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T D Fitzgerald - One of the best experts on this subject based on the ideXlab platform.
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thermal properties of the tent of early instar colonies of the eastern tent caterpillar Malacosoma Americanum lepidoptera lasiocampidae
Journal of Thermal Biology, 2012Co-Authors: T D Fitzgerald, Steven Miller, Michael SmithAbstract:Abstract The extent to which the small tents of the early instars of Malacosoma Americanum warmed when irradiated by sunlight was investigated by continuous electronic monitoring of field colonies for 137 colony-days. Tent temperatures exceeded the threshold for larval growth of 15 °C on 88–96% of the study days, exceeding in degree-minutes the ambient excess-over-threshold by a factor of approximately five. In still air, tents constructed by third instar caterpillars achieved greater temperature excesses over ambient than did a model of a tightly sealed glass house, but smaller tents and tents exposed to simulated wind did not perform as well. Tents of M. Americanum warmed more rapidly and to a high temperature than silk nests of markedly different design constructed by other species.
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Depletion of Host-Derived Cyanide in the Gut of the Eastern Tent Caterpillar, Malacosoma Americanum
Journal of Chemical Ecology, 2002Co-Authors: T D Fitzgerald, P. M. Jeffers, D. MantellaAbstract:Using a colorimetric procedure, we assessed the HCN-p of black cherry leaves ( Prunus serotina ) ingested by the eastern tent caterpillar, Malacosoma Americanum , and the cyanide content of the bolus as it passed thorough the caterpillar's digestive tract and into the detritus pool. The mean HCN-p of leaves in our study area was 1902 ± 174 (SE) ppm. Young leaves found at the tips of growing branches, which the caterpillars preferred, had a significantly higher HCN-p (3032 ± 258 ppm) than older leaves found at the middle (1542 ± 243 ppm) or base of the shoot (1131 ± 159 ppm). Following a bout of overnight feeding on young leaves, the cyanide content of the foregut and midgut boluses of early sixth-instar caterpillars averaged 631 ± 161 ppm, and 14 ± 3 ppm, respectively, indicating that host-derived cyanide is rapidly depleted as the bolus transits the gut. Some cyanide, however, remains. In three studies, the mean cyanide content of fresh fecal pellets ranged from approximately 20 to 38 ppm, while the dried, compacted pellets ranged from 63 to 85 ppm. Food in the foreguts of mature caterpillars dispersing over the ground in search of pupation sites had 417 ± 99 ppm cyanide. The potential impact of this egested and caterpillar-transported cyanide on the consumer and detritivore communities is discussed.
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Communal Foraging Behavior and Recruitment Communication in Gloveria sp.
Journal of Chemical Ecology, 1998Co-Authors: T D Fitzgerald, D. L. A. UnderwoodAbstract:The caterpillars of Gloveria sp. mark trails with a pheromone they deposit by dragging the ventral surface of the tip of the abdomen along branch pathways as they move between their communal nest and distance feeding sites. The threshold sensitivity of the caterpillar for an extract prepared from the secretory site was approximately 0.5 × 10^−3 caterpillar equivalents/cm of trail. Bioassays show that Gloveria follows neither authentic trails of Malacosoma Americanum nor artificial trails prepared from 5β-cholestane-3-one, a chemical previously reported to elicit trail following from other social caterpillars. Although our observations show that fed caterpillars mark heavily as they return to their nest, we found no evidence that individual caterpillars are able to recruit hungry nestmates to new food finds. In this species, recruitment to food occurs only after many caterpillars have reinforced a trail to a newly discovered food source. In contrast, hungry caterpillars of the confamilial species M. Americanum , tested under identical conditions, responded strongly to the postprandial trails of individual caterpillars and rapidly abandoned depleted sites in favor of new food finds. We postulate that the difference in the efficiency with which these two species recruit nestmates to food evolved in response to differences in the spatial distribution of their food supplies.
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Foraging behavior and growth of isolated larvae of a social caterpillar, Malacosoma Americanum
Entomologia Experimentalis et Applicata, 1996Co-Authors: T D Fitzgerald, C. R. VisscherAbstract:In laboratory experiments, isolated eastern tent caterpillars, Malacosoma Americanum (Fabricius) (Lepidoptera: Lasiocampidae), grew more slowly than their grouped siblings even though factors previously reported to give grouped caterpillars an advantage were eliminated from our experimental design. Analysis of time-lapse videorecordings of daily foraging bouts showed that, despite their slower growth, isolated individuals fed significantly more often than their grouped siblings. This finding is consistent with previous observations showing that the rate at which tent caterpillars assimilate food is largely independent of foraging frequency and suggests that increased metabolic costs associated with superfluous activity may cause isolated caterpillars to grow slower. More rapid growth of grouped caterpillars also appears attributable to the significantly longer periods of time solitary caterpillars spent inactive during episodes of molting. Our study shows that the distinctive temporal pattern of foraging characteristic of intact colonies of eastern tent caterpillars is a emergent property of the group.
