Illinois Natural History Survey - University of Illinois


Edward J. Armbrust, Director

The Center for Economic Entomology serves the citizens of Illinois by investigating and resolving entomologically related issues in four important sectors: agriculture, medicine, the environment, and the urban setting. In addition, it assembles and distributes information resulting from and pertaining to these research activities. Composed of research scientists, extension specialists, and support personnel, all with expertise in the insect sciences, the Center is jointly funded through the Survey and the College of Agriculture at the University of Illinois, Urbana-Champaign. This long-standing dual sponsorship provides an infrastructure that enables the Center to fulfill its many responsibilities and contributes to entomological research and extension activities within the Office of Agricultural Entomology in the College of Agriculture.




Public Service

The Center provides many educational programs and opportunities to disseminate general entomological knowledge related to the biological and natural resources of the state. Scientific information is provided to appropriate audiences in a usable form. These activities often involve staff participation and provide a learning experience for children. Insect Theatre, through a series of plays, sketches, and skits, teaches young audiences about insects by using a multifaceted approach. Various components of Insect Theatreinclude human-sized, true-to-life insect costumes, puppets, songs, and photographic images of actual insects and their activities. page30.gif

 For a more mature audience, exhibits of research activities prepared and staffed by Center personnel have been displayed at the National and North Central Branch meetings of the Entomological Society of America and the College of Agriculture's Agronomy Day, open house, and Hartley Gardens dedication. In addition, scores of classroom presentations are prepared for elementary, high school, and junior college students, and Center staff coordinate and produce the Survey's radio program entitled The Illinois Naturalist.

Survey entomologists cooperating with the federal Plant Protection and Quarantine Agency and college faculty are conducting surveys within Illinois for the deer tick, the pine bark beetle, various mosquito species, the golden nematode, and the tropical soda apple weed. These surveys provide valuable information for establishing a database for new pests within the state. For example, the pine bark beetle has been discovered in four new counties this year.

Five extension specialists, in cooperation with researchers and support personnel in the Center for Economic Entomology and the Office of Agricultural Entomology, provide up-to-date information on the management of insect pests of agricultural, horticultural, forest, and urban environments and on the control of mosquitoes and other medically important arthropods. Specialists are also involved in the dissemination of management information that will decrease pesticide contamination and reduce associated environmental and health hazards.

These extension specialists, in collaboration with extension specialists from other disciplines within the College of Agriculture, coordinate and produce three newsletters distributed to over 4,000 Illinoisans. The Home, Yard & Garden Pest Newsletter, published weekly during the growing season, provides homeowners and professionals in the landscape industry with up-to-date management information. By providing timely information about insect, weed, and disease pests of the home, yard, and garden, the newsletter informs clientele of potential pest problems and educates them on the most current integrated pest management techniques. The Pest Management & Crop Development Bulletin is also published weekly during the summer, with five additional issues released during the off-season. The bulletin alerts the agricultural community to current and emerging crop protection problems and suggests ways to reduce problems caused by crop pests through applied pest management strategies. Producers, newscasters, and representatives from all aspects of agriculture and industry subscribe to this quality publication. Illinois Fruit and Vegetable News discusses existing and potential insect and disease problems of fruit and vegetable production in the state. The publication focuses on integrated pest management to educate clientele in the judicious use of pesticides and how to reduce reliance on chemical control techniques.

Through the cooperation of the Center for Economic Entomology and the College of Agriculture, many additional special circulars, conferences, and workshops are provided. These materials focus on educating the diverse agricultural clientele within the state. The agricultural community, including industry and producers, has expressed its high regard for, and dependence on, these materials. The Center's insecticide evaluation program provides an impartial evaluation of chemical and biological pesticides applied to a variety of field, forage, and vegetable crops at several locations in Illinois.  page33.gif

National leadership in entomology has characterized the Center for several years. Its members serve on the technical steering committee for Illinois' Watchable Wildlife Viewing Guide and the State Museum's Interdisciplinary Study of Wetlands. Assistance to the Illinois Nature Preserve Commission's management programs is provided by the Center through interaction with that agency's advisory committee. Center staff participate in national agricultural research and extension planning through membership on various federal experiment station committees related to biological control of pests, integrative management strategies, and the movement and dispersal of biota.

In other national activities of the 1994-1995 fiscal year, Center staff served as representatives to North Central Regional Research Committees, and as reviewers of manuscripts for national and international journals as well as grant proposals for the Cooperative State Research Service, the National Science Foundation, the U.S. Department of Agriculture, and several other agencies. The Center staff serve on editorial boards of the Annual Review of EntomologyJournal of Economic Entomology, and American Entomologist. The Center is well represented in national and regional professional societies, and Center staff hold elected and committee positions in the Entomological Society of America and the American Association of Mosquito Control. Besides interacting with numerous University of Illinois committees on planning, administration, and outreach, Center staff consult with many agribusiness organizations, such as the Illinois Crop Improvement Association, Illinois Foundation Seeds, Inc., and the Illinois Seed Dealers Association.

Each year Center scientists and extension specialists, cooperating with scientists in the Center for Biodiversity, perform a time-consuming but much needed public service--the identification of insects and other arthropods for individuals. Commonly asked questions are What is it? What does it do? and How do I get rid of it? Insects are identified by comparing them with known examples or by the use of identifying taxonomic characters. Both methods require Survey staff to make use of the large collections of insects maintained by Survey entomologists.

