Evaluation of Metarhizium anisopliae (Metsch) Sorok. to target larvae and adults of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) in soil and fiber band applications

The aim of this work has been to evaluate in the laboratory the potential of entomopathogenic fungi against adults and larvae of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) through fiber band application and a potted plant bioassay with soil application, respectively. Our previous findings revealed that Metarhizium anisopliae EAMa 01/58-Su isolate was the most virulent against neonate larvae of the buprestid. In the present work, M. anisopliae EAMa 01/58-Su isolate has been also shown to be highly virulent against adult beetles by immersion in a conidial suspension; thus it was selected to accomplish our objectives. When adult beetles were stimulated to climb 100 x 200 mm non-woven commercial fiber bands impregnated with conidia of M. anisopliae EAMa 01/58-Su isolate, total mortality rates varied from 85.7% to 100.0%; whereas no significant correlation was detected between the time needed to cross the band (mean value 648.7+/-22.4s) and the time of death, with mean average survival time ranging between 10.3 and 16.0 days, compared to 28 days of the controls. Potted seedlings (5-6 months old) of cherry plum (Prunus myrobalana Lois.), a commonly used apricot rootstock, were used to study the efficacy of soil treatment with M. anisopliae EAMa 01/58-Su isolate against neonate C. tenebrionis larvae. The soil inoculation with M. anisopliae EAMa 01/58-Su isolate had a significant effect on the mean number of dead larvae recovered from the roots, with mean mortality ranging from 83.3% to 91.6%; whereas no significant differences were detected between the three fungal doses. In all cases, dead larvae found within roots exhibited external signs of fungal growth. Hence, it may be possible to use M. anisopliae EAMa 01/58-Su isolate in a biocontrol strategy targeting both adults and larvae of C. tenebrionis.     

Synergistic effect of entomogenous fungi on some insecticides against Bihar hairy caterpillar Spilarctia obliqua (Lepidoptera: Arctiidae)

A number of fungal parasites infect a wide range of insects and cause epizootics from time to time. Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin are two of the major disease-causing fungi in insects. Investigations were carried out to study the effect of these fungi on the toxicity of endosulfan, imidacloprid, lufenuron, diflubenzuron, dimethoate and oxydemeton methyl against 10-11 days old larvae of Spilarctia obliqua (Walker). For some products the combination treatments showed higher dose mortality response than the sole treatment of fungal conidia or the insecticide. The combination of insecticides with B. bassiana showed 1.26-35.8 fold increase in toxicity of insecticides over sole treatment, while the increase was 1.05-72.0 fold in case of M. anisopliae. Imidacloprid 17.8 SL and oxydemeton methyl 25EC may be used in combination with these fungi for management of S. obliqua.     

Characterization of Beauveria bassiana and Metarhizium anisopliae isolates for management of tarnished plant bug,Lygus lineolaris (Hemiptera: Miridae)

Selected morphological and physiological characteristics of four Beauveria bassiana (Balsamo) Vuillemin isolates and one Metarhizium anisopliae (Metschnikoff) Sorokin isolate, which are highly pathogenic to Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), were determined. There were significant differences in conidial size, viability, spore production, speed of germination, relative hyphal growth, and temperature sensitivity. Spore viability after incubation for 24h at 20 degrees C ranged from 91.4 to 98.6% for the five isolates tested. Spore production on quarter-strength Sabouraud dextrose agar plus 0.25% (w/v) yeast extract after 10 days incubation at 20 degrees C ranged from 1.6x10(6) to 15.5x10(6)conidia/cm(2). One B. bassiana isolate (ARSEF 1394) produced significantly more conidia than the others. Spore germination was temperature-dependant for both B. bassiana and M. anisopliae. The time required for 50% germination (TG(50)) ranged from 25.0 to 30.9, 14.0 to 16.6, and 14.8 to 18.0h at 15, 22, and 28 degrees C, respectively. Only the M. anisopliae isolate (ARSEF 3540) had significant spore germination at 35 degrees C with a TG(50) of 11.8h. A destructive sampling method was used to measure the relative hyphal growth rate among isolates. Exposure to high temperature (40-50 degrees C) for 10min had a negative effect on conidial viability. The importance of these characteristics in selecting fungal isolates for management of L. lineolaris is discussed.     

