A nutrition-defense tradeoff drives diet choice in a toxic plant generalist

Plant toxicity shapes the dietary choices of herbivores. Especially when herbivores sequester plant toxins, they may experience a tradeoff between gaining protection from natural enemies and avoiding toxicity. The availability of toxins for sequestration may additionally trade off with the nutritional quality of a potential food source for sequestering herbivores. We hypothesized that diet mixing might allow a sequestering herbivore to balance nutrition and defense (via sequestration of plant toxins). Accordingly, here we address diet mixing and sequestration of large milkweed bugs (Oncopeltus fasciatus) when they have differential access to toxins (cardenolides) in their diet. In the absence of toxins from a preferred food (milkweed seeds), large milkweed bugs fed on nutritionally adequate non-toxic seeds, but supplemented their diet by feeding on nutritionally poor, but cardenolide-rich milkweed leaf and stem tissues. This dietary shift corresponded to reduced insect growth but facili..., Performance and sequestration of O. fasciatus on non-preferred food sources
We examined performance and sequestration of seed bugs on the tropical milkweed (Asclepias curassavica), an important host plant in the southern end of the bug’s range. All bugs used in this experiment were from a colony (30 adult bugs) of wild-collected O. fasciatus from Tompkins County, NY, USA. The colony had been reared for several generations on common milkweed (Asclepias syriaca) seeds. First instar bugs (from a pool of clutches laid by several females) were divided into five experimental treatment groups within twenty-four hours after hatching: bugs with access to milkweed seeds (nutritionally adequate, toxic), bugs with access to milkweed seeds and milkweed plant tissue (nutritionally adequate, toxic + nutritionally inadequate, toxic), bugs with access to sunflower seeds (nutritionally adequate, nontoxic), bugs with access to sunflower seeds and milkweed plant tissue (nutritionally adequate, nontoxic + n..., Raw data are attached as .csv files. Analyses were performed in R version 4.1.2.