DOCSLIB.ORG

Hierarchical Population Structure Analysis of the Milkweed Beetle, Tetraopes Tetraophthalmus (Forster)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hierarchical Population Structure Analysis of the Milkweed Beetle, Tetraopes Tetraophthalmus (Forster) Heredity 58 (1987) 193—201 The Genetical Society of Great Britain Received 7 April 1986 Hierarchical population structure analysis of the milkweed beetle, Tetraopes tetraophthalmus (Forster) David E. McCauley and Department of General Biology, Vanderbilt Walter F. Eanes University, Nashville, TN 37235, U.S.A., and Department of Ecology and Evolution, SUNY at Stony Brook, Stony Brook, NY 11794, U.S.A. The population structure of the milkweed beetle Tetraopes tetraophthalmus (Forster) is tied intimately to the biology of its one host plant, Asciepias syriaca. The patchy distribution of the host plant and the limited dispersal of the beetle combine to organise the herbivore into numerous very localised populations. An analysis of hierarchical patterns of spatial variation in allozyme frequencies by means of Wright's F-statistics reveals that in some parts of the beetle's range this population structure can result in moderate genetic differentiation (F =0.03—0.06)among beetle populations inhabiting milkweed patches separated by only a few kilometres. Substantial differentiation occurs across the range of the species (F =0.154).A review of similar studies shows the values of F calculated for T. tetraophthalmus to be among the highest found for a flying insect. It is argued that the local differentiation results, in part, from a reduction in effective population sizes associated with the ephemeral nature of milkweed patches and that this population structure is favourable for the operation of Wright's Shifting Balance mode of evolution. INTRODUCTION though rarely are both approaches applied together. From recent reviews that have compiled Thespatial organisation of local populations and F-statistic data for numerous animal species (i.e., concomitant patterns of gene flow are important Eanes and Koehn, 1978; Wright, 1978; Ayala, determinants of the potential for a species to 1982; Barrowclough, 1983) it can be seen that, not become genetically differentiated over its geo- surprisingly, there is a general agreement between graphic range. This is true whether the agent of the relative degree of population structure as differentiation is spatial variation in selection measured by F(S x T) and the perceived vagility pressures or the chance effects of genetic drift. The of the species in question. For example, among study of population structure and associated gene animal species, sedentary groups such as land flow in natural populations can take two snails and salamanders tend to have relatively high approaches, one ecological and one genetic (Slat- values of F(S x T), while most species of flying kin, 1985a). Ecological studies of the dispersal of birds and insects have rather low values. individuals or their gametes use various mark and A further refinement of the application of F- recapture schemes to attempt to measure gene flow statistics to the analysis of population structure directly, and can be used to make predictions about involves hierarchical analysis. Here the total geo- the population structure of a species. In contrast, graphic component of genetic variance is parti- surveys of geographic patterns of gene frequency tioned into subcomponents due to (a) variance variation that utilise electrophoretic markers can among closely spaced local populations likely to be used to make inferences about ecological par- be exchanging migrants and (b) variance among ameters such as average local population size and groups of populations defined on a greater geo- rates of migration (e.g., Larson eta!., 1984; Slatkin, graphic scale. In one such analysis Selander and 1985b). The genetic data is often summarised by Whitham (1983) argue that localised measures of the use of F-statistics as suggested by Wright F(S x T) are most likely to reflect the effects of (1978) for the analysis of population structure. population structure and gene flow. Hierarchical Both approaches have been applied to the study F-statistic analysis was developed by Wright as of the population structure in a diversity of species, part of his Shifting Balance theory of evolution in 194 D. E. McCAULEY AND W. F. EANES which some evolutionary transitions due to the Adults can be found on the foliage of the host joint effects of selection, drift, and migration are plant from June until August, depending on loca- possible in highly structured populations but can tion. Adult beetles were collected from individual not occur in large panmictic units (Wright, 1977; milkweed patches according to a hierarchical col- 1978). lecting scheme. Milkweed patches were defined as The milkweed beetle Tetraopes tetraophthalmus nearly discrete aggregations of milkweed stalks (Forster) (Coleoptera: Cerambycidae) has been occupying from about 025 to 10 ha. All beetles the focus of several ecological studies of dispersal collected from the same patch are considered to and gene flow (McCauley et a!., 1981; McCauley, belong to the same population or random