RESUMO
Field observations suggest that, in the U.K., cattle are the preferred host of Stomoxys calcitrans (L.), followed by horses. Differences were observed in the numbers of flies feeding on individual animals both in the field and under controlled conditions. Analysis of the behaviour of four Friesian calves under attack from S. calcitrans in controlled conditions revealed that the differences in the levels of attack between individual hosts are dependent on the reactions of the host when under attack. Those hosts which respond vigorously by tail flicks, foot stamps and head-swings suffer less from attack by S. calcitrans than their more placid contemporaries.
Assuntos
Comportamento Animal , Doenças dos Bovinos/parasitologia , Bovinos/parasitologia , Mordeduras e Picadas de Insetos/veterinária , Muscidae/fisiologia , Animais , Bovinos/fisiologia , Comportamento Alimentar , Interações Hospedeiro-Parasita , Mordeduras e Picadas de Insetos/parasitologiaRESUMO
The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third. The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.
Assuntos
Antibacterianos/farmacologia , Calcimicina/farmacologia , Insetos/efeitos dos fármacos , Lasalocida/farmacologia , Sistemas Neurossecretores/efeitos dos fármacos , Animais , Grânulos Citoplasmáticos/ultraestrutura , Microscopia Eletrônica , Neurossecreção/efeitos dos fármacos , Sistemas Neurossecretores/ultraestruturaRESUMO
Intracellular recordings have been made from the cell bodies of both neurosecretory and non-neurosecretory multipolar neurons in the periphery of Carausius morosus. The neurosecretory neurons have cell bodies which are electrically excitable and produce overshooting action potentials, whilst the cell bodies of the non-neurosecretory neurons are electrically inexcitable.
