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Aphidicidal efficacy of two formulations ofBeauveria bassianastrain GHA conidia, an emulsifiable paraffinic oil dispersion (OD) and a clay-based wettable powder (WP), were compared to unformulated conidia (technical material, TC) in laboratory bioassays with adult melon/cotton aphids. For the initial 24 h post-treatment, aphids were incubated under differing humidity conditions: high (100%) versus 'low' (75 ± 3%) relative humidity (RH), and over the subsequent 6 days, all aphids were incubated under the low RH conditions. Mortality from the OD and TC treatments did not differ significantly under any test conditions, and ANOVA revealed no synergism ofB. bassianaactivity by the OD carrier ingredients. In contrast, formulation as a WP had a small, but significant, negative impact onB. bassianaefficacy. Mean LC50 across formulations was nearly 6.5-fold higher (3457 vs. 539 conidia/mm2) at low vs. high RH. The OD formulation was significantly more effective than the WP, increasing mortality a maximum of 27 percentage points. There were no significant effects of formulation on probit regression slopes. The equivalent slopes and small differences in efficacy of the OD formulation vs. TC preparation support a hypothesis that oils function primarily as spray stickers and spreaders, increasing the efficiency of spray applications. [ABSTRACT FROM PUBLISHER]

Aulacorthum solani ( Kaltenbach ) ( known as foxglove aphid or glasshouse potato aphid ) is a pest of increasing economic importance in several agricultural crops worldwide, including greenhouse vegetables and ornamentals. Developmental rates and age-specific life tables for a North American population of A. solani on pansy (Viola X wittrockiana) (Gams.) were determined at six constant temperatures, and comparisons were made to previous studies of A. solani from differing geographic regions and host crops. On pansy, A. solani developed fastest at 25°C, passing through the four nymphal instars in an average of 6.9 d. The highest intrinsic rates of population increase (0.410 and 0.445) and shortest population doubling times (1.69 and 1.56 d) were recorded at 20 and 25°C, respectively. Average total fecundity remained high from 10 to 20°C (74-68 nymphs/adult); a significant decrease to 39 nymphs/adult occurred at 25°C. For calculating developmental thresholds, we present here a method of adjusting the lower developmental threshold (tmin) using estimates from nonlinear models to provide an improved estimate of the thermal constant (K, in degree-days). We also call attention to the necessity of using a simulation method to estimate the true upper developmental threshold (Tmax) and optimum developmental temperature (Topt) from the Lactin-2 model of temperature-dependent development. [ABSTRACT FROM AUTHOR]

The effects of various spray-application parameters on the efficacy of Beauveria bassiana foliar treatments against Leptinotarsa decemlineata larvae were evaluated during three field seasons. Treatments were applied to small plots (6 rows × 7–12 m) using a CO2-powered backpack hydraulic sprayer with nozzles affixed to lateral drop tubes and directed upward at a 45° angle to target ventral leaf surfaces. The sprayer delivered 280 liters/ha at 3.45 bar. Three rates (1.25, 2.5, and 5 × 1013 conidia/ha) of an emulsifiable oil formulation of B. bassiana and two spray intervals (3–4 vs 6–8 days) were tested. Three applications at the medium and high rates made at 3- to 4-day intervals produced low to moderate levels of control (43–65%). The low rate and applications at weekly intervals were less effective. A wettable powder (WP) formulation was also compared to the oil formulation. Three applications at the medium rate were made at 3- to 4-day intervals. During one field season, rain commenced soon after two of the three initial applications. Under these conditions, the oil formulation was significantly more effective than the WP formulation (65% vs 8% control), suggesting greater rainfastness of the oil formulation. Tests with the oil formulation also compared applications from a sprayer configured with drop tubes as described above to those from a sprayer configured with nozzles directed to spray downward from 30 cm above the canopy. The sprayer with nozzles attached solely on drop tubes deposited an average of 752 conidia/mm2 on the upper surfaces of the leaves and 482 conidia/mm (39%) on the lower surfaces, whereas the alternative sprayer deposited 1062 conidia/mm2 onto the upper surfaces and only 50 conidia/mm2 (<5%) onto the leaf undersides. Applications from below canopy provided greater control of larvae than applications from above canopy when initiated against early instars. Applications initiated against late-instar larvae failed to provide useful control of larvae; however, nearly all treatments applied against late instars, including sprays at weekly intervals and from above canopy, produced significant reductions (53–84%) in populations of first-generation adult beetles. [Copyright &y& Elsevier]

