A New Method for the Identification of Key Factors from Life-Table Data

Podoler, H.; Rogers, David J.

doi:10.2307/3853

Cited by 217 publications

(137 citation statements)

References 28 publications

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“…Foi considerado como componente crítico de perdas aquele cuja correlação foi significativa pelo teste t a p<0,05 (Varley & Gradwell, 1960). Entretanto, se mais de uma dessas correlações foi significativa, foram realizadas análises de regressão linear entre essas perdas parciais em função das perdas totais, sendo considerado como componente crítico de perdas aquele cuja equação de regressão apresentou o maior coeficiente angular a p<0,05 (Podoler & Rogers, 1975). Processo similar foi usado para determinar a causa do fator-chave de perdas no componente crítico.…”

Section: Methodsunclassified

Intensidades de perdas, ataque de insetos-praga e incidência de inimigos naturais em cultivares de milho em cultivo de safrinha

Picanço¹,

Galvan²,

Galvão³

et al. 2003

Ciênc. agrotec.

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Conduziu-se este trabalho visando a estudar as intensidades de perdas, densidades de insetos-praga e inimigos naturais em 49 cultivares de milho (Zea mays L.) em cultivo de safrinha em Coimbra, MG, Brasil. A produtividade média das cultivares foi de 3438,74 kg/ha, sendo as cultivares Traktor, CDX98D06, CO9621, OC705 e 97TR61 as mais produtivas. Ocorreram 29,62% de perdas na produtividade das cultivares, devido principalmente ao ataque de Sitophilus zeamais (Motsch., 1865) (Coleoptera: Curculionidae) aos grãos. O inseto-praga mais abundante foi Dalbulus maidis (DeLong & Wolcott, 1923) (Homoptera: Cicadellidae), seguido por adultos de Diabrotica speciosa (Germ., 1824) (Coleoptera: Chrysomelidae) e lagartas de Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae). O inimigo natural mais abundante foi o predador Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae). As densidades desses insetos foram semelhantes nas cultivares, com exceção de D. maidis. As cultivares menos atacadas por D. maidis foram: SHS5060, COE9994, HT8A97, NB6077, Z8550, CD3351, Maister, AG122, HS12L1133, HT47C, 97TR61, CDX98D04 e A975.

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Section: Methodsunclassified

Intensidades de perdas, ataque de insetos-praga e incidência de inimigos naturais em cultivares de milho em cultivo de safrinha

Picanço¹,

Galvan²,

Galvão³

et al. 2003

Ciênc. agrotec.

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“…Subsequently, the b-values (slopes of the regression of k on K, where k is the k-value of the i-th develop mental stage and K is the k-value for the whole larval stage, were calculated (Podoler & Rogers, 1975;Yamamura, 1999).…”

Section: Discussionmentioning

confidence: 99%

Key life stages of two predatory ladybird species (Coleoptera: Coccinellidae)

Kindlmann¹,

Yasuda²,

Sato³

et al. 2000

Eur. J. Entomol.

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Abstract. Development and survival of larvae of two predatory ladybird species, Harmonia axyridis (Pallas) and Coccinella septem punctata L. on hibiscus (Hibiscus syridis L.) trees was followed daily outdoors during four seasons. Data were analysed and stagespecific mortality in a stage-structured model was estimated using Manly's (1997) method. Subsequently, key factor analysis was used to determine the life stages in which the daily mortality was best correlated with the total mortality during larval life. Consis tently with the results from the first two years, the larvae suffered the greatest mortality during the first and fourth instars. The k-values for these two instars were also best correlated with those for the whole larval life, especially in H. axyridis.

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“…The k i that covaries most closely with K is then identified as the ''key factor,'' and is assumed to be primarily responsible for observed population changes. The key factor may be identified visually by plotting K and k i , or based on regression analyses (Smith 1973, Podoler andRogers 1975). Although popular among ecologists until recently, the key factor analysis has been shown to be conceptually and statistically flawed and is no longer considered to be a reasonable approach to identifying demographic causes of population fluctuations (Royama 1996, Sibly andSmith 1998).…”

Section: Introductionmentioning

confidence: 99%

Yellow-Bellied Marmot Population Dynamics: Demographic Mechanisms of Growth and Decline

Oli

Armitage

2004

Ecology

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Abstract. Multiple environmental factors may act synergistically to influence demographic characteristics, and ultimately the dynamics, of biological populations. Using prospective and retrospective analyses of demographic data from a 40-year study of individually marked animals, we investigated the demographic mechanisms of the temporal and spatial dynamics of a yellow-bellied marmot (Marmota flaviventris) population. Prospective elasticity analyses indicated juvenile survival (P j ) would have the largest relative influence on the projected population growth rate (). Relative magnitudes of elasticities did not differ between years characterized by positive ( Ͼ 1.0) and negative ( Ͻ 1.0) population growth. However, retrospective analyses of a life table response experiment (LTRE) revealed that changes in fertility (F), followed by age of first reproduction (␣) made the largest contributions to observed annual changes in . Changes in F and ␣ made the largest contributions to annual declines in , whereas changes in P j also were important to cause increases in . Population dynamic differences among marmot colonies were due primarily to spatial variations in ␣ and P j . Our results indicate that changes in reproductive parameters (␣ and F) primarily drive the temporal dynamics of our study population, and that demographic mechanisms of population increases might differ from those of population declines. Studies of the regulation of yellow-bellied marmot populations should focus on the factors or processes influencing reproductive parameters.

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A New Method for the Identification of Key Factors from Life-Table Data

Cited by 217 publications

References 28 publications

Intensidades de perdas, ataque de insetos-praga e incidência de inimigos naturais em cultivares de milho em cultivo de safrinha

Intensidades de perdas, ataque de insetos-praga e incidência de inimigos naturais em cultivares de milho em cultivo de safrinha

Key life stages of two predatory ladybird species (Coleoptera: Coccinellidae)

Yellow-Bellied Marmot Population Dynamics: Demographic Mechanisms of Growth and Decline

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