Gut microbes play prime role in human health and have shown to exert their influence on various physiological responses including neurological functions. Growing evidences in recent years have indicated a key role of gut microbiota in contributing to mental health. The connection between gut and brain is modulated by microbes via neural, neuroendocrinal and metabolic pathways that are mediated through various neurotransmitters and their precursors, hormones, cytokines and bioactive metabolites. Impaired functioning of this connection can lead to manifestation of mental disorders. Around 1 billion of the world population is reported to suffer from emotional, psychological and neurological imbalances, substance use disorders and cognitive, psychosocial and intellectual disabilities. Thus, it becomes imperative to understand the role of gut microbes in mental disorders. Since variations occur in the conditions associated with different mental disorders and some of them have overlapping symptoms, it becomes important to have a holistic understanding of gut dysbiosis in these disorders. In this review, we consolidate the recent data on alterations in the gut microbes and its consequences in various neurological, psychological and neurodegenerative disorders. Further, considering these evidences, several studies have been undertaken to specifically target the gut microbiota through different therapeutic interventions including administration of live microbes (psychobiotics) to treat mental health disorders and/or their symptoms. We review these studies and propose that an integrative and personalized approach, where combinations of microbe-based therapeutic interventions to modulate gut microbes and in-use psychological treatment practices can be integrated and based on patient’s gut microbiome can be potentially adopted for effective treatment of the mental disorders.

Biological invasions threaten global ecosystems and economies, prompting the need for sustainable management approaches such as releasing natural enemies from the native range (i.e., classical biological control; CBC). While the release of multiple natural enemies can enhance the effectiveness of CBC, interactions between these agents and their host plants’ defenses are poorly understood. This study explored the interactions between two congeneric specialist herbivores introduced for the control of Dioscorea bulbifera (air potato) in Florida, USA: Lilioceris cheni (Coleoptera: Chrysomelidae), which feeds primarily on leaves and L. egena, which feeds primarily on the aerial reproductive structures (i.e., bulbils). Specifically, we investigated whether foliar herbivory by L. cheni or induced defenses by jasmonic acid (JA) or salicylic acid (SA) influenced L. egena’s feeding behavior and performance on bulbils. We conducted feeding assays to measure bulbil consumption and its relationship to pupal mass and adult eclosion as indicators of beetle performance. Additionally, we performed dose-dependent feeding assays to test how varying concentrations of saponins, a key defense compound in air potato, influenced feeding and survival of L. cheni and L. egena. Our results indicated no significant differences in bulbil feeding by L. egena across treatments; however, SA-treated plants produced significantly heavier pupae and adults compared to controls. Dose-response assays revealed non-linear, hump-shaped, feeding and survival patterns in L. cheni, while L. egena experienced reduced feeding and survival with increasing saponin concentrations. These findings suggest that the two beetles respond differently to plant defenses while occupying distinct feeding niches, likely allowing for additive impacts on D. bulbifera. This study provides insights into the role of plant defenses in CBC and informs strategies to optimize biocontrol programs for invasive species management.