ABSTRACT Speckled cockroaches (Nauphoeta cinerea) are an attractive insect model to study the effect of early life (i.e., juvenile) events on physiological function in adulthood. Like mammals, juvenile cockroaches share the same niche as adults, including diet, and undergo a gradual transformation to achieve reproductive maturity and adulthood. This is in stark contrast to more commonly used holometabolous insects such as dipterans (e.g., Drosophila melanogaster) where juveniles occupy a different niche than adults and undergo a profound transformation from larval to pupal to adult life stages. Within mammals, a transient reduction in food availability during prenatal and/or early postnatal life results in growth retardation and a subsequent period of rapid compensatory, or catch-up, growth to allow previously undersized individuals to achieve a normal body mass. Unfortunately, this growth comes at a cost, most notably in the form of metabolic dysregulation and reduced survival in later adult life. In this study, we also found that a period of rapid growth early in life significantly reduces longevity in speckled cockroaches, but only if they had unlimited access (ad libitum) to food during juvenile development. The lifespans of individuals from populations that experienced reduced food availability during juvenile development were unaffected, even though they exhibited a growth rate and final body mass that was comparable to the ad libitum fed population. The physiological basis for this difference remains unknown, but we suspect that carbohydrate and/or lipid metabolism may be markedly different among the food restricted and ad libitum populations.
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