OVIPOSITION AND INCUBATION ENVIRONMENTAL-EFFECTS ON EMBRYONIC DIAPAUSE IN A GROUND CRICKET

Maternal effects on offspring phenotype are well known in organisms in habiting seasonal environments. Mothers that perceive climatological c hanges indicative of winter's onset will often produce increasing numb ers of offspring that enter a state of arrested morphogenesis known as 'diapause'. In this study of bivoltine Allonemobius socius ground cri ckets, we manipulated the abiotic environment experienced by ovipositi ng females (i.e. maternal-oviposition environment) and that experience d by offspring incubating as eggs (i.e. egg-incubation environment) to assess the degree to which mothers contribute to the expression of em bryonic diapause in her offspring. Analysis of variance components ind icated that variation in maternal-oviposition environment contributed only about 4% to the total variation in diapause incidence, compared t o about 24% from embryos responding directly to variation in their inc ubation environment. Moreover, the 8% contribution from between-family variation was significant, suggesting that parental genes and materna l biotic and abiotic environments contribute to diapause expression in offspring. Although these findings suggest that maternal physiology i tself contributes little to embryonic diapause variation in A. socius, they do not preclude other maternal behaviours (e.g. placement of egg s at different soil depths) that may affect offspring diapause. (C) 19 98 The Association for the Study of Animal Behaviour.