The influence of clone and morph on the parameters of intrinsic rate of increase in the cereal aphids Sitobion avenae and Rhopalosiphum padi

1991 ◽  
Vol 58 (3) ◽  
pp. 211-220 ◽  
Author(s):  
J. C. Simon ◽  
C. A. Dedryver ◽  
J. S. Pierre ◽  
Sylvie Tanguy ◽  
P. Wegorek
2011 ◽  
Vol 39 (No. 2) ◽  
pp. 61-64 ◽  
Author(s):  
V. Jarošík ◽  
A. Honěk ◽  
A. Tichopád

Population growths of three aphid species colonising winter wheat stands, Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae, were analysed by regression method. The calculations were based on counts in 268 winter wheat plots at 3 or 7 day intervals over 10 (leaves) or 6 (ears) years. The population dynamics of a particular species differed widely between years. Density independent exponential growth of the population was most common, but its rate differed significantly between species, and for S. avenae also between populations on leaves and ears, on which the populations grew fastest. Field estimates of the intrinsic rate of increase derived from the exponential growths ranged between 0.010–0.026 in M. dirhodum, 0.0071–0.011 in R. padi, and between 0.00078–0.0061 and 0.0015–0.13 in S. avenae on leaves and ears, respectively. In the populations with the most vigorous population growth, S. avenae on ears and M. dirhodum on leaves, the rate of population increase significantly decreased with increasing aphid density.  


2017 ◽  
Vol 108 (1) ◽  
pp. 84-92 ◽  
Author(s):  
A.M. Hamada ◽  
J. Fatehi ◽  
L.M.V. Jonsson

AbstractThiamine is a vitamin that has been shown to act as a trigger to activate plant defence and reduce pathogen and nematode infection as well as aphid settling and reproduction. We have here investigated whether thiamine treatments of seeds (i.e. seed dressing) would increase plant resistance against aphids and whether this would have different effects on a generalist than on specialist aphids. Seeds of wheat, barley, oat and pea were treated with thiamine alone or in combination with the biocontrol bacteriaPseudomonas chlororaphisMA 342 (MA 342). Plants were grown in climate chambers. The effects of seed treatment on fecundity, host acceptance and life span were studied on specialist aphids bird cherry-oat aphid (Rhopalosiphum padiL.) and pea aphid (Acyrthosiphon pisumHarris) and on the generalist green peach aphid (Myzus persicae, Sulzer). Thiamine seed treatments reduced reproduction and host acceptance of all three aphid species. The number of days to reproduction, the length of the reproductive life, the fecundity and the intrinsic rate of increase were found reduced for bird cherry-oat aphid after thiamine treatment of the cereal seeds. MA 342 did not have any effect in any of the plant-aphid combinations, except a weak decrease of pea aphid reproduction on pea. The results show that there are no differential effects of either thiamine or MA 342 seed treatments on specialist and generalist aphids and suggest that seed treatments with thiamine has a potential in aphid pest management.


Author(s):  
S Ahamd ◽  
Z Hera ◽  
MS Hanif ◽  
AH Syed

Aphids are the most commonly occurring, destructive, sap sucking and serious threat to cereal crops especially wheat (Triticum aestivum). Bird Cherry Oat aphid Rhopalosiphum padi (L.), is one of the most important aphids on T. aestivum which is one of the most consumed food and a source of nutrition in Pakistan. It causes considerable yield loss in wheat. Carbosulfan, a carbamate, is of the most commonly used pesticide against R. padi. The effects of Carbosulfan on generations of R. padi were performed under standard lab conditions by exposing adult aphids to three different concentrations (1.4×10-7 ppm, 1.4×10-10 ppm, 1.4×10-13 ppm) of Carbosulfan (Advantage® EC). Based on the results, all three concentrations noticeably reduced the pre-adult survival rate. 1.4×10-13 significantly extended the development duration of 1st instar, 2nd instar and 3rd instar nymphs. 1.4×10-13 ppm also extended the total pre-adult period and female longevity of R. padi. The total longevity was increased by 1.4×10-10 ppm. However, the fecundity decreased the most at 1.4×10-10 ppm. While the TPRP and APRP increased the most at 1.4×10-13 ppm. In the  life table parameters, both the intrinsic rate of increase (r) and the finite rate of increase (ƛ) decreased at 1.4×10-7 ppm and 1.4×10-10 ppm, as well as the net reproductive rate (R0) also decreased at 1.4×10-7 ppm and 1.4×10-10 ppm, while mean generation time (T) showed increase  at 1.4×10-13 ppm. Thus, at the concentrations of Carbosulfan tested here, there were negative impacts on R. padi fitness and biology by decreased pre-adult survival rate, λ, r, and R0. The concentrations also slowed down the development of some stages and extended T. My results would be helpful in assessing the overall effects of Carbosulfan on R. padi and should be taken into consideration when use Carbosulfan as a seed dressing insecticide for management of R. padi in wheat crop.


