Resistance to Low Temperatures of the Overwintering Stages of Two Introduced Parasites of the European Pine Shoot Moth, Rhyacionia buoliana (Schiff.) (Lepidoptera: Olethreutidae)

1960 ◽  
Vol 92 (9) ◽  
pp. 701-704 ◽  
Author(s):  
J. A. Juillet
Keyword(s):  
Low Temperatures ◽  
Laboratory Experiments ◽  
Field Observations ◽  
Southern Ontario ◽  
Larval Stages ◽  
Winter Temperatures ◽  
Possible Cause

Two introduced hymenopterous parasites of the European pine shoot moth, Rhyacionia buoliana (Schiff.), are established and widely distributed in southern Ontario: the braconid Orgilus obscurator (Nees) and the ichneumonid Temelucha interruptor (Grav.). Though these two species are economically important in the control of the shoot moth in Europe, they have never become efficient in Canada. A possible cause of their lack of efficiency may be their susceptibility to low temperatures.This paper is a report on an investigation of the ability of these parasites to withstand low winter temperatures. Laboratory experiments were conducted to determine the resistance of the overwintering larval stages of the parasites to low temperatures. Field observations on the mortality of host and parasites were made at the Waterloo County Reforestation Area, Elmira, near Guelph, Ontario, during the winter of 1958–1959.

The Toxicity of Malathion, Perthane, Maneb and Zineb to Trialeurodes vaporariorum (Westwood)

1964 ◽  
Vol 96 (3) ◽  
pp. 541-549 ◽  
Author(s):  
R. D. McMullen
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Laboratory Experiments ◽  
Trialeurodes Vaporariorum ◽  
Antagonistic Effects ◽  
Larval Stages ◽  
First Instar ◽  
Wettable Powder

AbstractIn laboratory experiments wettable and emulsifiable malathion and Perthane were most toxic to adult T. vaporariorum and progressively less so to the larval stages in order of development. Eggs were not killed. Perthane was most toxic at low temperatures, malathion at high temperatures. Malathion was more toxic than Perthane and the emulsifiable formulations of both more toxic than the wettable formulations. Against first-instar larvae, at the LD50, level, 70% maneb and 50% Perthane wettable powders were equally toxic but 65% zineb wettable powder was less toxic. Against adults, 70% maneb and 65% zineb wettable powders were one-half and one-third as toxic as 50% Perthane wettable powder at the LD50, level. Tests of spray mixtures against larvae with either 25% malathion or 50% Perthane wettable powders added to either 70% maneb or 65% zineb wettable powders showed neither synergistic nor antagonistic effects.

EFFECT OF LOW TEMPERATURES ON MORTALITY OF HIBERNATING CODLING MOTH LARVAE AND FERTILITY OF SURVIVING ADULTS (LEPIDOPTERA: OLETHREUTIDAE)

1977 ◽  
Vol 109 (1) ◽  
pp. 123-127
Author(s):  
E. A. C. Hagley
Keyword(s):  
Low Temperatures ◽  
Larval Mortality ◽  
Codling Moth ◽  
Adult Survival ◽  
Southern Ontario ◽  
Georgian Bay ◽  
Bay Area ◽  
Winter Temperatures ◽  
Cent Mortality

AbstractMortality of hibernating codling moth larvae from the Georgian Bay area and the Niagara peninsula of southern Ontario was not affected after exposure to temperatures as low as −16.7°C for 48 h. One hundred per cent mortality occurred at −20.0°C after pre-conditioning the larvae for several weeks by exposure to gradually decreasing temperatures. In neither area were the minimum winter temperatures low enough nor of sufficient duration to significantly affect larval mortality. There was no effect on pupal or adult survival or on the fecundity and fertility of surviving adults following exposure of larvae to low temperatures.

scholarly journals Hydraulic transmissivity inferred from ice-sheet relaxation following Greenland supraglacial lake drainages

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ching-Yao Lai ◽  
Laura A. Stevens ◽  
Danielle L. Chase ◽  
Timothy T. Creyts ◽  
Mark D. Behn ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Ice Sheet ◽  
Drainage System ◽  
Greenland Ice Sheet ◽  
Field Observations ◽  
Surface Uplift ◽  
Drainage Networks ◽  
Order Of Magnitude ◽  
Lake Drainage ◽  
Magnitude Increase

AbstractSurface meltwater reaching the base of the Greenland Ice Sheet transits through drainage networks, modulating the flow of the ice sheet. Dye and gas-tracing studies conducted in the western margin sector of the ice sheet have directly observed drainage efficiency to evolve seasonally along the drainage pathway. However, the local evolution of drainage systems further inland, where ice thicknesses exceed 1000 m, remains largely unknown. Here, we infer drainage system transmissivity based on surface uplift relaxation following rapid lake drainage events. Combining field observations of five lake drainage events with a mathematical model and laboratory experiments, we show that the surface uplift decreases exponentially with time, as the water in the blister formed beneath the drained lake permeates through the subglacial drainage system. This deflation obeys a universal relaxation law with a timescale that reveals hydraulic transmissivity and indicates a two-order-of-magnitude increase in subglacial transmissivity (from 0.8 ± 0.3 $${\rm{m}}{{\rm{m}}}^{3}$$ m m 3 to 215 ± 90.2 $${\rm{m}}{{\rm{m}}}^{3}$$ m m 3 ) as the melt season progresses, suggesting significant changes in basal hydrology beneath the lakes driven by seasonal meltwater input.

