The Mormon cricket (MC),Anabrus simplex (Orthoptera:Tettigoniidae),has a long and negative history with agriculture in the western states of the USA where MC often migrates in large groups and causes significant damage to forage plants and cultivated crops.In this review, virulence to MC of isolates of the insect-pathogenic fungus Metarhizium anisopliae varieties acridum and anisopliae were compared in an effort to identify isolates with promise for use as MC biological control agents.All of the isolates tested induced 100% or nearly 100% mortality by six days post application of the fungal conidia.Searches for new Metarhizium isolates with high heat and UV-B tolerance included isolation fungi from field-caught MC and grasshopper after they died in the laboratory and culturing fungi from soil samples collected from numerous western USA sites.The survey was preceded by development of a dodine based selective medium that,at 0.002% active ingredient,permitted growth of M.anisopliae var.acridum,but inhibited most contaminating fungi.The M.anisopliae var.acridum isolates examined to date have much higher tolerance to heat and UV-B irradiation than M.anisopliae var.anisopliae isolates,and this may be critical to successful field applications.The variety acridum has not yet been found in the USA,so our search for such isolates continues.Several new M.anisopliae var.anisopliae and Beauveria spp.were found,and the Metarhizium isolates are being characterized as to stress tolerance and virulence to insects.Characterization includes comparisons of new and pre-existing Metarhizium isolates by amplified fragment-length polymorphism (AFLP) analysis.Finally, experiments on MC developmental biology were conducted to gather data needed to develop a degree day model and to establish laboratory colonies of MC.
An invasive long-horned beetle,Anoplophora glabripennis,was first reported in the northeastern and midwestern United States and eastern Canada between 1996 and 2004 and has been given the common name Asian longhorned beetle(ALB).This beetle has also been found in several countries in Europe.ALB is difficult to control because larvae are found within the wood of living trees and the long-lived adults often occur high in tree canopies.This species is native to China and Korea and,because it has been a major tree killer in China,government agencies in the U.S.and Canada are working to eradicate ALB from North America.Our laboratory has been developing a microbial control approach targeting ALB adults,based on the Japanese product Biolisa Kamikiri which is used to control cerambycids in orchards.Entomopathogenic fungi are grown within non-woven fiber bands(= fungal bands)and placed around tree trunks and branches where ALB adults become inoculated when walking across bands.We have conducted bioassays with Beauveria brongniartii,Beauveria bassiana and Metarhizium anisopliae against ALB larvae and adults to identify effective isolates and now focus our efforts on M.anisopliae F52(ARSEF 7711).Caged field trials conducted in China to compare fungal sprays with fungal bands(2000,2001)demonstrated decreased ALB longevity and fitness for both application methods but longer activity of fungi in cages treated with fungal bands compared with sprays.Uncaged field trials(2001,2002)yielded faster ALB adult mortality in fungal-treated plots and decreased fitness.Studies in New York City testing the longevity of activity of fungal bands in the field have documented that bands retain>1×107 conidia·cm-2(the threshold for activity of Biolisa Kamikiri)for over 3 months.In contrast,studies with unformulated conidia sprayed onto tree trunks in New York documented conidial survival of only a few days.Sublethal effects of exposure of adult female ALB to fungal bands have been investigated further in the laboratory.After either newly eclosed or reproductively active females are exposed to fungal bands,few viable larvae are produced before death of the females.When females are exposed to fungal bands and then caged with males,males become infected.
There are several biopesticides based on entomopathogenic fungi available in the market for use against insect pests in greenhouse ecosystems.Although most are compatible for use with predators and parasitoids in greenhouse ecosystems,much more research is needed to determine the intraguild interactions for each combination of host,pathogen,predator,and parasitoid.Our research has demonstrated that,although direct effects on the predators could be demonstrated in laboratory bioassays,different results were found under greenhouse conditions,indicating that results obtained in the laboratory may be a poor predictor of what occurs in the greenhouse.In both cases,additive effects were obtained under greenhouse conditions,demonstrating compatibility.In addition,there is increasing evidence that entomopathogenic fungi have significant potential for dual management of invertebrate pests and plant pathogens.Our studies demonstrated that 3 species of Lecanicillium had significant effects on both aphids and cucumber powdery mildew,Sphaerotheca fuliginea;that the fungus Paecilomyces fumosoroseus was compatible with a mirid predator,Disyphus hesperus,when used concurrently against greenhouse whitefly,Trialeurodes vaporariorum;and that Lecaniciullium longisporum was compatible with a predatory midge,Aphidoletes aphidimyza when used concurrently against green peach aphids.