breeding 1983). These studies have concluded that the unit as evidenced by dispersal studies (McCauley, limited dispersal of the insect, combined with the 1983). Some number of populations (4-19) were patchy, island-like distribution of its host plant, sampled from each of 5 localities called regions. the common milkweed Asciepias syriaca, organise Each region consisted of an area of less than 30 x the species into thousands of local populations 30 km. Regions were defined in southern New across its range in eastern North America. Thus, Hampshire (NH), southwest Virginia (VA), middle the species would appear to have the potential for Tennessee (TN), and northern Illinois (ILL). Col- a high degree of genetic differentiation across its lections were made in New Hampshire in 1983, geographic range and should exhibit genetic Illinois in 1984, and Tennessee in 1985. Most Vir- differences between populations separated by as ginia populations were sampled in 1984, though a little as a few kilometres. The one limited genetic few localities were sampled in 1983 or 1985. All study of this species (Eanes et aL, 1977) used data presented for a particular population are polymorphic allozyme markers to document allele derived from a single generation. Because of the frequency heterogeneity among seven collections univoltine nature of this species only two gener- of T tetraophthalmus taken from individual milk- ations separate the 1983 and 1985 collections. In weed patches located in Suffolk Co., N.Y. addition, data taken from collections made on Here, we report on gene frequency variation at Long Island, New York (NY) in 1975 and three polymorphic loci derived from a more sys- described by Eanes et aL (1977) were used to tematic and hierarchical collection of beetles taken constitute a fifth region. Fig. 1 presents these across a broad geographic area. The collections regional locations against the range of the host were designed to examine whether the degree of plant as described by Chemsak (1963). local population structure documented by Eanes Beetles were stored at —70°C until they could eta!. (1977) in New York is representative of other be prepared for starch gel electrophoresis. Eanes localised regions across the species' range, and et a!. (1977) present data for leucine aminopep- also to estimate the total geographic component tidase (LAP) and phosphoglucomutase (PGM), of genetic variance. Groups of milkweed patches the only polymorphic loci they found in their were sampled on an individual patch basis within original survey. In that survey amylase, glucose-6- four 30 x 30 km regions, the regions being spaced phosphate dehydrogenase, glutamate oxaloacetate across a major portion of the range of the species. transaminase, isocitrate dehydrogenase, lactate The data, when combined with that reported by dehydrogenase, peptidase and phosphogluco- Eanes et aL (1977) are used in a hierarchical F- isomerase were resolved but found to be monomor- statistic analysis that partitions the total geo- phic (Eanes, unpubi.). Similar techniques were graphic component of genetic variance into com- followed for the resolution of LAP and PGM in ponents due to among patch variance within the the more recent samples with the following excep- local regions and a component among regions. The tions. Both enzymes could be resolved with an results are discussed in the context of the known electrode buffer described as "salamander B" by ecology of the beetle and its host plant, as well as Werth (1985) and a gel buffer consisting of a 1:9 in the context of a survey of F-statistics calculated dilution of the electrode buffer. B-mercaptoethanol for other species of insects. was added to the grinding buffer to stabilise the PGM electromorphs. A more recent enzyme survey was able to resolve two additional enzymes, malic MATERIALSAND METHODS enzyme and hexokinase. Hexokinase (HK) proved to be polymorphic when resolved with a tris-citrate Tetraopestetraophthalmus is a univoltine beetle electrode buffer (pH 8.0). The discovery of the HK whose adults and larvae feed almost exclusively polymorphism came after the on set of the Virginia on the common milkweed, Asc!epias syriaca. collecting. As a consequence not all Virginia popu- POPULATION STRUCTURE OF MILKWEED BEETLE 195 Figure1 The location of five regions from which adult Tetraopes retraophthalmus were collected. Numbers refer to the number of individual milkweed patches sampled in each region. Stippled area defines the range of the host plant, Asciepias syriaca as described by Chemsak (1963). lations were assayed for HK. Samples from various RESULTS regions were occasionally run side by side to stan- dardise allelic nomenclature. Resultsare presented as allele frequencies and Gene frequency variation was quantified by sample sizes for LAP, PGM and HK in tables 1-3 hierarchical F-statistics as suggested for the study respectively. All populations sampled expressed of population structure by Wright (1978). See Weir two electrophoretic alleles for LAP (named F and and Cockerham (1984) and Slatkin (1985a) for S), though there was considerable variation in recent discussions of the application of F-statistics frequency from region to region.