Author(s):  
Yingchao Ji ◽  
Guohua Li ◽  
Chenggang Zhou ◽  
Shuyan Yin

Abstract Temperature is one of the main factors affecting insect growth, development and reproduction. The effects of temperatures (10, 15, 20, 25 and 30°C) on the development and reproduction of Cinara cedri Mimeur (Hemiptera: Aphidoidea: Lachnidae) fed on Cedrus deodara (Roxb.) G. Don were evaluated in this study. With the increase of temperature from 10 to 30°C, the development duration at different development stages gradually shortened. There was a significant positive correlation between the developmental rates and temperature, following a quadratic regression model. The lower developmental threshold temperature (C) and effective accumulated temperatures (K) for completing a generation were 4.13°C and 263.4 degree-days, respectively. The highest fecundity was observed at 20°C with 25.74 first-instar nymphs/female. Both the highest intrinsic rate of increase (r, 0.11 ± 0.03) and net reproduction rate (R0, 19.06 ± 2.05) were observed at 20°C, whereas the lowest values of r (0.05 ± 0.01) at 10°C and R0 (5.78 ± 0.88) at 30°C were observed. The results suggest that temperature significantly affects the biology of C. cedri and the optimal temperature for its development is 20°C.


Author(s):  
Limei He ◽  
Shengyuan Zhao ◽  
Abid Ali ◽  
Shishuai Ge ◽  
Kongming Wu

Abstract Ambient humidity can directly affect the water balance in insects. The migratory fall armyworm, Spodoptera frugiperda Smith, has spread to more than 60 countries and regions in Africa, Asia, and Oceania that have a great difference in average ambient humidity. Understanding the effects of ambient humidity changes on its development, survival, and reproduction can help to predict its population dynamics in different habitats. Therefore, we evaluated the effects of atmospheric relative humidity (RH) on the development, survival, and reproduction and soil moisture on the pupation and emergence of fall armyworm. As a result, survival and pupal mass increased significantly with increasing RH. Among the five RHs tested, 80% RH was the most suitable for fall armyworm with the highest intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0). The population growth at the different RHs in decreasing order was 80 > 100 > 60 > 40 > 20%. A relative moisture (RM) of soil from 6.80 to 47.59% was suitable for fall armyworm pupation, survival, and eclosion, but fall armyworm could not pupate normally in soil with 88.39 and 95.19% RM. The survival and emergence rate of fall armyworm pupae were reduced by irrigation that increased the RM after the mature larvae entered the soil. These findings may be helpful for refining laboratory rearing protocols, population forecasting, and management of fall armyworm.


2009 ◽  
Vol 277 (1683) ◽  
pp. 963-969 ◽  
Author(s):  
Katie E. Marshall ◽  
Brent J. Sinclair

While insect cold tolerance has been well studied, the vast majority of work has focused on the effects of a single cold exposure. However, many abiotic environmental stresses, including temperature, fluctuate within an organism's lifespan. Given that organisms may trade-off survival at the cost of future reproduction, we investigated the effects of multiple cold exposures on survival and fertility in the model organism Drosophila melanogaster . We found that multiple cold exposures significantly decreased mortality compared with the same length of exposure in a single sustained bout, but significantly decreased fecundity (as measured by r , the intrinsic rate of increase) as well, owing to a shift in sex ratio. This change was reflected in a long-term decrease in glycogen stores in multiply exposed flies, while a brief effect on triglyceride stores was observed, suggesting flies are reallocating energy stores. Given that many environments are not static, this trade-off indicates that investigating the effects of repeated stress exposure is important for understanding and predicting physiological responses in the wild.


