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Compilation of reports written by participants of a 14-day experimental pilot project in environmental education and biological field studies, designed and conducted under the guidance of Professor James A. Cunningham.
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The ED50 of a strain of Serratia marcescens for microinjected instar III and IV gypsy moth larvae was 7.5 and 14.5 viable cells, respectively. Percentage and rate of mortality were found to be highly variable among replicates of the same instar and between instars in free-feeding bioassays. Mortality in second instar larvae occurred before ecdysis, whereas practically no mortality occurred in third and fourth instars until the molting period. Neither Boivin endotoxin preparations nor culture filtrates were toxic to instar III larvae when administered per os or by microinjection. Histological evidence indicated that the microorganism invaded the hemocoel of healthy or predisposed insects through the gut wall. The rapid multiplication of the bacterium in the hemocoel of infected insects, followed by death in the absence of extensive tissue damage, indicated mortality was due to a septicemia. The histological and biological evidence presented indicated that the microorganism would be less than effective if utilized as a conventional microbial insecticide. © 1976.
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A gram-negative bacillus, pathogenic for gypsy moth larvae, was characterized culturally, morphologically, and physiologically as a member of the Serratia group of the family Enterobacteriaceae. The microorganism lacked the pigmentation characteristic of the group but was generally distinguished from closely related members of the family by its inability to produce gas from glucose, inositol, glycerol, and cellobiose; its rapid liquefaction of gelatin; and its failure to ferment raffinose or arabinose. The microorganism displayed lecithinase, deoxyribonuclease, and chitinase activity. The percentage of G + C in DNA from this bacterium was within the range reported for known strains of Serratia marcescens. © 1976.
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1. 1. The influence of thermal acclimation on cable constants of the median giant axon of earthworms, Lumbricus terrestris L., has been studied using standard intracellular stimulating and recording techniques. 2. 2. Acute cooling of axons from warm-acclimated worms resulted in changes in cable constants, some of which were partially compensated for (reversed) after cold acclimation. 3. 3. Of special interest is the relative behavior of specific axoplasm resistance in response to acute temperature change in warm- and cold-acclimated worms. 4. 4. The results suggest that thermal acclimation alters the properties of the axoplasm and that the resulting changes in cable constants contribute to compensatory adjustments in nerve conduction velocity after acclimation. © 1973.
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Growth and survival of scaled sardine, Harengula pensacolae, larvae were evaluated in laboratory rearing experiments at temperatures ranging from 21 to 35 C. Fertilized eggs were obtained in plankton collections made near Miami, Florida, in summer 1971. Larvae were reared for 15 days after hatching in temperature-controlled, 75-liter aquaria. Hatching success was high at all temperatures but larvae did not survive at 35 C, and survival was poor at 21-23 C. Survival was best at temperatures between 26 and 32 C. Mean daily growth increments ranged from 0.056 mm at 21-23 C to 1.035 mm at 32 C. Growth in relation to temperature was expressed by the equation Y = -0.8474 + 0.0537X, where Y equals daily growth increment and X equals temperature. Larval behavior was normal at 26 to 33.5 C. Critical high and low temperatures for larval survival were 35 C and approximately 20 C. © 1972 by the American Fisheries Society.
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