Research Project Index


Biological Control of Invasive Plants

1.

Hoary Cress Research

2.

Leafy Spurge Reserach

3.

Multitrophic Interaction in Biological Control

4.

Saltcedar Research Projects
 

Crop Insect Pest Management

1.

Sugar Beet Root Maggot Research

2.

Wheat Stem Sawfly's Impact on the Northern Great Plains
 

Grasshopper and Mormon Cricket Ecology and Management

1.

Controlling Grasshoppers With Fungal Entomopathogens

2.

Grasshopper Ecology and Preventative Management

3.

Tracking Mormon Crickets

 

 

 

 

Contributing Scientists: Gerald Anderson (Ecologist)

 

 

Hoary Cress Research


Research Findings, Reports, and Publications for this Project


Hoary cress (Lepidium draba) is a perennial herbaceous weed that has invaded agricultural and natural areas of western North America. Invasions are often composed of dense patches, and it is unclear whether clonal growth via horizontal roots or seedling recruitment is the dominant method of patch expansion. To study the clonal structure of this invasive, we will analyze patches from U.S. populations using AFLPs (a DNA fingerprinting method). Known siblings and clones will also be included to insure sufficient variation for discrimination between clonal and non-clonal plant parts. Knowledge of its primary reproductive mode under field conditions will give us a better understanding of how the species became a successful invader, which may help determine management decisions. 

 

Contributing Scientist:  John Gaskin (Botanist)



Visit our Hoary Cress Consortium website for more information and numerous sources relating to the noxious weed.
The Hoary Cress Consortium was formed in 2001 and includes representatives and researchers from more than a dozen research facilities worldwide.


 

Latest Research Findings/Reports


Evolutionary biology as a tool towards a more customized biological control strategy of weeds: Hoary cress as a case study
 

By: Boris Fumanal, Jean-François Martin, Rouhollah Sobhian, John Gaskin (NPARL Botanist) and Marie-Claude Bon

Download this Poster (PDF: 252KB)

 

The collar gall weevil Ceutorhynchus assimilis is widely distributed in Eurasia where it colonizes the indigenous weed Cardaria draba and other Brassicaceae, including crops. Within the framework of a biological control program of C. draba, which is considered an invasive weed in North America, Ceutorhynchus assimilis has been targeted as a potential biological control agent.



 

 

Leafy Spurge Research


Two flea beetles, Aphthona nigriscutis and A. lacertosa, are generally thought to be the most successful biological control agents for leafy spurge. Adult populations of these 2 species have markedly different sex-ratios; most populations of A. nigriscutis are 90% or more females whereas A. lacertosa populations average about 50% female. Further,  A. nigriscutis is infected by Wolbachia, an intracellular parasitic bacterium, whereas A. lacertosa is not. Wolbachia is well-known to alter the reproductive biology of its arthropod hosts and is found in many insects. Wolbachia may be responsible for the female-biased sex ratios in A. nigriscutis through mechanisms that could either increase or decrease the population growth rates of the beetles. Ongoing studies are seeking to determine the mechanism by which Wolbachia may be causing the biased sex ratios in A. nigriscutis using antibiotic and heat treatments, real-time PCR and other experimental approaches.

 

Contributing Scientist:  David Kazmer (Entomologist)



 


Visit our TEAM Leafy Spurge website for hundreds of articles and other sources of information on leafy spurge and its management.


TEAM Leafy Spurge was a 6-year research and demonstration program that was highly effective at developing and demonstrating ecologically based integrated pest management (IPM) strategies that landowners and land managers could use to achieve effective, affordable and sustainable leafy spurge control. The system incorporated biological control agents with other more traditional management tools that lead to not only a dramatic reduction in leafy spurge infestations, but also to significant reductions in herbicide use.

 

 

 

Multitrophic Interactions in Biological Control


Latest Research Findings, Reports, and Publications for this Project

 

Effects on plant community composition through interactions among herbivores, microbes and plants are an increasing area of interest in research in plant community ecology. This is a major theme of research for NPARL Research Plant Pathologist, Anthony Caesar, since discovering that insect/plant pathogen synergisms are fundamental to effective biological control of herbaceous, perennial invasive plants. In research, at every stand of Euphorbia esula/virgata (leafy spurge) surveyed, foreign and domestic, that was subject to root-attacking insects, a set of soil borne plant pathogens was isolated from the damaged root tissue of the plants.