A series of experiments investigated genetically diverse strains of Beauveria bassiana (Bb) isolated from coffee berry borer (CBB). Objectives included assessment of their biocontrol potential, particularly in comparison to Bb commercial strain GHA currently applied for CBB control, and identification of various attributes potentially contributing to their comparatively greater epizootic potential in CBB populations. Bioassays identified one strain from Hawai'i Island and one from Puerto Rico with virulence greater than GHA based on equal weights of unformulated conidial powder (CP); however, the greater potency of the CPs was ultimately explained by their 2.4-fold greater conidial densities (ca. 3.1 vs 1.3 × 10 11 viable conidia/g CP). Density was explained, in large part, by conidial size, but not by size alone. Bb-inoculated CBB held on moist filter paper were more susceptible to infection than those held on cooked green coffee bean (CGCB). A Bb strain representative of the most common Hawaiian haplotype produced 2.6x more conidia after death of CGCB-held beetles than GHA (19.1 vs 7.3 x10 6 conidia/cadaver). Following host death, no difference was observed in time to emergence and initial conidial production by GHA and a selected group of Hawaiian strains; however, mass sporulation was initiated within 2 days by strain GHA compared to 4-5 days by the Hawaiian strains. In a preliminary evaluation of conidial mass-production potential, CP yields of several strains were comparable to GHA on a weight basis and significantly greater than GHA on a conidial basis (1.3-1.6 vs 0.7 × 10 13 viable conidia/kg barley substrate)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The insect pathogenic fungus Hirsutella eleutheratorum was first reported as a pathogen of coffee berry borer (CBB) Hypothenemus hampei in Colombia in 1993. A similar CBB pathogen identified as Hirsutella sp. was reported also from Colombia in 2007; attempts at isolation and in vitro culture of this fungus were unsuccessful. During 2016 and 2017 on the island of Hawai'i, extensive sampling of CBB populations was conducted in coffee fields treated with Beauveria bassiana-based biopesticides and in untreated fields. Among the samples collected from two high-elevation sites in the district of South Kona were rare findings of adult foundress CBB infected with a species of Hirsutella fitting the description of H. eleutheratorum. Prevalence of the pathogen was, in all cases, very low (<1%), having no significant impact on pest populations, even under conditions supporting epizootics of B. bassiana. The fungus was readily isolated from freshly-killed CBB and cultured on potato dextrose agar (PDA). Molecular characterization identified the fungus as a member of the Hirsutella citriformis clade, which includes species recently placed in the genus Ophiocordyceps. Adult CBB exposed to fungus-killed beetles or to PDA cultures of the fungus succumbed to infection within 10-14 days. Under high-humidity laboratory conditions, the fungus emerged from the killed host and produced long, conidia-bearing synnemata characteristic of the species. To our knowledge, this is the first record of H. eleutheratorum from CBB in Hawai'i and the first account of isolation, in vitro culture, genetic characterization, host-to-host transfer, and culture-to-host transfer of this fungal pathogen., (Published by Elsevier Inc.)

Beauveria bassiana (Bb) strain GHA is a major component of an areawide pest management program for coffee berry borer (CBB) in Hawai'i. Recent studies have aimed to provide comprehensive assessments of the efficacy of the Bb-spray component of these programs for economic analyses; however, evaluations have been complicated by activity of naturally-occurring strains of this pathogen infecting CBB. Investigations were therefore undertaken to characterize these strains, assess their natural epizootic potential, and account for their contribution to CBB population suppression. A number of field sites were encountered with no history of significant use of commercial Bb-based biopesticides and where strain GHA was not detectable. Sampling of these sites was conducted early in the coffee season. Greatest activity of wild-type Bb strains was observed on high-elevation farms (>500 m), where 24-42% of foundress beetles in green coffee berries were infected. In contrast, infection rates did not exceed 4% on farms at low elevations (<300 m). Rates of 23-29% infection, comparable to those on high-elevation farms, were recorded in a stand of feral coffee at 293 m elevation, but the coffee was completely shaded and ventilation restricted by a dense overstory of vegetation. Despite high activity of naturally-occurring Bb at some sites (primarily sites at high elevations with humid, moderate-temperature environments and dense pest populations), these fungi did not prevent CBB from exceeding the economic threshold for commercial spray applications. Nevertheless, the high natural epizootic potential of these fungal strains suggests strong potential for development as microbial biocontrol agents., (Published by Elsevier Inc.)