Mortality of Delia floralis, Galleria mellonella and Mamestra brassicae treated with insect pathogenic hyphomycetous fungi

Abstract:  The susceptibility of Delia floralis eggs, neonates and larvae and the susceptibility of Galleria mellonella and Mamestra brassicae larvae to seven different Norwegian isolates of the insect pathogenic, hyphomycetous fungi Tolypocladium cylindrosporum , Metarhizium anisopliae and Beauveria bassiana , were investigated. Metarhizium anisopliae isolate ARSEF 5520 was highly virulent to G. mellonella larvae and caused 100% mortality when tested at a concentration of 3.6 × 10⁶ conidia/ml. The same M. anisopliae isolate was not virulent to D. floralis larvae. Isolates of T.cylindrosporum , were equally virulent to G. mellonella and D. floralis causing up to 36.0% mortality of larvae. It is suspected, however, that the use of grated rutabaga as a food source in the D. floralis bioassay reduced the fungal virulence of both M. anisopliae and T. cylindrosporum to D. floralis . Among three T. cylindrosporum isolates tested at a concentration of 1.0 × 10⁷ conidia/ml against eggs of D. floralis none of them reduced the hatching percentage. One isolate, ARSEF 5525 did, however, significantly reduce the longevity of neonates. Beauveria bassiana isolates ARSEF 5510 and ARSEF 5370 tested at a concentration of 1.0 × 10⁷ conidia/ml resulted in M. brassicae mortality levels of 70.0 and 55.0%, respectively. The B. bassiana isolate ARSEF 5557, however, was not virulent to M. brassicae . Among the three isolates tested against M. brassicae the two virulent isolates produced a red pigment, probably oosporein, when cultured in Sabouraud dextrose agar.     

Selection of a Highly Virulent Fungal Isolate,Metarhizium anisopliae Ma TB 101, for Control of Taro Beetle,Papuana uninodis (Coleoptera: Scarabaeidae)

Fungal isolates (31 Metarhizium anisopliae var. anisopliae , five M. anisopliae var majus , three Beauveria bassiana and four B. brongniartii ) originating from a wide range of geographical locations, insect species and soil types were tested against Papuana uninodis (Coleoptera: Scarabaeidae). In a first test series, spores were applied topically to third-instar larvae and adults. The most effective strain against P. uninodis larvae and adults was Ma TB 101, a M. anisopliae isolate from adult P. woodlarkiana . For adults, strain Ma FI 384, a M. anisopliae from Popillia japonica , was almost equally effective. The 11 most effective isolates (nine M. anisopliae var. anisopliae , one B. brongniartii and one B. bassiana ) with LT values of less than 6 weeks in 50 adults and/or less than 4 weeks in larvae were tested for their efficacy against adults and larvae of P. uninodis by application of spores to soil (107 spores/g). Ma TB 101 was significantly more effective against both adults and larvae (LT ca. 10 days) than all other isolates (LT > 50 50 3 weeks). Two other M. anisopliae strains, Ma F 248 from soil and Ma FI 384 from P.japonica , were more effective than most isolates in adults. The latter three M. anisopliae isolates were tested in a concentration series against third-instar larvae and adults. Mortality was concentration related. Isolates Ma F 248 and Ma FI 384 did not achieve 50% mortality within the test period at concentrations lower than 107 spores/g of soil or feed. For concentrations of Ma TB 101 from 1 107 to 2 105 spores/g the LT ranged from 13 to 30 days in adults and 12 to 24 50 days in third-instar larvae. Accordingly, concentrations causing 50% mortality (LC ) for Ma 50 TB 101 were significantly lower than for the two other M. anisopliae isolates tested.     

Pathogenicity of Metarhizium anisopliae (Metsch.) Sorokin and Beauveria bassiana (Balsamo) Vuillemin,to three adult fruit fly species: Ceratitis capitata (Weidemann), C. rosa var. fasciventris Karsch and C. cosyra (Walker) (Diptera :Tephritidae)