Load more

Recommended publications
  • 4 Reproductive Biology of Cerambycids
    4 Reproductive Biology of Cerambycids Lawrence M. Hanks University of Illinois at Urbana-Champaign Urbana, Illinois Qiao Wang Massey University Palmerston North, New Zealand CONTENTS 4.1 Introduction .................................................................................................................................. 133 4.2 Phenology of Adults ..................................................................................................................... 134 4.3 Diet of Adults ............................................................................................................................... 138 4.4 Location of Host Plants and Mates .............................................................................................. 138 4.5 Recognition of Mates ................................................................................................................... 140 4.6 Copulation .................................................................................................................................... 141 4.7 Larval Host Plants, Oviposition Behavior, and Larval Development .......................................... 142 4.8 Mating Strategy ............................................................................................................................ 144 4.9 Conclusion .................................................................................................................................... 148 Acknowledgments .................................................................................................................................
    [Show full text]
  • 5 Chemical Ecology of Cerambycids
    5 Chemical Ecology of Cerambycids Jocelyn G. Millar University of California Riverside, California Lawrence M. Hanks University of Illinois at Urbana-Champaign Urbana, Illinois CONTENTS 5.1 Introduction .................................................................................................................................. 161 5.2 Use of Pheromones in Cerambycid Reproduction ....................................................................... 162 5.3 Volatile Pheromones from the Various Subfamilies .................................................................... 173 5.3.1 Subfamily Cerambycinae ................................................................................................ 173 5.3.2 Subfamily Lamiinae ........................................................................................................ 176 5.3.3 Subfamily Spondylidinae ................................................................................................ 178 5.3.4 Subfamily Prioninae ........................................................................................................ 178 5.3.5 Subfamily Lepturinae ...................................................................................................... 179 5.4 Contact Pheromones ..................................................................................................................... 179 5.5 Trail Pheromones ......................................................................................................................... 182 5.6 Mechanisms for
    [Show full text]
  • 1 the RESTRUCTURING of ARTHROPOD TROPHIC RELATIONSHIPS in RESPONSE to PLANT INVASION by Adam B. Mitchell a Dissertation Submitt
    THE RESTRUCTURING OF ARTHROPOD TROPHIC RELATIONSHIPS IN RESPONSE TO PLANT INVASION by Adam B. Mitchell 1 A dissertation submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Entomology and Wildlife Ecology Winter 2019 © Adam B. Mitchell All Rights Reserved THE RESTRUCTURING OF ARTHROPOD TROPHIC RELATIONSHIPS IN RESPONSE TO PLANT INVASION by Adam B. Mitchell Approved: ______________________________________________________ Jacob L. Bowman, Ph.D. Chair of the Department of Entomology and Wildlife Ecology Approved: ______________________________________________________ Mark W. Rieger, Ph.D. Dean of the College of Agriculture and Natural Resources Approved: ______________________________________________________ Douglas J. Doren, Ph.D. Interim Vice Provost for Graduate and Professional Education I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: ______________________________________________________ Douglas W. Tallamy, Ph.D. Professor in charge of dissertation I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: ______________________________________________________ Charles R. Bartlett, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: ______________________________________________________ Jeffery J. Buler, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy.
    [Show full text]
  • Science Journals
    RESEARCH ARTICLE EVOLUTIONARY BIOLOGY 2016 © The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. Distributed Darwinian sex roles confirmed across the under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). animal kingdom 10.1126/sciadv.1500983 Tim Janicke,1* Ines K. Häderer,2 Marc J. Lajeunesse,3 Nils Anthes2 Since Darwin’s conception of sexual selection theory, scientists have struggled to identify the evolutionary forces underlying the pervasive differences between male and female behavior, morphology, and physiology. The Darwin- Bateman paradigm predicts that anisogamy imposes stronger sexual selection on males, which, in turn, drives the evolution of conventional sex roles in terms of female-biased parental care and male-biased sexual dimorphism. Al- though this paradigm forms the cornerstone of modern sexual selection theory, it still remains untested across the animal tree of life. This lack of evidence has promoted the rise of alternative hypotheses arguing that sex differences are entirely driven by environmental factors or chance. We demonstrate that, across the animal kingdom, sexual Downloaded from selection, as captured by standard Bateman metrics, is indeed stronger in males than in females and that it is evolution- arily tied to sex biases in parental care and sexual dimorphism. Our findings provide the first comprehensive evidence that Darwin’s concept of conventional sex roles is accurate and refute recent criticism of sexual selection theory. INTRODUCTION (usually the female) becomes a limiting resource for the less caring Understanding the numerous behavioral, morphological, and physio- sex (usually the male) so that the latter competes for access to the http://advances.sciencemag.org/ logical differences between the sexes constitutes a central theme in many former (10).
