Insect responses to plant water deficits. II. Effect of water deficits in soybean plants on the growth and survival of Mexican bean beetle larvae

Abstract

Abstract. 1. We examined the effect of water deficits in soybean, Glycine max [L.] Merr., on the growth and survival of Mexican bean beetle larvae, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae).2. Larvae were reared under growth chamber, glasshouse, and field conditions on foliage from plants that were either well‐watered or subjected to water deficits.3. Larval survival, growth rate and pupal weight were reduced, and development time was increased when larvae were reared on foliage from plants subjected to water deficits. These results are contrary to White's (1974) hypothesis that water deficits in plants cause increased growth and survival of herbivorous insects.4. Changes in foliage chemistry caused by water deficits, possibly in the concentration of free amino acids, are the most likely causes of the observed effects on growth rate and development time. However, under glasshouse and field conditions, physical changes in foliage and/or the foliage's environment that accompany water deficits are also important.