The Mormon crickets were then individually housed in cylindrical, metal hardware cloth cages on treated grass.
Both fungi demonstrated only marginal success in reducing immature Mormon cricket survival in the field cages. Potential daily body temperatures were determined for the entire post-treatment observation period using special thermal surrogates. Thermal surrogates were used to develop models for predicting onset of mortality from infections. The surrogate data indicated mortality should begin between 8 and 26 days after treatment with M. The timing of mortality in field cages was consistent with the upper boundaries of the temporal models developed from the thermal surrogates, i.
Keywords: Beauveria bassiana; Metarhizium brunneum; Anabrus simplex; Mormon cricket; fungal pathogens 1. Introduction The Mormon cricket Anabrus simplex Haldeman , a flightless shieldbacked katydid Orthoptera: Tettigoniidae related to grasshoppers, has been a pest since the original agricultural development of the western USA Wakeland and Parker Email: Nelson.
Foster aphis. Foster et al. Mormon cricket have amounted to millions of dollars. Even though Paranosema locustae and Beauveria bassiana are registered for use against grasshoppers on US rangeland, neither is in current use in operational programs.
There are no generally accepted entomopathogen treatments available for use against grasshoppers and Mormon Downloaded by [Montana State University Bozeman] at 08 March crickets in the USA. In areas of grasshopper or Mormon cricket infestations this situation at best complicates but more often prevents much needed local or area-wide treatments. Non-chemical options are highly desirable in the diverse Mormon cricket habitat in the western USA. The entomopathogenic, hypocrealean ascomycete fungi, Beauveria bassiana Balsamo Vuillemin and Metarhizium anisopliae Metschnikoff Sorokin sensu lato, have been studied for many years as biocontrol agents of a wide range of insects.
The history of their development and safety record has been recently summarized Zimmermann a, b. The Orthoptera have been considered targets for use of these fungi for a number of years Lomer, Bateman, Johnson, Langewald, and Thomas The orthopteran-specific M.
In the early s, extensive work on the development of the fungus B. Another entomopathogenic fungus, M. In laboratory bioassays with immature Mormon crickets, Foster, Jaronski, Reuter, Black, and Schlothauer observed that the F52 strain was highly infectious and virulent, more so than B. Beauveria bassiana has generally been ineffective against unconfined field populations of grasshoppers Inglis, Johnson, and Goettel ; Foster et al. The most popular current belief concerning ineffective results of B.
This behavior results in an elevated body temperature that is non-conducive to fungal growth for much of each day. Additionally, fungal growth can slow greatly after sundown because body temperatures, as tracked in past field studies, may drop below the optima for the fungi. The combination of both occurrences yield only a few hours each day during which grasshopper body temperatures can be conducive, much less optimal, for fungal growth.
As a result, the mycosis takes so long to advance to a fatal degree that detection of population reductions attributable to the fungus, compared to a natural population decline, is difficult at best. Lower daytime environmental temperatures, such as occur under cloudy weather or in the spring, may promote mortality due to fungal infection. Turnbow , which are higher than those permissive for vegetative growth of both fungi Fargues, Goettel, Smits, Ouedraogo, and Rougier ; Ouedraogo, Fargues, Goettel, and Lomer Previous work Foster et al.
In their study, post-treatment field observations were conducted for only 14 days. The surrogate body temperature observations, however, indicated that a considerably longer period of time could be required before mortality would result from M. Our objectives in the present study were to 1 further evaluate and compare B.
Materials and methods 2. Production and formulation of fungi Conidia of B. Conidia of M. Salem, VA. As such, both represented fourth passage from an insect, thus minimizing potential loss of virulence. For the present tests, conidia of M. Cultures were observed daily and crumbled by Downloaded by [Montana State University Bozeman] at 08 March hand within spawn bags as needed to prevent binding of the substrate and provide aeration throughout the culture substrate.
Conidia were harvested by mechanical sieving through 20 and ASTM mesh sieves 0. Conidial fractions B mesh were retained for use. The M. A minimum of conidia were examined for germination; a conidium was considered viable germinated if it had produced a visible germination peg during the specified incubation time. Viability of the B. There were four treatments: B. Conidial concentrations were verified by diluting a sample of each formulation with kerosene and counting the conidia in a hemocytometer.
The fungal formulations were applied at an intended rate equivalent to 9. An oil-only carrier control and an untreated control were included in the study. Each treatment consisted of 60 cages 1 Mormon cricket per cage, selected randomly from a large pool of insects. The cages were arranged in six replicate blocks of 10 cages for each treatment. Therefore, the study utilized a total of cages. The study area was located on the outskirts of Sidney MT N 43?
Application of treatments Treatments were applied to small areas of improved rangeland delimited with metal wire rings, each encompassing 0. Rings were separated from adjacent rings by 2 m. Dillion Harper Steven St. Naomi Woods Dillion Harper. Girls Way. Dillion Harper Charlotte Stokely. Zoey Monroe Dillion Harper. Lana Rhoades Dillion Harper. Dillion Harper Romi Rain. Alexis Fawx Dillion Harper. Mona Wales Dillion Harper. Dillion Harper Elle Alexandra. Dillion Harper Tyler Nixon.
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