INSECTS AND SHRUB DIE OFF IN WESTERN STATES: 1986-89 SURVEY RESULTS B. Austin Haws George E. Bohart C. Riley Nelson David L. Nelson ABSTRACT a few other shrubs. Previous surveys of insects on Atriplex have been reported by Haws and others (1983). The paper reports results of a 1986-89 survey of Collecting insects requires several methods, since insects shrub insects, mainly those of shadscale (A triplex con­ may be active at different times of the day, night, or sea­ fertifolia), fourwing saltbush (A. canescens), and sage­ sons. Even when active, the insects may be flying, crawl­ brush (Artemisia spp. ), as part of a multidisciplinary ing on the soil surface, tunneling through the soil, or may study to determine which insects might be a~sociated with be nearly or entirely stationary while feeding on or in the rangeland shrub dieoff. The importance of acollection of plants. Before an insect is definitely shown to be associ­ rangeland insects at Utah State University is explained. ated with a specific shrub, it must be observed feeding, Photographs and information about major insect suspects developing, or laying eggs on or in the plant. Insects cap­ in shrub dieoff and their injury to plants are presented. tured on a plant may just be resting or incidentally passing Possible associations of chromosome races (ploidy) and by as they travel through a shrub community. dieoff, and uses of insect management through Integrated Presently, the names of the thousands of insects that Interdisciplinary Pest Management are suggested. we have had identified, together with the numbers of each species collected, are being summarized in a final report to SCOPE OF THE INSECT SURVEY the Intermountain Research Station, Forest Service, U.S. Department of Agriculture, through cooperative agreement This paper is a report of the insect aspects of a research No. 22-C-6-INT-124. Where possible, each species is being team's efforts to discover factors associated with the dieoff evaluated as to its suspected association with shrub dieoff. of shrubs native to Utah and several surrounding States Evidently the evaluations will be limited, for many of the (Idaho, Nevada, and Oregon). insects are new species and their biology not known. The The entomological approach to the shrub dieoff problem biology of even many of the identified species is unknown. has been to survey the insects in the native shrub commu­ Several taxonomists, in addition to the authors, have nities, to evaluate them and their damage to shrubs, and helped identify many of the thousands of insects in the to identify those insects most likely to be associated with Utah State University (USU) range insect collection-all shrub dieoff. A broad survey of shrubs was made over a of which will be properly acknowledged in our final report. large geographical area during 1986-89. It was not possi­ Books on the taxonomy of insects by Arnett (1985), Borror ble to study every species of shrub and its insect associ­ and others (1989), Gillott (1980), and numerous shorter ates in detail, but the survey was a beginning in the de­ scientific publications, have been helpful in the identifica­ velopment of an overall view of the insects in our native tion of specimens. These sources also contain useful sum­ shrub communities. The initial goals were not to make maries of the biology of major insect families and genera. a detailed biological study or formulate management A few of the most important insect families, and a few strategies. noninsect groups collected on four of the many survey sites, Insects were collected mainly from fourwing saltbush are shown in table 1. If the species of insects belonging to (Atriplex canescens [Pursh] Nutt.) and shadscale (Atriplex the various families can be identified, their names will be confertifolia [Torr·.& Frem.] Wats.); however, some insects listed in the final technical report. Some individual fami­ were collected from sagebrush (Artemisia spp.), bitter­ lies, such as the family Chrysomelidae (a group of beetles) brush (Purshia spp.), winterfat (Ceratoideslanata), and are estimated to include 20,000 species. The order Coleop­ tera, to which the family Chrysomelidae belongs, is esti­ mated to contain 300,000 species (Gillott 1980). Thus, it is evident that the list of species will be greatly expanded Paper presented at the Symposiwn on Cheatgrass Invasion, Shrub Die­ Off, and Other Aspects of Shrub Biology and Management, Las Vegas, NV, when known species names are added to our list. April 5-7, 1989. In addition to a technical report, we also hope to publish B. Austin Haws is Professor Emeritus, Department of Biology, at Utah a practical guide, which will help in identifying major State University, Logan, UT 