Center staff frequently volunteer to judge entries at local science fairs and at the Illinois State Fair, willingly contribute their time and expertise by presenting lectures and seminars as part of various science courses and curricula offered by the University of Illinois, and advise and support graduate students in several departments of the university.


Special Recognition 

Members of the Center for Economic Entomology and the Office of Agricultural Entomology strive for excellence in all aspects of their work. Recognition for special professional achievement is often granted by peers. During the past year, several members of the Center and Office received such recognition.  page29.gif

Dr. Michael E. Gray and Dr. Kevin L. Steffey were each presented the 1994 Outstanding Extension ESA Award for a Scientific Presentation by the Entomological Society of America (ESA) and the ESA Meritorious Award for presenting scientific information on a cluster analysis of granular soil insecticides as a necessary pest management tool for the future. Dr. Steffey also received the ESA Distinguished Achievement Award for Extension Entomology and was nominated for the University of Illinois College of Agriculture's prestigious Paul A. Funk Recognition Award. Dr. Steffey's commitment to furthering science, especially that related to applied agriculture, is outstanding.

Expertise is often recognized by appointments to special committees in national societies and federal agencies. Dr. Richard A. Weinzierl was appointed program chair for the 1995 North Central Branch Entomological Society annual meeting, and Dr. Catherine E. Eastman is a member of the society's nominating committee. Dr. Michael E. Irwin is a member of the program committee for the Fourth International Conference on Plant Virus Epidemiology, and Dr. Robert J. Novak is president of the American Mosquito Control Association.

Excellence in research is often recognized by successfully obtaining grants and contracts from external funding agencies. Center staff have been awarded numerous such competitive funds from the National Science Foundation, National Institutes of Health, U.S. Department of Agriculture, Illinois Soybean Check-off Board, National Soybean Operating Board, and various other support groups. Support of this nature is vital to the continuation of the Center's research activities and provides the necessary resources to investigate areas of fundamental and applied entomology.


Research Reports
In addition to numerous technical reports, popular articles, and extension circulars, a total of 33 peer-reviewed papers and book chapters were published. The research reports that follow bear witness to the breadth and depth of the Center's research program. Much of what is reported could not have been initiated without support external to that provided by the Department of Energy and Natural Resources and by the College of Agriculture of the University of Illinois. The Center thanks the many government agencies, private foundations, companies, and commodity groups that contributed support during the past year. We cordially invite these groups and the citizens of Illinois to visit with us when the opportunity presents itself.

Pine shoot beetle survey

C. Helm
The common pine shoot beetle, a serious foreign pest of pines, has been detected in 10 northeastern Illinois counties since its initial discovery in Ohio in 1992. Survey scientists are cooperating with the Illinois Department of Agriculture and federal Plant Protection and Quarantine officials to determine the extent of pine shoot beetle distribution throughout the state and to assess the impact beetles may have on Illinois pines. An extensive detection survey using traps baited with attractants is under way in 19 high-risk counties, ranging from northern locations near established infestations southward into the Shawnee National Forest.

Chinese soybean acquisitions evaluation 
C. Helm, R. Nelson
The recent acquisition of over 1,200 primitive soybean lines from central and south China offers a unique opportunity to evaluate genetic material from their Center of Genetic Diversity. A comprehensive multidisciplinary evaluation of these lines for insect and disease resistance, improved agronomic traits, and more healthful seed composition involves researchers from the Survey, the University of Illinois, and the U.S. Department of Agriculture Soybean Germplasm Collection. Laboratory and field screening for new sources of insect resistance from within these newly acquired lines is a major component of the overall project that will be of great benefit to the development of insect-resistant varieties.

Spatial dynamics of potato leafhopper 
E. Armbrust, S. Roberts
The potato leafhopper is a destructive pest of second and third-crop alfalfa in Illinois. Adults do not overwinter in Illinois and infestations are a result of spring-migrating adults. Movement of the potato leafhopper was monitored in Champaign and St. Clair counties using sticky traps to determine the arrival of adults from overwintering sites in the southern states and to access the movement of adults between habitats. Information of this type is useful in developing alfalfa integrated pest management and scouting programs for the potato leafhopper.

Control of alfalfa weevil larvae 
J. Shaw, S. Roberts, E. Armbrust
Alfalfa weevil larvae feeding reduces the quality of first-crop alfalfa hay. Management practices for control of this pest often require the use of insecticides combined in a program of cultural and biological control. Insecticides were evaluated for control of alfalfa weevil larvae at the Southern Illinois University Belleville Research Center in 1994. Several pyrethroid insecticides were compared with the commonly used insecticide Furadan 4F. All three pyrethoid insecticides reduced the population of alfalfa weevil larvae by 80 to 85% within three days after treatment. Residual control was extremely good.

Corn hybrids and rootworm injury
M. Gray, K. Steffey, J. Shaw
In 1994, 12 corn hybrids were evaluated for their ability to compensate for corn rootworm larval injury. Experiments were conducted at the Northern Illinois Agronomy Research Center (DeKalb) and the Entomology Research Farm located near Urbana. Root pruning was severe at the Urbana site and the corn hybrids had great difficulty in compensating for the extreme level of root injury. At the DeKalb location, rootworm larval injury was moderate and more typical of a producer's field in northern Illinois. Corn hybrids compensated very well for moderate root injury and in general would not have required a soil insecticide.

