Does Skipping a Meal Matter to a Butterfly's Appearance? Effects of Larval Food Stress on Wing Morphology and Color in Monarch Butterflies

Abstract

In animals with complex life cycles, all resources needed to form adult tissues are procured at the larval stage. For butterflies, the proper development of wings involves synthesizing tissue during metamorphosis based on the raw materials obtained by larvae. Similarly, manufacture of pigment for wing scales also requires resources acquired by larvae. We conducted an experiment to test the effects of food deprivation in the larval stage on multiple measures of adult wing morphology and coloration of monarch butterflies (Danaus plexippus), a species in which long-distance migration makes flight efficiency critical. In a captive setting, we restricted food (milkweed) from late-stage larvae for either 24 hrs or 48 hrs, then after metamorphosis we used image analysis methods to measure forewing surface area and elongation (length/width), which are both important for migration. We also measured the brightness of orange pigment and the intensity of black on the wing. There were correlations between several wing features, including an unexpected association between wing elongation and melanism, which will require further study to fully understand. The clearest effect of food restriction was a reduction in adult wing size in the high stress group (by approximately 2%). Patterns observed for other wing traits were ambiguous: monarchs in the low stress group (but not the high) had less elongated and paler orange pigmentation. There was no effect on wing melanism. Although some patterns obtained in this study were unclear, our results concerning wing size have direct bearing on the monarch migration. We show that if milkweed is limited for monarch larvae, their wings become stunted, which could ultimately result in lower migration success.

Phytochemical changes in milkweed induced by elevated CO2 alter wing morphology but not toxin sequestration in monarch butterflies

“…Notably, herbivorous arthropods maintain target ratios of carbohydrates to protein in their diet through behavioural shifts in consumption (Simpson et al, 2015). Therefore, it is possible that the monarchs in our study increased the amount of foliage consumed to compensate for reductions in foliar nutrient content under eCO 2 (Hunter, 2001;Johnson, Solensky et al, 2014;Lincoln, Sionit, & Strain, 1984;Zavala, Nabity, & DeLucia, 2013).…”

“…Migratory monarchs also have higher wing loading values, correlated with larger energy reserves for stronger powered flight (Dudley & Srygley, ). However, despite an extensive body of literature detailing the importance of dietary chemistry for insect fitness (Awmack & Leather, ), few studies have explored the effects of diet on wing morphology and flight ability (Boggs & Freeman, ; Johnson, Solensky, Satterfield, & Davis, ; Pellegroms, Van Dongen, Van Dyck, & Lens, ). Food restriction reduces monarch wing size (Johnson, Solensky et al, ), but no study to date has examined the effects of changing phytochemistry on monarch wing morphology.…”

Intraspecific variation in wing colour is related to larval energy reserves in monarch butterflies (Danaus plexippus)

“…In the model examining orange hue, there was no support for the inclusion of the interaction term (sex × residual mass; F 1,203 = 1.72, P = 0.1915). The model with main effects only showed a significant effect of sex (F 1,204 = 138.4, P < 0.0001), which was expected because males have lower hue scores in this species (Davis, 2009;Johnson et al, 2014). Importantly, residual mass was a significant predictor of orange hue (F 1,204 = 6.80, P = 0.0010).…”

Describing Variability in Wing Shapes among Three Populations of Plesispareichei Using Landmark-Based Geometric Morphometric Analysis

“…The variations observed in P.reichei may be attributed to the effects of latitude and altitude as has been observed in Drosophila melanogaster [21], [22]. Moreover these wing morphology changes including wing asymmetry may also be attributed to the diet during development [23], relative humidity and rainfall [24], [25].…”