Physiological costs during the first maternal care in the wolf spider Pardosa saltans (Araneae, Lycosidae)

International audienceMany arachnids like other terrestrial arthropods, provide extensive maternal care. Few studies havequantified the underlying physiological costs of maternal care. We investigated how maternal care affectsthe free-moving wolf spider’s (Pardosa saltans) energy requirements. We described in detail their basicreproduction biology (i.e. carrying cocoon and young) and we evaluated the variation in the females’energy reserves during maternal care. Our results show that mothers guard eggs until hatching and thenguard their spiderlings for 27–30 more days. Laboratory observations indicated that spiderlings startleaving the maternal abdomen gradually 5–7 days after hatching. Females carry an egg sac (cocoon) thatcan weigh up to 77% of their post-reproduction weight and carry young that weigh 87–100% of their bodymass. Females lost weight over time despite regular food intake, while carrying cocoon and young; buttheir weights increased gradually during the dispersal of young. The contributions of proteins, glucoseand triglycerides to maintain females’ energy were calculated. Their energetic state varied duringmaternal care, in particular lipid levels declined, during the care of spiderlings when the females’ predatorybehaviour was inhibited. Our results show that the maternal care provided by P. saltans females isparticularly costly physiologically, during the 30 days following egg sac formation and development ofspiderlings, even when food is available