Cryptic maternal effects in Hippodamia convergens vary with maternal age and body size

Abstract

Maternal effects can mold progeny phenotypes in various ways and may constitute ecological adaptations. By examining the effect of oviposition sequence on progeny produced by different size classes of female ladybird beetles (produced by controlling larval access to food), we show that maternal signals can change through adult life and alter the developmental programs of progeny, ostensibly to synchronize their life histories with predictable resource dynamics, thus maximizing maternal fitness. We also show that female body size, as determined by larval food supply, interacts with female age to influence progeny fitness. When fed ad libitum as adults, small females reared with limited food access laid fewer, smaller eggs than large females reared with ad libitum food access. Maternal body size interacted with oviposition sequence to influence progeny development, but the latter had greater impact. Eggs laid later by medium and large females hatched faster than those laid earlier, larvae fed longer in the fourth instar, their pupation period was shorter, total developmental time was reduced, and adults emerged with greater mass, most notably daughters. Oviposition sequence effects on progeny from small mothers were non‐significant for total developmental time and progeny mass. Only large mothers increased egg size over time and egg mass was not consistently correlated with developmental parameters, indicating that progeny phenotype was impacted by other, more cryptic, maternal signals. Such signals appear costly, as food limitation during development constrained not only fecundity and egg size but also maternal ability to manipulate progeny phenotype. The production of faster‐developing offspring that mature to larger sizes late in the oviposition cycle may be adaptive for exploitation of ephemeral aphid outbreaks with predictable dynamics of prey abundance and competition.

Age‐specific maternal effects interact with larval food supply to modulate life history in Coleomegilla maculata

“…Mousseau & Dingle, 1991;Tschinkel, 1993). In contrast, H. convergens larvae from later cohorts develop faster than those from earlier ones, largely as a result of faster egg hatching and shorter pupation times (Vargas et al, 2012c). However, there are ecological reasons why female C. maculata may benefit by increasing egg size (and offspring quality) as a function of oviposition sequence.…”

“…A nitrogen-deficient diet will induce the soybean looper, Pseudoplusia includens (Walker), to extend development and for some larvae to undergo supernumary stadia (Wier & Boethel, 1995). In coccinellids, maternally-mediated changes in duration of life stages, developmental rate, and number of moults are most likely cued by either genomic imprinting or allohormonal signals in the egg and appear independent of changes in egg size, even although they are sensitive to female condition (Vargas et al, 2012c). Similarly, development on low-quality food plant results in supernumary instars in the tortricid Acleris minuta (Robinson) (Weatherby & Hart, 1986).…”

“…On the High Plains, females of aphidophagaous species normally encounter only a single reproductive opportunity (aphid outbreak) in either spring or fall (Michaud & Qureshi, 2006) and do not oviposit in the same outbreak that supports their development. In H. convergens, females accomplish this by shortening progeny developmental time in later clutches, in particular by reducing the duration of the most vulnerable stages, egg, and pupa (Vargas et al, 2012c). In H. convergens, females accomplish this by shortening progeny developmental time in later clutches, in particular by reducing the duration of the most vulnerable stages, egg, and pupa (Vargas et al, 2012c).…”

“…Cryptic maternal effects, for example subtle changes in development or behaviour, have also been reported in birds (Groothuis et al, 2005) and mammals (Dloniak et al, 2006). Recently, Vargas et al (2012c), demonstrated age-specific maternal effects in H. convergens that appeared unrelated to changes in egg mass, but affected progeny developmental rate, the relative duration of particular developmental stages (fourth instar and pupa) and final adult size.…”

Polyandry restores female fertility and paternal effects diminished by inbreeding in Hippodamia convergens

“…Until recently, the more indirect benefits of polyandry were often ignored as inconsequential if direct benefits were evident (Tuni et al, 2013). However, it is possible that polyandry also has epigenetic consequences for offspring phenotype development, which could be mediated by maternal effects (Fox & Mousseau, 1998;Marshall et al, 2008;Shea et al, 2011;Vargas et al, 2012aVargas et al, ,2012b. Paternal effects are also recognised, especially in insects (Hunt & Simmons, 2000;Bonduriansky & Head, 2007;Michaud et al, 2013;Mirhosseini et al, 2014).…”