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.

Differential inhibition of egg hatching in Aedes aegypti populations from localities with different winter conditions

2020 ◽  
pp. 1-8
Author(s):  
Raúl E. Campos ◽  
Gabriela Zanotti ◽  
Cristian M. Di Battista ◽  
Javier O. Gimenez ◽  
Sylvia Fischer
Keyword(s):  
Aedes Aegypti ◽  
Low Temperatures ◽  
Buenos Aires ◽  
Geographical Origin ◽  
Larval Mortality ◽  
Acclimation Temperature ◽  
Subtropical Region ◽  
Egg Hatching ◽  
Winter Conditions ◽  
Winter Temperatures

Abstract In Argentina, the mosquito Aedes aegypti (L.) (Diptera: Culicidae) is distributed from subtropical to temperate climates. Here, we hypothesized that the expansion of Ae. aegypti into colder regions is favoured by high-phenotypic plasticity and an adaptive inhibition of egg hatching at low temperatures. Thus, we investigated the hatching response of eggs of three populations: one from a subtropical region (Resistencia) and two from temperate regions (Buenos Aires City and San Bernardo) of Argentina. Eggs collected in the field were raised in three experimental colonies. F1 eggs were acclimated for 7 days prior to immersion at 7.6 or 22°C (control eggs). Five immersion temperatures were tested: 7.6, 10.3, 11.8, 14.1 and 16°C (range of mean winter temperatures of the three localities). A second immersion at 22°C was performed 2 weeks later to assess the inhibition to hatch under favourable conditions. After the first immersion, we compared the proportions of hatched eggs and dead larvae among treatment levels, whereas after the second immersion we compared the hatching response among the three populations. The factors that most influenced the egg hatching response were the geographical origin of the populations and the immersion temperature, but not the acclimation temperature. The proportions of hatching and larval mortality at low temperatures were higher for Resistencia than for Buenos Aires and San Bernardo, whereas the hatching response at ambient temperature was lower for San Bernardo than for Buenos Aires and Resistencia. The results support the hypothesis that populations from colder regions show an adaptive inhibition of egg hatching.

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.

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 toxicity of insecticides to larvae of the codling moth, Cydia pomonella (L.). II.—Maintenance of a toxic deposit in the field

1965 ◽  
Vol 56 (2) ◽  
pp. 377-388 ◽  
Author(s):  
M. Gratwick ◽  
J. M. Sillibourne ◽  
R. P. Tew
Keyword(s):  
Larval Mortality ◽  
Cydia Pomonella ◽  
Field Performance ◽  
Heavy Rain ◽  
Codling Moth ◽  
Chemical Methods ◽  
Azinphos Methyl ◽  
Field Control ◽  
Wettable Powder ◽  
Rates Of Decay

