Social density, but not sex ratio, drives ecdysteroid hormone provisioning to eggs by female house crickets (Acheta domesticus)

Abstract

Social environment profoundly influences the fitness of animals, affecting their probability of survival to adulthood, longevity, and reproductive output. The social conditions experienced by parents at the time of reproduction can predict the social environments that offspring will face. Despite clear challenges in predicting future environmental conditions, adaptive maternal effects provide a mechanism of passing environmental information from parent to offspring and are now considered pervasive in natural systems. Maternal effects have been widely studied in vertebrates, especially in the context of social environment, and are often mediated by steroid hormone (SH) deposition to eggs. In insects, although many species dramatically alter phenotype and life‐history traits in response to social density, the mechanisms of these alterations, and the role of hormone deposition by insect mothers into their eggs, remains unknown. In the experiments described here, we assess the effects of social environment on maternal hormone deposition to eggs in house crickets (Acheta domesticus). Specifically, we tested the hypotheses that variable deposition of ecdysteroid hormones (ESH) to eggs is affected by both maternal (a) social density and (b) social composition. We found that while maternal hormone deposition to eggs does not respond to social composition (sex ratio), it does reflect social density; females provision their eggs with higher ESH doses under low‐density conditions. This finding is consistent with the interpretation that variable ESH provisioning is an adaptive maternal response to social environment and congruent with similar patterns of variable maternal provisioning across the tree of life. Moreover, our results confirm that maternal hormone provisioning may mediate delayed density dependence by introducing a time lag in the response of offspring phenotype to population size.

Diet composition and social environment determine food consumption, phenotype and fecundity in an omnivorous insect

“…Considered separately, nutritional imbalance alone negatively affects a plethora of biological phenomena, for instance, development and reproduction [1][2][3][4], and additionally can induce long-lasting behavioural changes [5][6][7]. Likewise, the social environment bears the capacity to change gene expression patterns [8] and phenotype [9][10][11] in non-social animals. The combined effects of population density and food availability have been addressed in several studies [12][13][14][15][16][17].…”

Population density and temperature influence the return on maternal investment in wild house mice

“…Density-dependent maternal effects have been reported mainly in avian systems, where mothers adapt androgen allocation to the current social density (Remeš et al 2011, Mazuc et al 2003. Recently, similar effects of population density have been recorded in crickets, where females adjusted hormonal levels of their eggs to the experienced social environment (Crocker and Hunter 2018). Also, in mammals, population density was shown to alter maternal investment and increase offspring growth at high population densities to increase the probability of surviving winter periods.…”

A multifactorial proteomics approach to sex‐specific effects of diet composition and social environment in an omnivorous insect

“…Acheta domesticus, differential expression, house cricket, IDA, liquid chromatography, multifactorial experiment, nutritional ecology, SWATH, tandem mass spectrometry In a recent study (Gutiérrez, Fresch, et al, 2020), we subjected the house cricket A. domesticus to a factorial experiment where diet composition and social environment were manipulated. Such experimental factors are considered largely influential on the survival, development, and fitness of animals (Clark et al, 2015;Crocker & Hunter, 2018;Dávila & Aron, 2017;Han & Dingemanse, 2017;Swift et al, 1996). We showed that A. domesticus exhibited considerable sex-specific differences to disparate rearing conditions.…”