    [Show full text]
  • On the Factors That Promote the Diversity of Herbivorous Insects and Plants in Tropical Forests
    On the factors that promote the diversity of herbivorous insects and plants in tropical forests Judith X. Becerra1 Department of Biosphere 2, University of Arizona, Tucson, AZ 85721 Edited by Paul R. Ehrlich, Stanford University, Stanford, CA, and approved February 27, 2015 (received for review November 13, 2014) Some of the most fascinating and challenging questions in ecology relationship and potential feedback loop between divergent plant are why biodiversity is highest in tropical forests and whether the chemical defenses in a community and insect herbivore speciali- factors involved are unique to these habitats. I did a worldwide test zation that could have effects on insect and plant diversities (12, of the hypotheses that plant community divergence in antiherbi- 13). In places with mostly highly specialized herbivore–plant as- vore traits results in higher insect herbivore diversity, and that sociations, plant communities tended to have a strong pattern of predominant attack by specialized herbivores promotes plant chemical disparity. This result suggests that disparate defensive richness. I found strong correlative support for both ideas. Butterfly systems in a plant community might promote insect specialization diversity was greatest in regions where the community average because it is difficult to attack other plants that have very different species-pairwise dissimilarity in antiherbivore traits among plant antiherbivore traits relative to those of the current host (14). At species was highest. There was also a strong positive relationship the same time, the tendency of insects to specialize on plants between specialized (insect) vs. generalized (mammal) herbivores species sharing the same defenses would favor plant communities and plant richness.
    [Show full text]
  • Insects of Western North America 1
    INSECTS OF WESTERN NORTH AMERICA 1. A Survey of the Cerambycidae (Coleoptera), or Longhomed Beetles of Colorado Contributions of the C.P. Gillette Museum of Arthropod Diversity Department ofBioagricultural Sciences and Pest Management Colorado State University ISBN 1084-8819 Cover illustration. Moneilema armatum Leconte, illustration by Matt Leatherman. Copies of this publication may be ordered for $10. 00 from Gillette Museum ·of Arthropod Diversity, Department ofBioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado 80523. Make check to Gillette Museum Publications. See inside back cover for other available publications. INSECTS OF WESTERN NORTH AMERICA 1. A Survey of the Cerambycidae (Coleoptera), or Longhomed Beetles, of Colorado by Daniel J. Heffern 10531 Goldfield Lane Houston, Texas 77064 1998 Figures 1-5. 1. Leptura propinqua Bland, Larimer Co., P.A. Opler; 2. Plectrodera scalator (Fabricius), Prowers Co., P.A. Opler; 3. Megacyllene robiniae (Forster), larvae, Larimer Co., S. Krieg; 4. Tetraopesfemoratus (LeConte), Larimer Co., P.A. Opler; 5. Monochamus c. clamator (LeConte), Larimer Co., D. Leatherman. i A Sunrey of the Cerambycidae (Coleoptera), or Longhorned Beetles of Colorado Daniel J. Heffern 10531 Goldfield Lane Houston, TX 77064 Abstract The purpose of this publication is to provide an account of the longhomed beetles of Colorado, to present new distributional records and to bring pertinent literature records together. One hundred ninety-three species and subspecies in 88 genera are listed, including thirty-eight new state records. The overall species distributions and host plants are included to provide an understanding of the zoogeography and possible origins of the species in the state. All available county records are included from the major institutional collections in Colorado, literature records, and numerous private collections.