The pathogenicity of two isolates of Beauveria bassiana and 12 of Metarhizium anisopliae towards adult fruit flies, Ceratitis capitata and Ceratitis rosa var. fasciventris was tested in the laboratory. Fruit flies were exposed to dry conidia evenly spread on velvet material covering the inner side of a cylindrical plastic tube. All isolates tested were pathogenic to both species of fruit flies. Mortality ranged from 7 to 100% in C. capitata and from 11.4 to 100% in C. rosa var. fasciventris at 4 days post-inoculation. Six isolates, M. anisopliae ICIPE 18, 20, 32, 40, 41 and 62, were highly pathogenic to both C. capitata and C. rosa var. fasciventris. The LT90 values of the most pathogenic isolates ranged between 3-4 days in both insects. Because of the difficulties in rearing C. cosyra, only the isolates that were highly pathogenic to both C. rosa var. fasciventris and C. capitata were tested against adult C. cosyra. They caused mortality of between 72-78% at 4 days post-inoculation. The LT90 values in all the isolates did not exceed 4 days. One of the most pathogenic isolates, M. anisopliae ICIPE 20, was evaluated against C. capitata and C. rosa var. fasciventris in cage experiments using three autoinoculators (maize cob, cheesecloth and Petri dish) in an autoinoculative device consisting of plastic mineral bottle. Mortality of between 70-93% was observed in flies of both species that were captured from the cages and held under laboratory conditions. These results indicate the possibility of fruit fly suppression with entomopathogenic fungi using an autoinoculative device.     

Mortality in Three African Tephritid Fruit Fly Puparia and Adults Caused by the Entomopathogenic Fungi, Metarhizium anisopliae and Beauveria bassiana

The pathogenicity of 13 isolates of Metarhizium anisopliae and two isolates of Beauveria bassiana to Ceratitis capitata and Ceratitis var. rosa fasciventris exposed as late third instar larvae in sand was evaluated in the laboratory. All isolates caused a significant reduction in adult emergence and a corresponding large mortality on puparia of both species. All isolates also induced large deferred mortality in emerging adults following treatment as late third instar larvae. On C. capitata , seven isolates ( M. anisopliae ICIPE 18, 20, 32, 60 and 69 and B. bassiana ICIPE 44 and 82) caused significantly higher mortality on puparia than other isolates. With the exception of ICIPE 32, the other four isolates of M. anisopliae above were the most pathogenic against C. r. fasciventris . Dose-response study carried out with these isolates of M. anisopliae on the two species of flies above plus another species, Ceratitis cosyra showed that the dose-mortality regression lines of ICIPE 18 and 20 were steeper with lower LC 50 values when compared with ICIPE 60 and 69 on the three species. When these two isolates were evaluated with regard to their pathogenicity to different pupal age, adult emergence was found to increase with increasing pupal age with a corresponding decrease in mortality in puparia and emerging adults in the three species of fruit flies. M. anisopliae ICIPE 18 and 20 were equally pathogenic to all pupal ages tested in C. capitata and C. cosyra but ICIPE 18 was more pathogenic to older puparia of C. r. fasciventris than ICIPE 20. Our results suggest that soil inoculation with M. anisopliae under mango trees might form an important component of integrated pest management strategies in areas where these three species of fruit fly coexist.     

Food consumption by Chilo partellus (Lepidoptera: Pyralidae) larvae infected with Beauveria bassiana and Metarhizium anisopliae and effects of feeding natural versus artificial diets on mortality and mycosis

Second and third instar Chilo partellus larvae were infected with Beauveria bassiana and Metarhizium anisopliae (both at 1x10(8)conidia/ml) and daily consumption of maize leaves was measured. Infection by the fungi was associated with reduced mean daily food consumption. Reduction in food consumption became evident 3-4 days after treatment with the fungi for second instar larvae and 4-5 days for third instar larvae. Four conidial concentrations, 1x10(5), 1x10(6), 1x10(7), and 1x10(8)conidia/ml, were tested against second instar larvae. Food consumption dropped by 70-85% when the second instar larvae were treated with the fungi at 1x10(8)conidia/ml. Reduction in food consumption by C. partellus larvae infected with B. bassiana and M. anisopliae may offset the slow speed of kill of the fungi. The effect of artificial versus natural diets on mortality and mycoses of second instar larvae treated with the fungi at 1x10(8)conidia/ml was determined. Larvae provided with artificial diet suffered little mortality and mycoses than larvae provided with maize leaves. The LT(50) was longer for larvae provided with artificial diet.     

