MANDUCA QUINQUEMACULATA'S OPTIMIZATION OF INTRA-PLANT OVIPOSITION TO PREDATION, FOOD QUALITY, AND THERMAL CONSTRAINTS

Abstract

To examine the hypothesis that intra-plant oviposition preferences of Man- duca quinquemaculata on Nicotiana attenuate optimize predation risk and nutritional needs of developing larvae and eggs, we measured oviposition behavior of adults and larval mortality, movement, performance, and body temperatures at different leaf positions in a natural population. Nearly 70% of the eggs were oviposited on young central stem leaves of elongated plants. Intra-plant movement was very rare in the first and common in the second to fourth larval instars. The oviposition preference for, and larval movement toward, younger leaves was correlated with a 40% lower predation risk and a 6.3-fold greater mass gain, suggesting higher nutritive value despite 2. 1-fold higher nicotine concentrations and 4.6-fold higher polyphenol oxidase activities. The predatory bug, Geocoris pallens, which consumed eggs and larvae with instar- and leaf position-specific preferences, was respon- sible for the vast majority of M. quinquemaculata mortality and may shape the moth's oviposition preference.