    [Show full text]
  • The Cerambycidae of North-Central Texas
    The Coleopterists Bulletin, 47(2):159-191. 1993. THE CERAMBYCIDAE OF NORTH-CENTRAL TEXAS STEVEN W. LINGAFELTER' AND NORMAN V. HORNER Department of Biology, Midwestern State University, Wichita Falls, TX 76308, U.S.A. ABSTRACT A fauna! study of the long-horned beetles (Coleoptera: Cerambycidae) from the 37 counties comprising north-central Texas produced records of 107 species and subspecies. Represented are 68 genera and 36 tribes from four subfamilies. Natural history obser­ vations including information on distribution, seasonal occurrence, and host vegetation are given for each taxon. Comments on morphological variation and taxonomic problems are included. Lists of county records accompany each species account. The Cerambycidae are a large family of morphologically diverse beetles, many of which are phytophagous on woody vegetation during their larval stage. Depending on the classification used, this family may include as many as 35,000 species worldwide (Lawrence 1982). The abundance, distribution, and diversity within the family has established its popularity among amateur and professional coleopterists. In the tropical and subtropical regions, where much attention is being directed toward the family, the diversity and abundance of these beetles is much greater than that of a temperate region like north-central Texas. This difference is shown by a study in Jalisco, Mexico, in which 13 successive early morning trips to an illuminated roadside sign yielded a total of 101 species (Chemsak et al. 1988). In contrast, this comprehensive, comparatively long­ term study of temperate north-central Texas revealed a total of only 107 taxa. The area of north-central Texas (hereafter abbreviated NCT) included in this survey is shown in Fig.
    [Show full text]
  • A NOTE on the LIFE-CYCLE of TETRAOPES FEMORATUS LECONTE (Cerambcidze) by R
    1941] Life-cycle of Tetraopes tetrophthalmus 169 A NOTE ON THE LIFE-CYCLE OF TETRAOPES FEMORATUS LECONTE (CERAMBCIDzE) By R. W. WILLIAMS, University of Illinois While making a study of the bionomics of the common milkwood beetle, Tetraopes tetrophthalmus (Forst.), during the summer of 1940 at Urbana Illinois, I found, on August 11, a fully developed Tetraopes larva tunneling through the center of the horizontal root of the common milkweed, Asclepias syriaca. This larva was identified at the United States National Museum as being different from those thought to be T. tetrophthalmus. Unfortunately the species could not be determined since investigators had never asso- ciated larvm similar to this one with an adult beetle. Since tetrophthalmus and femoratus were the only species of Tetraopes seen during my observations I believe that this single specimen was a representative of femoratus. The size of the individual would also warrant this conclusion since the adult of femoratus is the largest species of Tetraopes found in the state. This specimen was 2.3 mm. in length. Larvm of T. tetrophthalmus, which were found during the fall of 1939, ranged from 13 to 19 mm. in length. The first adult of T. femora.tu.s was seen on July 23. It seemed highly improbable that eggs could have been de- posited and the larvm from these eggs could have reached a fully developed condition within a period of twenty days or even a month, assuming that the adults were present earlier. These facts, therefore, seem to indicate that at least some individuals of this species may spend two or more years in the larval condition about the roots of milkweed.
    [Show full text]
  • Milkweeds a Conservation Practitioner’S Guide
    Milkweeds A Conservation Practitioner’s Guide Plant Ecology, Seed Production Methods, and Habitat Restoration Opportunities Brianna Borders and Eric Lee-Mäder The Xerces Society FOR INVERTEBRATE CONSERVATION The Xerces Society for Invertebrate Conservation 1 MILKWEEDS A Conservation Practitioner's Guide Brianna Borders Eric Lee-Mäder The Xerces Society for Invertebrate Conservation Oregon • California • Minnesota • Nebraska North Carolina • New Jersey • Texas www.xerces.org Protecting the Life that Sustains Us The Xerces Society for Invertebrate Conservation is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. Established in 1971, the Society is at the forefront of invertebrate protection, harnessing the knowledge of scientists and the enthusiasm of citizens to implement conservation programs worldwide. The Society uses advocacy, education, and applied research to promote invertebrate conservation. The Xerces Society for Invertebrate Conservation 628 NE Broadway, Suite 200, Portland, OR 97232 Tel (855) 232-6639 Fax (503) 233-6794 www.xerces.org Regional offices in California, Minnesota, Nebraska, New Jersey, North Carolina, and Texas. The Xerces Society is an equal opportunity employer and provider. © 2014 by The Xerces Society for Invertebrate Conservation Acknowledgements Funding for this report was provided by a national USDA-NRCS Conservation Innovation Grant, The Monarch Joint Venture, The Hind Foundation, SeaWorld & Busch Gardens Conservation Fund, Disney Worldwide Conservation Fund, The Elizabeth Ordway Dunn Foundation, The William H. and Mattie Wat- tis Harris Foundation, The CERES Foundation, Turner Foundation Inc., The McCune Charitable Founda- tion, and Xerces Society members. Thank you. For a full list of acknowledgements, including project partners and document reviewers, please see the Acknowledgements section on page 113.
