Response to cecropia cocoons of Mus musculus and two species of Peromyscus
SummaryIn rural areas cocoons of overwintering Hyalophora cecropia spum close to the ground are opened and the pupae eaten by small mammals, but in urban areas, where cecropia populations are much larger, the cocoons are almost never opened by mammals. Peromyscus leucopus noveboracensis and P. maniculatus bairdii are abundant in rural areas, but are largely replaced by Mus musculus in urban areas. In laboratory experiments P. l. noveboracensis invariably opened cecropia cocoons and ate the pupae. P. m. bairdii were slower to open cecropia cocoons and two of twelve did not open one at all. M. musculus, on the other hand, never opened cecropia cocoons although they gnawed the silk and ate uncovered pupae. Cocoons opened in the laboratory by the two species of Peromyscus cannot be distinguished from each other or from cocoons opened in the field.
Ecological Observations upon the Enemies of Cecropia, With Particular Reference to Its hymenopterous Parasites
Within the Chicago area near Summit, Illinois, there is a level prairie community supporting scattered clumps of black willow, box elder, and wild cherry. These trees were found to be heavily infested with cocoons of Samnia cecropia (Linnaeus), the infestation being reasonably constant from year to year. The writer became engaged in a study of the feeding interrelationships existing between these trees, the Cecropian larvae, and the involved chain of hymenopterous parasites and hyperparasites (Marsh, '34), and this opportunity is taken to discuss briefly certain general aspects of the problem, e.g. the biotic balance between moth, predators, and parasites.
Soil organic matter and microbiological development of technosols in the South Wales Coalfield
Abstract Degraded land (formerly ‘reclaimed’) after surface-coal-mining is a serious problem in South Wales. This project uses forestation to foster soil development on opencast coal-mine spoil technosols. It compares records of humification and the soil microbiological system (microcoenosis) using paired data from the same plantings in 1998 and 2018. Statistical analysis finds no significant difference between samples collected under trees planted by the pit-planting versus trench planting method or trees planted using organic or mineral fertilizer. However, there are strong significant differences in both soil organic matter and microflora components and significant correlations with time since tree planting. Most components of the soil organic carbon (TOC) and the microflora increase, often significantly. However, compared to 2018, 1998 samples contain significantly greater maximum levels of Insoluble Carbon while the microflora had significantly more Ammonifying bacteria. Decreases in Insoluble Carbon explain the relatively small increase in TOC between 1998 and 2018. The % extracted with 0.1 N H2SO4 is significantly larger in 2018, suggesting active weathering. Similarly, both the maxima and minima of total Humic and Fulvic acids content, extracted with 0.1 M Na4P2O7 + 0.1 M NaOH, are significantly greater in 2018. Total microflora shows significant positive correlations with time-since-tree-planting as do the proportions of bacilli and actinomycetes but the correlation with ammonifying bacteria is negative. In 1998, the microflora was dominated by non-spore-forming bacteria while, in 2018, bacilli and actinomycetes prevail; both are involved in the transformation of complex organic compounds and humification. This indicates active transformation of more complex organic compounds and advancing humification. In sum, forestation of these degraded, formerly reclaimed, opencast coal-mine spoils has resulted in a massive increase in both the size and functioning of the soil organic system.