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Trail following and recruitment: Response of eastern tent caterpillarMalacosoma Americanum to 5β-cholestane-3,24-dione and 5β-cholestan-3-one
Journal of Chemical Ecology, 1993Co-Authors: T D FitzgeraldAbstract:Studies were conducted to determine the relative effectiveness of 5β-cholestane-3,24-dione (diketone) and 5β-cholestan-3-one (monoketone) in eliciting trail following from eastern tent caterpillars, Malacosoma Americanum . In Y maze tests, trails prepared from the monoketone were followed preferentially over diketone trails, even when the diketone trail was several orders of magnitude stronger. Under field conditions, colonies readily abandoned well-developed trail systems in favor of artificial trails that were established with the monoketone. Other tests in which the caterpillars selected trails prepared from the monoketone (but not the diketone) more often than their own recruitment trails indicate that the monoketone constitutes the chemical basis of recruitment communication in this insect. The study also shows that tent caterpillars are highly sensitive to small differences in the amount of monoketone in a trail and can distinguish between new and aged trails prepared from the compound.
James T Costa - One of the best experts on this subject based on the ideXlab platform.
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Trail-Based Communication in Social Caterpillars of Eriogaster lanestris (Lepidoptera: Lasiocampidae)
Journal of Insect Behavior, 2001Co-Authors: Claudia Ruf, James T Costa, Konrad FiedlerAbstract:Caterpillars of Eriogaster lanestris (Lepidoptera: Lasiocampidae) mark trails as they move between feeding sites and their communal tent. They prefer new trails over aged ones. Hungry caterpillars prefer trails marked by fed caterpillars returning to the tent. Thus successful foragers direct tentmates to profitable food finds, in a manner similar to that of Malacosoma Americanum. E. lanestris readily follows trails prepared from 5β-cholestane-3-one, a component of the trail marker of M. Americanum, when applied at a rate of ≥10^−10 g/cm. In choice tests, they preferred more highly concentrated over weaker trails. New trails are always established in groups, and the velocity increases from early to late caterpillars traversing a new trail.
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hierarchical genetic structure and gene flow in macrogeographic populations of the eastern tent caterpillar Malacosoma Americanum
Evolution, 1994Co-Authors: James T Costa, Kenneth G RossAbstract:Genetic structure and inferred rates of gene flow in macrogeographic populations of the eastern tent caterpillar Malacosoma Americanum were analyzed at two hierarchical scales: local demes and regional subpopulations. Wright's F-statistics were used to estimate population genetic structure using multilocus genotypic data generated electrophoretically. Estimated values of FST and the distribution of private alleles were then used to obtain indirect estimates of gene flow. We found modest, though significant, genetic structure at both spatial scales, a pattern consistent with high rates of gene flow over the large distances involved. Modest values obtained for Nei's genetic distance also suggested high levels of gene flow across the range of this species, although some gene-flow restriction resulting from isolation by distance was suggested by a positive regression of genetic distance on geographic distance. The observed homogeneity at enzyme loci across the range of M. Americanum parallels the reported uniformity in morphology, suggesting a general absence of local genetic differentiation in this widely distributed species. The genetic homogeneity observed in this wide-ranging insect is discussed in terms of organism-specific environmental experience at different spatial scales. Some organisms occupying apparently heterogeneous environments may ameliorate unsuitable local conditions through microhabitat selection or behavioral modification of their microenvironment. This may be accomplished in M. Americanum through group shelter construction and behavioral thermoregulation, closely tying thermoregulation to social biology in this species. If in this way the tent helps produce an effectively homogeneous environment for this species across its extensive range, this system may provide a unique example of how social behavior can influence the distribution of genetic variation in a population.
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Seasonal decline in intracolony genetic relatedness in eastern tent caterpillars: implications for social evolution
Behavioral Ecology and Sociobiology, 1993Co-Authors: James T Costa, Kenneth G RossAbstract:Genetic relatedness in social insect colonies may vary spatially or temporally as a result of changes in colony membership due to immigration or to variation in patterns of maternity and paternity. We estimated relatedness for eastern tent caterpillars ( Malacosoma Americanum ) in laboratory colonies derived from egg masses using multilocus genotypic data derived from electrophoresis. This estimate is compared with estimates obtained from colony samples taken in the field at four intervals spanning the larval developmental season. We found that average intracolony relatedness is close to 0.5 initially but declines through the developmental season due to colony merging, showing that caterpillars do not discriminate between siblings and nonsiblings in order to preserve colony family structure. Using the intracolony values together with relatedness values for higher levels of population structure, we estimated the effective mean number of simple families represented in single colonies through the season. The overall effective number of families per tent increased from one at the time of eclosion to 1.3 by the end of the season. Average intracolony relatedness remained relatively high despite the occurrence of colony merging, apparently as a result of the low density of tents on most trees, combined with high relatedness within the original colonies. Thus, high intracolony relatedness is maintained in M. Americanum populations through the effects of adult dispersal, mating, and oviposition patterns, rather than through behavioral discrimination mechanisms of the larvae. These findings underscore the importance of considering the causes of temporal variation in genetic relatedness as well as the consequences for the indirect component of inclusive fitness.
