title: Balanced intake of protein and carbohydrate maximizes lifetime reproductive success in the mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae).
abstract: Recent developments in insect gerontological and nutritional research have suggested that the dietary protein:carbohydrate (P:C) balance is a critical determinant of lifespan and reproduction in many insects. However, most studies investigating this important role of dietary P:C balance have been conducted using dipteran and orthopteran species. In this study, we used the mealworm beetles, Tenebrio molitor L. (Coleoptera: Tenebrionidae), to test the effects of dietary P:C balance on lifespan and reproduction. Regardless of their reproductive status, both male and female beetles had the shortest lifespan at the protein-biased ratio of P:C 5:1. Mean lifespan was the longest at P:C 1:1 for males and at both P:C 1:1 and 1:5 for females. Mating significantly curtailed the lifespan of both males and females, indicating the survival cost of mating. Age-specific egg laying was significantly higher at P:C 1:1 than at the two imbalanced P:C ratios (1:5 or 5:1) at any given age throughout their lives, resulting in the highest lifetime reproductive success at P:C 1:1. When given a choice, beetles actively regulated their intake of protein and carbohydrate to a slightly carbohydrate-biased ratio (P:C 1:1.54-1:1.64 for males and P:C 1:1.3-1:1.36 for females). The self-selected P:C ratio was significantly higher for females than males, reflecting a higher protein requirement for egg production. Collectively, our results add to a growing body of evidence suggesting the key role played by dietary macronutrient balance in shaping lifespan and reproduction in insects.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Myung Suk
authors.initials: MS
authors.lastname: Rho
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea. Electronic address: kwanglee@snu.ac.kr.
authors.forename: Kwang Pum
authors.initials: KP
authors.lastname: Lee
mesh_terms: D000818:Animals; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D008297:Male; D010058:Oviposition / Q000187:drug effects*; D011897:Random Allocation; D012737:Sex Factors; D013712:Tenebrio / Q000502:physiology*
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins
keywords: Carbohydrate; Coleoptera; Fecundity; Lifespan; Nutrient self-selection; Protein