Biological control of European corn borers
M. Gray, J. Shaw, K. Steffey
The second year of a three-year study regarding the potential utility of parasitic wasps,Trichogramma maidis, for the management of European corn borers was conducted near Urbana. This research is part of a multistate effort. The cooperating states have agreed to focus efforts on the second generation of corn borers for 1995. The logistics of using the parasites for control of first-generation borers are difficult. This study should continue to offer the seed industry some insights on the practicality of usingTrichogramma maidis for the management of European corn borers.

Biological control of stalkborers
R. Wiedenmann
The host-selection and host-suitability processes of parasites of stalkborers are being investigated to determine the ability of a braconid parasite to attack multiple hosts, and how this affects progeny allocation. Three braconid species and one ichneumonid parasite have been evaluated against the European corn borer. The three braconids are all encapsulated by the borer, indicating the immune response of the borer kills the parasite and thus parasite development is unsuccessful. Preliminary results show physiological and behavioral compatibility with the ichneumonid parasite and European corn borer.

Zoophytophagy in a heteropteran predator
R. Wiedenmann
Investigations were initiated to determine how the facultative phytophagy by the heteropteran predator, Orius insidiosus, may be affected by feeding on plants infected with soybean mosaic virus. Feeding sites within the plant show that the predator feeds in the vascular bundles. This has been thought to occur only in specialized plant-feeders, not in facultative phytophages. Radiolabeling compounds will determine what nutrients are obtained by the specialized feeding.

Biological control of purple loosestrife
R. Wiedenmann
Colonies of Galerucella calmariensis and G. pusilla, which are parasite beetles of purple loosestrife plants, have been established in the Survey greenhouse. Experiments on alternative photoperiod and releases of immature stages have just begun; no results have yet been obtained. This research program involves representatives from county conservation and forest districts and the Illinois Department of Conservation. Parasite releases and their evaluation will be coordinated with the participating units.

Insect/pathogen database
D. Onstad
A computerized database of the world's insect pathogens is being developed. Over 3,600 associations between pathogens and insects are now part of the database. Most of the pathogens are fungi or viruses. The database can be used by scientists or regulators interested in microbial control of insect pests. Ecological and taxonomic information is included in the database.

Gypsy moth and other Lepidoptera
D. Onstad, M. Jeffords
When the gypsy moth becomes established in Illinois in a few years, management will likely be based either on use of a microbial pesticide called Bacillus thuringiensis or on no intervention. In the latter case, extensive defoliation of trees will result. Either scenario has possible impacts on butterflies and other moths that inhabit the parks, preserves, and forests of Illinois. In this study, potential impacts will be evaluated species by species.

Gypsy moth and its disease
D. Onstad, J. Maddox, L. Solter, M. Jeffords
In cooperation with the U.S. Forest Service, Survey researchers are studying the field ecology and population dynamics of the gypsy moth and one of its microsporidian diseases that was imported from Portugal in 1985. Fieldwork is under way in Michigan where wild populations of gypsy moth exist. As yet, Illinois populations are sporadic and eradicated as soon as they are discovered. A mathematical model is being developed to help predict microbial control.

Modeling the European corn borer
D. Onstad
The development of a mathematical model of European corn borers infesting corn that has been genetically engineered to include the toxin made by Bacillus thuringiensisallows researchers to develop strategies for slowing the buildup of resistance by the pest to the natural and useful toxin.

Western corn rootworm problems
E. Levine
Corn rootworms are serious insect pests of nonrotated corn. Reports of damage to first- year corn following soybeans by western corn rootworm larvae are increasing in number. Prolonged diapause does not appear to be involved. Most of the problems are appearing in the east-central part of the state where a high percentage of cornfields are rotated with soybeans. Increased western corn rootworm beetle counts in soybean fields near problem cornfields suggest that there may have been selection for populations that lay eggs in soybeans. Cage studies are under way to determine if this has actually occurred.

Prolonged diapause in corn rootworms
E. Levine
>Prolonged diapause, a trait that allows northern corn rootworm eggs to pass through two or more winters before hatching, permits larvae to damage corn following another crop. Prolonged diapause in Illinois northern corn rootworms ranges from two to four years and the incidence of the trait varies by region in the state, with greater frequencies occurring where crop rotation is regularly practiced. For females collected in Champaign, the percentage of eggs with the prolonged diapause trait ranged from 18 to 94%, depending on which female laid the eggs. This suggests that there is probably a genetic component for this trait.

Bean leaf beetle survival on alternate hosts
E. Levine
The bean leaf beetle can be a serious pest of soybeans in Illinois. The insect overwinters as an adult in woodlots, clumps of grass, leaf litter, or in soybean fields of the previous season. The adults become active in April, moving into alfalfa and clover fields. Research has demonstrated that these beetles much prefer to feed on soybeans over these alternative hosts and that adult survival and egg production on alfalfa, and to some extent clover, is poor. This probably explains why late planting of soybeans often results in population crashes of this insect.

