Effects of wing polyphenism, aphid genotype and host plant chemistry on energy metabolism of the grain aphid, Sitobion avenae

Wing dimorphism has been proposed as a strategy to face trade-offs between flight capability and fecundity In aphids individuals with functional wings have slower development and lower fecundity compared with wingless individuals However differential maintenance costs between winged and wingless aphids have not been deeply investigated In the current study we studied the combined effect of wing dimorphism with the effects of aphid genotypes and of wheat hosts having different levels of chemical defences (hydroxamic acids Hx) on adult body mass and standard metabolic rates (SMR) of winged and wingless morphs of the grain aphid Sitobion avenae We found that wingless aphids had higher body mass than winged aphids and that body mass also increased towards host with high Hx levels Furthermore winged aphids showed a plastic SMR in terms of Hx levels whereas wingless aphids displayed a rigid reaction norm (significant interaction between morph condition and wheat host) These findings suggest that winged aphids have reduced adult size compared to wingless aphids likely due to costs associated to the development of flight structure in early-life stages These costs contrast with the absence of detectable metabolic costs related to fuelling and maintenance of the flight apparatus in adults (C) 2010 Elsevier Ltd All rights reserved