Flower cold hardiness: a potential determinant of the flowering sequence exhibited by bog ericads

1979 ◽  
Vol 57 (9) ◽  
pp. 997-999 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Low Temperatures ◽  
Cold Hardiness ◽  
Vaccinium Macrocarpon ◽  
Southern Ontario ◽  
Air Temperatures ◽  
Insect Pollinators ◽  
Cold Hardy ◽  
Vaccinium Myrtilloides ◽  
Potential Determinant ◽  
Ledum Groenlandicum

In laboratory freezing trials, cold hardiness of six types of bog ericad flowers differed significantly (i.e., Chamaedaphne calyculata > Andromeda glaucophylla > Kalmia polifolia > Vaccinium myrtilloides > Ledum groenlandicum > Vaccinium macrocarpon) at air temperatures between −4 and −10 °C but not at temperatures above −2 °C. At the Luther Marsh bog in southern Ontario, low temperatures (−3 to −7 °C) would select against May flowering by the least cold hardy ericads. Availability of pollinators, on the other hand, would encourage May flowering by the most cold hardy species. Presumably, competition for insect pollinators has promoted the diversification of bog ericad flowering peaks, while air temperature, in conjunction with flower cold hardiness, determined the order in which flowering peaks were reached.

Trend surface analysis of major late Wisconsinan till sheets, Brantford–Woodstock area, southern Ontario

1978 ◽  
Vol 15 (6) ◽  
pp. 1025-1036 ◽  
Author(s):  
W. R. Cowan
Keyword(s):  
Strong Relationship ◽  
High Energy ◽  
Field Observations ◽  
Trend Surface Analysis ◽  
Southern Ontario ◽  
Niagara Escarpment ◽  
Regional Trends ◽  
Grade Material ◽  
Late Wisconsinan ◽  
Relationship Of

Linear and quadratic trend surfaces were computed for textural, carbonate, clast, and heavy mineral properties of the Catfish Creek (Nissouri Stadial), Port Stanley (Port Bruce Stadial), Tavistock (Port Bruce Stadial), and Wentworth (Port Huron Stadial) tills.Catfish Creek Till pebble grade material provided trend surfaces reflecting the underlying bedrock. However, an overall lack of regional trends in Catfish Creek Till is consistent with field observations that indicate remarkable uniformity for this till over several hundred square kilometres, a phenomenon that is believed to reflect the high energy of this ice sheet. Carbonates in Port Stanley Till were found to increase from east to west as the Silurian–Devonian contact was crossed. Tavistock Till was found to have increasing sand content and decreasing silt content from northwest to southeast owing to incorporation of underlying glaciofluvial sediments; pebble trends reflect the underlying bedrock for the most part. Wentworth Till trend surfaces for carbonates and pebbles show high dolomite near the Niagara Escarpment to the east and northeast with a dilution of dolomite and influx of limestone to the southwest.The strong relationship of the trend surfaces to substrate materials indicates the basal nature of the tills and the local origin of most glacial deposits. Pebble lithologies provide much information about local bedrock and drift prospectors should give close consideration to coarse fragments.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

scholarly journals A sink host allows a specialist herbivore to persist in a seasonal source

2021 ◽  
Vol 288 (1958) ◽  
pp. 20211604
Author(s):  
Alicja Laska ◽  
Sara Magalhães ◽  
Mariusz Lewandowski ◽  
Ewa Puchalska ◽  
Kamila Karpicka-Ignatowska ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Laboratory Experiments ◽  
Field Observations ◽  
Stepping Stones ◽  
Specialist Herbivore ◽  
Negative Growth Rate ◽  
Evolutionary Rescue ◽  
Main Host ◽  
Negative Growth

In seasonal environments, sinks that are more persistent than sources may serve as temporal stepping stones for specialists. However, this possibility has to our knowledge, not been demonstrated to date, as such environments are thought to select for generalists, and the role of sinks, both in the field and in the laboratory, is difficult to document. Here, we used laboratory experiments to show that herbivorous arthropods associated with seasonally absent main (source) habitats can endure on a suboptimal (sink) host for several generations, albeit with a negative growth rate. Additionally, they dispersed towards this host less often than towards the main host and accepted it less often than the main host. Finally, repeated experimental evolution attempts revealed no adaptation to the suboptimal host. Nevertheless, field observations showed that arthropods are found in suboptimal habitats when the main habitat is unavailable. Together, these results show that evolutionary rescue in the suboptimal habitat is not possible. Instead, the sink habitat functions as a temporal stepping stone, allowing for the persistence of a specialist when the source habitat is gone.

Sign in / Sign up

Export Citation Format

Share Document