Studies were undertaken to further characterize the previously identified synergistic activity of Bacillus thuringiensis- and Beauveria bassiana-based biopesticides against Colorado potato beetle (CPB). A flowable concentrate of B. thuringiensis morrisoni strain tenebrionis (Bt) (Novodor® FC) and a wettable powder of B. bassiana strain GHA (Bb) (Mycotrol® 22WP) were applied against CPB larval populations infesting potato in field plots. Novodor FC and an oil-dispersion formulation of Bb (Mycotrol ES) were applied against second-instar CPB larvae on potted potato plants in greenhouse tests under low relative humidity (RH), variable-temperature conditions. Each pathogen was applied alone and in combination (tank-mixed) with the other pathogen. In the field tests, each biopesticide was also combined with the spray-carrier (formulation without active ingredient) of the other pathogen. Results from the greenhouse tests showed that under warm, dry conditions, low activity of Mycotrol was counterbalanced by high activity of the Novodor, and under cool, somewhat more humid conditions, low Novodor activity was balanced by high activity of Mycotrol, with the result being a constant level of synergism (CPB mortality ca. 20 percentage points higher than predicted by independent action). Similar levels of synergism were observed under the markedly different conditions of the field and greenhouse environments, and the synergism was confirmed as arising from interaction of the two micobes, as the Bt spray carrier had no significant effect on efficacy of the Mycotrol product and the Bb spray carrier had no effect on the efficacy of Novodor. The great capacity of these two control agents to act in concert to control CPB is well documented (the fast-acting, toxic Bt acting to protect potato crops from defoliation and the slow-acting Bb reducing survival to the adult stage). These finding further underscore the strong complementary action of these agents applied jointly against CPB., (Published by Elsevier Inc.)

Seeking new isolates of entomopathogenic fungi with greater virulence against greenhouse aphid pests than those currently registered in North America for control of these insects, single-dose screening assays of 44 selected fungal isolates and 4 commercially available strains were conducted against first-instar nymphs of Myzus persicae and Aphis gossypii. The assays identified a number of Beauveria and Metarhizium isolates with virulence equal to or greater than that of the commercial strains against the nymphal aphids, but none exhibited exceptionally high virulence. Virulence of Isaria isolates was unexpectedly low (<31% mortality at doses>1000conidia/mm(2)). In dose-response assays, Beauveria ARSEF 5493 proved most virulent against M. persicae and A. gossypii; however, LC50s of this isolate did not differ significantly from those of B. bassiana commercial strain JW-1. Dose-response assays were also conducted with Aulacorthum solani, the first reported evaluations of Beauveria and Metarhizium against this pest. The novel isolate Metarhizium 5471 showed virulence⩾that of Beauveria 5493 in terms of LC25 and LC50, but 5493 produced a steeper dose response (slope). Additional tests showed that adult aphids are more susceptible than nymphs to fungal infection but confirmed that infection has a limited pre-mortem effect on aphid reproduction. Effects of assay techniques and the potential of fungal pathogens as aphid-control agents are discussed., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Forty-three isolates of the entomopathogenic fungus Beauveria bassiana were screened for virulence against second-instar larvae of diamondback moth (Plutella xylostella) (DBM), European corn borer (Ostrinia nubilalis) (ECB), corn earworm (Helicoverpa zea) (CEW), and fall armyworm (Spodoptera frugiperda) (FAW); 30 of these isolates were tested against beet armyworm (Spodoptera exigua) (BAW). Highly virulent isolates were also tested against black cutworm (Agrotis ipsilon) (BCW), and the most virulent isolate was also assayed against imported cabbage worm (Pieris rapae) (ICW) and cabbage looper (Trichoplusia ni) (CL). All lepidopteran species tested were susceptible to B. bassiana. Corn earworm and beet armyworm were most susceptible to fungal infection, and fall armyworm was least susceptible. Limited testing suggested low susceptibility of black cutworm and cabbage looper. B. bassiana isolate 1200 exhibited virulence against all pest species greater than or equal to commercial strain GHA of B. bassiana currently registered in the USA as BotaniGard. In assays in which larvae were topically sprayed and maintained on the treated substrate for 24h at 100% relative humidity, 6-day (25 degrees C) median lethal concentrations (LC(50)s) of this isolate against CEW, BAW, DBM, FAW, ICW, ECB, CL, and BCW were 4, 5, 7, 11, 12, 98, 125, and 273 conidia/mm(2), respectively. The respective LC(50)s of commercial strain GHA against these pest species were 9, 67, 97, 1213, 29, 1668, 541, and 3504 conidia/mm(2). Use of LC(50) versus median lethal concentration ratios (comparing LC(50)s of each isolate to a "standard" strain) generated similar rankings of isolate virulence. Results from parametric ANOVAs of log LC(50) values followed by Tukey HSD multiple comparisons tests and those from Kruskal-Wallis nonparametric analyses followed by sequential Bonferroni tests for means comparisons were nearly identical., (Published by Elsevier Inc.)