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Estimates of heterozygosity in two social insects using a large number of electrophoretic markers
Heredity, 1992Co-Authors: D Dewayne Shoemaker, James T Costa, Kenneth G RossAbstract:An extensive electrophoretic survey of enzyme and protein markers was conducted for a haplodiploid eusocial insect, the red imported fire ant ( Solenopsis invicta ), and for a diploid communal insect, the eastern tent caterpillar ( Malacosoma Americanum ). This survey resulted in the discovery of 110 electrophoretic loci for S. invicta (15 of which were polymorphic at the 95 per cent level) and 37 electrophoretic loci for M. Americanum (seven polymorphic). Expected heterozygosities (mean H _exp±S.E.) were 0.051 ± 0.013 and 0.092 ± 0.030 for S. invicta and M. Americanum , respectively. Although these values do not differ significantly, they are consistent with the frequently reported pattern of low gene diversity in the eusocial Hymenoptera relative to non-eusocial diploid insects. This pattern persists when a large number of markers is scored in different life stages and castes, as in S. invicta in this study, and when a direct comparison is made using data generated in a single laboratory.
D. L. A. Underwood - One of the best experts on this subject based on the ideXlab platform.
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Communal Foraging Behavior and Recruitment Communication in Gloveria sp.
Journal of Chemical Ecology, 1998Co-Authors: T D Fitzgerald, D. L. A. UnderwoodAbstract:The caterpillars of Gloveria sp. mark trails with a pheromone they deposit by dragging the ventral surface of the tip of the abdomen along branch pathways as they move between their communal nest and distance feeding sites. The threshold sensitivity of the caterpillar for an extract prepared from the secretory site was approximately 0.5 × 10^−3 caterpillar equivalents/cm of trail. Bioassays show that Gloveria follows neither authentic trails of Malacosoma Americanum nor artificial trails prepared from 5β-cholestane-3-one, a chemical previously reported to elicit trail following from other social caterpillars. Although our observations show that fed caterpillars mark heavily as they return to their nest, we found no evidence that individual caterpillars are able to recruit hungry nestmates to new food finds. In this species, recruitment to food occurs only after many caterpillars have reinforced a trail to a newly discovered food source. In contrast, hungry caterpillars of the confamilial species M. Americanum , tested under identical conditions, responded strongly to the postprandial trails of individual caterpillars and rapidly abandoned depleted sites in favor of new food finds. We postulate that the difference in the efficiency with which these two species recruit nestmates to food evolved in response to differences in the spatial distribution of their food supplies.
K J Mcdowell - One of the best experts on this subject based on the ideXlab platform.
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eastern tent caterpillars Malacosoma Americanum cause mare reproductive loss syndrome
Journal of Insect Physiology, 2004Co-Authors: Bruce A Webb, Walter E Barney, D L Dahlman, Stephanie N Deborde, Claire Weer, Neil M Williams, J M Donahue, K J McdowellAbstract:Abstract A new equine abortigenic disease, mare reproductive loss syndrome (MRLS), was recognized and significantly impacted the Ohio Valley in the springs of 2001 and 2002. MRLS caused ~$ 330 million in losses in 2001. An epidemiological investigation of MRLS associated occurrence of the disease with exposure to eastern tent caterpillars ( M. Americanum ). This work investigates the epidemiological association between M . Americanum and MRLS to determine if this association was correlative or causative. A pilot study and Experiment 1 simulated exposure to M . Americanum and their excreta on pasture grasses. The pilot study advanced exposure of pregnant mares to M . Americanum materials and 18 of the 29 mares in the study aborted with symptoms of MRLS before other cases were reported in the region. In Experiment 1 , three of seven mares exposed to M . Americanum aborted, while mares in control ( n =6) and M . Americanum frass ( n =7) treatments had no losses. In Experiment 2 , mares were fed frozen insect larvae in feed buckets mixed with oats. Abortions occurred in three of five mares receiving frozen M . Americanum , while mares that were fed autoclaved M . Americanum ( n =5) or frozen gypsy moth larvae ( n =4) had no abortions due to MRLS. In Experiment 3 , M . Americanum larvae were dissected and fractionated. Statistically significant numbers of abortions occurred only in the positive control group and in association with the M . Americanum exoskeleton. All abortions induced by exposure to M . Americanum exhibited changes in echogenicity of fetal fluids and bacteriological findings post abortion that were consistent with MRLS. These studies support the hypothesis that ingestion of M . Americanum larvae induces the MRLS-type equine abortions, and provide experimental evidence that this lepidopteran larva can cause an abortigenic disease in a vertebrate host.