84322-5305. George E. Bohart is Collabora­ tor at Utah State University/USDA Agricultural Research Service, Logan, shrub insects and their injury to shrubs for use by laymen UT 84322-5305. C. Riley Nelson is Research Scientist at the University and users of rangelands. ofTexas, Austin, TX 78712. David L. Nelson is Plant Pathologist, Inter­ mountain Research Station, Forest Service, U.S. Department of Agricul­ Major participants of the research team have included ture, Shrub Sciences Laboratory, Provo, UT 84606. a plant pathologist and specialists in plant development, 127 This file was created by scanning the printed publication. Errors identified by the software have been corrected; however, some errors may remain. Table 1-A list offering a general view of the insects and non insects collected on four of many sites in a 1986-89 survey of native western rangeland shrubs1 San Juan Co. Tooele Co. Grand Co. Tooele Co. BLM enclosure railroad Thompson Pass watermound site site site site Insect families Pit Net Pit Net Pit Net Pit Net and noninsects2 trap sweep trap sweep trap sweep trap sweep Total Acrididae 11 5 18 Alleculidae 8 8 Alydidae 1 1 Anthicidae 3 4 Anthocoridae 3 3 Apidae 2 4 3 11 20 Asilidae 6 2 10 18 Beetles 2 7 13 22 (unidentified) Bethylidae 14 14 Bombyliidae 762 3 766 (bee flies)2 Braconidae 1 1 Buprestidae 16 2 18 (Acmaeodera) Carabidae 44 42 38 57 76 257 (predators) Cercopidae 2 Chilopoda 2 5 8 (centipedes) Chironomidae 4 4 Chrysomelidae 1 6 20 7 35 (beetles) Cicadellidae 39 5 78 14 69 27 60 292 (leafhoppers) Cicindelidae 3 22 26 Cleridae 1 1 Coccinellidae 1 Collembola 15 6 22 Coniopteryg idae 3 3 Curculionidae 8 8 15 31 (snout beetle) Delphacidae 1 Dictyopharidae 2 2 Elateridae 2 Formicidae 284 18 295 88 1,045 35 181 1,946 (ants) Gryllacrididae 3 7 11 Grylidae 3 3 Halictidae 4 4 82 90 Hemerobildae 1 3 4 Hesperiidae 2 1 3 Histeridae 9 2 2 10 2 25 (beneficial beetles) lchneumonidae 2 2 lssidae 1 Lygaeidae 2 2 Mantidae 6 6 13 Meinertellidae 1 Meloidae 3 4 7 Melyridae 5 1 6 Miridae 1 5 7 13 Muscidae 8 2 4 3 100 118 (flies) Mutillidae 7 3 17 27 (velvet ants) Noctuidae 2 2 Pentatomidae 6 6 Polyphagidae 1 (con.) 128 Table 1 (Con.) San Juan Co. Tooele Co. Grand Co. Tooele Co. BLM enclosure railroad Thompson Pass watermound site site site site Insect families Pit Net Pit Net Pit Net Pit Net and noninsects2 trap sweep trap sweep trap sweep trap sweep Total Pompilidae 4 3 7 3 17 Psocidae 38 38 (bark lice) Pulicidae 2 2 Reduviidae 5 2 7 Scarabaeidae 2 17 3 23 Scelionidae 6 6 Scoliidae 2 2 Scutelleridae 4 3 7 Silphidae 18 9 12 6 47 92 (beneficial beetle) Simuliidae 2 2 Solpugidae 4 9 13 Sphecidae 3 4 Staphylinidae 1 3 4 Tachinidae 11 3 1 15 Tenebrionidae 17 71 18 151 18 276 (plant-eating beetles) Tenthredinidae 1 Tephritidae 1 Termitidae 2 2 Tettigoniidae 4 5 Thripidae 8 27 35 (thrips) Thyreocoridae 6 6 Tiphiidae 6 6 Lizards2 10 1 11 Mites2 22 109 8 62 202 Scorpions2 3 11 15 Spiders2 14 56 67 29 166 1A detailed report comparing sampling methods, species collected, dates, and collection sites is being prepared for the Forest Service. The current range insect species list is more than 70 pages long and will likely be appended in the future. 2Common names of insects with 25 or more specimens collected. Some families include both beneficial and pest insects. range science, and chemistry. Many persons, too many to or from the Utah State University Bulletin Room, UMC acknowledge in this report, have contributed time, mate­ 5015, Logan, UT 84322. rials, and years of experience to the planning and implem­ Associating the various individual stages that belong entation of research plans, and to discussions of possible in an insect's life cycle is often a giant jigsaw puzzle. The factors involved in shrub dieoff. Some of the dieoff team immature and adult forms may be on different plants or participants have prepared papers for this symposium locations on a plant or in the ecosystem (fig. 1). Some­ (Stevenson and ~thers; Nelson and others). times the only way to connect these immature and adult ~urther evidence of the complexity of tasks involved forms is to rear the immature ones. It is doubtful that all in an insect survey was shown by the literature review of shrub insects will be identified in the foreseeable future, native shrub insects prepared by Haws and others (1988). inasmuch as new ones are constantly being introduced Approximately 6,000 insects associated with approximately into our rangelands. The worldwide movement of insects 1,000 shrubs are listed in the literature reviewed in the emphasizes the need to continually monitor rangeland publication: "Index to Information on Insects Associated resources for insects. with Western Wildland Shrubs," General Technical Report INT-248.