 

The same situation has been found with regard to Centaurea spp. and more recently insect/plant pathogen interactions have been found occurring with Carderia (=Lepidium) spp., which exhibit root galls, typically caused by Ceutorhynchus spp. This has confirmed the central importance of fungal or bacterial synergists in successful biocontrol. Harnessing fungi found to be partners in synergistic interactions would enable their application at the time of release or after insects have become established to enable the effective synergism.

 

There is ample evidence that information gained from the study of these interactions can form the interface between biological control and restoration, which should be considered as part of biological control. Investigations of how plant communities affect microbial communities has been supplemented with studies on how, in turn, microbial communities can affect the composition of plant communities.

 

Parallel Studies
 

Parallel studies are the investigation of the comparative ecology of an invasive species in its native and invaded range. For my program this means study of microbial factors associated with the effects of insects or how specific plant pathogens (such as rusts or smut fungi) impact the target in its native range. The elucidation of key biotic factors associated with the sparse density and scattered distribution of an invasive species in its native range is a major goal. In contrast, invasives achieve high density and rapid spread in the invaded range, and significant disease is rare in the invaded setting. Dr. Caesar found that soil borne plant pathogens are keystone factors limiting the vigor and distribution of invasive plant species in their native ranges. 

 

Because most highly invasive species in rangelands are herbaceous, deep-rooted perennials, a prolonged and sustained attack is necessary to cause mortality and thereby reduce stand density of the target species. Such a sustained and prolonged attack in the form of insect/microbial synergisms is constantly evident in the native range of the invasive species causing the sparse and restricted populations of the invasives there. Synergisms effective in the native range can provide microbial agents that can be used in prerelease testing of candidate agents for capacity to synergize. The particular value of a candidate agent should be assessed by the effectiveness of the synergisms it may engage in upon release. Additionally, candidate rusts and smuts can be assessed for their overall effects in the native range to provide clues on their likely impact once introduced for biological control.

 

Soil microbial community structure associated with biocontrol can be compared to that of both weed-invaded and uninvaded soil to assess the nature of the feedback and patterns of plant community succession. Of central interest is whether microbial community structure might also predict the success of attempts to reestablish native species. Further, comparing microbial community structure in the native range with that of the above three states can provide insight into whether the status of the soil negative feedback might predict when insects should be released for successful insect plant pathogen synergism, and thus impact, to occur.

 

Retrospective Studies
 

Retrospective studies are the review of past successes often for broad trends such as which insect taxonomic groups have been successful in biological control of weeds. For my research retrospective studies consist of the review of successful programs for clues on whether and how plant pathogens may have contributed to successful weed biocontrol.

 

Past biocontrol studies contain valuable clues, which when examined in a new light and placed in proper context with more recent findings, can be used to improve biological control. New avenues of research to improve the screening of candidate agents for the capacity to synergize with plant pathogens are a major prospective benefit of retrospective studies. Studies early in the history of biological weed control have already provided data and principles leading to the conclusion that insect/pathogens synergisms caused control of some major target weed species such as prickly pear and St John’ s wort. As described above, this correlates with recent findings that confirm the importance of synergisms in successful biocontrol of leafy spurge

 

Practical Outcomes

Practical outcomes would be the utilization of important soilborne plant pathogens occurring on diseased stands in the native and invaded ranges or found associated with insect damage (usually foreign) for invoking synergisms and for inclusion as part of prerelease testing of candidate agents for the capacity to synergize with the pathogens. Testing agents for synergistic ability can ultimately reduce the costs of screening, host range testing, release, redistribution and monitoring of new agents in biocontrol programs by restricting released agents to those with clear evidence of impact in prerelease studies. Increasing overall impact as early as possible through insect/pathogen synergistic action can additionally reduce the hazard of nontarget effects. An ultimate goal of biocontrol should be the restoration of a healthy, productive and sustainable plant community and the themes discussed above seek to find means to achieve that goal. 

 

Contributing Scientist:  Anthony Caesar (Plant Pathologist)

 

Latest Research Findings/Reports


Soilborne fungi associated with root galls of Lepidium draba caused by Ceutorhynchus spp.
 

By: Anthony J. Caesar (Plant Pathologist)

Download this Poster (PDF: 340KB)

Isolation of fungi from insect-damaged roots of Lepidium draba in Switzerland, Hungary and Austria revealed that this species was often infected with one or more soilborne fungi. Plants with evident stunting and/or chlorosis and reddening of leaves nearly always exhibited root damage by one or more insects.