Kenneth G Ross - One of the best experts on this subject based on the ideXlab platform.
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hierarchical genetic structure and gene flow in macrogeographic populations of the eastern tent caterpillar Malacosoma Americanum
Evolution, 1994Co-Authors: James T Costa, Kenneth G RossAbstract:Genetic structure and inferred rates of gene flow in macrogeographic populations of the eastern tent caterpillar Malacosoma Americanum were analyzed at two hierarchical scales: local demes and regional subpopulations. Wright's F-statistics were used to estimate population genetic structure using multilocus genotypic data generated electrophoretically. Estimated values of FST and the distribution of private alleles were then used to obtain indirect estimates of gene flow. We found modest, though significant, genetic structure at both spatial scales, a pattern consistent with high rates of gene flow over the large distances involved. Modest values obtained for Nei's genetic distance also suggested high levels of gene flow across the range of this species, although some gene-flow restriction resulting from isolation by distance was suggested by a positive regression of genetic distance on geographic distance. The observed homogeneity at enzyme loci across the range of M. Americanum parallels the reported uniformity in morphology, suggesting a general absence of local genetic differentiation in this widely distributed species. The genetic homogeneity observed in this wide-ranging insect is discussed in terms of organism-specific environmental experience at different spatial scales. Some organisms occupying apparently heterogeneous environments may ameliorate unsuitable local conditions through microhabitat selection or behavioral modification of their microenvironment. This may be accomplished in M. Americanum through group shelter construction and behavioral thermoregulation, closely tying thermoregulation to social biology in this species. If in this way the tent helps produce an effectively homogeneous environment for this species across its extensive range, this system may provide a unique example of how social behavior can influence the distribution of genetic variation in a population.
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Seasonal decline in intracolony genetic relatedness in eastern tent caterpillars: implications for social evolution
Behavioral Ecology and Sociobiology, 1993Co-Authors: James T Costa, Kenneth G RossAbstract:Genetic relatedness in social insect colonies may vary spatially or temporally as a result of changes in colony membership due to immigration or to variation in patterns of maternity and paternity. We estimated relatedness for eastern tent caterpillars ( Malacosoma Americanum ) in laboratory colonies derived from egg masses using multilocus genotypic data derived from electrophoresis. This estimate is compared with estimates obtained from colony samples taken in the field at four intervals spanning the larval developmental season. We found that average intracolony relatedness is close to 0.5 initially but declines through the developmental season due to colony merging, showing that caterpillars do not discriminate between siblings and nonsiblings in order to preserve colony family structure. Using the intracolony values together with relatedness values for higher levels of population structure, we estimated the effective mean number of simple families represented in single colonies through the season. The overall effective number of families per tent increased from one at the time of eclosion to 1.3 by the end of the season. Average intracolony relatedness remained relatively high despite the occurrence of colony merging, apparently as a result of the low density of tents on most trees, combined with high relatedness within the original colonies. Thus, high intracolony relatedness is maintained in M. Americanum populations through the effects of adult dispersal, mating, and oviposition patterns, rather than through behavioral discrimination mechanisms of the larvae. These findings underscore the importance of considering the causes of temporal variation in genetic relatedness as well as the consequences for the indirect component of inclusive fitness.
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Estimates of heterozygosity in two social insects using a large number of electrophoretic markers
Heredity, 1992Co-Authors: D Dewayne Shoemaker, James T Costa, Kenneth G RossAbstract:An extensive electrophoretic survey of enzyme and protein markers was conducted for a haplodiploid eusocial insect, the red imported fire ant ( Solenopsis invicta ), and for a diploid communal insect, the eastern tent caterpillar ( Malacosoma Americanum ). This survey resulted in the discovery of 110 electrophoretic loci for S. invicta (15 of which were polymorphic at the 95 per cent level) and 37 electrophoretic loci for M. Americanum (seven polymorphic). Expected heterozygosities (mean H _exp±S.E.) were 0.051 ± 0.013 and 0.092 ± 0.030 for S. invicta and M. Americanum , respectively. Although these values do not differ significantly, they are consistent with the frequently reported pattern of low gene diversity in the eusocial Hymenoptera relative to non-eusocial diploid insects. This pattern persists when a large number of markers is scored in different life stages and castes, as in S. invicta in this study, and when a direct comparison is made using data generated in a single laboratory.