The persistence, as assessed by biological and chemical methods, of field deposits on apples from two spray programmes, each of DDT, carbaryl or azinphos-methyl, was compared throughout eight weeks following the first application in an orchard in south-eastern England. Newly emerged larvae of the codling moth, Cydia pomonella (L.), were used to assess, in the laboratory, the biological activity of the deposits. The spray programmes studied were (1) two applications of conventional concentrations (i.e., 0·1 per cent, for DDT and for carbaryl, 0·04 per cent, for azinphos-methyl) three weeks apart and (2) three applications of half these concentrations at two-weekly intervals. DDT wettable powder, carbaryl and azinphos-methyl were compared in 1961, DDT emulsion, DDT wettable powder and carbaryl in 1963. Results of biological and chemical assessment of the deposits are presented graphically. Over-all, the performance of the three-application programmes was as satisfactory as that of the two-application programmes, although a smaller amount of chemical was used. The serious reduction in deposit caused by heavy rain shortly after the first application of DDT wettable powder and of carbaryl in 1961 is noted. In the absence of heavy rain, carbaryl was biologically the most persistent, but the best performances of the other chemicals were almost as good as that of carbaryl.LD50 values of fresh deposits obtained by field spraying were shown to be similar to those obtained by laboratory dipping.Comparison of the toxicity of fresh and weathered field deposits of similar magnitude indicated that the biologically available proportion of a DDT deposit from either formulation decreases as a result of weathering. This phenomenon was not found to occur with carbaryl and either not at all or to a much lesser extent with azinphos-methyl.The deposits obtained in the comparison of the spray programmes were separated into their fresh and aged components, so that differences in the contribution to the final deposit provided by each application could be seen. With the very persistent DDT emulsion, only about half of the six-week deposits was composed of chemical from the final application, but, with the much less persistent carbaryl and azinphos methyl, the six-week deposits were almost entirely derived from the final application. By substitution in an equation to obtain the rates of decay of the deposits from the three-application programmes of all chemicals, it is shown that deposits from the second and third applications were, in all cases, more persistent than those from the first. Possible reasons for this difference are discussed.The significance, in terms of field control, of the results for the larvicidal activity of the deposits from the different spray programmes is indicated. It is concluded that data on the LD90 of insecticidal deposits on apples, together with measurement of their persistence in the field, can be used to assess the probable field performance of codling-moth insecticides and to determine the most efficient means of employing them, although the deposit level that ensures 90 per cent, larval mortality in the field is higher than the LD90 determined in the laboratory.

Pathogenecity of Metarhizium anisopliae on Helicoverpa armigera larvae instars

2019 ◽  
Vol 5 (01) ◽  
pp. 105-109
Author(s):  
Ankush Taliyan ◽  
Ajay Kumar ◽  
Rajendra Singh ◽  
Rohit Rana ◽  
Shekhar Rana
Keyword(s):  
Helicoverpa Armigera ◽  
Metarhizium Anisopliae ◽  
Larval Mortality ◽  
Larval Instars ◽  
Cent Mortality ◽  
Helicoverpa Armígera

Studies on pathogenicity of M. anisopliae against Ist - VIth instar H. armigera larvae revealed that larval mortality. The effect of Metarhizium anisopliae spore/ml against Helicoverpa armigera larval instars was significantly higher recorded showed that in the results revealed that all the treatments were significantly larval mortality. The results revealed that all the treatments were significantly higher effective in larval mortality as compared to other larval instars. The data recorded on 4, 6, 8 11 and 14 day after pathogencity of various larval instars in the Ist instar of H. armigera with 1.8 x 109 spores suspension, was the best Ist instars larva H. armigera per cent mortality by M. anisopliae up to (35.63) followed by 73.39 (85.69) (98.37) and (100.0) production was significantly recorded.

The Effect of extreme Temperatures on different Stages of Aëdes aegypti (L.)

1957 ◽  
Vol 48 (3) ◽  
pp. 593-599 ◽  
Author(s):  
Micha Bar-Zeev
Keyword(s):  
Aedes Aegypti ◽  
High Temperatures ◽  
Low Temperatures ◽  
Extreme Temperatures ◽  
Fourth Stage ◽  
Wetting And Drying ◽  
The Third ◽  
Adult Females ◽  
Cent Mortality

Earlier investigations of the effects of extreme temperatures on different stages of Aëdes aegypti (L.) were supplemented by studies of eggs, larvae and pupae in water, and of eggs and adult females in air at various relative humidities.Larvae of the same stage, young pupae (defined as those less than half-an-hour old) and old pupae (at least 36 hours old), in groups of 100, 25 and 25, respectively, were kept for various periods at low temperatures in incubators, or, at high temperatures in glass cylinders closed at their lower ends by cloth filters and inserted into water baths, and then transferred to water at 28°C. and the mortality determined from the numbers surviving 24 hr. later (in the case of larvae) or becoming adult (in the case of pupae). Eggs in batches of 1,000 were similarly treated, except that periods of 24 hr. in water at 28°C. with yeast as food added were alternated with 24-hr. periods of drying, and mortality determined on the number that hatched and survived to the third or fourth stage. Adult females (four days old) were exposed in groups of 50 for various periods in jars over appropriate solutions giving a complete range of relative humidities and kept at low, medium and high temperatures. Eggs in batches of 1,000 were subjected to the same treatments. The adults were kept at 28°C. and 60 per cent. R.H. before treatment and for 24 hr. afterwards and mortality then determined. Mortality of eggs was determined after alternate 24-hr. periods of wetting and drying at 28°C., as in the case of eggs treated in water. The results of all the experiments were expressed as the exposure-times required to give 50 per cent. mortality (T50), calculated from the observed data.

