Reduction In Feeding Activity Research Articles

The effect of hydrocarbons and drilling fluids on the fecal pellet production of the deposit feeder Abra alba

The fccal pellet production of Abra alba was measured during exposure to different concentrations of diesel oil, drilling muds with different base fluids, oil-based cuttings and barite. For oil-based drilling muds a curvilinear regression ( y = ax + b log x + c), gave a very good description of the relationship between fecal pellet production ( y) and concentration of drilling mud in the sediment ( x). EC 50) (5 days) values calculated from the regression equation ranged from 57 to >1000 mg kg −1. The response was significantly correlated to the content of naphthenics in the mud. After 5 days of exposure to diesel oil and to two oil-based muds, no increase in the concentration of total hydrocarbons was found in the soft tissue of A. alba, and normal fecal pellet production was restored within 4–6 days in uncontaminated sediment. This suggests that the reduction in fecal pellet production may be due to a negative stimulus to feeding activity and ingestion, as well as to internal toxic effects on the organism. A reduction in feeding activity of A. alba may slow down the bioturbation of the sediments.

Particle retention and selection by larvae and spat of Ostrea edulis in algal suspensions

Grazing rates and electivity indices of larvae and spat of Ostrea edulis L. were, measured and examined in relation to certain physical parameters using a flow-through system. Retention and size-selection were determined for the major particle sizes present in cultures of Isochrysis galbana Parke, an alga used frequently as food for bivalves. Cultures of the algae Dunaliella tertiolecta Butcher and Phaeodactylum tricornutum Bohlin were used as sources of particle suspensions of various sizes and shapes, respectively. While increases in flow rate caused increased grazing, the mode of selection of I. galbana particles remained constant. Filtration rate, F f was related to body size, W, by the general allometric equation R f =aWb,while particle-size preference in suspensions of I. galbana by both larvae and spat of O. edulis was independent of W. Grazing rates increased with temperature to an optimum temperature, which was related to the acclimation temperature. Increases above this optimum caused a reduction in feeding activity. No significant change in particle size-preference in the I. galbana suspension with temperature was observed. Grazing rates and selection were dependent, however, on particle number and volume. Both larvae and spat displayed maximum retention at optimum particle concentrations which tended to decrease with increasing particle size. Variations in cell shape of P. tricornutum had no measurable effect on selectivity by O. edulis.

SUSCEPTIBILITY OF SOME FOREST INSECTS TO MIXTURES OF COMMERCIAL BACILLUS THURINGIENSIS AND CHEMICAL INSECTICIDES, AND SENSITIVITY OF THE PATHOGEN TO THE INSECTICIDES

AbstractExperiments were designed to determine the effects of low doses of some insecticides on the viability and physiological characteristics of commercial Bacillus thuringiensis (Berliner) as a prelude to studies on the susceptibility of lepidopterous forest defoliators to mixtures of bacteria and insecticides.The results show that the insecticides tested had no effect on viability or physiological integrity of the bacteria.Bacteria–insecticide combination effects varied from strongly antagonistic to strongly supplemental depending on insecticide or Thuricide® formulations and concentrations and on the relative susceptibility of the test species to either agent applied separately. Pyrethrum at 10−3 was highly potentiating to BT at 10−1 against third instar Halisidota argentata. Among Hyphantria cunea, a supplemental effect always resulted from combining Thuricide® at 10−2 with low concentrations of malathion, phosphamidon, or pyrethrum.There was generally a drastic reduction in feeding activity among BT-treated insects and a further reduction among BT-chemical-insecticide-treated ones compared with controls.

Seasonal Changes in Feeding Rate in Balanus Balanoides

In Balanus balanoides (L.) several abrupt physiological changes occur after the breeding season in November. They include loss of gonads and associated organs, the acquisition of a high degree of cold tolerance (Crisp & Ritz, 1967), interruption of the regular sequence of moulting cycles (Crisp & Patel, 1960) and the reduction in feeding activity.

Locomotor activity, sexual behaviour, and the corpus allatum hormone in males of Locusta

An actograph was used to record daily levels of locomotor activity shown by individual male locusts taken from groups of allatectomized and sham-operated locusts during a period of 24 days after the operation. The recordings show that the general level of locomotor activity in male locusts is not diminished following allatectomy: in fact; the allatectomized locusts show a considerable degree of movement associated with sexual behaviour. The possibility that the hypertrophy of the fat body, which follows the removal of the corpora allata, is due to lethargy is considered to be unlikely. The relationships between the various events characterizing sexual maturation in the male locust are discussed—in particular the significance of the reduction in feeding activity and the breakdown of the fat body in the mature male.

Rumination in sheep: Effects of morphine, deslanoside and ablation of area postrema

Abstract Continuous long-term recording of masticatory movements was obtained in four sheep housed in individual stalls. Total rumination time occupied about 33 per cent, and feeding activity an additional 25 per cent of the whole day. Intravenous injection of morphine sulfate, 1.0 mg/kg, did not produce a significant alteration in feeding or rumination behavior. By contrast, intracerebroventricular administration of morphine, 0.4 to 2.0 mg total, elicited compulsive and uninterrupted chewing activity for up to 15 hr. Apomorphine produced an effect similar to that of morphine, but of short duration. Intravenous injection of deslanoside, 0.04–0.08 mg/kg, resulted in complete inhibition of rumination for as long as 18 hr with little or no reduction in feeding activity. Forestomach (reticular) movements were also inhibited by the deslanoside. Vomiting was not elicited by any form of drug treatment. Chronic ablation of area postrema in the lower brain stem did not notably influence the character of spontaneous feeding and rumination behavior; it did not modify the compulsive chewing response to morphine; it abolished the inhibition of rumination as well as of reticular movements caused by deslanoside.