Preferences and performance of a specialist herbivore on N- and/or P-fertilized host plants

Background/Question/Methods

Tomato plants grown from commercially–available seed were germinated and fertilized every other week with one of seven fertilizer treatments: three high-fertilizer treatments (high-N, high-P, and balanced N/P), three low-fertilizer treatments (low-N, low-P, and balanced N/P), and a no-fertilizer control. Three sets of experiments are in progress using the herbivore Manduca sexta: larval performance, larval feeding preference (neonate and late-instar), and female oviposition preference. 

Results/Conclusions

We plan to look for correlations between larval performance and the preferences of both larvae and ovipositing females. At this point, data are still being generated for all of these experiments. Preliminary analyses have shown no significant differences, perhaps due to small preliminary sample sizes, but suggest that low-phosphorus fertilized plants and unfertilized plants may be equally unpalatable to caterpillars. A team of undergraduate researchers are continuing efforts to collect more data, and the project will reach a conclusion in time for this meeting.