The Susceptibility of Boophilus annulatus (Ixodidae) Ticks to Entomopathogenic Fungi

The pathogenicity of five species of entomopathogenic fungi (Deuteromycetes, species: Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, Paecilomyces fumosoroseus and Verticillium lecanii ) to the various developmental stages of Boophilus annulatus ticks was compared under laboratory conditions. M. anisopliae and B. bassiana strains were most virulent to engorged females and caused 85-100% mortality within 7-10 days post-inoculation (PI). The highest mortality of engorged females caused by other fungi reached only 25-60%. All tested fungi prevented or reduced the egg laying capability of the ticks several days before their death. Females surviving after treatment with the most virulent M. anisopliae strain (Ma-7) reached only 7-8% of their egg laying capacity as compared with the control. Other fungi caused a reduction of the weight of laid eggs by 35.4-80.8% as compared with untreated females. Only M. anisopliae and B. bassiana strains caused 70-98% mortality of the treated eggs. Unfed larvae of Boophilus annulatus were sensitive to M. anisopliae and M. flavoviride strains. The Ma-7 strain was most virulent to unfed larvae, with a mortality rate of 80.4% at a concentration of 1 ×107 spores ml -1 and 100% mortality at a concentration of 1 ×108 spores ml -1 .     

Sporulation of Metarhizium anisopliae and Beauveria bassiana on Coptotermes formosanus and in vitro

The sporulation of 22 total isolates of Metarhizium anisopliae and Beauveria bassiana was quantified on cadavers of the Formosan subterranean termite, Coptotermes formosanus. Conidial production increased significantly over 11 days post-death. Effects of isolates of M. anisopliae and B. bassiana on in vivo sporulation were significant. Although the overall effects of fungal species on in vivo sporulation were not significant, the interactions between fungal species and certain times post-death were significant, indicating different sporulation patterns between the two fungal species. B. bassiana isolates could be categorized into a group with high total sporulation (day 11) and low quick sporulation (on days 2 and 3), while M. anisopliae isolates fell into another group with high quick sporulation and low total sporulation. This could give M. anisopliae an advantage over B. bassiana in termite microbial control due to termite defensive social behaviors. Conidial production was significantly higher in vitro than in vivo. In vitro and in vivo sporulation differed by as much as 89x and 232x among the selected isolates of B. bassiana and M. anisopliae, respectively. Correlation between in vivo and in vitro conidial production was positive and significant. This may allow preliminary in vitro screening of a large number of isolates for high in vivo sporulation.     

Effects of Metarhizium anisopliae (Metsch.) Sorok. and Beauveria bassiana (Bals.) Vuill. on the predatory stinkbug Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae)

Entomopathogenic fungi and the predatory stinkbug Podisus nigrispinus (Dallas) can target simultaneously the same or different pests in agroecosystems. Topical contact during fungal dispersion or spraying, walking on plant surfaces and ingestion of contaminated prey are some of possible ways of interactions between fungi and the predatory stinkbug. The impact of three isolates of Metarhizium anisopliae (Metsch.) Sorok. (866, 1022 and 1189) and Beauveria bassiana (Bals.) Vuill. (604, 634 and 561) against nymphs and adults of P. nigrispinus was investigated under laboratory conditions. M. anisopliae caused higher mortality compared to B. bassiana either by topical application or by dry residue on cotton leaves. Topic contact with both fungi caused higher mortality to the predator. No mortality confirmation was reported for the adults. Nymphs fed with cotton leafworm larvae Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) contaminated by the fungi had their reproduction affected, but this was not observed when adult predators fed on contaminated larvae. These findings suggest that isolates of M. anisopliae can cause mortality of P. nigrispinus nymphs by topical contact, while isolates of B. bassiana were less harmful by all ways of infection as compared to M. anisopliae.     

Pathogenicity of entomopathogenic fungi to different developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae).

The pathogenicity of 4 species of entomopathogenic fungi (Hyphomycetes species: Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, and Paecilomyces fumosoroseus) to various developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae) ticks was compared under laboratory conditions. The most virulent isolate, M. anisopliae-108, caused 92-96% mortality to unfed larvae and nymphs on day 7 postinfection (PI) and 100% mortality to unfed adults and engorged females on day 21 PI. The pathogenicity of M. anisopliae-108 to engorged larvae and nymphs was lower--82.6 and 60%, respectively. All tested B. bassiana, M. flavoviride, and P. fumosoroseus isolates were significantly less virulent (P < 0.05) or avirulent toward most life stages of R. sanguineus. The M. anisopliae and M. flavoviride isolates also prevented or reduced the ability of the ticks to lay eggs several days before their deaths. Female ticks infected by the fungi achieved only 11.3-60.8% of their egg-laying capacity compared with the controls.     

