229) and Isaria fumosorosea Wise (strain CG1228) conidial suspensions against whiteflies. Germination of hydrophobic conidia of both isolates were unaffected by these surfactants over the range 100–1000 ppm. The combinations of both fungi with trisiloxane carriers significantly increased nymphal mortality with mostly additive and synergistic effects on early and late nymphs, respectively. In screenhouse trials, both fungi (10⁷ conidia ml^?1) mixed with 200 ppm of Silwet^® L-77 significantly improved effectiveness against early nymphs (72–74 % mortality) compared with controls treated with water and Silwet^® L-77 alone. In addition, reduced volume rates of I. fumosorosea in Silwet^® L-77 (equivalent to 100 l ha^?1) were at least as effective against late nymphs as higher volume rates (200 l ha^?1) at equivalent conidial doses. Our findings underline the compatibility and enhanced activity of silicon-based surfactants with B. bassiana and I. fumosorosea for use in integrated whitefly management programs.     

Pathogenicity of Beauveria bassiana (Deuteromycotina: Hypomycetes) to Larvae of the Small Poplar Longhorn Beetle, Saperda populnea (Coleoptera: Cerambycidae)

The small poplar longhorn beetle, Saperda populnea is an important pest of Lombardy poplars (Populus nigra L.) in Turkey. A survey for natural entomopathogenic fungi of S. populnea larvae was made in Erzurum, Turkey, during the period 2004–2005. Larvae (13.5%) infected with a strain of the fungus Beauveria bassiana were found. The pathogenicity of B. bassiana strain 46 was conducted with different concentrations of conidia (10⁶, 10⁷ and 10⁸ conidia/ml) of this isolate on S. populnea larvae. The lowest concentration (10⁶ conidia/ml) caused about 56% mortality within 6 days. One hundred percent mortality was achieved after median lethal time (LT₅₀) of 4.6 and 4.4 days for 10⁷ and 10⁸ conidia/ml, respectively. There were no significant differences between median lethal times. This is the first record of natural infection of S. populnea larvae by B. bassiana.     

Influence of commercial fungicides on the germination,growth and virulence of four species of entomopathogenic fungi

The influence of 15 commercially available fungicides on the germination, growth and virulence of Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Lecanillium longisporum was evaluated. The influence of the fungicides on conidial germination was dependant on the fungicide type and dose. Most fungicides retarded conidial germination of all the fungi tested at 10× and at the recommended rate of application, however, their toxicity declined at lower concentrations. Most of the fungicides inhibited mycelial growth of B. bassiana, whereas L. longisporum growth was unaffected. Only two and eight fungicides influenced mycelial growth of I. fumosorosea and M. anisopliae, respectively. None of the fungicides influenced the virulence of B. bassiana and L. longisporum, however, tolylfluanid and azoxystrobin reduced the virulence of M. anisopliae and I. fumosorosea, respectively. These studies clearly show that certain fungicides have the potential to inhibit germination of entomopathogenic fungi in vitro but appear to have little or no effect on their virulence against target insects.     

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).