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Abstract Insect colouration mediated by melanization can assist in dealing with environmental temperatures. However, melanin synthesis can be costly and depends on the ability of insects to acquire enough energy and nutrients from their diets. Due to the increased plant C:N ratio associated with elevated CO2concentrations, insect herbivores' melanization could be limited by the amount of nitrogen they acquire from their host plants.To investigate how diet C:N impacts the potential colour response to temperature, we usedManduca sextacaterpillars reared at different combinations of temperatures and diet C:N ratios, and measured pupal mass and development time (performance metrics) and colour morphology.The high‐temperature treatment (27°C) had a positive impact on larval performance, whereas a nitrogen‐poor diet was related to lower performance. Using a fitness metric that considers both pupal mass and development time, we found a positive effect of both high temperature and nitrogen‐rich diet treatments on larval fitness.We found that diet and temperature affected the colouration of larvae, in which larvae reared at the low‐temperature treatment (18°C) and fed a nitrogen‐rich diet were darker than their counterparts.Our results provide experimental evidence of the impact of diet on melanization and suggest that CO2‐related changes in plant quality could be associated with changes in insect herbivore performance and colouration.
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Population divergence in nutrient-temperature interactions in Pieris rapae
The interaction between larval host plant quality and temperature can influence the short-term physiological rates and life-history traits of insect herbivores. These factors can vary locally, resulting in local adaptation in responses to diet and temperature, but the comparison of these interactions between populations is infrequently carried out. In this study, we examine how the macronutrient ratio of an artificial diet determines the larval growth, development, and survival of larvalPieris rapae(Lepidoptera: Pieridae) at different temperatures between two invasive North American populations from different climatic regions. We conducted a fully factorial experiment with three temperature treatments (18°C, 25°C, and 32°C) and three artificial diet treatments varying in terms of the ratio of protein to carbohydrate (low protein, balanced, and high protein). The effects of diet on life-history traits were greater at lower temperatures, but these differed between populations. Larvae from the subtropical population had reduced survival to pupation on the low-protein diet in the cold temperature treatment, whereas larval survival for the temperate population was equally high for all temperature and diet treatments. Overall, both populations performed more poorly (i.e., they showed slower rates of consumption, growth, and development, and had a smaller pupal mass) in the diet with the low protein ratio, but larvae from the temperate population were less sensitive to diet ratio changes at all temperatures. Our results confirm that the physiological and life-history consequences of imbalanced nutrition for insect herbivores may depend on developmental temperatures, and that different geographic populations ofP. rapaewithin North America vary in their sensitivity to nutritional balance and temperature.
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- Award ID(s):
- 1950055
- PAR ID:
- 10512128
- Publisher / Repository:
- Frontiers in Insect Science
- Date Published:
- Journal Name:
- Frontiers in Insect Science
- Volume:
- 3
- ISSN:
- 2673-8600
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/finsc.2023.1237624