Laboratory evaluation of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae against puparia and adults of Ceratitis capitata (Diptera: Tephritidae)

Laboratory experiments were done to measure the pathogenicity of 10 autochthonous isolates of Beauveria bassiana (Balsamo) Vuill. and of five Metarhizium anisopliae (Metsch.) Sorok. toward puparia and adults of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Although all isolates applied via inoculation of the fungal suspensions on the ventral surface of the abdomen were pathogenic to adults, with mortality rates ranging from 30 to 100% and average survival times (ASTs) from 6.5 to 8.6 d, when C. capitata puparia were immersed in the conidial suspensions, only B. bassiana Bb-1333 and EABb 01/103-Su and M. anisopliae EAMa 01/58-Su isolates caused >50% mortality of puparia. In a second series of bioassays conducted on five selected isolates, adults were sprayed with four 10-fold concentrations ranging from 1.0 x 10(5) to 1.0 x 10(8) colony-forming units (cfu)/ml. The median lethal concentrations (LC50) of the four most virulent isolates ranged from 4.9 x 10(5) to 2.0 x 10(6) cfu/ml with estimated time to kill 50% of the insects ranging from 4.6 to 5.3 d. The effect of a sublethal dose (ca. LD50) of either B. bassiana EABb 01/103-Su or M. anisopliae EAMa 01/58-Su isolate was studied by reciprocal crossing. Treatment with B. bassiana reduced fecundity and fertility at 6, 8, and 10 d after treatment, with fecundity and fertility reductions ranging from 20.0 to 71.2% and from 33.6 to 60.0%, respectively. These reductions occurred in pairing combinations of treated females with either treated or nontreated males. M. anisopliae was more effective in reducing fecundity and fertility at 6 d after treatment, with the reduction varying from 58.4 to 72.1% and from 28.6 to 45.9%, respectively. In addition, the first oviposition was significantly delayed for 1 d in females treated by either fungal species. The above-mentioned five selected isolates were assayed against C. capitata puparia treated as late third instars in sterilized soil at 25'C under three moisture conditions (-0.1, -0.01, and -0.0055 MPa). At -0.01 MPa, all isolates were low pathogenic to C. capitata puparia, whereas significant differences in the puparia mortality occurred between isolates at -0.1 and -0.0055 MPa. The highest pupal mortalities ranged from 52.5 to 70.0%, as a function of soil moisture and were caused by EAMa 01/58-Su and Bb-1333 isolates.     

Pathogenicity of Beauveria bassiana,Metarhizium anisopliae and Serratia marcescens to the banana weevil Cosmopolites sordidus

Two exotic fungal isolates, one of Beauveria bassiana (268–86) and another of Metarhizium anisopliae (100–82), three local isolates of B. bassiana (isolates I, II, III) and one of the entomogenous bacteria Serratia marcescens, were tested for pathogenicity against the banana weevil Cosmopolites sordidus. All four isolates of B. bassiana and the one of M. anisopliae were found to be pathogenic to third—instar larvae of C. sordidus, causing mortalities of 98–100% by 9 days post—exposure to dry fungal spores. M. anisopliae was the least pathogenic to larvae with LT₅₀ of 4.2 days, compared to 3.5, 3.3, 3.6 and 4.0 respectively for isolates I, II, III and 268–86. B. bassiana was also pathogenic to adult C. sordidus, causing mortalities varying from 63–97% by 35 days post—exposure depending on isolate. As for larvae M. anisopliae exhibited low pathogenicity for the adult C. sordidus. In general, all the fungi tested were less pathogenic to adult weevils (LT₅₀ = 17.5; 12.5; 8.0 and 22.0 days) for isolates I, II, III and 268–86 respectively, while isolate 100–82 failed to kill 50% of adults even by 35 days post—exposure. Incubation of dead weevils in a moist environment led to development of surface mycelia starting from intersegmental junctions. Histopathology revealed extensive destruction of internal organs by hyphae which invaded most of the organs. The LT₅₀ for S. marcescens against C. sordidus larvae was 2.8 days. However, the bacterium did not kill adult C. sordidus even at 10 times the concentration applied on larvae.     

