The Innate Capacity for Increase in Numbers in the Pulmonate Snail, Lymnaea columella

1958 ◽  
Vol 77 (3) ◽  
pp. 290 ◽  
Author(s):  
Robert M. DeWitt ◽  
William C. Sloan
Keyword(s):  
Pulmonate Snail ◽  
Innate Capacity ◽  
Capacity For Increase

Studies on rates of development and reproduction of California red scale, Aonidiella aurantii (Mask.) (Homoptera : Diaspididae) on citrus

1972 ◽  
Vol 20 (1) ◽  
pp. 37 ◽  
Author(s):  
JR Willard
Keyword(s):  
Leaf Disk ◽  
Distilled Water ◽  
Aonidiella Aurantii ◽  
Innate Capacity ◽  
Disk Method ◽  
Capacity For Increase

Red scale were reared in the laboratory on disks cut from lemon leaves floated on distilled water in plastic vials. Scales could be reared to maturity on the disks and females would produce crawlers. Rates of development measured at four temperatures using the leaf disk method were similar to data reported by earlier authors. Unfertilized females were found to remain alive and could be fertilized up to 16 weeks after the second moult. On the average, the longevity of unfertilized females was shown to be 3.5 weeks longer than that of fertilized females. The fecundity of females collected from the field was measured at a series of constant temperatures. Estimates of the capacity for increase (rc) and the innate capacity for increase (rm were obtained at four temperatures. Both these statistics were shown to be greatly influenced by temperature; rc was found to be an underestimate of rm at higher temperatures.

BIOLOGY, LIFE TABLES, AND INNATE CAPACITY FOR INCREASE OF THE TWOSPOTTED SPIDER MITE, TETRANYCHUS URTICAE (ACARINA: TETRANYCHIDAE)

1981 ◽  
Vol 113 (5) ◽  
pp. 371-378 ◽  
Author(s):  
H. J. Herbert
Keyword(s):  
Tetranychus Urticae ◽  
Spider Mite ◽  
Life Stage ◽  
Life Tables ◽  
Threshold Temperature ◽  
Reproduction Rate ◽  
Twospotted Spider Mite ◽  
Innate Capacity ◽  
Capacity For Increase ◽  
Twospotted Spider

AbstractThe threshold temperature of development, life table, and innate capacity for increase of the twospotted spider mite, Tetranychus urticae Koch, were established from life stage development studies at constant temperatures. The threshold for development was determined to be 10.0°C. The durations in degree-days above 10°C from the beginning of the egg stage to adult for females were 141.3, 152.3, and 139.8; for males 134.2, 144.7, and 135.2 at 15°, 18°, and 21°C, respectively. Life tables were constructed and innate capacity for increase was .069, .156, and .372; net reproduction rate 20.8, 38.4, and 58.1; and mean generation time 44.0, 23.4, and 10.9 at 15°, 18°, and 21°C, respectively.

The effects of temperature and humidity on the oviposition rate of Tribolium castaneum (Hbst.) (Coleoptera, Tenebrionidae)

1962 ◽  
Vol 53 (2) ◽  
pp. 301-310 ◽  
Author(s):  
R. W. Howe
Keyword(s):  
Tribolium Castaneum ◽  
Low Temperatures ◽  
Adult Life ◽  
Oviposition Rate ◽  
Optimum Temperature ◽  
Preoviposition Period ◽  
Innate Capacity ◽  
Effects Of Temperature ◽  
Capacity For Increase ◽  
Coleoptera Tenebrionidae

The rate of oviposition of isolated pairs of Tribolium castaneum (Hbst.) on finely divided wheatfeed was measured over the entire adult life at 25°C. and 70 per cent. R.H. It was also measured over a period of seven weeks from the start of oviposition at 30 and 70 per cent. R.H. at 25, 30 and 35°C., respectively, at 70 per cent. R.H. only at 22·5, 27·5, 32·5 and 37·5°C. and at 2 per cent. R.H. at 30°C.At 25°C. and 70 per cent. R.H. each female laid, on the average, 360 eggs at the rate of 2·5 per day for about one hundred days and then at a decreasing rate for the next hundred days. When this experiment was repeated over a seven-week period, each female laid on average about 3 eggs per day. At 70 per cent. R.H., the optimum temperature for oviposition was about 32·5°C., at which about 11 eggs per day per female were laid over the seven-week period. These rates fell to just over 2 per day at 22·5°C. Only one egg was laid by 15 females at 20°C. At 37·5°C. the rate was about 10 eggs per day initially but it declined to about 3 per day by the end of seven weeks, whereas at lower temperatures the decline in laying was slight. Compared with 70 per cent. R.H., the oviposition rate at 30 per cent. R.H. was almost halved at 25°C., but was only slightly reduced at 35°C. At 30°C. and 2 per cent. R.H., females laid well, averaging over 4 eggs per female per day. The periodic provision of water for drinking at 25°C. and 30 per cent. R.H. depressed oviposition.The preoviposition period was 2 days at 37·5°C. and increased steadily at lower temperatures to 10 days at 22·5°C. It also varied more between females at low temperatures.The number of eggs recovered in this work was lower than the number obtained by Park & Frank (1948), who used considerably more food in their oviposition chambers. In this work, some eggs were eaten by the adult beetles. However, the innate capacity for increase of the species calculated on these data is extremely high, and could not be maintained for long because of the cannibalistic habits of this species.

