# Examining the Effects of Induced Plant Defenses on _Spodoptera frugiperda_ Performance
## 1 Introduction  
Knowing the duration during which herbivore pests are present in the environment feeding on a plant commodity is vital for developing and implementing a sound management scheme. These data, in turn, can be used to create life tables to document the maturation of an organism. When combined with phenological observations and data, the resulting information can also be used to time crop planting dates, predict pest emergence, and determine likely pesticide treatment dates/intervals [1]. For general phytophagous insects, though, these predictions can be problematic or prone to error if data has not been collected from pests feeding on numerous different host plants and/or cultivars for calibration [2]. Further still, upon herbivore attack, plants induce defenses to protect themselves from herbivore damage, which is mediated by the jasmonic (JA) and salicylic acid (SA) phytohormone pathways [3, 4]. These plant defenses are toxic and antinutritive to herbivore pests. This increases herbivore mortality and slows their development [5, 6, 7]. Within a plant species, because of differences in plant secondary metabolite concentration and inducibility upon herbivore damage, different cultivars can greatly affect insect life history and performance [5, 6, 7, 8, 9]. Collecting these data is vital for applied research and making informed management decisions [1]. From an empirical perspective, knowing the maturation schedule of an insect pest across plant cultivars varying in resistance to herbivory is useful for parameterizingmodels, whether for determining pest population dynamics, entomopathogen spread, or other lines of inquiry [10; 11; 12]. This information is also useful for implementing control efforts, such as how biopesticides will perform when applied in the environment [13; 14]. Understandably, one cannot test every cultivar and species combination a generalist phytophagous insect consumes, especially if the breadth of their host plant diet extends to hundreds of species, so research should focus on cultivars within a crop commodity with known variations in plant resistance traits to insect herbivores. This relates to how current plant domestication syndrome research is conducted [6]; information that would allow researchers and growers to make sound predictions while also balancing labor and resource costs [2; 14]. With that framework in mind, we report here the performance (i.e., survival, development time, and pupal mass) of the fall armyworm on jasmonic acid (JA) induced and non-induced _Glycine max_ (soybean) cultivars. We also document female fall armyworm fecundity over a mass gradient when reared on an artificial diet to gauge how differences in pupal mass affect fecundity. We predict that larvae-fed induced host plants would have higher mortality and lower performance than those on uninduced plants. We also predict that plant cultivars should interact with inducible defenses to influence insect performance due to varying secondary metabolite profiles and inducibility between cultivars. Lastly, we predict that lighter female moths would lay fewer eggs (i.e., be lessecund) than heavier female moths. Background and Study SystemThe fall armyworm, _Spodoptera frugiperda_, (Lepidoptera: Notutiade), is a global insect pest of economic importance. It is native to the western hemisphere but was introduced into Africa in 2016 and has now spread to Asia and Australia [15; 16; 17; 18]. This insect pest is fond of cereal crops such as corn, sorghum, rice, and cotton, but is a generalist herbivore utilizing numerous plant species [15; 19]. Specifically, in poorly managed _Zea mays_ (corn) fields under crop rotation with legumes, these insects have also been known to infest soybeans, causing economic damage. In Brazil, because of crop rotation, _S. frugiperda_ is reported to have switched onto soybeans as a preferred host, much like the corn rootworm did in North America [20; 21]. _S.