Inter‐annual variation in the abundance of specialist herbivores determines plant resistance in Datura stramonium

• Published in: Ecology and evolution 2023-12, Vol.13 (12), p.e10794-n/a
• Main Author: de La Cruz Arguello, Ivan M.
• Format: Article
• Language: English
• Subjects: Abundance; Annual variations; Chemical defense; Damage; Datura stramonium; Ecology; Ekologi; Genetic crosses; Herbivores; Herbivory; Hypotheses; Larvae; Natural environment; Pest resistance; phenotypic selection; Plant resistance; Populations; relative growth rate; resource allocation; Seeds; Tradeoffs
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.10794

The expression of plant resistance traits against arthropod herbivores often comes with costs to other essential plant functions such as growth and fitness. These trade‐offs are shaped by the allocation of limited resources. However, plants might also possess the capability to allocate resources to both resistance and growth, thereby ensuring their survival when under herbivore attacks. Additionally, the extent of damage caused by herbivores could vary across different years or seasons, subsequently impacting plant performance. In this study, we aimed to investigate how the annual variations in herbivore abundance and damage levels affect plant performance. We generated F2 progeny through a cross between two populations of the annual herb Datura stramonium (Solanaceae). These populations are known to have differing levels of chemical defense and herbivory. These F2 plants were cultivated in a common natural environment for two consecutive years (2017 and 2018). Our findings reveal that plants with higher resistance, attained higher seed production but this trend was evident only during 2018. This relationship coincided with a five‐fold increase in the abundance of Lema daturaphila (Chrysomelidae) larvae in 2018. Indeed, the plants experienced a 13‐fold increase in damage during this second year of study. Furthermore, our results indicated that there was no trade‐off between resistance, growth, and fitness in either of the 2 years. In contrast, during 2018, when plants faced stronger herbivore pressure, they allocated all available nutritional resources to enhance both resistance and growth. Our study highlights how the selection for plant resistance is dependent upon the inter‐annual variation in herbivore abundance. The study underscores the influential role of specific herbivores in driving plant resistance and offers fresh insights into the inter‐annual evolutionary dynamics of plant resistance.