Conclusion
The presence of salt as an abiotic stressor in agricultural soils is a serious problem, with research focusing primarily on plant tolerance to salt. However, the inclusion of biotic stressors, such as insect pest infestations, leads to varied plant responses. Understanding plant responses under interacting stresses is vital to developing better crop varieties and insect control. Moreover, salinity-influenced changes to plant quality and composition affect insect herbivores feeding on these plants.
In our study, we observed that a notorious pest, Helicoverpa zea,performed poorly on salinity-affected tomato plants. Although our study focused exclusively on a leaf-chewing, generalist herbivore, it would be interesting to investigate how different insect feeding guilds (specialist leaf chewers, phloem feeders, gall makers, leaf miners, etc.) respond to soil salinization. Our work demonstrates the need to study how insect pests are indirectly affected by environmental changes, as this has implications for their survival and performance in agricultural settings. Thus, along with deciphering the molecular basis behind plant responses to multiple stresses, we also need to understand their ecological implications so that we can formulate accurate IPM strategies.
For future work, we wish to investigate salinity-based changes to plant indirect defenses. Salinity can influence other trophic levels in plant-insect interactions, including predators, parasitoids, and local microbiota. Insect quality as a food source for predators or a potential host for parasitoids and microbes drives predator and parasitoid choices, which would in turn affect insect population dynamics in the field.