1. Although preference–performance relationships in insects are typically studied in a bi-trophic context, it is well known that host plants can affect both the preference and performance of natural enemies of herbivorous insects. 2. This study presents evidence from field and laboratory studies that two species of milkweeds, the putatively less defended Asclepias incarnata and the putatively more defended Asclepias syriaca, differentially affect adult oviposition and larval performance in Aphidoletes aphidimyza, an aphid-feeding predatory midge, independent of aphid density. 3. Host plant species affected predatory fly larvae abundance by a factor of 50 in the field and a factor of 8 in the laboratory. Larval and adult emergence rates in our laboratory studies provided strong evidence for reduced performance on A. syriaca. Oviposition in choice and no-choice settings provided some evidence for preference for A. incarnata, and a potentially suppressive effect of A. syriaca. 4. The results provide limited support for the hypothesis that natural selection can lead to positive correlations between adult oviposition preferences and larval performance upon various food sources, even when predatory insects oviposit onto host plants of their herbivorous prey. 5. Preference and performance are not perfectly aligned in this system, however, because ovipositing females do not reject A. syriaca entirely. Potential explanations for mismatches between preference and performance in this system include the neural constraints associated with being a generalist, adaptive time-limited foraging strategies, and unique evolutionary histories of laboratory colonies compared with wild insects.
Bibliographical noteFunding Information:
We thank Ruth Shaw for helpful comments on an earlier version of the manuscript, Mark Bee for suggestions during the development of the project methods, Chris Buyarski and Sarah Hobbie for use of the growth chamber, and Logan Fees and Jonathan Dregni for assistance in the laboratory. We gratefully acknowledge funding from the University of Minnesota, the Bell Museum of Natural History Dayton Fund Fellowship, and the University of Minnesota's NSF IGERT traineeship on ecological risk assessment of introduced species and genotypes for funding in support of EKM and logistical support from the University of Minnesota Experiment Station. The authors declare there are no conflicts of interest. Furthermore, there are no disputes over the ownership of the data presented in this paper and all contributions have been attributed appropriately.
© 2020 The Royal Entomological Society
- Aphis nerii
- Tri-trophic interaction
- preference–performance hypothesis