Changes in insect populations in the field in relation to preceding weather conditions

1951 ◽  
Vol 138 (890) ◽  
pp. 130-156 ◽  
Keyword(s):  
Minimum Temperature ◽  
Population Change ◽  
Geometric Mean ◽  
Light Trap ◽  
Population Level ◽  
Weather Conditions ◽  
Single Species ◽  
Great Accuracy ◽  
Insect Population ◽  
Logarithmic Scale

An attempt has been made to measure changes in a mixed insect population under natural conditions in the field, and to see to what extent they are quantitatively related to previous weather conditions. To obtain a measure of the population, insects were caught in a light-trap at Harpenden, about 25 miles north of London, every night for four years from 1933 to 1937, and again for four years from 1946 to 1950. In all about 1,440,000 insects, mostly Diptera, were captured on about 2850 nights. The measure of population level in any one month was the geometric mean catch per night, obtained by calculating the arithmetic mean of log ( n + 1), where n is the number of insects caught in one night. This figure has to be corrected for the effect of prevailing weather conditions on activity. The departure of each month, on the logarithmic scale, from the average value for all repetitions of the same month gives a measure of how the population in this particular month is differing from the level to be expected for that time of the year. These departures were then made the basis of six-factor multiple regressions, in which the population change was the dependent variable, and the rainfall and minimum temperature departures from normal in each of the three preceding months were the independent variables. It is shown that a very high proportion of the mean changes of the population in the field can be accounted for by the effect of rainfall and minimum temperature in the three previous months. An examination of the regressions in the different seasons shows that rainfall has a high positive effect in the summer and autumn but little or no effect in the winter. Minimum temperature, on the contrary, has its lowest effect in the summer, so that the relation between population and minimum temperature one month previous is negative in the summer, and with temperature two months previous is negative in the autumn. The analysis of the available data has so far only been carried out on the total insect population, against rainfall and minimum temperature. Work is continuing on other weather conditions, other time intervals, and also on special groups of insects, but it is unlikely that the method can be applied with any great accuracy in the near future to single species of insects.

Studies in the effect of weather conditions on the activity and abundance of insect populations

1961 ◽  
Vol 244 (713) ◽  
pp. 331-378 ◽  
Keyword(s):  
Light Trap ◽  
Population Level ◽  
Weather Conditions ◽  
Logarithmic Scale ◽  
Scottish Highlands ◽  
Activity Effect ◽  
The Family ◽  
Insect Populations ◽  
South East England ◽  
Trap Catches

This paper is a statistical analysis of captures of insects every night for over 4 years in traps in a locality in the Scottish Highlands. It should be considered in relation to a similar account of work in south-east England (Williams 1951 a ). From the trap catches (on a logarithmic scale), and meteorological records taken alongside the traps, statistical analyses, chiefly by multiple regressions, were made to show (1) the relation between day to day changes in log catch and corresponding changes in temperature and wind, and (2) the relation between changes in mean log catch in the same month in different years and changes in rainfall and temperature in the three previous months. The former is an activity effect, and the latter a population effect. Details are given for total Diptera, for the bloodsucking flies of the family Simuliidae, and for total Lepidoptera in a light trap, and for total Diptera in a suction trap, this latter for activity only. The results show quantitatively the very high dependance, more so in some groups and at certain seasons, of the activity of insects on the current weather conditions, and of the population level on the previous weather. A fuller summary is included in the paper, pp. 367 to 369.

scholarly journals Elaboration and industrial implementation of lean alloy steel rolled stock production for structures of road bridges

2020 ◽  
Vol 76 (3) ◽  
pp. 228-233
Author(s):  
A. A. Pridein ◽  
L. V. Prokopenko ◽  
O. V. Samokhina ◽  
S. P. Zubov ◽  
D. A. Shablya ◽  
...  
Keyword(s):  
Alloy Steel ◽  
Minimum Temperature ◽  
Steel Production ◽  
Steel Structures ◽  
Weather Conditions ◽  
Rolled Stock ◽  
Steel Bridge ◽  
Welding Technology ◽  
Trial Batch ◽  
Technical Specifications

Within the national project “Safe and quality automobile roads” realization a big number of bridge passages will be constructed, including steel road bridges with small (14–42 m) spans instead of reinforced concrete bridges. Application of metal rolled products of 10ХСНД, 15ХСНД, 10ХСНДА, 15ХСНДА steels in the steel structures of bridges with small spans results in unreasonable increase the costs of the bridges structures. This circumstance stipulates necessity to elaboration and implementation of cheap lean alloy steel for manufacturing standard short-spanned bridges. The steel production should involve minimal and lean alloying method and ensure complex of operation properties in normalized state. At JSC “Ural Steel” an experiment work was accomplished for elaboration lean alloy steel 12Г2СБД due to STO 13657842-1 having standard yield strength 345 MPa. In cooperation with NIZ “Mosty”, OJSC “CNIIS” and CNIIchermet after I.P. Bardin technical specifications of plates for short-spanned bridges were elaborated and approved. Comprehensive technology of 12Г2СБД steel plate production was elaborated. A trial batch of 12Г2СБД steel plates was produced and shipped to ZAO “Kurganstalmost”. Study of welding and technological characteristics of the trial batch plates was carried out. The study showed, that the plates of 12Г2СБД steel have low sensitiveness against heat action of a welding thermal cycle and can be used in welding structures of steel bridge spans providing keeping the plant and assembling welding technology by standard regimes (due to welding technology of steel 10–15ХСНД). Application of the plant and assembling technology at welding by standard regimes makes it possible to use the plates of the elaborated steel for manufacturing metal structures of short-spanned metal bridges for various weather conditions. The plated can be used for both a regular performance (the calculated minimum temperature is down to –40 °С inclusive) and a northern performance Zone A (the calculated minimum temperature is down to –50 °С inclusive).

