The Responses of Grasshoppers to Ecological Changes Produced by Agricultural Development in Southwestern Manitoba

Abstract

Southwestern Manitoba, a semiarid area subject to periodic droughts, was originally covered by a mixed prairie on light sandy soil. Settlement commenced on the completion of the land survey in 1890. By 1913 all the land was taken up and a cereal grain economy had developed. Soil drifting became a problem and was particularly severe during the drought years of 1929 to 1934. Local species of grasshoppers, Melanoplus sanguinipes (Fabricius), Melanoplus bivittatus (Say) and Camnula pellucida (Scudder) first became pests during a minor drought in 1901 and occurred in a severe outbreak in the major drought period. Recently abandoned fields suffered severe wind erosion and drift ridges of soil provided the most favorable egg laying sites for M. sanguinipes and to a lesser extent for M. bivittatus. The effect of slope of ground on egg deposition and grasshopper behavior in relation to temperature and moisture are recorded. Succulent, introduced weeds and cereal crops supplied abundant food. C. pellucida, a grass feeder, was favored by the planting of cereal crops adjacent to egg bed sites among Carex stenophylla Wahl., and Agropyron smithii Rydb. on the roadsides. Methods of farming designed to prevent wind erosion, the use of herbicides and the grading of roadsides have shown the possibilities of ecological management to reduce grasshopper increase.

MIGRATION IN THE GRASSHOPPERMELANOPLUS SANGUINIPES(FAB.). I. THE CAPACITY FOR FLIGHT IN NON-SWARMING POPULATIONS

“…Flight tests were conducted between 3 and 12 hours after sunrise or lights-on. These conditions simulate those observed to be necessary for occurrence of migratory flights in the field (Parker et al, 1955;Bird et al, 1966) and flight in a wind tunnel (Riegert, 1962). Take-off was initiated by breaking tarsal contact or by moving the tethered animal rapidly through the air in a horizontal figure-8 pattern for several seconds.…”

Genetic variation in prairie populations of Melanoplus sanguinipes, the migratory grasshopper

“…No data on the migratory status (there are reportedly morphometric differences between migratory and nonmigratory M. san guinipes-see Paul and Putnam, 1960;Beirne, 1972) were given. Reports on causes of movement (these usually centre on the availability of food), role of wind, and direction of movement are contradictory (Corkins, 1922;Shotwell, 1930;Parker et a!., 1955;Bird et a!., 1966; 1968; Beirne, 1972;Turnock, 1977); reports on direction are assumed to be accurate. Of particular interest is Turnock's statement that there have been easterly movements towards the parkland area and the subsequent establishment of populations (northerly, northwesterly and southerly movements have also been recorded with respect to the study area).…”

Density‐dependent physiological phase in a non‐migratory grasshopper Aiolopus thalassinus

“…For some species, the degradation of the natural habitat is detrimental. Other, more adaptable species, may assume minor or major pest status as a consequence of cultivation (Bird et al, 1966;Amatobi et al, 1988). Thus, Aiolopus savingnyi (=A.…”

“…Seasonal influx may cause considerable damage even when the invading grasshoppers find the crop unsuitable and do not establish permanent populations within the irrigated fields. Chronic damage to agricultural crops and rangeland by endemic or seasonally migrating grasshoppers, is a major feature of the Sahelian ecosystem (Bindra & Amatobi, 1981) and of the great plains of North America (Bird et al, 1966).…”