A Proposed Role for the Cuticular Fatty Amides of Liposcelis bostrychophila (Psocoptera: Liposcelidae) in Preventing Adhesion of Entomopathogenic Fungi with Dry-conidia

Maximum challenge exposure of Liposcelis bostrychophila to Beauveria bassiana, Paecilomyces fumosoroseus, Aspergillus parasiticus or Metarhizium anisopliae resulted in no more than 16% mortality. We investigated several of L. bostrychophila's cuticular lipids for possible contributions to its tolerance for entomopathogenic fungi. Saturated C14 and C16 fatty acids did not reduce the germination rates of B. bassiana or M. anisopliae conidia. Saturated C6 to C12 fatty acids that have not been identified in L. bostrychophila cuticular extracts significantly reduced germination, but the reduction was mitigated by the presence of stearamide. Cis-6-hexadecenal did not affect germination rates. Mycelial growth of either fungal species did not occur in the presence of caprylic acid, was reduced by the presence of lauric acid, and was not significantly affected by palmitic acid. Liposcelis bostrychophila is the only insect for which fatty acid amides have been identified as cuticular components. Stearamide, its major fatty amide, did not reduce germination of B. bassiana or M. anisopliae conidia or growth of their mycelia. Adhesion of conidia to stearamide preparations did not differ significantly from adhesion to the cuticle of L. bostrychophila. Pretreatment of a beetle known to be fungus-susceptible, larval Oryzaephilus surinamensis, with stearamide significantly decreased adhesion of B. bassiana or M. anisopliae conidia to their cuticles. This evidence indicates that cuticular fatty amides may contribute to L. bostrychophila's tolerance for entomopathogenic fungi by decreasing hydrophobicity and static charge, thereby reducing conidial adhesion.     

Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera

Abstract:  The western corn rootworm Diabrotica virgifera virgifera Le Conte (Col., Chrysomelidae), a serious pest of maize, has been recently introduced into Europe. Several approaches for its control are presently under investigation including microbial agents. During a field survey in Hungary in 2005, naturally occurring entomopathogenic fungi were found to attack this pest. These novel isolates together with standard isolates were tested for virulence against D. v. virgifera larvae and adults. Twenty strains of Metarhizium anisopliae , Beauveria bassiana and Beauveria brongniartii were used in bioassays in the laboratory. Larvae and adults were dipped into a spore suspension with a concentration of 1 × 10⁷ conidia (con.)/ml. They were kept for 14 days at 22°C (±2°C) and 70% relative humidity. The number of infected larvae and adults were counted and infection rates were calculated. Adults were significantly more susceptible to entomopathogenic fungi than larvae. The most virulent isolate infected about 47% of larvae ( M. anisopliae Ma2277), whereas the infection rate in adults was up to 97% ( M. anisopliae Ma2275). Isolates of M. anisopliae caused significantly higher mortalities than isolates of B. brongniartii and B. bassiana . Most of the adult beetles were killed within 12 days. Isolates from D. v. virgifera were more virulent than those from other hosts.     

Effectiveness of different species of entomopathogenic nematodes for biocontrol of the Mediterranean flatheaded rootborer, Capnodis tenebrionis (Linné) (Coleoptera: Buprestidae) in potted peach tree

The susceptibility of larvae of the Mediterranean flatheaded rootborer (Capnodis tenebrionis) to 13 isolates of entomopathogenic nematodes was examined using GF-677 potted trees (peachxalmond hybrid) as the host plant. The nematode strains tested included nine Steinernema feltiae, one S. affine, one S. carpocapsae and two Heterorhabditis bacteriophora. Nematodes showed the ability to locate and kill larvae of C. tenebrionis just after they enter into the roots of the tree. S. feltiae strains provided an efficacy ranging from 79.68% to 88.24%. H. bacteriophora strains resulted in control of 71.66-76.47%. S. carpocapsae (B14) and S. affine (Gspe3) caused lower control of C. tenebrionis larvae (62.03% and 34.76%, respectively). The influence of foraging strategy and the use of autochthonous nematodes to control C. tenebrionis larvae inside the roots is discussed.     