scholarly journals Agricultural losses related to frost events: use of the 850 hPa level temperature as an explanatory variable of the damage cost

2014 ◽  
Vol 14 (9) ◽  
pp. 2375-2386 ◽  
Author(s):  
K. Papagiannaki ◽  
K. Lagouvardos ◽  
V. Kotroni ◽  
G. Papagiannakis
Keyword(s):  
Minimum Temperature ◽  
Crop Production ◽  
Methodological Approach ◽  
Weather Conditions ◽  
Lower Atmosphere ◽  
Crop Damage ◽  
Daily Minimum Temperature ◽  
Near Surface ◽  
Damage Costs ◽  
Agriculture Risk

Abstract. The objective of this study is the analysis of damaging frost events in agriculture, by examining the relationship between the daily minimum temperature in the lower atmosphere (at an isobaric level of 850 hPa) and crop production losses. Furthermore, the study suggests a methodological approach for estimating agriculture risk due to frost events, with the aim of estimating the short-term probability and magnitude of frost-related financial losses for different levels of 850 hPa temperature. Compared with near-surface temperature forecasts, temperature forecasts at the level of 850 hPa are less influenced by varying weather conditions or by local topographical features; thus, they constitute a more consistent indicator of the forthcoming weather conditions. The analysis of the daily monetary compensations for insured crop losses caused by weather events in Greece shows that, during the period 1999–2011, frost caused more damage to crop production than any other meteorological phenomenon. Two regions of different geographical latitudes are examined further, to account for the differences in the temperature ranges developed within their ecological environment. Using a series of linear and logistic regressions, we found that minimum temperature (at an 850 hPa level), grouped into three categories according to its magnitude, and seasonality, are significant variables when trying to explain crop damage costs, as well as to predict and quantify the likelihood and magnitude of damaging frost events.

scholarly journals Shell form in Venerupis rhomboides

1961 ◽  
Vol 41 (3) ◽  
pp. 705-722 ◽  
Author(s):  
N. A. Holme
Keyword(s):  
Shell Height ◽  
Single Species ◽  
Significant Negative Correlation ◽  
Small Samples ◽  
Logarithmic Scale ◽  
Sea Floor ◽  
Probability Paper ◽  
Straight Line ◽  
Two Samples ◽  
Rates Of Growth

SUMMARYTwo forms of Venerupis rhomboides occur in Plymouth waters. A more slender form, corresponding to that described by Pennant, occurs in the Eddystone shell gravel, and a more robust form, corresponding to the Venus sarniensis of Turton, occurs at the mouth of the River Yealm. The two forms differ in ratios of shell height, width and lunule width relative to shell length. A population with intermediate ratios is found at 6-5 m in Plymouth Sound.Plots of height/length ratios of these and another intermediate sample on probability paper did not indicate that the intermediate populations were composed of mixtures of the two extreme forms, and it was provisionally concluded that these were all variants of a single species.If the height/length ratios of series of samples from different localities are plotted against depth of water on a logarithmic scale, an inverse relationship, approaching a straight line, is obtained. Regression lines for median ratios in the 3-4 and 4-5 cm length groups have been plotted separately, as there is some change in proportion with increasing length. These show a highly significant negative correlation between shell ratios and depth.From the regression lines it has been possible to obtain an estimate of the depth inhabited by even quite small samples of shells. Depth estimations have been made for eight samples, consisting mainly of dead shells. Six samples lay within the expected limits, and discrepancies in the other two samples are attributed to transport along the sea floor.The possible causes of the differences in shell ratios are discussed. Previous work suggests that shell ratios may be affected by different rates of growth. Soil grade, temperature, food supply, and light penetration are considered unlikely causes of the observed differences in shell ratios, and it is suggested that the pattern of growth may be affected by pressure.The Appendix contains a key to British species of Venerupis.

