The effect of temperature and moisture on the Immature Stages of Aphodius tasmaniae Hope (Scarabaeidae) in the lower South-east of South Australia.

1961 ◽  
Vol 9 (2) ◽  
pp. 173 ◽  
Author(s):  
DA Maelzer
Keyword(s):  
Mortality Rate ◽  
Water Content ◽  
South Australia ◽  
Effect Of Temperature ◽  
Annual Rainfall ◽  
Field Observations ◽  
Immature Stages ◽  
Rate Of Increase ◽  
Lower South ◽  
Third Instar Larvae

The distribution and abundance of the univoltine species A. tasmaniae in the lower south-east of South Australia appears to be related to annual rainfall. The effects of moisture on the mortality rates of the immature stages were consequently studied and observations were made of the effects of variations in moisture in the field. Laboratory experiments and field observations suggested that variations in soil moisture have little effect on the eggs and the diapausing prepupae in the field. Eggs absorbed water and hatched normally within a pF range of 2.50-3.75 in a sand and in a clay loam. At pF 4.0 in both soils, eggs lost weight and did not hatch. The adults, however, tend to lay the eggs well within the pF range in which the eggs can develop, and soil samples suggested that eggs would develop with little mortality in the kinds of places in which they are usually laid. When prepupae enter diapause they have a water content of c. 77%. When desiccated in the laboratory, few prepupae died until their water content fell below 62%. The mortality rate then increased sharply, and it was estimated that 50% of the prepupae died when their water content dropped to 57%. Droughts of sufficient duration and intensity to kill 50% of the prepupae have never been recorded from the study area, and field observations suggested that few prepupae died of desiccation in summer. Unlike the two stages above, the first and third instar larvae may be markedly affected by variations in moisture in the field. The first instar larvae, after hatching, do not move to the surface of the soil and do not feed much until the soil is saturated with rain. As rainfall is variable at this time of the year, the larvae may be in dry soil for many weeks before they are stimulated to extend their burrows to the surface and search for food. Many larvae may die of starvation during this time, and the mortality rate of the larvae was related empirically to the length of the autumn "drought". Third instar larvae may be affected, on the other hand, by excessive water. In wet winters, vast numbers of larvae are drowned when extensive flooding occurs on the poorly-drained soils, and on well-drained soils a large proportion of larvae are killed by the entomophagous fungus Cordyceps aphodii. The above data have suggested that moisture is one of the major factors affecting the distribution and abundance of the species. Temperature has little effect on the rate of increase of the species.

The ecology of Oncopera Fasciculata (Walker) (Lepidoptera: Hepialidae) in South Australia. 1. Field observations on the nubers of O. Fasciculata and the factors influencing birth rate and death rate.

1956 ◽  
Vol 4 (3) ◽  
pp. 315 ◽  
Author(s):  
PE Madge
Keyword(s):  
Death Rate ◽  
Birth Rate ◽  
South Australia ◽  
Field Observations ◽  
Severe Damage ◽  
Factors Influencing ◽  
Large Numbers ◽  
Lower South ◽  
Area Of Study

During some years the underground grass caterpillar, Oncopera fasciculata (Walker), appears in large numbers and causes severe damage to improved pastures in the lower south-east of South Australia and the Central and Western Districts of Victoria. The present paper, which is the first of several, includes a description of the area of study and an account of field observations on the components of the environment that may influence the survivaI rate of the species.

Effect of temperature on life table parameters of Phytoseius plumifer (Phytoseiidae) fed on Eotetranychus hirsti (Tetranychidae)

2017 ◽  
Vol 22 (3) ◽  
pp. 410 ◽  
Author(s):  
Jahanshir Shakarami ◽  
Fereshteh Bazgir
Keyword(s):  
Linear Model ◽  
Effect Of Temperature ◽  
Intrinsic Rate Of Increase ◽  
Thermal Constant ◽  
Temperature Threshold ◽  
Immature Stages ◽  
Degree Days ◽  
Rate Of Increase ◽  
Phytoseius Plumifer ◽  
Increasing Temperature

Eotetranychus hirsti Pritchard & Baker (Tetranychidae) is one of the important pests of fig trees that is widely distributed in fig orchards of Iran. The predatory mite Phytoseius plumifer Canestrini & Fanzago is a phytoseiid mite on fig that can feed and reproduce on E. hirsti. The effect of four constant temperatures (20, 25, 30 and 35°C) on demographic parameters of P. plumifer fed on nymphal stages of E. hirstiwas determined under laboratory conditions at 50 ± 5% RH and a photoperiod of 16:8 h (L: D). The total developmental time of immature stages of this predator decreased with increasing temperature from 20°C to 35°C, and varied from 17.13±0.23 to 6.55±0.19 days for females. The lower temperature threshold (Tmin) and thermal constant (K) for the total immature stages of this predator was estimated 10.33˚C and 166.67 degree-days by the ordinary linear model, 11.17˚C and 147.87 degree-days by the Ikemoto linear model, respectively. Female longevity was 67.79, 47.00, 35.11, and 27.42 days at 20, 25, 30 and 35°C, respectively. The highest values of total fecundity and daily fecundity were obtained at 25˚C (35.71±1.73 eggs) and 30˚C (1.57±0.02 eggs), respectively. The value of the intrinsic rate of increase (rm) increased as increasing temperature from 20°C (0.064±0.0012 day−1) to 30°C (0.180±0.0023 day−1), and then decreased at 35°C (0.153±0.0037 day−1). The highest and lowest values of the mean generation time (T) were 32.75±0.95 and 14.18±0.51 days, which were obtained at 20°C and 35°C, respectively. The results of this study revealed that of P. plumifer is effective predator of the fig spider mite and develops effectively at a broad range of temperatures.

