OBSERVATIONS ON THE WHITE APPLE LEAFHOPPER, TYPHLOCYBA POMARIA (HEMIPTERA: CICADELLIDAE), AND ON THE MIRID PREDATOR BLEPHARIDOPTERUS ANGULATUS, AND MEASUREMENTS OF THEIR COLD-HARDINESS

1979 ◽  
Vol 111 (4) ◽  
pp. 487-490 ◽  
Author(s):  
A. W. MacPhee
Keyword(s):  
Nova Scotia ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Second Generation ◽  
Freezing Points ◽  
Two Generations ◽  
Predatory Mirid

AbstractTyphlocyba pomaria McA., with two generations per year, damages the leaves and defaces the fruit of apple. It was reduced in numbers in an experimental orchard by the predatory mirid Blepharidopterus angulatus (Fall.) which attacked the second generation. The cold-hardiness of T. pomaria and B. angulatus overwintering eggs, which had mean freezing points of −35 °C and −34 °C respectively, was sufficient to protect these species from winter low temperatures in Nova Scotia.

Cold-Hardiness, Habitat and Winter Survival of Some Orchard Arthropods in Nova Scotia

1964 ◽  
Vol 96 (4) ◽  
pp. 617-625 ◽  
Author(s):  
A. W. MacPhee
Keyword(s):  
Nova Scotia ◽  
Air Temperature ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Winter Survival ◽  
Kings County ◽  
Winter Conditions ◽  
Cold Hardy

AbstractIn Kings County, Nova Scotia, low temperatures in the coldest nights of winter can differ by as much as 10°F. from one area to another. This has an important bearing on winter survival of some arthropods. Overwintering sites of orchard arthropods range from exposed situations which remain at air temperature to well protected ones on the ground where temperatures rarely go below 20°F. The cold-hardiness of each of 24 species of arthropods was measured: seven were sufficiently cold-hardy to survive any winter conditions in Nova Scotia, five were less cold-hardy but overwinter in well protected sites and twelve had marginal cold-hardiness, their mortality varying with the winter and the locality.

INFLUENCE OF MOISTURE CONTENT AND TEMPERATURE ON COLD-HARDINESS OF HIBERNATING INSECTS

1956 ◽  
Vol 34 (4) ◽  
pp. 283-294 ◽  
Author(s):  
R. W. Salt
Keyword(s):  
Moisture Content ◽  
Natural Environment ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Cold Hardening ◽  
Freezing Points ◽  
Wide Range ◽  
Blood Density ◽  
Moisture Conditions ◽  
The Relationship

Moisture content affected cold-hardiness, measured as ability to supercool, only to the extent that it affected the concentration of body fluids and hence their freezing points. Supercooling remained approximately constant in amount over a wide range of moisture conditions. Only when desiccation was severe did it produce appreciable cold-hardening. Chilling at constant low temperatures was effective in increasing the cold-hardiness of Bracon cephi (Gahan), ineffective in Melanoplus bivittatus (Say) and Cephus cinctus Nort., and of doubtful effect in Loxostege sticticalis (L.). The variable temperatures of the natural environment produced significant cold-hardening in all four species; occasional periods of developmental temperatures are considered more likely to be responsible than chilling. Blood density appeared to be related to cold-hardiness, but its ready response to other factors obscured the relationship.

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.

The Brown Mite, Bryobia arborea Morgan and Anderson (Acarina: Tetranychidae), on Apple in Nova Scotia.: I. Influence of Intratree Distribution on the Selection of Sampling Units. II. Differences in Habits and Seasonal Trends in Orchards With Bivoltine and Trivoltine Populations. III. Distribution of Diapause Eggs. IV. Hatching of Diapause Eggs

1965 ◽  
Vol 97 (12) ◽  
pp. 1303-1318 ◽  
Author(s):  
H. J. Herbert
Keyword(s):  
Nova Scotia ◽  
First Generation ◽  
Second Generation ◽  
Central Area ◽  
Third Generation ◽  
Apple Trees ◽  
Seasonal Trends ◽  
Sample Unit ◽  
The Third ◽  
Selection Of