We report six different field trials testing the efficacy of Metarhizium anisopliae,an entomopathogenic fungus,against varroa mites in honey bee hives.Varroa mites are parasitic on honey bees and cause serious damage to Apis mellifera colonies.Several control methods are available for varroa mites,none are very effective,so new,more effective methods are being sought.Varroa has previously been shown to be highly susceptible to M.anisopliae infections,and in our first two field trials,we found some efficacy from spore applications.However,in subsequent field trials,we were not able to obtain any varroa control,despite attempting several different application methods,two different strains of the fungus,and testing in different climates and during different phenological states of the honey bee colony.We conclude that microbial control of varroa using fungi is not likely to be effective unless some way is found to prolong the survival of the spores(or other infective units)in the hive environment.
Only two fungus species,Beauveria bassiana and Metarhizium anisopliae,have been given serious attention as possible microbial controls for stored-product pests.Their host ranges are broad,but their potency for the various target insects varies greatly,and some of the most important pests such as the red flour beetle are very tolerant of fungi.Accordingly,strategies are needed to improve the fungal performance.One such strategy is combination with other environmentally benign treatments such as controlled desiccant dusts and controlled atmospheres.Ironically the relatively dryness of stored-product environments favors fungal efficacy.Desiccation stress renders some insects more vulnerable to fungi.The longevity of fungus spores is also best under dry conditions.The prospects of fungi for control of stored-product pests can be improved by taking advantage of these phenomena and judicious selection of use venues and application strategies.
This paper reviews the potential for using insect pathogens to control the Colorado potato beetle,Leptinotarsa decemlineata,and summarizes results from nearly 10 years of research by USDA-ARS-PPRU scientists aimed at developing methods and strategies for integrated use of Bacillus thuringiensis and Beauveria bassiana for biologically-based management of potato beetles in the northeastern USA.The described studies have resulted in 1)design of a tractor-mounted hydraulic spray system that improved targeting and consequent efficacy of microbial control agents,2)discovery of synergism between the bacterial pathogen Bacillus thuringiensis(Bt)and the fungal pathogen Beauveria bassiana(Bb),3)findings that substantial mortality of beetle larvae treated with B.bassiana during foliar spray programs did not occur until after they entered the soil to pupate,and 4)observations that spray applications made in the evening(at sunset)were significantly,but not substantially,more effective than applications made during the morning hours.These findings have led to development of a bio-based pest management system based on three spray applications made in the following order at 3-5-day intervals:Bt alone,Bt and Bb mixed,and Bb alone.This spray program,with the applications initiated at 50% egg hatch,is intended to control the actively feeding larval stages(providing protection from defoliation)and reduce survivorship to the adult stage(providing long-term control by reducing populations of overwintering adults).In the initial test of the integrated management system,beetle control and potato yields were statistically equivalent to those in plots in which the beetles were controlled with chemical insecticides.Demonstration of the effectiveness of this program will continue over the next 2-3 field seasons.