Gypsy moth biological control 
J. Maddox, L. Solter, M. Jeffords, D. Onstad, M. McManus
>Five species of microsporidia from gypsy moths were isolated in 1985. Microsporidia are important biological control agents in Europe, but are not presently established as control agents in North America. In 1993 Maddox and McManus obtained viral and microsporidian pathogens from Romania and viral pathogens from Siberia. In 1994 they obtained four additional species of microsporidia from Slovakia and Austria. In 1995 they plan to examine gypsy moths collected in Bulgaria for the presence of microsporidian diseases. The ultimate objective is to establish the most promising pathogens as permanent biological control agents of North American gypsy moths.

Storage of microsporidia in liquid nitrogen
J. Maddox, L. Solter
The Illinois Natural History Survey maintains one of the world's largest collections of viable microsporidia from which Survey scientists routinely supply other scientists who request microsporidia. Many species of microsporidia have been successfully stored in liquid nitrogen, some for over 27 years. In addition to serving as a valuable resource for biological control agents, this collection allows Survey researchers to conduct comparative experiments using several different taxonomic groups of microsporidia. The Survey is continuing to enlarge this collection.

Microsporidian host specificity
L. Solter, J. Maddox, M. McManus
Most biological control agents are relatively host specific. This remains the most important question relative to the safety of biological control agents. When nontarget hosts are exposed to biological control agents under laboratory conditions, few biological control agents are absolutely host specific. Ecological host specificity under field conditions is the most important question relative to introduced exotic biological control agents. Microsporidian pathogens will often infect several species of insects in the laboratory, but are generally host specific in the field. We are examining the variables that influence laboratory host specificity, ecological host specificity, and tissue specificity of microsporidian species.

Biology of microsporidia
J. Maddox, L. Solter, C. Vossbrinck, M. Baker
Microsporidia are obligate pathogens that use hosts from most animal phyla. They are of interest to entomologists because they are important biological control agents of many insect pests. Although over 1,000 species of microsporidia have been described, most authorities for this group of organisms agree that only a fraction of existing species have been described. Using information on life cycles, host range, ultrastructural characteristics, and molecular sequences, we are describing and characterizing species of microsporidia.

Control of European corn borers
J. Shaw, K. Steffey, M. Gray
A new biological control approach of particular interest to an integrated pest management program is the use of transgenic (Bt) maize. An assessment of the efficacy of various microbial insecticide formulations of Bacillus thuringiensis (Bt) and conventional and experimental chemicals were compared to a transgenic (Bt) maize for the control of first-generation European corn borers. Of all the compounds evaluated, the Bt maize controlled European corn borer larvae as effectively as did conventional insecticides.

Control of insects in corn
J. Shaw, M. Gray, K. Steffey
The efficacy of registered, soon-to-be-registered, experimental, and biological insecticides were evaluated for control of corn rootworms, black cutworms, and wireworms in Illinois. These tests provide an impartial evaluation of crop protection strategies for the Illinois grower and are an essential part of making proper recommendations for insect pest management. Extension programs provide up-to-date information.

Biotic interchange
M. Irwin, R. Allen
Plant viruses can be a severe problem in neotropical agricultural regions. These diseases, which are transmitted by insects (leafhoppers, aphids, etc.), can devastate crops. The role of forests or natural areas in the spread of these diseases is not clear. In cooperation with the Costa Rican Institute for Biodiversity, this project investigates the biotic interchange of these insects between a natural forest and managed agricultural landscape. The results of this study may improve agricultural production by suggesting ways of avoiding plant virus epidemics through proper planning.

Soybean nodule fly in Illinois
M. Patel, M. Irwin
Several species of the fly genus Rivellia occur in Illinois, each feeding on a different legume host. However, only R. quadrafasciata, the soybean nodule fly, has been reported in both natural and agricultural habitats. In our changing landscape, R. quadrafasciata may be in the process of switching from its native host to soybeans. The interest of Survey researchers lies in the genetic and ecological nature of this host plant switch. A survey of Rivellia species and host plants as well as species interactions and movement patterns is being conducted at Revis Hill Prairie in Mason County.

Higher classification of the Leucopinae
S. Gaimari, M. Irwin
The fly family Chamaemyiidae contains species with predacious larvae that feed on many pest species of aphids, scales, and mealybugs. Because of their potential importance in biological control, Survey researchers seek a better understanding of the systematics of the subfamily Leucopinae, and of where it fits within the larger family. Researchers have been studying thousands of specimens obtained from insect collections worldwide. Along with traditional adult taxonomic work, Survey researchers are considering morphological characters of immature stages, general life histories, and molecular systematics techniques in their treatment of the subfamily.

Spread of viruses in crops
G. Fondufe, M. Irwin, H. Bottenberg, G. Kampmeier
The effect of virus nonhost plants on the spread of soybean mosaic virus and maize dwarf mosaic virus was assessed in monocultures of soybean, sorghum, or corn and mixtures of different proportions of these crops. The incidence and spatial spread patterns of these viruses were monitored weekly throughout the growing season. Although aphid landing rates were higher in the mixtures than in the monocultures, incidence and spatial spread were greater in monocultures than in mixtures. Nonhost plants of the viruses were extremely important in reducing the spread of both viruses, which probably overcomes any disadvantage associated with increased landing rates.