2014 ◽  
Vol 74 (3) ◽  
pp. 691-697 ◽  
Author(s):  
PP Marafeli ◽  
PR Reis ◽  
EC. da Silveira ◽  
GC Souza-Pimentel ◽  
MA. de Toledo

The predatory mite, Neoseiulus californicus(McGregor, 1954) (Acari: Phytoseiidae) is one of the principal natural enemies of tetranychid mites in several countries, promoting efficient control of those mites in several food and ornamental crops. Pest attacks such as that of the spider mite, Tetranychus urticaeKoch, 1836 (Acari: Tetranychidae), is one of the problems faced by farmers, especially in the greenhouse, due to the difficulty of its control with the use of chemicals because of the development of fast resistance making it hard to control it. The objective of this work was to study the life history of the predatory mite N. californicus as a contribution to its mass laboratory rearing, having castor bean plant [Ricinus communis L. (Euphorbiaceae)] pollen as food, for its subsequent use as a natural enemy of T. urticae on a cultivation of greenhouse rosebushes. The studies were carried out in the laboratory, at 25 ± 2°C of temperature, 70 ± 10% RH and a 14 hour photophase. The biological aspects and the fertility life table were appraised. Longevity of 32.9 days was verified for adult females and 40.4 days for males. The intrinsic rate of increase (rm) was 0.2 and the mean generation time (T) was 17.2 days. The population doubled every 4.1 days. The results obtained were similar to those in which the predatory mite N. californicus fed on T. urticae.


1981 ◽  
Vol 38 (8) ◽  
pp. 968-977 ◽  
Author(s):  
Derek A. Roff

Murphy's hypothesis that variation in reproductive life span is an adaptive response to variation in the predictability of reproductive success is examined. Murphy's contention that this hypothesis explains the variation in reproductive life span within the clupeids is reexamined incorporating further data on the Peruvian anchovy (Engraulis ringens). A nonsignificant correlation is now obtained between reproductive life span and brood strength variation; thus, the hypothesis is called into question. An alternative explanation is presented that considers the interaction between life history parameters: because it is necessary for the intrinsic rate of increase to exceed zero, variation in one parameter must be associated with variation in at least one other parameter. In the clupeids it is noted that the age of maturity and reproductive life span vary in concert and it is suggested that this provides an explanation of variation in reproductive life span. These two hypotheses are examined using data on the family Pleuronectidae, the flatfish. No correlation exists between reproductive life span and the degree of fluctuation in brood strength but there is a significant correlation between reproductive life span and age of maturity. It is concluded that variation in reproductive life span within the flatfish group is not a response to variation in reproductive success but rather a correlate of variation in age of maturity.Key words: flatfish, Pleuronectidae, iteroparity, natural selection, reproduction, clupeids


Acarologia ◽  
2018 ◽  
Vol 58 (1) ◽  
pp. 52-61
Author(s):  
Samah Ben Chaaban ◽  
Brahim Chermiti ◽  
Serge Kreiter

The old world date mite Oligonychus afrasiaticus is an important spider mite pest of the date palms Phoenix dactylifera L. mostly in North Africa and the Middle East. A population of the predaceous mite Typhlodromus (Anthoseius) athenas has been recently found in Tunisia in association with a decrease of O. afrasiaticus densities. The objective of this paper was to assess the development and reproduction abilities of T. ( A.) athenas on O. afrasiaticus under laboratory conditions at two temperatures: 27 and 32 °C. The results obtained show that females of T. (A.) athenas develop in 5 days at 27 °C and 4.1 days at 32 °C. The mean fecundity of T. (A.) athenas was 32.1 and 23.2 eggs per female at 27 and 32 °C, respectively. Life table parameters were stimated: the net reproductive rate (Ro) 27.9 and 17.9 eggs/female, the intrinsic rate of increase (rm) 0.322 and 0,344 female/female/day and the mean generation time (T) 10.3 and 8.4 days at 27 and 32 °C, respectively. At both temperatures tested, T. (A.) athenas intrinsic rate of increase was greater than that of O. afrasiaticus (rm = 0.213 at 32 °C,against rm = 0.166 day1 at 27 °C). Typhlodromus (A.) athenas would be able to develop at a wide range of temperatures feeding on O. afrasiaticus and seems to be able to potentially control it.


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