AbstractIn Nova Scotia one leaf cluster with an adjoining 1 inch of twig taken from the inside of each of 10 apple trees replicated four times is an adequate sample unit to measure the density of the brown mite.The brown mite has one generation with a partial second in some orchards and one with a partial second and partial third in others. The first generation adults in the bivoltine and trivoltine populations lay summer eggs on the leaves and twigs, and diapause eggs on tin twigs. The second generation adults in the bivoltine populations lay only diapause eggs; in the trivoltine populations they lay both summer and diapause eggs. The adults of the third generation lay only diapause eggs.The brown mite is found on both the leaves and woody parts of the tree. In orchards with bivoltine populations the proportion of mites on leaves reached a peak of 80% by mid-July, but thereafter gradually decreased to 10% by the end of August. However, in orchards with trivoltine populations the proportion of mites on leaves reached a peak of 80 to 90% by mid-July, remained constant until mid-August, and thereafter decreased to approximately 40% by the end of August.The number of diapause eggs laid by adults of each generation in both the bivoltine and trivoltine populations varies widely. The eggs are deposited on the trunk as well as on the branches, with the heaviest deposition in the central area of the tree. The diapause eggs laid by adults of the first generation are the last to hatch and those laid by the third generation are the first to hatch the following spring.The factors responsible for the differences in the number of generations and in the number of diapause eggs laid are unknown.

REPEATED TRENDS OF FOLDS AND CROSS-FOLDS IN PALAEOZOIC ROCKS, PARRSBORO, NOVA SCOTIA

1964 ◽  
Vol 1 (3) ◽  
pp. 167-183 ◽  
Author(s):  
W. K. Fyson
Keyword(s):  
Nova Scotia ◽  
Vertical Movements ◽  
Clastic Rocks ◽  
Three Generations ◽  
The North ◽  
North Side ◽  
Two Generations ◽  
Major Fault ◽  
Granitic Intrusions ◽  
Middle Carboniferous

On the north side of a major fault three generations of folds F1, F2, F3 affect pre-Carboniferous phyllites; south of the fault two generations, C1, C2, affect middle Carboniferous clastic rocks. The F1 folds are isoclinal and obscure. The main folds, F2 in the phyllites and C1 in the Carboniferous rocks, trend east-northeast parallel to the fault. F2 are overturned southward and C1 northward, both toward the fault. Cross-folds, F3 in the phyllites and C2 in the Carboniferous rocks, trend northnortheast. Steeply plunging F3 and C2 are asymmetric and Z-shaped in plan profile.The F2 folds in the phyllites, though similar in geometry to folds in the middle Carboniferous rocks, appear, like F1 and F2, to have formed prior to the middle Carboniferous. This is indicated by the occurrence of unfolded Devonian(?) granitic intrusions crossing F3 folds, and a few miles north of the major fault, by middle Carboniferous rocks lying unconformably- above similar intrusions.One possible explanation for the repeated trends, which also accounts for the sense of overturning and asymmetry of the folds, relates the folding to alternating vertical and horizontal movements along the major fault. The vertical movements were followed by gravity sliding toward the fault to produce the main folds, and the horizontal movements, repeatedly dextral in sense, resulted in the Z-shaped cross-folds.

scholarly journals Toxicity and bioaccumulation of 2,2', 4,4'-tetrabromodiphenyl ether (BDE47) in a laboratory aquatic food chain

2021 ◽  
Author(s):  
Emily Rachel Awad
Keyword(s):  
Polybrominated Diphenyl Ethers ◽  
First Generation ◽  
Second Generation ◽  
Dietary Exposure ◽  
Maternal Exposure ◽  
Water Exposure ◽  
Aquatic Food Chain ◽  
Two Generations ◽  
Survival And Reproduction ◽  
Aquatic Food

Rising levels of polybrominated diphenyl ethers (PBDEs) have been ovserved in the environment, humans, and animlas. Studies have shown that these compounds can elicit toxic effects in animals (e.g. neurotoxicity and thyroid toxicity). This research investigated the effects of BDE47 on the survival and reproduction of Daphnia magna over two generations. The impacts of water-borne exposure were compared to dietary exposure using the following treatments: dosed water (DW), dosed algae (DA) and dosed water and algae (DWA). In the first generation, significant impacts on reproduction were observed in daphnids in the DA and DWA treatments. In the second generation, no significant impacts on reproduction were observed indicating a recovery from maternal exposure. When second generation daphnids were exposed to BDE47, there was high mortality in the DWA treatment anad reduced reproduction in all dosed treatments. Dietary exposure to BDE47 had a more profound impact on daphnid reproduction than water exposure. In the second generation, dietary exposure affected both survival and reproduction and water exposure reduced reproduction, indicating that maternal exposure was a factor.