Disease-induced behavior in earworms
D. Guyot, J. Maddox, S. Fahrbach, M. Irwin
Infection by the HzSNPV baculovirus alters the behavior of corn earworms. In laboratory experiments, 70-90% of diseased caterpillars, regardless of instar, climbed to the top of their rearing chambers, where they died; however, light does not appear to be a factor in the climbing behavior of the diseased caterpillars. The climbing behavior of infected caterpillars is thought to enhance the dispersal of baculoviruses in nature. Understanding the dispersal of insect diseases may enable scientists to manipulate disease epidemics in important insect pest populations.

Plant stress and predator survival
C. Armer, R. Wiedenmann, M. Irwin
The insidious flower bug, Orius insidiosus, is a predator of thrips, mites, aphids, and insect eggs. In addition to feeding on small insects, it feeds on plants when no prey is available. Plant stresses, such as infection by soybean mosaic virus, can raise the protein levels in the plant tissues, thus increasing the nutrients available to the flower bug. The availability of more nutrients may allow the flower bug to lay more eggs and to live longer when prey is scarce. Predator/plant stress interactions may increase the success of the insidious flower bug as a biological control agent.

Dispersal of Russian wheat aphids
S. Isard, G. Kampmeier, M. Irwin, D. Dazey
A two-year cooperative project with scientists from Colorado State University, the Illinois State Water Survey, and the University of Illinois Institute of Aviation investigated the dispersal dynamics of the Russian wheat aphid (RWA) using helicopter-mounted isokinetic collectors to determine aerial densities and vertical distributions of the RWA and other small insects in the atmosphere. An early morning flight found aphids within a low-level jet wind blowing from the south at 22 mph about 2,200 ft above ground level, indicating a likely origin for these aphids of 150-250 miles further south, the site of large overwintering populations of this introduced pest.

Natural water catchments and virus vectors
M. Irwin
This research, funded by the International Arid Lands Consortium, is a collaborative effort with Dr. Benny Raccah, Volcani Center, Israel. Situated in the arid natural habitat of the Hazeva Field School, Arava Valley, Israel, where high-intensity agriculture is practiced, these experiments monitor flight activity with yellow pan, emergence, flight, and suction traps of aphids, leafhoppers, whiteflies, and thrips that vector plant viruses. Vectors collected this season are being curated and will be identified by taxonomic specialists. A second season begins in early 1996. Vector dynamics under differing water capture regimes will allow us to forecast vector movement into crops.

Factors governing aphid ascent
S. Isard, M. Irwin, G. Kampmeier
In a series of experiments conducted in a large greenhouse wind tunnel, the structure of airflow and the flight aptitude of aphids were regulated, enabling evaluation of ascent flight scenarios under a wide variety of controlled environmental conditions. Results suggest that aphids initiating flight during midday and afternoon, when the atmosphere is often unstable, are likely to move long distances, while those that take off during the morning hours, when the atmosphere is usually stable, probably disperse locally. The results of this study may lead to improved forecasts of aerial movement of aphids and other weakly flying insects.

Bt-corn for corn borer control
R. Barrido, K. Steffey
Experimental corn hybrids have been genetically modified to express an insecticidal gene from a bacterium, Bacillus thuringiensis, that kills many species of caterpillars, including European corn borers. During the summer of 1994, a transgenic corn hybrid (Bt-corn) was tested for efficacy against first- and second-generation corn borers. Bt-corn was very effective in controlling corn borer larvae; the level of control was much greater than that provided by conventional insecticides. Use of Bt-corn could reduce the use of chemical insecticides, but certain issues, like resistance management, must be addressed before commercial release of this new crop technology.

Control of cabbage pests
C. Eastman, J. Shaw
Formulations of experimental organochemical insecticides were evaluated against larvae of the diamondback moth, imported cabbageworm, and cabbage looper--the major Midwest pests of cole crops--while another insecticide was examined for efficacy against aphids. Caterpillar pest populations were moderate in 1994, with diamondback moth larvae the most prevalent pest. Aphid populations (a mixture of green peach and turnip aphids) were the highest seen in several years. Performance of the experimental insecticides was slightly less than or equal to that of commercial insecticide standards. All products performed well enough to produce market-quality cabbage (insect damage ratings of <= 3) at harvest.

Cover-crop mulches for pest management 
C. Eastman, J. Masiunas, H. Bottenberg, 
D. Eastburn (University of Illinois)

Cover-crop mulches used to reduce soil loss and control weeds may also affect other pest groups. A 1994 interdisciplinary study compared the impact of conventional tillage with that of reduced tillage plus mulches of cereal rye, rye and clover, or excelsior on incidence of weeds, insects, and pathogens in cabbages and snapbeans. Rye regrowth in the rye and clover treatments after herbicide application hampered growth of the vegetable crops. Caterpillar pest numbers in cabbages were variable depending on the insect species and mulch treatment. Potato leafhopper populations on snapbeans were greatest in conventional tillage and least in rye and clover plots.

Reservoirs of viruses and aphid vectors
S. Post, C. Eastman, M. Irwin, G. Kampmeier, T.-S. Chu, A. Hewings, L. Domier (U.S. Department of Agriculture and University of Illinois)
The role of grasses as reservoirs of barley yellow dwarf viruses and aphid vectors between small-grain cropping seasons is being examined in a multidisciplinary study. Turfgrass plots inoculated with a unique virus isolate are being monitored for long-term virus survival. Results from field trials to determine spread of the unique isolate from oats to selected grasses and from grasses to wheat indicate the presence of some type(s) of barley yellow dwarf virus(es). Tests are in progress to determine if the viruses present are the introduced unique isolate and/or wild strains brought by migrant aphids.

