The effect of energy trade-offs on life history and fitness in the rice weevil, Sitophilus oryzae

• Published in: Oikos 1992-09, Vol.64 (3), p.441-450
• Main Authors: Povey, S.R, Holloway, G.J. (Reading Univ., Whiteknights (United Kingdom))
• Format: Article
• Language: English
• Subjects: ADAPTACION; ADAPTATION; Animal and plant ecology; Animal, plant and microbial ecology; Animals; ARROZ; Autoecology; Biological and medical sciences; Coleoptera; Curculionidae; DESINTOXICACION; DETOXIFICATION; Eggs; ENVIRONMENTAL FACTORS; EVOLUCION; EVOLUTION; Evolutionary genetics; FACTEUR DU MILIEU; FACTORES AMBIENTALES; Fundamental and applied biological sciences. Psychology; Grains; GUISANTE; Invertebrates; MATHEMATICAL MODELS; MODELE MATHEMATIQUE; MODELOS MATEMATICOS; Mortality; Oviposition; PEAS; PLAGAS DE PRODUCTOS ALMACENADOS; POIS; Population genetics; Protozoa. Invertebrata; Quantitative genetics; RAVAGEUR DES DENREES ENTREPOSEES; RICE; RIZ; SITOPHILUS ORYZAE; SORGHUM; STORED PRODUCTS PESTS
• ISSN: 0030-1299; 1600-0706
• DOI: 10.2307/3545159

Trade-offs between fitness characters were examined in the rice weevil using a reciprocal transplant procedure. The weevil populations had been reared in the laboratory for more than 50 generations on either wheat, sorghum or yellow split-pea. The selective forces operating in the three environments had resulted in the evolution of different, presumably adaptive, life histories. Yellow split-pea and probably also sorghum contain toxic phytochemicals. It was argued that the need to detoxify these chemicals favoured higher investment in detoxification mechanisms to maintain survival (in the sorghum and pea populations) at the expense of other fitness characters, such as development rate and fecundity. These trade-offs were expected based on previous studies of the life history genetics and the physiology of detoxification mechanisms in the same weevil populations. When in a common environment, the relative positions of three populations in options sets between pairs of fitness characters were accurately predicted. The values of all fitness characters measured were combined in models of fitness in order to quantify the fitnesses of the populations in each environment. Fitness was calculated using two methods which made different assumptions concerning the oviposition behaviour of the insects in response to old grain. Only in the yellow split-pea environment were we able to show that the pea population had a higher fitness than the other two populations. No significant fitness differences were found between the populations in the wheat environment.