Nearest Neighbor Analysis of the Effects of the Rust Fungus Uromyces scutellatus on Euphorbia spp. in Europe
 

By: Anthony J. Caesar (Plant Pathologist)

Download this Poster (PDF: 921KB)

Biological control of exotic invasive plants is based on the Enemy Release Hypothesis. In practice, this entails searches within the native range of the invasive for insects or plant pathogens that can damage or cause disease on the “target” plant species.

 

 

 

Saltcedar Research Programs


 

A recent comprehensive study of saltcedar distribution in northern Montana suggested that in certain cases, garden plants may have played a role in starting local invasions, because garden plants were found to be older than the invasions, and no other seed sources were nearby. A specific example cited was the Musselshell River, infested with an estimated 24,500 saltcedars ranging from seedlings to approximately 25 years old. Dispersal mechanisms other than localized spread of seed from ornamentals were also suggested for other areas in the study, including long distance seed movement by wind, water, earth-moving equipment, and towed boats. Earlier research, which included a very limited number of garden saltcedars from other areas in the western U.S., indicated that the garden and invasive saltcedar plants were most often different chloroplast genotypes, though the garden genotype did show up rarely within an invasion. We will use chloroplast and nuclear DNA sequence markers to compare genetic identity of garden and invasive saltcedars of the Northern Plains, and thus determine the influence that garden plants have on starting or contributing to nearby invasions.

 

Contributing Scientist:  John Gaskin (Botanist)

 

An experimental release program is ongoing for Diorhabda elongata, a leaf beetle that is the first deliberately-introduced biological control agent for saltcedar (Tamarix spp. and their hybrids). The primary goals of the program are to determine rates of establishment, population growth and dispersal of the beetles as well as the impact of the beetles on saltcedar and nontarget plants. NPARL is responsible for 3 experimental release sites in Montana and Wyoming while state, university and federal cooperators have responsibility for other sites throughout the western U.S. Results to date range from complete failure to spectacular and perhaps unprecedented rates of beetle population growth and dispersal. For example, at one site in Montana, over 215,000 adult beetles have been released but this has not resulted in detectable beetle populations in subsequent generations. In contrast, at the Wyoming site, the beetles, numbering over 1,000 per plant in some cases, completely defoliated over 200 acres of saltcedar in just the second growing season after they were first released. The full impacts of defoliation by the beetles on saltcedar are not yet known as this woody shrub is extremely resilient. Ongoing studies will determine the impacts of beetle defoliation on saltcedar fitness components, how this varies with environmental factors such as precipitation and winter temperatures, and how beetle defoliation changes saltcedar recruitment rates.

 

A variety of hypotheses have been developed to account for the extremely variable results obtained thus far with D. elongata. Ongoing studies at NPARL include common garden experiments to determine how different saltcedar genotypes affect beetle fitness components, predator exclusion and inclusion experiments to determine how predation affects beetle establishment and population growth rates, DNA studies of the D. elongata complex to better understand species and subspecies boundaries, and field plot studies to determine how water stress in saltcedar affects beetle oviposition and feeding preferences, larval growth rates, and plant response to defoliation.

 

Contributing Scientist:  David Kazmer (Entomologist)

 

 

Sugar Beet Root Maggot Research


Sugarbeet root maggot (Tetanops myopaeformis) is the most significant pest of sugar beets, primarily in Minnesota, North Dakota, and Idaho, and secondarily in Nebraska, Colorado, Montana, and Wyoming. The insect affects 49% of a total of approx. 567,000 sugarbeet hectares in the U.S. Without control tools, yield losses in the Red River Valley would commonly reach 40%. The organophosphates terbufos, phorate, and chlorpyrifos, and the carbamate aldicarb are the mainstay control tools. In 1998 and 1999 an average of 390,000 sugarbeet hectares (65% of all acreage) were treated with chemical insecticides, mostly terbufos. Cultural controls and host plant resistance are in early stages of development. Biological control has been pursued by USDA since the early 1990s, but without success for any stand-alone organisms. Thus, there is a critical need for a biologically based, IPM system that will reduce farmer's reliance with restricted use of pesticides.

 

We are focusing on the development of a fungus, Metarhizium anisopliae, into a commercially feasible mycoinsecticide to manage the sugarbeet root maggot, as well as wireworms and the sugarbeet root aphid -- important secondary pests of this crop. Metarhizium has been known for over 100 years as an insect pathogen and has been commercialized in a number of countries for use against a variety of insects. Spores of this fungus, similar to spores of a bread mold, will germinate when they land (or are placed by human application) on the surface of an insect. Using a cocktail of enzymes and mechanical pressure the fungi penetrates through the cuticle of an insect within 24 hours and start to grow through the body. There is not much defense that an insect can offer. Infection is almost always fatal. These fungi are specific to insects, because they don’t infect amphibians, fish, birds, or mammals.

