HEAT TOLERANCE OF LAST-INSTAR LARVAE OF THE LARCH SAWFLY, PRISTIPHORA ERICHSONII (HYMENOPTERA: TENTHREDINIDAE)

1967 ◽  
Vol 99 (11) ◽  
pp. 1150-1156 ◽  
Author(s):  
R. J. Heron
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Heat Tolerance ◽  
Free Water ◽  
Temperature Acclimation ◽  
Mortality Factor ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Conditioning Temperature

AbstractLaboratory tests of heat tolerance of last-instar larvae of the larch sawfly, Pristiphora erichsonii (Htg.), were made to provide information for the evaluation of the role of high temperature as a mortality factor in field populations.Test larvae were reared from eggs at 21 ± 1.5 °C and 50 ± 10% relative humidity. LT50's were determined at 37°, 39°, 40°, and 41 °C for larvae conditioned at 30 °C and 75% relative humidity.Larvae were less heat resistant during the first 24 hours after molting than they were 24 to 48 hours after molting. The conditioning temperature and the duration of conditioning had very significant effects on heat tolerance. Differences in acclimation due to heat treatment could not be accounted for by differences in free water content.Temperature acclimation will occur in field populations and must be considered in evaluating the role of high temperature as a natural mortality factor.Larvae may encounter lethal temperatures when wandering on branches or tree trunks or crawling on dry ground in open sunshine.

An Outbreak of the Larch Sawfly (Pristiphora erichsonii (Htg.)) in the Maritime Provinces (Hymenoptera: Tenthredinidae) and the Role of Parasites in its Control

1954 ◽  
Vol 86 (10) ◽  
pp. 471-480 ◽  
Author(s):  
W. A. Reeks
Keyword(s):  
Prince Edward Island ◽  
Ecological Study ◽  
Maritime Provinces ◽  
Forest Insect ◽  
Staff Members ◽  
The Past ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Insect Survey

At least four outbreaks of the larch sawfly, Pristiphora erichsonii (Htg.), have occurred in the Maritime Provinces within the past 70 years. The first (1) occurred from about 1883 to 1885, the second from about 1906 to 1909 (1), and the third from 1919 to 1927. The last outbreak started in 1933 and ended in 1942. Despite extensive sampling by the Forest Insect Survey from 1943 to 1953, only six samples have been taken during this period in the three Maritime Provinces, and each was an isolated colony. Although an ecological study of the insect was not attempted during the latest outbreak, general observations were made by the writer and other staff members of the Survey. These observations are summarized in the present paper to record the outbreak and some of the factors that contributed to its termination. Another outbreak has persisted in Newfoundland from 1942 and perhaps earlier, but the present discussion is largely confined to events in New Brunswick, Nova Scotia, and Prince Edward Island.

FACTORS INFLUENCING THE FALL EMERGENCE OF BESSA HARVEYI (TACHINIDAE: DIPTERA)

1973 ◽  
Vol 105 (3) ◽  
pp. 399-409 ◽  
Author(s):  
W. J. Turnock
Keyword(s):  
Mortality Factor ◽  
Regression Analyses ◽  
Strong Negative Correlation ◽  
Factors Influencing ◽  
Long Day ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Host Development ◽  
Common Parasite ◽  
Heavy Mortality

AbstractBessa harveyi (Townsend) is a common parasite of the larch sawfly, Pristiphora erichsonii (Hartig), in southeastern Manitoba but it is ineffective in preventing or terminating outbreaks of its host. Bivoltinism acts as a mortality factor in B. harveyi populations because bivoltine individuals do not contribute progeny to the next generation. Heavy mortality due to bivoltinism occurs when the parasite eggs are laid under long-day conditions and the summer is warm and prolonged. Regression analyses show that most of the variation in the incidence of bivoltinism between years and between dates within years can be described by equations involving the incidence of bivoltinism in the previous year, photoperiod, and temperature. The importance of a genetic factor in determining the incidence of bivoltinism was indicated by a strong negative correlation between the incidences in consecutive years. Photoperiod and temperature during development were positively correlated with incidence. The persistence of bivoltinism in Manitoba is postulated to be related to variability in weather and host development plus developmental advantages associated with the bivoltine phenotype.

