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

Abstract

1. Maternal effects can modify progeny phenotypes to improve their survival under variable conditions, such as changes in food supply. In aphidophagous coccinellids, maternal effects can influence egg size, developmental rate, and final adult body size.2. Four cohorts of Coleomegilla maculata De Geer larvae were reared from four different points in their mothers' reproductive lives (1st, 12th, 24th, and 36th oviposition days) and divided into two diet treatments for rearing; 30-min daily access to eggs of Ephestia kuehniella Zeller or ad libitum.3. Progeny survival was lower on restricted food but increased over the first 12 oviposition days in both treatments, suggesting mothers did not conform to the theoretical norm of producing their 'best' progeny first.4. Larval development was delayed on the restricted diet, but there was no effect of oviposition day on total developmental time, although pupation was faster in the final cohort than in the first.5. The results suggest that mothers employ a mixed strategy and produce subsets of progeny that vary in response to food limitation. A small fraction adopt an 'optimistic' strategy and undergo an additional instar to take advantage of any possible improvement in the food supply, whereas a larger fraction adopt a 'pessimistic' strategy, forgoing an instar and the costs of a moult to pupate at a small size.6. The restricted diet increased the percentage of larvae that added or subtracted an instar, but larvae from later clutches were more likely to pupate after only three instars, independent of treatment, suggesting that a larger proportion of later-hatching progeny are maternally programmed for pessimism, as would be adaptive for larvae exploiting aphid populations in decline.

Maternal diet and age alter direct and indirect relationships between life‐history traits across multiple generations

“…Along with external environmental cues, intrinsic characteristics of the mother may also influence offspring fitness (Vargas, Michaud, Nechols, & Moreno, 2014). In many species, maternal age results in shifts in the relationship between early reproduction and life span, where older mothers produce offspring that maximize early reproduction at the expense of life span (Marshall, Heppell, Munch, & Warner, 2010;Metcalfe & Monaghan, 2001).…”

Limb ablation and regeneration in Harmonia axyridis: costs for regenerators, but benefits for their progeny

“…Thus, another transgenerational impact of ablation/regeneration was positive, again contradicting our initial hypothesis. Coccinellids are known to exert maternal and paternal effects on their progeny, probably to raise their own fitness (Vargas et al., ,, ; Mirhosseini et al., ). If limb regeneration in H. axyridis cues an epigenetic cascade that involves the activation of many genes, some could be responsible for pleiotropic enhancement of parental effects.…”

“…We hypothesized that processes associated with the recovery from ablation and limb regeneration would require the up‐regulation of many developmental genes in the pupal stage, with the potential for a cascade of secondary effects on subsequent physiology and life history. As parental effects in coccinellids are quite sensitive to parental condition (e.g., Vargas et al., ,, , ), we also hypothesized that physiological and pleiotropic effects associated with regeneration would be transgenerational and that regenerative costs would be evident in the life histories of progeny.…”

Estimating the effect of plant‐provided food supplements on pest consumption by omnivorous predators: lessons from two coccinellid beetles

“…3,4 The recorded effect of maternal origin on the ability of H. variegata larvae to survive on a pollen diet calls for further investigation to determine the cause of this variation among egg batches. For example, Vargas et al 24 found that maternal age affected the number of larval instars before pupation in Coleomegilla maculata (DeGeer); larvae from later-hatching progeny were more likely to pupate quicker, giving them an advantage when aphid populations are in decline. The recorded variation in H. variegata larval survival on pollen may be determined genetically or through maternal effects.…”