 

Metarhizium can be, and is being, mass produced on a ton scale. Our main candidate strain of this fungus – “F52” – has been registered by a company with the U.S. Environmental Protection Agency (EPA) for use against other insects, thus overcoming the expensive obstacle of generating safety data for a registration before it can be used by farmers. 

 

We have been evaluating different methods of applying the fungus to sugar beets: (1) as granules applied at planting into the furrow along with seed, granules that support the subsequent growth and sporulation of the fungus to create an “infectious minefield” through which larvae have to crawl to reach the root; (2) as a spray of fungal spores applied to the bases of plants just before the adult flies lay their eggs so that newly hatched maggots have to crawl through that infectious minefield of spores and thus become infected; and (3) as a seed coat of spores that germinate after planting and allow the fungus to potentially colonize the developing root and thus intercept the young maggots as they begin to feed.

 

Our field trials since 2001 have demonstrated that Metarhizium can be a successful control of the maggot, equal to terbufos, when insect pressures are light, such as in Montana and Wyoming. But when sugarbeet root maggots are very numerous, such as in the northern Red River Valley, the fungus cannot be used by itself. Other tools are needed, such as integration with an oat or rye cover crop, or with reduced rates of chemical insecticides. Such integrated pest management approaches are being evaluated for effectiveness and practicality in a collaborative program with North Dakota State University.

 

In parallel with field trials of the fungus, we have been examining the many and varied biotic and abiotic soil factors that can affect both the persistence of the fungus and its efficacy against the maggot. These factors include soil texture (silt:sand:clay ratio), pH, organic content, moisture, temperature, and the microorganisms inhabiting the sugarbeet root surface and adjacent soil (“rhizosphere”).

 

Colonization of a sugarbeet root system by Metarhizium, or its “cousin ” species, Beauveria bassiana, has not yet been conclusively demonstrated. We have transformed several strains of each fungus with the gene for producing a green fluorescent (gfp) protein, which glows when illuminated by UV light. This gfp-transformation allows us to directly observe the fungus on the root system of a plant.  Root colonization by these fungi does occur, at least in a microorganism-free system. We are using this tool to examine all the factors, especially the many bacteria and fungi associated with sugar beet roots in nature, that may affect root colonization by Metarhizium and Beauveria. We are also examining the competitive interactions between several strains of these fungi, the sugarbeet rhizosphere organisms, and plant pathogenic fungi.

 

Contributing Scientist:  Stefan Jaronski (Insect Pathologist)

 

 

Wheat Stem Sawfly's Impact on the Northern Great Plains


Latest Research Findings/Reports for this Project

 

The wheat stem sawfly, Cephus cinctus (Hymenoptera: Cephidae), is an important pest of wheat and other grain crops in the northern Great Plains. The insect is found across much of western North America though damage to wheat occurs primarily in Montana, the Dakotas, western Nebraska, eastern Wyoming, and the Canadian Prairie Provinces. Sawfly larvae feed inside the stem, reducing the number and weight of the kernels. The sawfly larva moves to the base as the plant senesces and cuts the stem to construct a pupation chamber. The weakened stem breaks and the grain lodges, adding to yield losses and making harvesting difficult. Field infestation levels of greater than 80% have been reported with yield losses of as much as 20% in some years and locations. Damage caused to wheat in Montana alone has been estimated at $25 million annually.

 

Current management practices for the wheat stem sawfly, resistant wheat cultivars and various cultural practices, have not been effective in minimizing losses. An alternative strategy, biological control using exotic parasitoids, is the focus of research at NPARL. Biological control of the wheat stem sawfly using parasitoids from England and France was attempted unsuccessfully in Canada and the US in the 1930s, and again in the 1950s. In contrast to these failures, these parasitoids were successfully established at about the same time on the European wheat stem sawfly (Cephus pygmaeus) in eastern North America. Why didn’t it work in western North America? There may be several reasons including host incompatibility, lack of synchronization, and environmental unsuitability. European parasitoids may be well suited to  climatic conditions in eastern North America but poorly adapted to the colder, drier weather of the northern Great Plains.