Innate Capacity for Increase

2008 ◽  
pp. 1925-1925
Author(s):  
John B. Heppner ◽  
D. G. Boucias ◽  
J. C. Pendland ◽  
Andrei Sourakov ◽  
Timothy Ebert ◽  
...  
Keyword(s):  
Innate Capacity ◽  
Capacity For Increase

Experiments on the relative abundance of two sibling species of grain weevils.

1954 ◽  
Vol 2 (1) ◽  
pp. 66 ◽  
Author(s):  
LC Birch
Keyword(s):  
Relative Abundance ◽  
Sibling Species ◽  
Large Strain ◽  
Small Strain ◽  
The Other ◽  
Stored Grain ◽  
Stored Wheat ◽  
Innate Capacity ◽  
Series Of Experiments ◽  
Capacity For Increase

The small "strain" and the large "strain" of Calandra oryzae L. are sibling species. The small "strain" is common in stored wheat and rare in stored maize. The reverse is true for the large "strain." A series of four experiments showed how wheat favoured the small "strain" and how maize favoured the large "strain." Given a choice of wheat and maize the small "strain" and the large "strain" laid most of their eggs in wheat but the proportion was larger for the small "strain" as compared with the large "strain." When the insects were reared for several generations in wheat they laid more of their eggs in wheat. Likewise when reared in maize they laid more of their eggs in maize. But this "host conditioning" was not sufficient to prevent them from laying many eggs in the "wrong" grain. The innate capacity for increase of the small "strain" was greater than that of the large "strain" in wheat but in maize the large "strain" had a greater innate capacity for increase than the small "strain." In crowded cultures wheat again favoured the small "strain" by permitting greater maximum populations as compared with the large "strain." Maize favoured the large "strain" in this respect. When the two "strains" occurred together in crowded cultures one always drove the other out. The small "strain" was the successful one in wheat and the large "strain" was the successful one in maize. Although these four series of experiments illustrate ways in which wheat favours the small "strain" and maize favours the large "strain" they do not, in themselves alone, account for the segregation of the two "strains" in stored grain.

The biology of Cryptolestes capensis (Waltl) (Coleoptera, Cucujidae)

1962 ◽  
Vol 53 (3) ◽  
pp. 529-535 ◽  
Author(s):  
L. P. Lefkovitch
Keyword(s):  
Larval Density ◽  
Total Duration ◽  
Immature Stages ◽  
Adult Males ◽  
Optimal Conditions ◽  
Innate Capacity ◽  
Harmful Effects ◽  
Capacity For Increase

Cryptolestes capensis (Waltl) has been reared successfully upon wheatfeed at constant temperatures of 15 to 32·5°C., at intervals of 2·5°C., and 90 per cent. R.H., and at 30°C. and 10 to 70 per cent. R.H. Newly formed adult males were found to weigh more than females bred under the same conditions. Oviposition was investigated at 90 per cent. R.H. and 17·5, 20, 30 and 32·5°C.; the highest rate was at 30°C. It was concluded that 30°C., 90 per cent. R.H. were the optimal conditions of those observed. Comparison with C. turcicus (Grouv.) which occurs in the same habitat as C. capensis, shows that the temperature limits of the former are higher, but that at those temperatures at which both species can breed, there is little, if any, difference between the total duration of the immature stages. At the observed optimum for the two species, C. capensis has a higher innate capacity for increase than C. turcicus. These observations do not account for the rarity of C. capensis in comparison with C. turcicus, and it is postulated that C. capensis is, like C. ferrugineus (Steph.), more susceptible to the harmful effects of high larval density than is C. turcicus.

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