REDUCED COLD-HARDINESS OF PEAR PSYLLA (HOMOPTERA: PSYLLIDAE) CAUSED BY EXPOSURE TO EXTERNAL WATER AND SURFACTANTS

1996 ◽  
Vol 128 (5) ◽  
pp. 825-830 ◽  
Author(s):  
David R. Horton ◽  
Tamera M. Lewis ◽  
Lisa G. Neven
Keyword(s):  
Low Temperatures ◽  
Cold Hardiness ◽  
Dilute Solutions ◽  
Subzero Temperatures ◽  
Pear Psylla ◽  
External Water

AbstractOverwintering pear psylla, Cacopsylla pyricola (Foerster), were misted with water or with one of several dilute solutions of water and surfactant, and then exposed to a range of subzero temperatures for 24 h. Misted psylla had significantly greater mortality than unmisted controls. Increases in mortality occurred at temperatures as warm as −6°C, a temperature well within the range of conditions in the field. At extreme low temperatures (−18°C) there was virtually no mortality in the unmisted controls, whereas mortality approached or reached 100% in several of the misted groups. Temperatures necessary to kill 50% of insects estimated for topically treated psylla ranged between −2.6 and −12.7°C for surfactant-treated insects, and below −18°C for water-treated or control insects. The possibility of using surfactants and water for control of overwintering pear psylla is discussed.

Variation in Australian and Some Overseas Populations of Emex australis and E. spinosa

1979 ◽  
Vol 27 (5) ◽  
pp. 631 ◽  
Author(s):  
PW Weiss ◽  
DM Simmons
Keyword(s):  
South Africa ◽  
Western Australia ◽  
First Generation ◽  
Second Generation ◽  
Emex Australis ◽  
Hierarchical Grouping ◽  
Two Generations

Australian populations of the widespread Emex australis and the more restricted E. spinosa were tested for subspecific variation. The plants were grown for two generations in a glasshouse from seed collected from field populations. The results from growing the first generation showed that two groupings of E. australis could be made on the basis of hierarchical grouping analysis, but the populations were much more similar in the second generation and such groupings could not be made. There were no marked differences between E. australis populations from Australia and South Africa, although one from Hawaii was less vigorous than the others. Amongst Australian populations of E. spinosa, one from Western Australia was less vigorous than the others. It was also found that Australian populations of E. spinosa were generally similar to those from Portugal and slightly more vigorous than those from Morocco.

Parasites and low temperatures

Parasitology ◽  
1999 ◽  
Vol 119 (S1) ◽  
pp. S7-S17 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Life Cycle ◽  
Cold Tolerance ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Free Living ◽  
Rate Of Growth ◽  
Subzero Temperatures ◽  
Growth Development ◽  
Epidemiological Significance

SUMMARYLow temperatures affect the rate of growth, development and metabolism of parasites and when temperatures fall below 0°C may expose the parasite to the potentially lethal risk of freezing. Some parasites have mechanisms, such as diapause, which synchronise their life cycle with favourable seasons and the availability of hosts. Parasites of endothermic hosts are protected from low temperatures by the thermoregulatory abilities of their host. Free-living and off-host stages, however, may be exposed to subzero temperatures and both freezing-tolerant and freeze-avoiding strategies of cold hardiness are found. Parasites of ectothermic hosts may be exposed to subzero temperatures within their hosts. They can rely on the cold tolerance adaptations of their host or they may develop their own mechanisms. Exposure to low temperatures may occur within the carcass of the host and this may be of epidemiological significance if the parasite can be transmitted via the consumption of the carcass.

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