Reproductive investment in spiders: how female condition and oviposition timing influence egg sac quality

Abstract

Maternal condition and environmental factors can strongly influence reproductive investment and offspring quality. We investigated how female body condition and oviposition timing (first versus second half of the reproductive season) affect egg sac characteristics and biochemical composition in the spider Holocnemus pluchei. We analyzed egg sac weight, egg number, and the characterization and concentration of proteins, lipids, and fatty acids in postvitellogenic females and their egg sacs. Females in good condition produced heavier egg sacs with more eggs, particularly when oviposition occurred early in the season. Total protein concentrations in egg sacs and females remained constant across groups, although hemocyanin levels varied without a clear association with condition or timing. Lipid analysis revealed greater investment in early-season reproduction, with females allocating approximately 52% of their lipid reserves to eggs. Notably, females in poor condition during the second half of the season exhibited the lowest total lipid levels. Fatty acid profiles indicated limited seasonal or condition-dependent changes, suggesting stable prey types throughout the season but reduced prey quantity later in the reproductive period. Our results highlight how both maternal condition and oviposition timing shape reproductive strategies and resource allocation in H. pluchei, with potential consequences for offspring survival and population dynamics.