An Analysis of the Effects of Temperature upon the Growth and Reproduction of Dysdercus fasciatus Sign. (Hemiptera, Pyrrhocoridae). I.—The Intrinsic Rate of Increase

1959 ◽  
Vol 50 (2) ◽  
pp. 387-405 ◽  
Author(s):  
Kenneth U. Clarke ◽  
Jaivant B. Sardesai
Keyword(s):  
Mortality Rate ◽  
Live Weight ◽  
Intrinsic Rate ◽  
Reproductive Capacity ◽  
Effect Of Temperature ◽  
Intrinsic Rate Of Increase ◽  
Preoviposition Period ◽  
Fertile Female ◽  
Rate Of Increase ◽  
Increasing Temperature

In laboratory studies of Dysdercus fasciatus Sign., populations were exposed to constant temperatures of 15, 20, 25, 30, 35 and 40°C. and a relative humidity of 60 per cent., and to 28°C. and 70 per cent. R.H. After hatching, the insects were supplied with cotton seed as food and water to drink. Development of eggs was incomplete below 25°C., of nymphs below 20°C., and of both above 30°C. To allow comparison of growth and rate of reproduction at temperatures outside the embryonic range, this stage was ignored in calculating values of the intrinsic rate of increase, r, and the mortality rate and length of life were measured from the time of hatching, the eggs being incubated under optimum conditions (those at 28°C.) and the freshly hatched nymphs then moved to the appropriate temperature. The value of r was found to increase with increasing temperatures up to 30°C., and to do so more rapidly between 25 and 28°C. than between 20 and 25°C. The age-schedule of deaths for populations living at 28°C. showed a distribution of deaths that was almost ideal, in that their highest frequency did not occur until the reproductive period was advanced. The principal deviation from this ideal was due to the high mortality rate found in the first instar. At 20°C., the death rate approached constancy throughout the life-span of the population. The interval between generations decreased with increasing temperature, the rate of decrease being approximately 4·6 days per 1°C. rise in temperature.Further analysis of r was made by considering separately the growth and reproductive characteristics of the insect, and the effect of temperature upon them.The rate of post-embryonic growth, as measured by live weight, increased with temperature, within the range of 20–30°C. At 15°C., growth did not proceed beyond the third instar, or beyond the fifth instar at 35°C. The principal cause of the increase in growth rate was the decrease and eventual disappearance of the periods between initial ecdysis and start of growth, and between the end of growth and final ecdysis, the rate at which growth actually took place differing but slightly.The size of the insect just after the final ecdysis had an important effect on r because the number of eggs laid by small insects (mean weight 68·6 mg.) was only about half that of large ones (mean weight 100·2 mg.). Any decrease in size observed with increasing temperature was slight compared with that produced by restricting the insect's access to drinking water.Copulation and oviposition occurred in adults maintained at any of the temperatures except 15 and 40°C. The percentage of females that laid eggs differed according to the temperature, the highest recorded being 90 per cent, at 28°C. and the lowest 30 per cent, at 20°C. The total time spent in copulation also varied with temperature, being least (9 days) at 28°C. and most (26·3 days) at 20°C. The change of weight of the female after moulting largely represented growth of the ovaries; at 15°C., this is slow and not completed before the female dies; at 40°C. the ovaries do not mature; at other temperatures tested (20–35°C.) growth is fairly rapid, the ovary being full grown in about four days.The fertile female lays her eggs in batches, the maximum observed being six batches, at approximately three-day intervals. A few females survived the laying of the sixth batch of eggs by a period longer than their interoviposition period. At 28°C., the preoviposition period and the time spent in copulation were less, more egg-batches, and hence more eggs, were produced and a higher proportion of females mated, than at any other temperature. In the unmated female, the average life was twice that of the mated one, the preoviposition period was the same, the interoviposition period approximately three times as long, the egg-batches half as numerous, and the number of eggs per batch nearly the same. All fertile females were observed to lay eggs, but only 20 per cent, of the unmated ones did so. At 35°C., mated females produced one or two batches of eggs; unmated ones produced none, and although the ovary matured normally up to the fourth day, the yolk was subsequently reabsorbed, this process being complete by the 14th day.These studies have indicated that in D. fasciatus the decrease in the value of r with decreasing temperature is caused by a rise in pre-reproductive mortality and a fall in reproductive capacity, as well as by the increase of the generation length, which other workers have found to be of predominating importance in the case of other insects.