Mosquito identification 
B. Debrunner-Vossbrinck, C. Vossbrinck, A. Zvilius, M. Vodkin, R. Novak
The primary vectors of St. Louis encephalitis virus are mosquitoes in the subgenusCulex. Adult females in this mosquito complex cannot be identified using "traditional" morphological techniques. We have developed an identification system using ribosomal DNA for species identification. A specific variable region of the mosquito's r-DNA is used to identify species and subspecies of the Culex complex. Using this method, a single mosquito leg is all that is needed for identification. This preserves the rest of the specimen for virus isolation, a voucher specimen, or any other required uses.

Biology of a predatory mosquito
H. Lee, E. Ontiveros, R. Novak
Mosquito larvae in the genus Toxorhynchites are predacious on other mosquito larvae. The adults in this genus feed on plant nectars and do not require a blood meal as do other mosquito species. The nutritional needs of Toxorhynchites larvae are therefore quite different than other mosquito species. The purpose of this investigation is to examine the influence of larval food (prey) on development and on the reproductive capabilities of adults. Results from this study will help to characterize this species and evaluate its use as a biological agent in artificial containers, such as used tires.

Mosquitoes and waste tires 
R. Lampman, S. Hanson, R. Novak
Ten species of mosquitoes were collected in tires at a waste-tire site in Jasper County. The most abundant species, relative to the total number of larvae collected, were Culex pipiens and Cx. restuans. The most prevalent species were Aedes albopictus (70% of all tires) and Cxpipiens (58% of all tires). Other species that were collected includeAedes atropalpus, Ae. triseriatus, Cx. salinarius, Cx. territans, Orthopodomyiaspp., Anopheles punctipennis, and An. barberi. Since this used-tire site is adjacent to a tree-lined stream, investigations on the dispersal of Ae. albopictus are currently being studied.

Mosquito oviposition attractants 
R. Lampman, R. Novak
The rapid dispersal and establishment of Aedes albopictus in Illinois, primarily in used tires, has serious public health implications. This species is a potential vector of numerous human and animal pathogens. This investigation focuses on monitoring gravid (egg bearing) adult females using oviposition attractants. Laboratory preference tests showed that these females preferred infusions of grass sod over pure water for oviposition. Olfactometer tests revealed that both males and nongravid females respond to volatiles from the sod infusion. This chemical ecology research may result in the development of effective tools for both mosquito surveillance and control.

Mosquito oviposition sites
R. Lampman, R. Novak
Many Culex species of mosquitoes prefer to oviposit in organically polluted or eutrophic aquatic sites. Oviposition traps and gravid traps mimic these natural oviposition sites through the use of crude infusion lures. Unfortunately, variability in number of mosquitoes per trap could represent either changes in actual density or microbial changes in the infusions. This investigation focuses on identifying methods that standardize the attractants by understanding biological activity. The major volatile components, bacteria species, and specific chemicals found in active infusions are currently being field tested.

Mosquitoes and storm drain tunnels
R. Lampman, S. Hanson, K. McClellan, 
R. Novak

Drainage tunnels in Urbana and Champaign are being surveyed for the presence of overwintering mosquitoes. In the initial study, a 1.4 km drainage tunnel in Champaign was monitored monthly during 1994. The number of mosquitoes and their locations in the tunnel were recorded twice a month. This underground site and the data gained from this study will provide baseline data for a long-term study on the overwintering biology ofCulex pipiens and Cx. restuans. Anecdotal evidence from city and utility personnel indicate that they frequently encounter large numbers of mosquitoes when servicing storm tunnels.

Mosquito feeding preferences
R. Lampman, R. Novak, N. Krasavin
A preliminary study was undertaken to determine whether a colony of Culex pipienscould be maintained on human blood as the sole source of protein for eggs. Mosquitoes that had been feeding for a year using quail as the primary blood source were allowed to feed only on human blood. Little is known about the proclivity of Culex pipiens to feed on mammals. However, a shift in feeding behavior from birds to mammals is a critical event in the successful transmission of St. Louis encephalitis virus.

Spore-forming bacteria in mosquito habitats
J. Siegel, R. Novak, J. Maddox
As part of a continuing project to identify mosquito pathogens in waste-tire dumps, water and soil samples were collected from tire dumps throughout Illinois. Spore-forming bacteria were cultured from the samples and identified by a variety of techniques including gas liquid chromatography. A catalog of species is being compiled that will provide important baseline information on potential food sources for mosquitoes.

Identification of microbial insecticides
J. Siegel, A. Smith, J. Maddox, R. Novak
Cellular fatty acid profiles have been created for microbial insecticides used in mosquito vector control. Additional work is being conducted to create similar profiles for microbial insecticides used in agriculture that also have some mosquito activity. These profiles are an essential tool for evaluating whether indigenous bacteria with mosquito activity can in fact be commercially produced. This technique will enable Survey researchers to quantify the persistence of commercial microbial insecticides in tires and in other areas where they are applied.

Protozoan pathogens of mosquitoes
J. Siegel, R. Novak
Research is being conducted on the protozoan pathogen Ascogregarina barretti. It is native to Illinois and infects the eastern treehole mosquito, Aedes triseriatus. We are interested in the impact that this pathogen may have on competition between Aedes triseriatus and the Asian tiger mosquito, Aedes albopictus. Our current emphasis is on growing suitable numbers of Ascogregarina barretti in order to infect mosquitoes in the laboratory.

