Modifying oviposition behaviour in phytophagous insects and physiological bases thereof

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For many plant-feeding insects, successful development of the immature stages depends in part on the adult female making an appropriate choice of host plant on which to lay her eggs. Some insects appear to prefer hostplant species on which they themselves developed;  this is formally known as the Hopkins' host selection principle.  Previous investigations aimed at supporting this theory have often provided ambiguous, equivocal or conflicting results.  Recent investigations in my laboratory provide intriguing evidence that larval experience with specific plant chemicals can influence subsequent adult behaviour.  In our model system using the cabbage looper moth (Trichoplusia ni, Noctuidae), our data point to larval learning and memory retained through metamorphosis as a mechanism for this phenomenon. The objectives of the proposed research are:  (1) to determine the neural basis of this memory retained from larva to pupa to adult moth and the contribution of adult gustatory chemosensilla (taste organs) to hostplant choice;  (2) to attempt to demonstrate that insect behaviour can be manipulated such that adult insects lay eggs on marginal or unsuitable plants;  and (3) to explore the relationship between oviposition preference and larval performance.  The proposed research will expand our knowledge of neurophysiology as a mediator of insect-plant interactions and underscore the importance of learning and memory in plant-feeding insects.  Understanding insect host choice can provide a foundation for future strategies aimed at manipulating behaviour as a means of environmentally sound pest management.