Effect of Temperature on Development Rate, Survival and Fecundity of Cotton Tipworm, Crocidosema-Plebejana Zeller (Lepidoptera, Tortricidae)

1991 ◽  
Vol 39 (2) ◽  
pp. 191 ◽  
Author(s):  
JG Hamilton ◽  
MP Zalucki
Keyword(s):  
Linear Model ◽  
Development Rate ◽  
Population Increase ◽  
Effect Of Temperature ◽  
Direct Result ◽  
Immature Stages ◽  
Optimum Temperature ◽  
Development Rates ◽  
Non Linear ◽  
Female Weight

C. plebejana were reared from egg to adult at a range of constant temperatures. At 10-degrees-C no immature stages survived. Development rates increased over the temperature range 14-34-degrees-C; these were simulated with a non-linear model. Females emerged before males. Fecundity decreased with increased rearing temperature as a direct result of reduced adult female weight. At 34-degrees-C development rate and survival were reduced and all eggs laid were infertile. Optimum temperature for population increase was 28-degrees-C. Validation of a non-linear model for development rate shows that the species of host-plant affects mean development rates of tipworm. Although 5.3 tipworm generations are possible on cotton annually, only one occurs; reasons for this are suggested.

Specific Volume−Hole Volume Correlations in Amorphous Carbohydrates: Effect of Temperature, Molecular Weight, and Water Content

2010 ◽  
Vol 114 (4) ◽  
pp. 1568-1578 ◽  
Author(s):  
Sam Townrow ◽  
Mina Roussenova ◽  
Maria-Isabelle Giardiello ◽  
Ashraf Alam ◽  
Job Ubbink
Keyword(s):  
Molecular Weight ◽  
Water Content ◽  
Specific Volume ◽  
Effect Of Temperature

scholarly journals Evaluation of hillslope failure and community adjustment after extreme weather event, Waimarama 26-27 April, 2011

2021 ◽  
Author(s):  
◽  
Albert Edward Frampton
Keyword(s):  
Water Content ◽  
Small Businesses ◽  
Extreme Event ◽  
Extreme Rainfall ◽  
Field Measurements ◽  
Economic Loss ◽  
Laboratory Analysis ◽  
Annual Rainfall ◽  
Financial Loss ◽  
North West

<p>In 2011, Waimarama received 80% of its annual rainfall in 48 hours. This extreme event with a return period of >100 years caused saturated hillslopes to collapse forming 100s of shallow landslides in the Puhokio Valley. This study collected soil samples from 54 exposed slip scarp horizons for laboratory analysis of soil mechanical properties. Field measurements of slip and slope angles, length, width and depth to determine that 23,212m³ of sediment was volume lost, from the 54 landslides. The field and lab measurements were used to generate a coherent understanding of landsliding at Waimarama. Laboratory analysis for liquid limits water content showed a high of 88.5% to a low of 18.8% and plastic limit water content had a high of 51% in the A horizon (organics) and low of 16.1%. Specific gravity also indicated a high reading 1.74 g/cm³ with a low of 1.16 g/cm³. The A horizon was able to tolerate high levels of water content in most tests, while the B horizon was capable of coping with some increase in water content. The C horizon was only able to handle low volumes of water, and was the main initiator of regolith collapse. The laboratory results indicated high saturation levels within the horizons of weak lithology of marine regolith that over caps impervious marine bedrock. The main cause for hillslope collapse and exposure of multiple translational and debris flow landslides was extreme saturation. However, towards the height of the rainfall event a 4.5 magnitude earthquake was recorded with unknown collateral consequences. Most slip locations were found in the aspects of east, south-east, west, and north-west, and on slope angles 15 -25°. The study confirmed previous surveys that regolith depth 80-100cm on impervious sandstone, siltstone/mudstone, when saturated over lengthy wet spells or from extreme precipitation, will collapse. In addition to the physical geographic study a survey was included to record individual and family accounts of the weather phenomenon. A questionnaire was prepared with specific questions that required yes or no answers. These questions dealt with loss of buildings, loss of land, animals, financial loss and recovery, economic loss, insurance and mitigation plans. The most affected were farmers and the next affected were householders while the holiday park was the worst affected of small businesses. Insurance was a significant help in most recoveries. Land rehabilitation was mitigated with new plantings and some aerial sowing, otherwise many slips were left to revegetate naturally. Economic and financial loss was severe for most farmers, due to pasture loss and animal relocation. Extreme rainfall causes slips that affect humans, but they can be mitigated. The Waimarama event is one of many events that can happen countrywide, the results can be a disastrous loss of personal, economic and financial assets, loss of infrastructure, including roading, bridges and communication. These are factors that many people and communities only realise when it happens to them. Mitigation against such events might include adequate insurance and knowledge of what to do, and where to go should an event happen unexpectedly and without warning.</p>

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