Natural Causes and Rates of Early Larval Mortality in Gypsy Moths (Lepidoptera: Lymantriidae) Sampled from Field Populations in Different Density States

Yerger, Ellen H.; Rossiter, MaryCarol

doi:10.1093/ee/25.5.1002

Cited by 11 publications

(10 citation statements)

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“…The fungus Entomophaga maimaiga does not appear to be transported on egg masses (Yerger and Rossiter 1996). The fungus Entomophaga maimaiga does not appear to be transported on egg masses (Yerger and Rossiter 1996).…”

Section: Gypsy Moth Eggsmentioning

confidence: 94%

Effects of Synchrony with Host Plant on Populations of a Spring-Feeding Lepidopteran

Hunter

Elkinton

2000

Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Comparisons of traits of outbreaking and nonoutbreaking leaf-eating Lepidoptera and Symphyta have shown that spring-feeding species are more likely to have outbreaks than are summer-feeding species. It has been suggested that variable synchrony with host budburst causes the population sizes of spring-feeding species to be more variable primarily because of the negative effects of older leaves on insects. While much evidence exists that leaf age can directly affect survival and reproduction of insects, few studies have looked at the population-level effects of variable phenology, and especially the potential for complex direct and indirect interactions with natural-enemy effects. To examine the consequences of variable phenology for population growth of an outbreaking insect, we manipulated the timing of gypsy moth (Lymantria dispar) egg hatch in the field. We released large numbers of gypsy moth larvae into replicate plots in the field at three times relative to budburst. Survival of larvae in protective sleeves was high unless they were released very long before host budburst, and leaf age had a direct negative effect on fecundity: the later the release, the lower was the fecundity of insects reared on white oak and black oak. The later the release, however, the greater was the dispersal by ballooning, which had the effect of reducing local densities. Because the most important natural enemies impose density-dependent mortality, dispersal had the effect of raising survival rate for later release dates. The direct host-plant effect and natural-enemy effects exhibited opposing influences on population processes, because fecundity decreased with release date but survival increased. The survival advantage of the late release outweighed the loss in fecundity, so that the expected population growth rate was highest for the latest release. The net effects of phenology on insect population growth thus depend largely on natural-enemy effects.Very different conclusions would have been drawn had we measured mortality only in protective sleeves and not in the presence of natural enemies. The strong natural-enemy effects may explain the large variability in outcome of plant-herbivore interactions and contribute to the high variability in population size of spring-feeding species.

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Section: Gypsy Moth Eggsmentioning

confidence: 94%

Effects of Synchrony with Host Plant on Populations of a Spring-Feeding Lepidopteran

Hunter

Elkinton

2000

Ecology

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“…Agreement has been less forthcoming in empirical studies of maternal effects in natural populations. Two field studies of the gypsy moth have reported effects of maternal environment on offspring performance (Diss et al ., 1996; Yerger & Rossiter, 1996), whereas two other field studies have not (Myers et al ., 1998; Erelli & Elkinton, 2000). However, in my opinion, all four studies are flawed.…”

Section: Classic Casesmentioning

confidence: 94%

“…Subsequent work by Rossiter developed along two lines; studies of the causes and consequences of maternal provisioning (Rossiter et al ., 1993, 1996; Yerger & Rossiter, 1996), and the development of conceptual models of population dynamics that included time‐lagged contributions of maternal effects (Rossiter, 1994, 1995, 1996, 1997, 1998). For example, the dominant storage protein in gypsy moth eggs is vitellogin.…”

Section: Classic Casesmentioning

confidence: 99%

Maternal effects and the population dynamics of insects on plants

Hunter

2002

Agri and Forest Entomology

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“…After removing eggs from cold storage, we sterilized them in 10% formaldehyde for 1 h, then rinsed them under running water for 1 h. This treatment kills virus on egg surfaces (virus commonly occurs in high density populations). The fungus Entomophaga maimaiga does not appear to be transported on egg masses (Yerger and Rossiter 1996). In both years, the hatching phenology and percentage hatch were obtained by counting numbers emerging, out of the 1000 eggs per release date, subdivided into 10 subsamples of 100 eggs each.…”

Section: Gypsy Moth Eggsmentioning

confidence: 99%

Effects of Synchrony With Host Plant on Populations of a Spring-Feeding Lepidopteran

Hunter

Elkinton

2000

Ecology

115

View full text Add to dashboard Cite

Comparisons of traits of outbreaking and nonoutbreaking leaf-eating Lepidoptera and Symphyta have shown that spring-feeding species are more likely to have outbreaks than are summer-feeding species. It has been suggested that variable synchrony with host budburst causes the population sizes of spring-feeding species to be more variable primarily because of the negative effects of older leaves on insects. While much evidence exists that leaf age can directly affect survival and reproduction of insects, few studies have looked at the population-level effects of variable phenology, and especially the potential for complex direct and indirect interactions with natural-enemy effects. To examine the consequences of variable phenology for population growth of an outbreaking insect, we manipulated the timing of gypsy moth (Lymantria dispar) egg hatch in the field. We released large numbers of gypsy moth larvae into replicate plots in the field at three times relative to budburst. Survival of larvae in protective sleeves was high unless they were released very long before host budburst, and leaf age had a direct negative effect on fecundity: the later the release, the lower was the fecundity of insects reared on white oak and black oak. The later the release, however, the greater was the dispersal by ballooning, which had the effect of reducing local densities. Because the most important natural enemies impose density-dependent mortality, dispersal had the effect of raising survival rate for later release dates. The direct host-plant effect and natural-enemy effects exhibited opposing influences on population processes, because fecundity decreased with release date but survival increased. The survival advantage of the late release outweighed the loss in fecundity, so that the expected population growth rate was highest for the latest release. The net effects of phenology on insect population growth thus depend largely on natural-enemy effects. Very different conclusions would have been drawn had we measured mortality only in protective sleeves and not in the presence of natural enemies. The strong natural-enemy effects may explain the large variability in outcome of plant-herbivore interactions and contribute to the high variability in population size of spring-feeding species.

show abstract

Natural Causes and Rates of Early Larval Mortality in Gypsy Moths (Lepidoptera: Lymantriidae) Sampled from Field Populations in Different Density States

Cited by 11 publications

References 0 publications

Effects of Synchrony with Host Plant on Populations of a Spring-Feeding Lepidopteran

Effects of Synchrony with Host Plant on Populations of a Spring-Feeding Lepidopteran

Maternal effects and the population dynamics of insects on plants

Effects of Synchrony With Host Plant on Populations of a Spring-Feeding Lepidopteran

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