 

Therefore, the current wheat stem sawfly biological control effort is focusing on finding, identifying and evaluating wheat stem sawfly parasitoids from Asia. Collyria n.sp. (Hymenoptera: Ichneumonidae) was first collected in Gansu Province in China in 1999. We are currently evaluating this species in the insect quarantine laboratory at Montana State University-Bozeman.

 

Contributing Scientist:  Thomas Shanower (Entomologist) 

 

 

Latest Research Findings/Reports


The Wheat Stem Sawfly (Hymenoptera: Cephidae) and its Natural Enemies: Distribution and Impact
 

By: Thomas Shanower (Entomologist)

Download this Poster (PDF: 317KB)

 

The wheat stem sawfly, Cephus cinctus, has been a pest of wheat in the northern Great Plains since the late 1800s. Yield losses in Montana alone exceed $25 million annually.  Females lay eggs in wheat and hollow stemmed grasses where the developing larva feeds.  In the fall larvae move to the base of the stem, cut the stem and plug it.  Larvae overwinter in these stubs, completing development in the spring.

 

Wheat Stem Sawfly (Hymenoptera: Cephidae) Biological Control
 

By: T.G. Shanower, K.A. Hoelmer, J.L. Littlefield, W.L. Morrill, J.B. Runyon, D.K. Weaver


Download this Poster (PDF: 213KB)

 

The most important sawfly natural enemies are parasitic Hymenoptera, though nematodes and two fungal pathogens have been reported.  In wheat, two species of congeneric braconid, Bracon cephi and B. lissogaster attack the larvae of the wheat stem sawfly.  Morphologically the two species are very similar and have only recently been accurately differentiated.

 

Selection of new wheat stem sawfly natural enemies will be based upon several interrelated factors, including hot acceptance, host suitability and host specificity.  Prior to introduction of new exotic parasitoids into North America, a risk assessment must be developed to determine direct or indirect environmental impacts, or potential impacts of such introductions on indigenous organisms.  This selection process has begun on one parasitoid, Collyria sp. n.

 

Wheat Midge: Changes in Population Density 2000-2004

By: Thomas Shanower (Entomologist)

Download this Poster (PDF: 139KB)

 

 

 

Controlling Grasshoppers With Fungal Entomopathogens


 

Suppression, the third tier in grasshopper management, has traditionally relied on broad spectrum insecticides which often have negative impacts on nontarget organisms. Biologically based, environmentally friendly suppressive tools are lacking. Neither of the two U.S.-registered agents,  Nosema locustae and Beauveria bassiana, are very efficacious or cost effective on rangeland. The efficacy of these existence agents must be enhanced or new agents are needed to make biologically based suppression feasible.

 

Two approaches to increase efficacy are to enhance dose transfer to target insects via an “attracticide” formulation, and to prolong persistence thus expanding opportunity of contact with the agent. To do this, we have been concentrating on carriers that attract grasshoppers. One such is raw canola oil, which contains certain fatty acids that have been shown to mimic the odor of a dead grasshopper and stimulate necrophagy among these insects. Another is a confectionary industry by-product. 

 

The second major weak link in obtaining a commercially viable mycoinsecticide for outdoor use is poor persistence in the field. Solar radiation, primarily the UVA and UVB spectra, is a major factor compromising the consistent, persistent performance of fungal entomopathogens. On rangeland, efficacy from a single spray of commercial Beauveria is lost within 4 days. We are evaluating several novel formulation technologies for their applicability for grasshopper control.

 

The fungus Metarhizium anisopliae var. acridum  has been developed in Africa and Australia for the control of locusts, and is under development in Brazil, Mexico, and China. This fungus, which is specific to grasshoppers and locusts, could provide an effective, and economic, tool to control locust outbreaks in the U.S.  It is far more infectious for Orthoptera than the currently registered Beauveria. We are working to bring either or both of the existing isolates into the U.S. for large scale field trials in cooperation with USDA APHIS.

 

Contributing Scientist:  Stefan Jaronski (Insect Pathologist)

 

 

Grasshopper Ecology and Preventative Management


Latest Research Findings, Reports, and Publications for this Project

 

World-wide, grasshoppers and locusts are among the most economically important pests. Grasshoppers are an important native component of grassland ecosystems in the U.S., playing a role in nutrient cycling and serving as a critical food supply for wildlife. However, grasshoppers often reach outbreak densities in western North American grasslands, causing significant economic impact to the grazing industry from feeding, especially during drought periods when forage is already scarce. In addition, these outbreaks serve as a source of mass migration from large expanses of public rangeland to adjacent private cropland. It has been estimated that grasshoppers annually destroy on average at least 21 to 23% of available range forage in the western U.S. Traditional crisis-directed chemical control programs are economical only under certain conditions, do not provide predictable long-term control, have potentially important non-target effects, and may even exacerbate grasshopper problems.