DIFFERENCES IN POSTDIAPAUSE DEVELOPMENT AMONG GEOGRAPHICALLY DISTINCT POPULATIONS OF THE LARCH SAWFLY, PRISTIPHORA ERICHSONII (HYMENOPTERA: TENTHREDINIDAE)

1972 ◽  
Vol 104 (8) ◽  
pp. 1307-1312 ◽  
Author(s):  
R. J. Heron
Keyword(s):  
Relative Humidity ◽  
Northwest Territories ◽  
Cold Treatment ◽  
Adult Emergence ◽  
Population Differences ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
C 50 ◽  
The Times ◽  
Prolonged Diapause

AbstractDistinct differences were observed in postdiapause development and prolonged diapause of the larch sawfly, Pristiphora erichsonii (Hartig), obtained from the vicinity of Tazin River, Northwest Territories; near Riverton, Manitoba; and near Renovo, Pennsylvania. All populations had been reared under controlled laboratory conditions (21°±0.5 °C, 50±10% relative humidity, and a 15-hr daily photophase) for two or more generations.After 280 days cold treatment at 3°±1 °C, cocoons were dissected and the number of pronymphs and eonymphs was determined. Insects from each population were then reared at 5°, 10°, and 15 °C. Times to adult emergence, duration of individual stages, and numbers remaining in prolonged diapause at each temperature were determined.The most significant differences occurred among populations reared at 5 °C. At this temperature, the times to adult emergence and the duration of individual stages of development and the proportions remaining in prolonged diapause or arrested development, increased from northern to southern latitudes. Less significant population differences were noted at 10° and 15° than at 5 °C.

scholarly journals The Role of Chromium in Iron-based High-Temperature Water-Gas Shift Catalysts under Industrial Conditions

2021 ◽  
pp. 120465
Author(s):  
M.I. Ariëns ◽  
V. Chlan ◽  
P. Novák ◽  
L.G.A. van de Water ◽  
A.I. Dugulan ◽  
...  
Keyword(s):  
High Temperature ◽  
Water Gas Shift ◽  
High Temperature Water ◽  
Iron Based ◽  
Water Gas ◽  
Temperature Water

Small Mammals as Predators of Sawflies

1955 ◽  
Vol 87 (3) ◽  
pp. 121-123 ◽  
Author(s):  
C. H. Buckner
Keyword(s):  
Small Mammals ◽  
Biological Control Agent ◽  
Control Agent ◽  
Moderate Risk ◽  
Neodiprion Abietis ◽  
Ample Opportunity ◽  
Pristiphora Erichsonii ◽  
Mammalian Predators ◽  
One Year

The greatest predatory effect of small mammals is exerted upon insects that spend a portion of their life cycle on the ground or in the soil. Sawflies afford ample opportunity for mammalian predation, since they drop to the ground as mature larvae and spin cocoons in the soil. Such sawflies as Neodiprion abietis Harr., which remain within the cocoon for about three weeks, undergo only moderate risk of being preyed upon by small mammal. However, Pristiphora erichsonii (Htg.) remains within the cocoon from about mid-August until the following June, or even over more than one year, thus greatly extending the vulnerable period. Earlier investigations suggest that small mammals may comprise the largest single biological control agent acting against this insect (Graham 1928, Lejeune 1951), but the exact role of mammalian predators of forest insects has yet to be established.

scholarly journals Sex Ratios in a Warming World: Thermal Effects on Sex-Biased Survival, Sex Determination, and Sex Reversal

2021 ◽  
Vol 112 (2) ◽  
pp. 155-164
Author(s):  
Suzanne Edmands
Keyword(s):  
High Temperature ◽  
Sex Ratio ◽  
Sex Determination ◽  
Heat Tolerance ◽  
Sex Ratios ◽  
Sex Reversal ◽  
Survival Sex ◽  
Ratio Distortion ◽  
Warming World ◽  
Sex Ratio Distortion

Abstract Rising global temperatures threaten to disrupt population sex ratios, which can in turn cause mate shortages, reduce population growth and adaptive potential, and increase extinction risk, particularly when ratios are male biased. Sex ratio distortion can then have cascading effects across other species and even ecosystems. Our understanding of the problem is limited by how often studies measure temperature effects in both sexes. To address this, the current review surveyed 194 published studies of heat tolerance, finding that the majority did not even mention the sex of the individuals used, with <10% reporting results for males and females separately. Although the data are incomplete, this review assessed phylogenetic patterns of thermally induced sex ratio bias for 3 different mechanisms: sex-biased heat tolerance, temperature-dependent sex determination (TSD), and temperature-induced sex reversal. For sex-biased heat tolerance, documented examples span a large taxonomic range including arthropods, chordates, protists, and plants. Here, superior heat tolerance is more common in females than males, but the direction of tolerance appears to be phylogenetically fluid, perhaps due to the large number of contributing factors. For TSD, well-documented examples are limited to reptiles, where high temperature usually favors females, and fishes, where high temperature consistently favors males. For temperature-induced sex reversal, unambiguous cases are again limited to vertebrates, and high temperature usually favors males in fishes and amphibians, with mixed effects in reptiles. There is urgent need for further work on the full taxonomic extent of temperature-induced sex ratio distortion, including joint effects of the multiple contributing mechanisms.

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