Commercial biopesticides based on the fungal pathogen Beauveria bassiana strain GHA and the bacterial pathogen Bacillus thuringiensis tenebrionis were applied alone and in combination (tank mixed) against larval populations of the Colorado potato beetle, Leptinotarsa decemlineata, in small plots of potatoes over three field seasons. Interactions between the two products were evaluated in terms of pest-control efficacy. B. bassiana (formulated as Mycotrol) was applied at low and medium label rates of 1.25 and 2.5 x 10(13) conidia/ha, and B. thuringienis (formulated as Novodor) was applied at low and high label rates of 40.3 and 120.8 x 10(6) Leptinotarsa units/ha. Two weekly applications of the bacterial pesticide alone provided 50-85% control of beetle larvae within 14 days after the initial application, while applications of the mycopesticide alone produced no greater than 25% control. Maximum control, in nearly all tests, was produced by the combination of the two products. The combined treatments produced a statistically significant 6-35% greater reduction in larval populations than would have been predicted had the two biopesticides acted independently. This low-level synergistic interaction was observed during all field seasons and resulted from combinations at all rates, including, in one of two tests, the low rates of each product. These results indicate that B. thuringiensis and B. bassiana have strong potential for integrated biologically based management of Colorado potato beetle.

Field studies on the efficacy and persistence of an introduced strain of Beauveria bassiana for insect control require detection assays to differentiate the non-native strain from indigenous populations. In this study we developed strain-specific molecular markers based on polymerase chain reaction amplification of sequence-characterized amplified regions (SCAR) in combination with dilution plating on semi-selective medium to detect and estimate density of propagules of a commercial strain of B. bassiana (strain GHA) in field samples. Using random amplified polymorphic DNA (RAPD) analysis, unique fragments that distinguished GHA from other strains of B. bassiana were obtained. Three amplicons, OPA-14(0.44), OPA-15(0.44), and OPB-9(0.67), generated with RAPD primers were cloned and sequenced and used as bases for designing SCAR primers OPA14 F/R(445), OPA15 F/R(441), and OPB9 F/R(677), respectively. All three SCAR primers were highly sensitive, capable of detecting 100pg B. bassiana GHA genomic DNA, and thus could be used to detect varying levels of the fungus in the field.

Pathogenicities of three species of entomopathogenic fungi against preimaginal Bemisia argentifolii were measured and compared. Third-instar nymphs on excised leaves of Hibiscus rosa-sinensis were exposed to spray applications of 14 isolates of Beauveria bassiana, 22 isolates of Paecilomyces fumosoroseus, and five isolates of Paecilomyces farinosus. B. bassiana and P. fumosoroseus isolates of diverse origins were highly pathogenic to the whitefly nymphs; median lethal doses of 14 of the 22 P. fumosoroseus and four of the 13 B. bassiana isolates ranged between 50 and 150 conidia/mm2. Five isolates of P. farinosus were also pathogenic; however, LC50s were relatively high, ranging between 350 and 4000 conidia/mm2. Nymphs infected with all but one isolate of B. bassiana displayed a pronounced red pigmentation. Postmortem hyphal growth and sporulation of B. bassiana was relatively slow and usually confined to the region immediately surrounding the dead host. Whitefly nymphs patently infected with P. fumosoroseus and P. farinosus were lightly pigmented yellow or orange. Postmortem hyphal growth and sporulation of P. fumosoroseus rapidly covered the dead host and extended several millimeters onto the surrounding leaf surface. The results indicate that highly virulent strains of P. fumosoroseus and B. bassiana with considerable whitefly control potential are widespread and numerous., (Copyright 1998 Academic Press.)