Effect of temperature and poultry litter in Beauveria bassiana (bals.) Vuill. and Metarhizium anisopliae (Metsch) virulence against the lesser mealworm Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

This study was carried out to evaluate the influence of temperature and poultry litter on germination vegetative growth virulence and conidial production of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) isolates on larvae and adults of the lesser mealworm (Alphitobius diaperinus) (Panzer). The vegetative growth and conidial production were evaluated on culture media. Virulence was studied submerging larvae and adults in a conidial suspension (1 x 10(8) conidia/ml). All the experiments were carried out in growth chamber (26 degrees C and 32 degrees C and 14h photophase). Fungus-killed insects were daily collected and used for microscopic conidial counts. The poultry litter effect was evaluated by submerging the insects in a fungal suspension (10(8) conidia/ml) and then transferring them to cups containing poultry litter (new and used). B. bassiana isolates were more sensitive than M. anisopliae to high temperature because conidia viability, vegetative growth and virulence were negatively affected (P < 0.05). The conidial production was higher to B. bassiana in 26 degrees C (7 to 11 x 10(8) conidia/larval cadaver and 8 x 10(8) conidia/adult cadaver) (P < 0,05). Larval stage was about 10 times more sensitive to M. anisopliae at 26 degrees C than adults stage. Regarding B. bassiana, differences on sensitivity between larval stages and adults were not observed at this temperature. However, at 32 degrees C, larval stage was more sensitive for CB116 and UEL50 isolates. Mortality was higher when larvae and adults (15.7 and 66.7% respectively) were treated by B. bassiana and maintained on new poultry litter at 26 degrees C) (P < 0.05).     

Effects of virulence,sporulation, and temperature on Metarhizium anisopliae and Beauveria bassiana laboratory transmission in Coptotermes formosanus

Sporulation characteristics and virulence of Metarhizium anisopliae and Beauveria bassiana were examined in relation to laboratory transmission in Coptotermes formosanus. Fungal isolates significantly affected disease prevalence in termite populations. Sporulation of M. anisopliae played a more important role than virulence in producing epizootics within small groups of termites, but this was not the case for B. bassiana. Isolates characterized by quick sporulation (day 2 after death) did not exhibit better transmission in termites than those with high total sporulation (day 11 after death) in either fungal species. An isolate of M. anisopliae ranking highly in all three categories (virulence, quick sporulation, and total sporulation) produced better epizootics than an isolate that was inferior in all three characteristics. High temperatures (35 degrees C) significantly reduced fungal germination rates, leading to significant reduction of epizootics. M. anisopliae was better than B. bassiana in producing epizootics at 27 degrees C. Thus, fungal characteristics other than virulence should be considered for the seasonal colonization approach to termite microbial control.     

Interaction of Metarhizium anisopliae (Metsch.) Sorok., Beauveria bassiana (Bals.) Vuill. and the parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae) with larvae of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Chemical insecticides are broadly applied to control diamondback moth, Plutella xylostella (L.). Diamondback moth is a major pest of cruciferous worldwide, and resistance of this pest to insecticide has been often reported. Thus, this research investigated the interactions among the fungi Metarhizium anisopliae (Metsch.) Sorok., Beauveria bassiana (Bals.) Vuill., and the larval-pupal parasitoid Oomyzus sokolowskii (Kurdjumov) before and after application of the fungi on DBM larvae offered to the parasitoid. The experiment was carried out at 26+/-l degreeC, 75+/- 5% RH and 12h photophase using a completely randomized design, with eight treatments with six replications each. The isolates E9 of M. anisopliae and ESALQ 447 of B. bassiana, were used at the concentration of 10(7) conidia ml(-1). The results showed that M. anisopliae and B. bassiana reduced the parasitism of P. xylostella by O. sokolowskii. Additive effects were found on the mortality of P. xylostella with the different combinations among the fungi and parasitoid, except for the treatment B. bassiana inoculated 24h before exposition of the larvae to O. sokolowskii. The isolates were more efficacious when applied after exposition of the larvae to the parasitoid. The efficiency of O. sokolowskii was negatively influenced by the presence of the fungi, mainly when the fungi were applied 24h before diamondback's larvae were exposed to the parasitoid. The association of the fungi with the parasitoid presents potential to be tested in field. The use of these natural enemies in the integrated management of P. xylostella may economically improve the cabbage productive system, especially for organic farming.