Mosquito vector potential
J. Siegel, R. Novak
Historically, wing length has been an important predictor of blood-feeding success and longevity of female mosquitoes. A series of experiments to quantify nutritional and crowding factors that influence wing length is under way. This information will be used in turn to evaluate mosquitoes collected from waste-tire dumps. Researchers hope to compile an index so that tire dumps can be prioritized for cleanup.

Impact of tire removal on mosquitoes 
J. Siegel, R. Novak
Preliminary surveys have been conducted to collect baseline data on the vector mosquito species present in a large tire dump prior to cleanup. Collections will then be made several times each summer to determine if the number of species declines or their percent abundance changes as the tire dump is shredded. We anticipate studying several dumps of varying size in the state in order to quantify the effect of cleanup.

A survey of mosquito larvae in urban areas
S. Hanson, R. Novak, R. Lampman, M. Vodkin, W. Ruesink
A method of surveying urban land-use zones for mosquito larvae and their habitats, especially used tires, was developed and tested. A preliminary survey was conducted in Champaign and Urbana during the summer of 1994. Habitats were classified as ground water, tree holes, tires, catch basins, or other artificial containers. A total of 3,620 larvae were collected of which 51% were Culex restuans, 26% were Orthopodomyia signifera, and 19% were Culex pipiens. The remaining 4% included Anopheles barberiAedes triseriatus, Culex salinarius, Culex territans, and Orthopodomyia alba.

Mosquito cold hardiness 
S. Hanson, R. Novak
Currently, Aedes albopictus suffers considerable mortality in northern Illinois during the winter. However, is it possible that this mosquito could adapt to the severe Illinois winters. The objective of this investigation is to determine the ability of Ae. albopictus to adapt to repeated genetic selection for cold hardiness under laboratory conditions. The results of this study will help indicate whether Ae. albopictus can become better adapted to the northern Illinois climate, thus increasing both its distribution and numbers.

Hibernation of mosquito hybrids
S. Hanson, R. Novak
Culex pipiens pipiens and Culex pipiens quinquefasciatus both occur in Illinois. In many areas in southern Illinois, these subspecies occur in the same place and produce a large hybrid population. In the fall, shorter days cause adult female Culex pipiens pipiens to hibernate while Culex pipiens quinquefasciatus does not hibernate. However, it is unknown if the hybrids can hibernate. Determining the hibernation capabilities of these two types of mosquitoes may lead to possible control methods.

Winter survival of mosquito eggs
S. Hanson, R. Novak
The ability of Aedes albopictus eggs to survive the winter in Illinois and elsewhere in the United States is poorly understood. An ongoing investigation is comparing winter egg survival in tires in Chicago, Kankakee, Green Bay, Milwaukee, and Saginaw. The temperature of the eggs was monitored throughout the winter in order to determine critical limits for survival. During the winters of 1993-1994 and 1994-1995, the only eggs to survive were those located in Chicago, while 2% of the eggs survived the winter of 1993-1994 and 9% of the eggs survived the winter of 1994-1995.

Mosquito overwintering physiology 
K. McClellan, R. Novak
Culex pipiens and Culex restuans mosquitoes overwinter as inseminated adult females. Successful overwintering depends on the development of reproductive diapause in response to short photoperiods, cessation of blood-feeding, hypertrophy of the fat body, and development of cold hardiness. Hypertrophy of the fat body and cold hardiness in these females result in changing lipid composition during an overwintering period. This project is investigating lipid composition changes during the winter and how these changes relate to mosquito survival.

The Asian tiger mosquito in Illinois
R. Novak
This is an ongoing study made up of two components: (1) direct surveillance at specific sites in Illinois, and (2) investigations based on direct requests from agencies, municipalities, and the public. Direct surveillance and monitoring movement of the Asian tiger mosquito has been ongoing in Chicago and in Cook, Kankakee, Peoria, Tazewell, Champaign, St. Clair, Madison, and Pulaski counties. These surveillance investigations provide current information on the spread of the Asian tiger mosquito in Illinois in order to develop health risk assessments of tire piles.

Studies of mosquito population dynamics 
R. Novak, L. Szymczak, R. Cieslik, C. Etchison
The purpose of these investigations is to gather field information on mosquito distribution, density, and population dynamics. The mosquitoes of primary concern are the vectors species Culex pipiens and Cx. restuans (St. Louis encephalitis virus), Aedes triseriatus (La Crosse virus), and Ae. albopictus, which was recently introduced into the U.S. in used- tire casings and can transmit several local and exotic pathogens. These bionomic studies will include detailed temporal and spatial investigations of the egg, larvae, and adult stages and the pathogens they transmit.

St. Louis encephalitis virus surveillance 
M. Vodkin, R. Novak, M. Koll, R. Cieslik (Chicago Department of Health), L. Szymczak (Chicago State University)
The weekly deposition of Culex mosquito egg rafts, the prevalence of St. Louis encephalitis (SLE) virus-specific antibodies in feral birds, and the prevalence of virus in mosquito pools were monitored in 1993. A total of 4,623 egg rafts were collected, representing a twofold increase from 1992. Virtually all of the early-summer egg rafts were Culex restuans. After mid-July, Culex pipiens eggs accounted for 20-70% of the total rafts collected. The prevalence for SLE viral antibodies (avian) and RNA (mosquitoes) were 0.2% and 0.02%, respectively. Both values were about 25-fold lower than during epidemic years. Surveillance will continue during 1995.