    [Show full text]
  • Chromosome Numbers of Coleoptera*
    CHROMOSOME NUMBERS OF COLEOPTERA* STANLEY G. SMITH Forest Insect Laboratory, Sault Ste. Marie, Ontario Received 7.vi.52 THE present is a complete list of the chromosome numbers of Coleoptera. That in Makino's (I95I) An Atlas of the Chromosome Numbers in Animals is replete with errors : not in the numbers themselves -almost without exception, these have been faithfully recorded from the originals-but in the spelling of the specific, generic, and family names, as well as in the nomenclature and systematic disposition of many of the species. f Considering the difficulties with which Makino was faced, the coverage of the literature is good, perhaps no more than I4 determinations by nine authors being omitted. I had earlier intended to compile a list of some I6o chromosome determinations, which I have made as time permitted during the course of the past eight years, together with others that have appeared in print, and to publish them as a supplement bringing those given by Harvey (Igi6 and Ig2o) up to date, but it now appears that a complete revision of Makino's list is warranted. It is perhaps note­ worthy that II families find themselves represented for the first time and that the total of cytologically known Coleoptera now reaches 340. According to Makino's tabulation, this number is surpassed among Insecta only in the Orthoptera and Heteroptera but in no other animal group, and constitutes approximately IO per cent. of the species of animals whose chromosome numbers have been recorded. The distribution of species, genera, subfamilies, and families by haploid number of autosomes and by sex-chromosome type is given graphically in fig.
    [Show full text]
  • Feeding Biology of Cerambycids, Chapter 3
    3 Feeding Biology of Cerambycids Robert A. Haack USDA Forest Service Lansing, Michigan CONTENTS 3.1 Introduction .................................................................................................................................. 105 3.2 Adult Feeding Habits ................................................................................................................... 106 3.2.1 Types of Adult Food ........................................................................................................ 106 3.2.2 Food and Adult Reproduction ......................................................................................... 107 3.2.3 Food and Adult Flight, Pollination, and Disease Transmission ...................................... 107 3.2.4 Predatory Cerambycids ................................................................................................... 108 3.3 Larval Feeding Habits .................................................................................................................. 108 3.3.1 Larval Host Plants ........................................................................................................... 108 3.3.2 Plant Parts Utilized by Larvae .........................................................................................110 3.3.3 Host Tissues Utilized ........................................................................................................115 3.3.4 Host Range .......................................................................................................................116
    [Show full text]
  • Milkweed Longhorns
    Colorado Insects of Interest Milkweed Longhorns Scientific Names: Tetraopes annulatus LeConte; Tetraopes femoratus LeConte; Tetraopes mandibularis Chemsak; Tetraopes tetrophthalmus (Forster) (red milkweed beetle); Tetraopes pilosus Chemsak; Tetraopes discoideus LeConte Order: Coleoptera (Beetles) Family: Cerambycidae (Longhorned Beetles) Figure 1. Tetraopes femoratus adult Identification and Descriptive Features: The most common species are primarily reddish to reddish-orange with black spotting and range from about 10-16 mm in length. Tetraopes pilosus is lighter colored with fine hairs covering the wing covers; T. tetrophthalmus is darker red than other species and known by the common name “red milkweed beetle”. Tetraopes discoideus is much smaller than the other species (7-9 mm) with heavily marked wing covers. Substantial variation in patterning and coloring is common in most species. Distribution in Colorado: Tetraopes femoratus and T. annulatus are widespread and can be found throughout most of the state in association with its milkweed hosts. Tetropes pilosus occurs across the eastern plains; T. discoideus and is found in southeastern Colorado. T. tetrophthalmus, the most common species in the eastern US, ranges into eastern Colorado and is most commonly found in the southeastern counties. Relatively recently T. mandibularis has also been recognized as occuring in eastern Colorado. The occurrence of suitable species Figure 2. Tetraopes discoideus, a small of milkweed (Asclepias spp.) and soil type affect local milkweed longhorn associated with horsetail milkweed. distribution. Life History and Habits: All of the milkweed longhorns feed and develop on milkweeds (Asclepias spp.). Some may feed on a single milkweed species, such as the association of T. discoideus with horsetail milkweed (Asclepias subverticillata).
    [Show full text]