Host plant selection and development in <i>Spodoptera exigua</i>: do mother and offspring know best?

Abstract

Abstract We examined the ovipositional preference and larval development of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) on two common hosts in southern California, Chenopodium murale L. (Chenopodiaceae) and Apium graveolens L. (Umbelliferae) to determine if female oviposition preference is correlated with offspring performance. Greenhouse oviposition choice tests indicated that S. exigua oviposit more frequently on C. murale than on A. graveolens . However under laboratory conditions, larvae reared on C. murale had longer development times, lower relative growth rate, and lower survivorship than larvae reared on A. graveolens . larval and pupal masses were significantly greater on A. graveolens than on C. murale . Furthermore, pupal masses were significantly greater for individuals reared on A. graveolens than on C. murale . Because pupal masses and adult fecundity are positively correlated for Spodoptera spp., the fitness of S. exigua on A. graveolens is likely to be substantially higher than its fitness on C. murale . Despite better larval performance on A. graveolens , previous results from choice tests with whole plants and leaf discs indicate that the highly mobile S. exigua larvae strongly prefer C. murale over A. graveolens . Hypotheses attempting to explain this lack of correlation between larval and adult host preference versus development and survival in this system are discussed.