In Denmark,the weevils Strophosoma melanogrammum and S.capitatum cause economic damage in Noble fir due to the adult stage feeding on the needles.No chemical treatments of these weevils are allowed in Denmark,so biological control is an attractive solution.We evaluated the potential for microbial control of larvae of Strophosoma spp.based on laboratory bioassays and field applications,taking effect on both target and non-target into consideration,as well as persistence of the applied fungus.In the laboratory Beauveria bassiana,Paecilomyces farinosus and Metarhizium anisopliae were able to infect and cause mycosis in Strophosoma larvae.Among the tested isolates the most virulent isolate was M.anisopliae BIPESCO 5,which resulted in 80 % mortality.In the field experiment M.anisopliae,isolate BIPESCO 5,was applied to the soil as a conidial suspension against larvae of Strophosoma spp.The effect of the fungus on the target population was monitored at a weekly basis by counts of emerging adult weevils during their activity periods.The population of Strophosoma spp.was reduced by up to 60% in treated plots compared to control plots.The non-target effects of M.anisopliae were studied by sampling insects and ticks from both treated and control plots.Seven days after treatment,two sampled insect orders(Hemiptera and Coleoptera)and ticks were found with prevalences of M.anisopliae above 50%,compared to no infection in the insects collected from control plots.Infections in coccinellids were found as long as 277 days after treatment.However,the effect on population level of non-target is still unexplored.The persistence of the fungus was documented by plating a soil suspension onto agar.We documented that conidia of M.anisopliae could persist in the greenery plantation for at least 418 days after application.
The conidial tolerance of Metarhizium anisopliae var.anisopliae isolate ARSEF 2575 to UV-B irradiation is greatly influenced by growth-environment alterations.In this review,we report high variability in conidial UV-B tolerance in response to altered culture conditions.Conidia produced on insect cadavers[Zophobas morio(Coleoptera)or Galleria mellonella(Lepidoptera)] had low tolerance to UV-B radiation;and conidia produced on potato dextrose agar supplemented with yeast extract(PDAY)had medium UV-B tolerance;whereas conidia produced on a minimal medium without any carbon source(MM),on MM with a non-preferred carbon source such as lactose(=MML),on PDAY plus 1 M NaCl or KCl,or PDBY with high alkalinity had the highest UV-B tolerances.All of the above conditions that induced high UV-B tolerance,however,also greatly reduced conidial production.Comparisons between stress tolerance and conidial production,particularly with conidia produced under osmotic and nutritive stress,point out that the benefits of producing very tolerant conidia have the enormous cost of low conidial production.Growth under visible light also greatly improved conidial UV-B tolerance,but light did not negatively influence conidial production.Therefore,culture on rich media under light is proposed as the most promising approach to producing conidia with improved UV-B tolerance for biological control of pest insects in agriculture.
In China,there is a long history over 2300 years of entomogenous fungi used as medicines,but their use against insect pests did not start until mid 1950's.In 1970,the central government held a workshop to encourage the use of Beauveria bassiana against pine caterpillars,making the year a milestone in Chinese history of microbial pest control.Since then,quite a few fungi have been tried for control of over 60 forest and crop pests.In the past decades,low tech production has been being improved towards commercial production with higher techniques.Until 2006,5 products of fungal insecticides have been registered.Meanwhile,large scale application techniques have been being improved with molecular ecological approach towards a rational application strategy.
以山西朔州小黑杨(Populus×xiaohei T.S.Hvang et Liang)人工林为试验材料,研究了3种栽植密度(1000、500、250株·hm-2)对小黑杨树木生长、木材生长量和主要物理力学性质的影响.结果表明,栽植密度对树木冠幅、冠长、胸径、湿心材面积、边材面积和木材基本密度、顺纹抗压强度和MOE的影响达到极显著水平;对湿心材比例、边材比例和MOR的影响达到显著水平;对基本密度的径向变异有一定程度的影响,但不改变其变异的一般趋势,即从髓心向外,先下降后呈上升的变化趋势.
ICE(白细胞介素-1β转换酶)是caspase家族 (半胱氨酸天门冬氨酸蛋白酶cys-teinylaspartate specific proteinase)中最早发现的成员,在多细胞生物细胞凋亡的过程中起着重要作用.为了深入了解模式昆虫家蚕ICE在凋亡通路中的作用,采用紫外线刺激家蚕细胞,PCR克隆获得2个新的ice基因不同剪切体,分别命名为ice-2和ice-5(GenBank登录号:DQ360829和DQ360830),并将这2个剪切体分别克隆进原核表达载体pET28a中,在大肠杆菌中诱导表达,对表达产物进行了检测,结果显示ICE-2和ICE-5蛋白表达过程中能发生自我剪切.