Oviposition and incubation environmental effects on embryonic diapause in a ground cricket.

Maternal effects on offspring phenotype are well known in organisms inhabiting seasonal environments. Mothers that perceive climatological changes indicative of winter's onset will often produce increasing numbers of offspring that enter a state of arrested morphogenesis known as 'diapause'. In this study of bivoltine Allonemobius socius ground crickets, we manipulated the abiotic environment experienced by ovipositing females (i.e. maternal-oviposition environment) and that experienced by offspring incubating as eggs (i.e. egg-incubation environment) to assess the degree to which mothers contribute to the expression of embryonic diapause in her offspring. Analysis of variance components indicated that variation in maternal-oviposition environment contributed only about 4% to the total variation in diapause incidence, compared to about 24% from embryos responding directly to variation in their incubation environment. Moreover, the 8% contribution from between-family variation was significant, suggesting that parental genes and maternal biotic and abiotic environments contribute to diapause expression in offspring. Although these findings suggest that maternal physi-ology itself contributes little to embryonic diapause variation in A. socius, they do not preclude other maternal behaviours (e.g. placement of eggs at different soil depths) that may affect offspring diapause.Copyright 1998 The Association for the Study of Animal Behaviour.