OPTIMAL IMPULSIVE HARVESTING OF A SINGLE-SPECIES WITH GOMPERTZ LAW OF GROWTH

2006 ◽  
Vol 14 (02) ◽  
pp. 303-314 ◽  
Author(s):  
YUJUAN ZHANG ◽  
ZHILONG XIU ◽  
LANSUN CHEN
Keyword(s):  
Global Attractivity ◽  
Population Level ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Discrete Dynamical Systems ◽  
Optimal Harvesting ◽  
Sustainable Yield ◽  
Gompertz Law ◽  
Optimal Population ◽  
Impulsive Harvesting

In this paper we investigate the optimal harvesting problems of a single species with Gompertz law of growth. Based on continuous harvesting models, we propose impulsive harvesting models with constant harvest or proportional harvest. By using the discrete dynamical systems determined by the stroboscopic map, we discuss existence, stability and global attractivity of positive periodic solutions, and obtain the maximum sustainable yield and the corresponding optimal population level. At last, we compare the maximum sustainable yield of impulsive harvest with that of continuous harvest, and point out that proportional harvest is superior to constant harvest.

scholarly journals Impacts of insect outbreaks on tree mortality, productivity, and stand development

2015 ◽  
Vol 148 (S1) ◽  
pp. S138-S159 ◽  
Author(s):  
David A. MacLean
Keyword(s):  
Mountain Pine Beetle ◽  
Tree Mortality ◽  
Choristoneura Fumiferana ◽  
Population Level ◽  
Historical Record ◽  
Wildlife Habitat ◽  
Insect Population ◽  
Forest Composition ◽  
Stand Development ◽  
Insect Outbreaks

AbstractThe impacts of insect outbreaks on tree mortality, productivity, and stand development in Canada are reviewed, emphasising spruce budworm (Choristoneura fumiferana(Clemens), Lepidoptera: Tortricidae) and mountain pine beetle (Dendroctonus ponderosaeHopkins, Coleoptera: Curculionidae). Reduced growth and survival are a function of insect population and defoliation level. It is feasible to make short-term (annual) predictions of insect population and defoliation based upon sampling, but long-term, multi-year predictions are problematic. Given the historical record, it is expected that outbreaks will occur with relatively predictable frequency and basic host relationships and abiotic constraints will not change dramatically. However, the precision of predictions at fine scales is variable and reduced over time. Relationships between tree growth reduction, survival, and cumulative defoliation or beetle population level are available for major insect species. Understanding insect outbreak effects hinges on mortality, changes in interspecies competition, regeneration, and succession. Altered stand dynamics caused by insects can be interpreted for indicators such as wildlife habitat, old forest, riparian buffer cover, viewscapes, and connectivity. Anthropogenic changes are altering impacts via range expansions, northward shifts, and changes in forest composition. We can better understand effects of insect outbreaks and how best to ameliorate damage through a combination of empirical permanent plot studies, modelling, and manipulative experiments.

How to validate a length-based model of single-species fish stock dynamics

2006 ◽  
Vol 63 (11) ◽  
pp. 2531-2542 ◽  
Author(s):  
Kasper Kristensen ◽  
Peter Lewy ◽  
Jan E Beyer
Keyword(s):  
Survey Data ◽  
Gadus Morhua ◽  
Negative Binomial ◽  
Atlantic Cod ◽  
Population Level ◽  
Single Species ◽  
Model Complexity ◽  
Fish Stock ◽  
Statistical Hypotheses ◽  
The Baltic

This paper validates a new length-based model of the dynamics of fish stocks or crustaceans by hierarchically testing statistical hypotheses and thereby investigating model complexity. The approach is based entirely on scientific survey data and on determination of the statistical distributions of the number of fish caught per haul in each length class. In our example, the negative binomial distribution is statistically accepted and linked to the population level through the new length-based model. The model is derived from the characteristics of continuous recruitment, individually based growth, and continuous, length-dependent mortality rates. Continuous recruitment with annually varying recruitment peaks and individually based growth was crucial for obtaining a model that could be statistically accepted. Natural mortality was estimated as well by the model. The model was applied to survey data for Atlantic cod (Gadus morhua) in the Baltic. Its simple generic nature, as well as the validation procedure, is useful in studying and understanding life history and stock dynamics.

scholarly journals On a two lag differential delay equation

1983 ◽  
Vol 24 (3) ◽  
pp. 292-317 ◽  
Author(s):  
R. D. Braddock ◽  
P. van den Driessche
Keyword(s):  
Numerical Solutions ◽  
Population Level ◽  
Single Species ◽  
Time Lags ◽  
Stable Limit ◽  
Differential Delay Equation ◽  
Differential Delay ◽  
Constant Coefficients ◽  
Linear Differential ◽  
Image Position

AbstractThe non-linear differential difference equation of the formis investigated. This equation, with constant coefficients, is used to model the population level, N, of a single species, and incorporates two constant time lags T2 > T1 > 0; for example, regeneration and reproductive lags. The linear equation is investigated analytically, and some linear stability regions are described. The special case in which the two delay terms are equally important in self damping, B = C, is investigated in detail. Numerical solutions for this case show stable limit cycles, with multiple loops appearing when T2/T1 is large. These may correspond to splitting of major peaks in population density observations.

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