Detecting St. Louis encephalitis virus 
M. Vodkin, J. Siegel, R. Novak, S. Nawrocki, Y. Randle (Harris County Mosquito Control District)
A reverse transcriptase-polymerase chain reaction assay (RT-PCR) was compared with two other commonly used methods, tissue culture assay (TC) and enzyme-linked immunoabsorbent assay (EIA), to detect St. Louis encephalitis virus. A large number of samples with a low viral prevalence was tested. Because of speed, accuracy, and cost, either the RT-PCR or the EIA can be used as the primary screen. As the sole assay, RT-PCR has an advantage over EIA because the amplified product contains sequence information that can confirm its identity.

Flood-induced stress on urban trees
J. Lloyd, F. Miller, P. Weicherding
Research to examine the immediate and long-term effects of the 1993 flood on urban trees was initiated in the fall of that year as a collaborative effort among scientists at the Illinois Natural History Survey, University of Illinois, Western Illinois University, and the University of Northern Iowa with cooperation from the U.S. Army Corps of Engineers and the city of Davenport, Iowa, and other flood-affected communities. Our foremost objective is to determine the "urban" tree species most susceptible to prolonged late-season flooding. Secondarily, we are interested in determining the cause of mortality (insects, disease, etc.) in years following the flood.

Control of insects on ornamental plants
J. Lloyd, P. Nixon, F. Miller, T. Royer
New chemical and biologically derived insecticides are being evaluated for efficacy against insect pests of woody ornamental plants, turfgrass, and greenhouse plants. New compounds on the market need to be independently evaluated for efficacy against the myriad of insect pests infesting ornamental plants. New biologically derived compounds have shown promise against interiorscape and greenhouse insect pests. Evaluating efficacy on landscape ornamental plants is the next step. Independent evaluations of these compounds in various venues are needed to truly measure their effectiveness as tools for controlling insect pests of ornamental plants in Illinois.

White grub management in turfgrass
P. Nixon
Annual white grubs are the most damaging insect pests of turfgrasses in Illinois. Research is under way in residential yards and golf courses to find better ways of avoiding and controlling damage by these insects. Turfgrass conditions that are less likely to produce high grub populations and insecticides used for management of these pests are being evaluated. Irrigation regimes, tree canopy cover, and species of grass involved are some of the turfgrass conditions being evaluated. Insect-feeding nematodes, insect-attacking bacteria, new insecticides, and new combinations of insecticides are among the management methods included in these studies.

Thrips management on greenhouse crops
P. Nixon
Thrips are difficult pests to control in greenhouses. Their tendency to hide in unopened blossoms and leaf buds makes them less likely to be controlled with insecticides. In addition, they tend to feed on blossoms of many plants with a relatively small number being capable of causing noticeable damage. Several new insecticides, including some of biological origin, are being tested on chrysanthemums in the Survey greenhouse to determine their effectiveness in thrips management.

Ticks in Illinois
J. Bouseman, J. Nelson (Rush Presbyterian St. Luke's Medical Center, Chicago)
Ticks are among the arthropods submitted most frequently for identification to the Illinois Natural History Survey. Those most commonly received are the lone star tick (Amblyomma americanum), the American dog tick (Dermacentor variabilis), and the blacklegged tick (Irodes scapularis). The ticks submitted have almost invariably been taken from humans or pets. Because of the widespread concern regarding the status of these species as vectors of important disease-causing organisms of people, pets, and livestock in Illinois, researchers at INHS and elsewhere continue to monitor the distribution and abundance of ticks in the state and to track the status of the diseases they transmit.

Prairie insects
J. Bouseman
Approximately 60% of the vegetation of presettlement Illinois was prairie. In the course of the settlement of the state, pioneers recognized that prairie soils are highly productive of crops; as a consequence, almost nothing remains of the original prairie. It has been estimated that less than 1/100 of 1% remains. Those scattered remnants provide refuge for the insect species that once were widespread in the state and as such provide the only records for many such species. Scientists are attempting to census two of the larger Illinois prairie remnants.

Fruit insect pest management 
R. Weinzierl
Work continues on field evaluations of the use of mating disruption for the control of the codling moth in apple orchards. Studies conducted in 1994 near Urbana and Belleville indicated that the use of pheromones in plastic dispensers prevented mate attraction and mate finding by the codling moth; the result was effective prevention of fruit damage by this key pest. Ongoing efforts are focusing on the integration of this control practice in overall insect management in apple production.

Biological control of flies 
D. Keen, C. Jones, R. Weinzierl
As a part of ongoing studies of the biological control of livestock flies by pupal parasites, work conducted in 1994 focused on the release of Muscidifurax raptorellus. In the Plains states, this parasite has been shown to attack high numbers of fly pupae immediately after release. In our studies, this species was recovered after release but did not increase in numbers as the season progressed. We are attempting to develop methods that more accurately assess rates of parasitism of fly pupae and to determine why certain parasites do not increase in numbers around livestock facilities.

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