Grasshopper Numbers Research Articles

Some Ecological Factors Affecting the Grasshopper Populations of Western Canada

AbstractThe underlying causes of grasshopper outbreaks in Western Canada are of interest both as an academic problem in insect population dynamics and as a practical problem in modern agriculture. Grasshopper populations reach their annual low point in early July when they are in the adult stage and increase sharply in the fall at the time of oviposition. Any factor that influences the grasshoppers during this period may have a marked effect on the outbreak of the following year. The relationship between grasshopper population numbers and proceeding fall temperatures may either control grasshopper populations directly by affecting their physiology or indirectly by affecting their parasites, predators, and diseases. Studies at the University of Saskatchewan aimed at solving this problem include investigation of the microclimate to which grasshoppers are subjected under field conditions, a survey of their feeding habits as shown by crop analyses, and a study of their oviposition behaviour. On the basis of available information an attempt is being made to predict future outbreaks at least 6 months in advance.

Seasonal Losses in Rangeland Vegetation Due to Grasshoppers1

Livestock-free grazing areas were used for studies of grasshopper damage on Montana rangelands. Half of each study area was sprayed with an insecticide at the beginning of the season to eliminate nearly all grasshoppers. The grasshopper population remaining on the unsprayed portion of the area was assessed by the use of cages that were placed over representative areas at night. Within both the sprayed and unsprayed portions of an area, sites were selected which appeared comparable from the standpoint of both the composition and abundance of the vegetation. Quadrates were established at these sites in which production was measured by clipping the vegetation at ground level, air-dried, and weighed. A comparison of the yield from an area without grasshoppers was thus made with that from an area on which grasshoppers fed. Little correlation was found between numbers of grasshoppers per unit area and the loss of vegetation. This may be accounted for by the differences in feeding habits of the various species comprising any particular grasshopper population. Further evaluation of the data from the various studies has proved more difficult. Problems have arisen primarily because of the nonrandom distribution of both grasshoppers and vegetation even where so-called uniform types of vegetation were considered. Difficulties in interpretation have also been encountered by the lack of knowledge concerning the phenomena of plant growth as shown by a study of two comparable areas during 1950-1959. These areas were subjected to grazing by livestock during the winter months only and the numbers of grasshoppers remained much below 1 per square yard during the period. Differences in yield of vegetation from the two areas were measured and it was found that considerable loss in forage may take place during a season without grasshoppers being present.

An Abnormal Grasshopper with Two Median Ocelli (Orthoptera, Acrididae)

Among a number of grasshoppers caught near Iowa City in October 1957 a male Melanoplus differentialis differentialis (Thomas) with two median ocelli was found. The unusual condition was not noticed until the head had been removed for experimental work and the cut cervicum had been sealed with vaseline. Several hours later the head—still alive as indicated by the movements of mouth parts and antennae—was placed in 70 percent alcohol to which a little formalin had been added.

The Road Runner of North America

ONE of the most remarkable and interesting birds of the arid portions of North America is the road runner (Geococcyx californianus), a ground cuckoo, which is often seen running in the road, sharing this habit with the killdeer plover (Oxyechus vociferus). The genus extends southward to Nicaragua, being represented in that region by another species (Geococcyx affinis). The accompanying illustration (Fig. 1) of a road runner attacking a rattlesnake, was furnished by Mr. G. A. Pearl of Garden City, Kansas. He got it from a travelling photographer whose name he does not know. Mrs. Merriam Bailey states that in the stomach of a single road runner, taken in New Mexico, were a large black cricket, a number of big grasshoppers, remains of a caterpillar and some beetles, a centipede six inches long and a garter snake a foot long.