 

Due to the historical emphasis on grasshopper outbreak suppression and intervention, ecologically-based preventative management of grasshoppers has received limited attention. We are examining the use of habitat management techniques such as burning or livestock grazing on rangeland as a method of manipulating the quality of habitat available for grasshoppers and/or their primary predators, and as a result, reducing grasshopper outbreaks. A promising ARS study found that during an outbreak period both grasshopper densities and forage consumption were five to nine times lower in twice-over-rotational grazing pastures than in season-long grazing pastures. We have also found that late-summer or fall fires in the northern Great Plains lead to reduced grasshopper populations in the year following a fire, suggesting that fire may be useful as a management tool for grasshoppers.

 

Although grasshopper herbivory can have negative economic consequences, it may also have important ecological consequences of interest to land managers and conservation organizations such as effects on plant community structure and rangeland productivity. We are examining how grasshopper herbivory affects nutrient cycling and multi-year plant productivity, with a collaborator from the University of Notre Dame. Results indicate that selective grasshopper herbivory acts to increase nutrient cycling and plant production at some sites.

 

Contributing Scientists: David Branson (Entomologist)
 

 

Latest Research Findings/Reports


Effects of summer fire and post-fire grazing on grasshopper abundance and species composition
 

By: David H. Branson (Entomologist) & Lance T. Vermeire

Download this Poster (PDF: 1.57 MB)

 

Rangeland management practices such as burning or livestock grazing have the potential to be important tools in grasshopper management, by manipulating the quality of habitat available for grasshoppers and/or their predators.

 

The following recent publications are available to download in .PDF format:

 

Branson, D. H. 2006. Life-history responses of Ageneotettix deorum (Orthoptera: Acrididae) to host plant availability and population density. Journal of the Kansas Entomological Society. 79:146-155. (81KB)
 

Branson, D. H. 2005. Effects of fire on grasshopper assemblages in a northern mixed-grass prairie. Environmental Entomology. 34(5): 1109-1113. (76KB)

Branson, D. H. 2005. Direct and indirect effects of avian predation on grasshopper communities in northern mixed-grass prairie. Environmental Entomology. 34(5): 1114-1121. (113KB)

 

 

Tracking Mormon Crickets


Latest Research Findings, Reports, and Publications for this Project


Outbreaks of insect pests are common and can have devastating effects on natural and agricultural ecosystems. Little is known about the causes of these outbreaks, not to mention the causes of en masse migrations during outbreaks. Our research has focused on flightless Mormon crickets (Anabrus simplex  (Tettigoniidae)), a katydid species that forms large, mobile groups (migratory bands) during outbreak periods. Working with collaborators from Kent State University and the University of Toronto at Mississauga, we have been studying the process of migratory band formation and movement to facilitate the development of predictive models for Mormon cricket migration. We utilize radiotelemetry, a valuable tool for understanding animal movement patterns, to quantify movements of individual Mormon crickets under natural conditions.

 

To date, we have tested hypotheses about: (1) movement differences between insects in outbreak and non-outbreak populations; (2) wind direction as a cue determining band movement direction; and (3) the role of social interactions in migratory band formation and movement.  Our results indicate that Mormon crickets in outbreak populations exhibit collective movement patterns and travel much further than those in non-outbreak populations. Wind direction plays little if any role in determining the direction of migratory band movement.

 

Social effects have a major effect on both the distance and direction traveled by band members. In addition, we have shown that migratory band membership benefits individual insects by greatly reducing their probability of being killed by predators.  This suggests that migratory band formation has evolved as an anti-predator strategy that confers substantial protection to insects within the group.

 

Contributing Scientist:  Vice Sword (Ecologist)

 

Latest Research Findings/Reports


Radiotracking Mormon Crickets
 

By: Gregory A. Sword (Entomologist), Patrick D. Lorch, & Darryl T. Gwynne

Download this Poster (PDF: 4.93 MB)

 

Insect outbreaks can have devastating effects on natural and agricultural

ecosystems. Little is known about the causes of these outbreaks, not to mention the causes of en masse migrations during outbreaks. Our work focuses on flightless Mormon crickets (Anabrus simplex (Tettigoniidae)), a katydid species that forms large, mobile groups called migratory bands during outbreaks in the western United States.