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Immature Survival (immature + survival)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Influence of prey species on immature survival, development, predation and reproduction of Coccinella transversalis Fabricius (Col., Coccinellidae)

JOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2004
Omkar
Abstract: Six aphid species, viz. Aphis craccivora, Aphis gossypii, Aphis nerii, Myzus persicae, Lipaphis erysimi and Uroleucon compositae were provided as prey to the feeding stages of Coccinella transversalis (Fabricius). All of them were found to be essential prey, however the relative prey suitability varied. All the predatory stages of C. transversalis consumed and preferred A. gossypii, the most and A. nerii, the least. Significant effect of prey quality was observed on pre-imaginal developmental periods, wet weights and adult longevity. The complete development was shortest on A. gossypii (13.01 ± 0.18 days) and longest on A. nerii (20.51 ± 0.25 days). The total prey consumption by larva, adult male and female in their lifetime was maximum (665.30 ± 5.75, 4831.10 ± 123.54 and 5412.30 ± 94.51, respectively) on A. gossypii and minimum (434.80 ± 4.03, 802.80 ± 34.37 and 905.20 ± 52.48, respectively) on A. nerii. Immature survival, growth index and adult emergence of C. transversalis was maximum (68.33, 7.82 and 88.21%, respectively) when larval instars consumed A. gossypii and minimum (37.75, 2.18 and 60.69%, respectively) after feeding on A. nerii. Female reproduction was also prey quality dependent showing maximum reproductive performance in terms of fecundity and percentage viability, with a highest reproductive period and lowest non-reproductive period on A. gossypii, followed by A. craccivora, L. erysimi, M. persicae, U. compositae and A. nerii. Regression analysis revealed a positive correlation between: (1) daily prey consumption and relative growth rate, (2) adult weight and developmental rate, (3) weights of adult male and female, and (4) female longevity and fecundity. [source]

Parental care in the whitefly Aleyrodes singularis

ECOLOGICAL ENTOMOLOGY, Issue 5 2001
Moshe Guershon
Summary 1. Patches of Aleyrodes singularis nymphs are characterised by a distinctive phenotype composed of the nymphs' exuviae, which are piled on the nymph, and by a covering layer of wax secreted by the adults; these characteristics have been found to confer defensive properties against natural enemies. 2. In contrast to the behaviour typical for ovipositing females of other aleyrodids, A. singularis females tend to remain near the patch of their progeny throughout their development. These mothers were therefore tested to show whether they exhibited active defensive behaviour towards natural enemies, beyond their contribution to passive defence achieved through the secretion of wax on the immatures. 3. The behaviour of whitefly adults differed significantly when performed in the presence of conspecific adults from their behaviour in the presence of natural enemies (either a parasitoid or a predator). The differences were expressed in the mean time devoted to some behavioural events, the frequency at which events were performed, and the number of transitions between pairs of events. 4. Most of the recorded behavioural differences were associated with departure of the natural enemies, facilitating immature survival. 5. This is the first report of active behavioural changes that convey defence of immature offspring for the family Aleyrodidae. Conditions characterising these findings and their relationship with those in which parental care is expected are discussed. [source]

Mortality dynamics and population regulation in Bemisia tabaci

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2005
Steven E. Naranjo
Abstract Natural mortality is an important determinant of the population dynamics of a species, and an understanding of mortality forces should aid in the development of better management strategies for insect pests. An in situ, observational method was used to construct cohort-based life tables for Bemisia tabaci (Gennadius) Biotype B (Homoptera: Aleyrodidae) over 14 generations on cotton in central Arizona, USA, from 1997 to 1999. In descending order, median marginal rates of mortality were highest for predation, dislodgment, unknown causes, egg inviability, and parasitism. The highest mortality occurred during the 4th nymphal stadium, and the median rate of immature survival over 14 generations was 6.6%. Predation during the 4th nymphal stadium was the primary key factor. Irreplaceable mortality was highest for predation and dislodgment, with the absence of these mortality factors leading to the greatest increases in estimated net reproduction. There was little evidence of direct or delayed density-dependence for any mortality factor. Wind, rainfall, and predator densities were associated with dislodgment, and rates of predation were related to densities of Geocoris spp., Orius tristicolor (White), Chrysoperla carnea s.l. Stephens, and Lygus hesperus Knight. Simulations suggest that immigration and emigration play important roles in site-specific dynamics by explaining departures from observed population trajectories based solely on endogenous reproduction and mortality. By a direct measurement of these mortality factors and indirect evidence of adult movement, we conclude that efficient pest management may be best accomplished by fostering greater mortality during the 4th stadium, largely through a conservation of predators and by managing immigrating adult populations at their sources. [source]

Factors affecting density-independent survival of an island population of tsetse flies in Zimbabwe

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2001
J.W. Hargrove
Abstract Analysis is presented of the factors affecting survival probability in populations of tsetse flies Glossina morsitans morsitans Westwood and G. pallidipes Austen (Diptera: Glossinidae) on Antelope Island, Lake Kariba, Zimbabwe. For mature male and female adult G. m. morsitans mean temperature (Tbar) accounted for 70 and 50%, respectively, of the variance in mark-recapture estimates of survival when the flies were not subjected to trapping. Saturation deficit (SD) only accounted for 36 and 33%, respectively. Maximum temperature (Tmax) and SD accounted for 36,42% of the variance in male and female G. pallidipes. For the corresponding Moran curve estimates of the survival over all developmental stages, SD lagged by three weeks accounted for 61 and 41% of the variance for male and female G. m. morsitans, respectively, and 64 and 56% for G. pallidipes. The corresponding figures for plots against Tmax were 44, 23, 23, and 21%, respectively. The same patterns were seen in the whole data set once allowance was made for the effect of trapping on survival and for an effect of season, correlated with an index of photosynthetic activity. For male G. m. morsitans there was a significant effect of saturation deficit, but not temperature, on immature survival. Decreased adult survival at high temperatures results from the need to feed more frequently and hence to take more risks per unit time. High saturation deficits result directly in reduced emergence of healthy flies from pupae. [source]

Influence of prey species on immature survival, development, predation and reproduction of Coccinella transversalis Fabricius (Col., Coccinellidae)

Sex-biased juvenile survival in a bird with extreme size dimorphism, the great bustard Otis tarda

JOURNAL OF AVIAN BIOLOGY, Issue 3 2007
Carlos A. Martín
We explored sex-biased mortality patterns in a species showing the most extreme sexual dimorphism among birds, the great bustard Otis tarda. Between 1991 and 2005 we studied juvenile and immature survival in a sample of 361 great bustards radio-tagged at two different populations in Spain, Villafáfila and Madrid. Mortality decreased with age, from high rates during the first year (0.70), to 0.10 in the second year. Using the known-fate model in program MARK we found that monthly survival increased throughout the first year. Offspring showing higher body mass at marking, i.e. those hatched earlier in the season and those with better body condition, survived in higher proportion. This was probably related to the earlier breeding dates of more experienced mothers, as well as to the observed decrease in food availability as the season progresses. Monthly survival estimates were higher in females than in males, which suggests that juvenile males are more vulnerable to reduced food availability and other factors due to their much faster growth rates. The proportion of non-natural deaths increased with age, and was higher in the Madrid population, where illegal hunting and collision with powerlines showed a high incidence. The male-biased mortality found in young birds in this study explains the female-biased population sex ratios observed in great bustard populations. The different degrees of incidence of human-induced causes of mortality found between both populations studied suggest that such differences may contribute to the variation observed in the adult sex ratio among populations. [source]