scholarly journals Larvicidal action of Nux-vomica (Strychnus nux-vomica L.) against Diamond back moth (Plutella xylostella L.)

2017 ◽  
Vol 9 (4) ◽  
pp. 2291-2299
Author(s):  
C. Selvaraj ◽  
J. S. Kennedy ◽  
M. Suganthy
Keyword(s):  
Plant Extracts ◽  
Plutella Xylostella ◽  
Larval Mortality ◽  
Leaf Disc ◽  
Stem Bark ◽  
Negative Control ◽  
Root Bark ◽  
Cent Mortality ◽  
Hexane Extracts ◽  
Fruit Rind

The present investigation reports on larvicidal efficacy of plant extracts of Nux-vomica, Strychnus nux-vomica against Diamond back moth (DBM). In this investigation shade dried and powdered nux-vomica plant sam-ples (leaves, root bark, stem bark, seed and fruit rind) were extracted with organic solvents ethanol, methanol, ace-tone, hexane and chloroform and also formulated as Emulsifiable Concentrates (EC) using surfactant and solvents. This formulated plant extracts were tested against third instar larvae of DBM for larvicidal efficacy using leaf disc bioassay method under laboratory condition. Among the five solvent extracts tested, hexane extracts of root bark 11.11 EC @ 2 % showed highest larval mortality of 76.66 % followed by seed 14.25 EC, leaf 16.66 EC, stem bark 12.50 EC and fruit rind 12.50 EC extracts exhibited maximum mortality @ 2 % concentration recording 66.66, 63.33, 56.66 and 40.00 per cent mortality respectively. Positive and negative control such as respective solvent and water showed 10.00 and 3.33 % larval mortality respectively. The results of these experiment clearly indicate that nux-vomica plant possess promising larvicidal action against diamond back moth.

scholarly journals Ramet demography of Aechmea distichantha (Bromeliaceae) in two contrasting years in the understory and open areas of a South American xerophytic forest

Rodriguésia ◽  
2020 ◽  
Vol 71 ◽  
Author(s):  
Ignacio Martín Barberis ◽  
Graciela Klekailo ◽  
Juliana Albertengo ◽  
Juan Ignacio Cárcamo ◽  
José María Cárcamo ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Temporal Variations ◽  
Spatial And Temporal Variations ◽  
Woody Vegetation ◽  
South American ◽  
Extreme Temperatures ◽  
Herbaceous Vegetation ◽  
Winter Temperatures ◽  
Schinopsis Balansae ◽  
Sun And Shade

Abstract The Schinopsis balansae forests of the Wet Chaco are characterized by convex areas with woody vegetation and plain areas with herbaceous vegetation. In the Wet Chaco, Aechmea distichantha is a terrestrial bromeliad that forms dense colonies in the understory and open areas of these forests. The aim of this study was to analyze the spatial and temporal variations in population dynamics of this bromeliad species. We monitored ramets growing in sun and shade conditions during two contrasting years. We analyzed the spatial and temporal variations in survival, flowering, and ramet production. Variations in survival, flowering, and ramet production were more marked between years than between habitats. During the year with wetter and milder temperature conditions, survival and ramet production were higher than during the drier year with more extreme temperatures. Survival of vegetative ramets was less variable than survival of young and reproductive ramets. In the colder year, lower winter temperatures reduced the populations in all stages, being more important in the open areas. Our results highlight the importance of low temperatures on A. distichantha demography at this xerophytic forest located at the southernmost distribution range of this bromeliad species.

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