THE EFFECTS OF STEADY AND CYCLING TEMPERATURES ON THE ACTIVITY OF THE SLUG DEROCERAS RETICULATUM

At constant temperatures, crawling activity in the slug Derocerasreticulatum has an optimum at 13°C in late winter, and 17°Cin early summer. The optimum for feeding remains at 14°C.Activity has anendogenous basis, but daytime activity increaseswith temperature and long daylengths. Cycling temperatures producemore locomotor activity and less feeding in 24 h than constanttemperatures, even when the temperature is higher at night.However, cooling stimulates and warming inhibits activity duringthe period of change and when cooling occurs at dusk, over halfthe 24 h activity occurs in the next three hours. Faster ratesof cooling produce greater responses, but can result in loweroverall activity because the slugs remain longer at low temperatures. (Received 25 May 1984;