Ecology of Populations

Previous articleNext article No AccessEcology of PopulationsG. F. GauseG. F. Gause Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 7, Number 1Mar., 1932 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/394394 Views: 12Total views on this site Citations: 19Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Isabelle Marie Kramer, Marie Pfeiffer, Oliver Steffens, Friederike Schneider, Viviane Gerger, Parbati Phuyal, Markus Braun, Axel Magdeburg, Bodo Ahrens, David A. Groneberg, Ulrich Kuch, Meghnath Dhimal, Ruth Müller The ecophysiological plasticity of Aedes aegypti and Aedes albopictus concerning overwintering in cooler ecoregions is driven by local climate and acclimation capacity, Science of The Total Environment 778 (Jul 2021): 146128.https://doi.org/10.1016/j.scitotenv.2021.146128Ludmila Kirianova, Temirkhan Aleroev, Vladimir Griguletskiy Fractional Diffusion Equation as a Mathematical Model of the Incidence of Coronavirus Disease Covid-19, (Sep 2021): 527–537.https://doi.org/10.1007/978-981-16-2450-6_24I. G. Vorob’eva, E. Yu. Toropova On the Issue of Ecological Niches of Plant Pathogens in Western Siberia, Contemporary Problems of Ecology 12, no.66 (Dec 2019): 667–674.https://doi.org/10.1134/S1995425519060155Nataliia Kodash, Martin Fischer Georgy Gause’s shift from ecology and evolutionary biology to antibiotics research: reasons, objectives, circumstances, Theory in Biosciences 137, no.11 (Apr 2018): 79–83.https://doi.org/10.1007/s12064-018-0262-9Chia-Hsuan Hsu, Keryea Soong, Geerat J. Vermeij Mechanisms causing size differences of the land hermit crab Coenobita rugosus among eco-islands in Southern Taiwan, PLOS ONE 12, no.44 (Apr 2017): e0174319.https://doi.org/10.1371/journal.pone.0174319Frank N. Egerton History of Ecological Sciences, Part 55: Animal Population Ecology, Bulletin of the Ecological Society of America 96, no.44 (Oct 2015): 560–626.https://doi.org/10.1890/0012-9623-96.4.560 References, (Apr 2014): 385–440.https://doi.org/10.1201/b16805-14 References, (Mar 2012): 309–360.https://doi.org/10.1002/9781119968535.refs Real and Generic Data without Unconstrained Best-Fitting Verhulst Curves and Sufficient Conditions for Median Mitscherlich and Verhulst Curves to Exist, The American Mathematical Monthly 119, no.33 (Mar 2012): 211–234.https://doi.org/10.4169/amer.math.monthly.119.03.211Robert J. Henszey, Kent Pfeiffer, Janet R. Keough Linking surface- and ground-water levels to riparian grassland species along the Platte River in central Nebraska, USA, Wetlands 24, no.33 (Sep 2004): 665–687.https://doi.org/10.1672/0277-5212(2004)024[0665:LSAGLT]2.0.CO;2Giorgio Israel, Ana Millán Gasca References, (Jan 2002): 389–405.https://doi.org/10.1007/978-3-0348-8123-4_24Eric W. Seabloom, Kirk A. Moloney, Arnold G. van der Valk CONSTRAINTS ON THE ESTABLISHMENT OF PLANTS ALONG A FLUCTUATING WATER-DEPTH GRADIENT, Ecology 82, no.88 (Aug 2001): 2216–2232.https://doi.org/10.1890/0012-9658(2001)082[2216:COTEOP]2.0.CO;2Johann Hohenegger Depth estimation by proportions of living larger foraminifera, Marine Micropaleontology 26, no.1-41-4 (Dec 1995): 31–47.https://doi.org/10.1016/0377-8398(95)00044-5R. Hengeveld Ecological biogeography, Progress in Physical Geography: Earth and Environment 17, no.44 (Aug 2016): 448–460.https://doi.org/10.1177/030913339301700403William Tulio Divale, Frosine Chamberis, Deborah Gangloff War, Peace, and Marital Residence in Pre-Industrial Societies, Journal of Conflict Resolution 20, no.11 (Mar 1976): 57–78.https://doi.org/10.1177/002200277602000102S. S. Wasti, D. W. Hosmer, S. B. Blum Population density and larval competition in Diptera, Zeitschrift für Angewandte Entomologie 79, no.1-41-4 (Aug 2009): 428–435.https://doi.org/10.1111/j.1439-0418.1975.tb02365.xK. Friederichs Folgerungen aus den neuen Untersuchungen über die Forleule, Anzeiger für Schädlingskunde 11, no.22 (Feb 1935): 19–23.https://doi.org/10.1007/BF02336122G. F. Gause Über einige quantitative Beziehungen in der Insekten-Epidemiologie, Zeitschrift für Angewandte Entomologie 20, no.44 (Aug 2009): 619–623.https://doi.org/10.1111/j.1439-0418.1934.tb00386.xW. C. ALLEE RECENT STUDIES IN MASS PHYSIOLOGY 1, Biological Reviews 9, no.11 (Jan 1934): 1–48.https://doi.org/10.1111/j.1469-185X.1934.tb00872.x

Estimating the Abundance of, and Damage Done by Grasshoppers

Because of extreme activity the numbers of grasshoppers, Acrididae, are hard to estimate. By aid of a field glass the observer can stand at some distance and count those in a given unit. Many units of ground should be so counted in a field before an estimate of the grasshoppers can be made. A knowledge of the egg laying habits is necessary before an estimate of the number of eggs in a locality can be made. Estimating the per cent of damage in a particular field is done by comparison of the amount of damaged seed in several small units with the undamaged seed. When making up a statement of the damage done by grasshoppers over a wide area, the entomologist should, when possible, compare the yield of damaged sections with the yield of localities where there were no grasshoppers but which had other limiting factors equal. A comparison of the yield during the grasshopper infestation with the yield in the same localities but in years when there were few, if any, grasshoppers can be made but before the entomologist can estimate the damage done by grasshoppers, he must know the action, during the years under comparison, of other limiting factors such as rainfall, temperature, sunshine, winds, and crop diseases.