J. Insect Physiol. Vol. 43, No. 10, pp. 973–978, 1997  1997 Elsevier Science Ltd Pergamon All rights reserved. Printed in Great Britain 0022-1910/97 $17.00 + 0.00 PII: S0022-1910(97)00011-5 Effects of Starvation on Body Composition and Cold Tolerance in the Collembolan Orchesella cincta and the Isopod Porcellio scaber D. LAVY,* O. NEDVED,† H. A. VERHOEF*‡ Received 28 August 1996; revised 22 November 1996 The effects of long-term starvation on the body composition of the isopod Porcellio scaber (Latreille) and the collembolan Orchesella cincta (L.) were studied, by determining the body composition in starved and fed animals. A period under summer conditions (19°C, 75% RH and L/D 16/8 photoperiod), was followed by a period under winter conditions (5°C, 75% RH and LD 6/18 photoperiod). O. cincta was held under summer conditions for 3 weeks, during which its protein and lipid content decreased, while its water content increased. In P. scaber, the same occurred during the 6 weeks they were kept under summer conditions. During sub- sequent weeks under winter conditions, changes in cold tolerance of the animals were investi- gated. Cold tolerance and haemolymph osmolality were measured once a week. Starved ani- mals had lower cold tolerance than fed ones. For P. scaber a decreased haemolymph osmolality was found in starved animals compared to fed ones. This is assumed to be caused by a combi- nation of the consumption of carbohydrates out of the haemolymph and of protein reserves and the accumulation of body water. O. cincta appeared to be capable of osmoregulation, as haemolymph osmolality did not differ between starved and fed animals, despite differences in body water content. Decreased cold tolerance in starved animals of both species may be caused by increased water content or, more probably, by the decrease in reserves needed to produce cryoprotective substances.  1997 Elsevier Science Ltd. All rights reserved Soil arthropods Starvation Lipid Protein Overwintering INTRODUCTION Cold tolerance in poikilothermic animals can be achieved by the accumulation of low molecular weight substances with colligative action (polyols and sugars) and/or high molecular weight antifreeze proteins (AFPs), often in combination with gut clearance to remove food-derived ice nucleators (Bale, 1989; Block, 1990; Lee, 1991). When preparing for winter, these substances have to be produced in considerable amounts in a relatively short time. Therefore, we hypothesised that the body compo- sition of an animal is likely to affect its ability to produce these substances and thereby its cold tolerance. In a previous study (Lavy, 1996) this hypothesis was *Department of Ecology and Ecotoxicology, Faculty of Biology, Vrije Universiteit, de Boelelaan 1087, 1081 HV Amsterdam, The Nether- lands †Institute of Entomology, Academy of Sciences, and Faculty of Bio- logical Science, University of South Bohemia, Branisovska ´ 31, 370 05 Ceske ´ Budejovice, Czech Republic ‡To whom all correspondence should be addressed. 973 tested by feeding animals on food of different nitrogen content, followed by a test of their ability to become cold tolerant. Two soil arthropod species were chosen: the iso- pod Porcellio scaber (Latreille) and the collembolan Orchesella cincta (L.). Both are very common in the lit- ter layer in temperate regions and in winter they are regu- larly exposed to subzero temperatures. Unrelated species were chosen as the effect of a changed body composition on cold tolerance may vary between taxonomic groups. Dietary nitrogen content did not affect either the cold tolerance or the body composition in P. scaber (Lavy, 1996). In O. cincta dietary composition influenced the lipid:protein ratio (Lavy and Verhoef, 1996). This, how- ever, had no influence on the cold tolerance of the ani- mals (Lavy, 1996). In the haemolymph of cold-tolerant individuals of both species, no increase in osmolality or thermal hysteresis was found. Therefore, the animals may be expected to become cold tolerant without much biochemical/physiological effort. In the field, several abiotic conditions can cause diet- ary stress in soil arthropods, which may induce a change