Seaweeds are a natural marine resource containing many bioactive compounds such as amino acids, lipids, carbohydrates, proteins, phytohormones, and antimicrobial compounds. Since ancient times, seaweeds have been used in various sectors, including medicine, food, and the cosmetic industry. Currently, seaweeds are a promising alternative to reduce the application of harmful chemicals in agriculture. Seaweed and its derived products have been utilized for plant growth promotion, immunity enhancement, and the reduction of biotic and abiotic stresses. In the current global scenario, synthetic fertilizers and chemical pesticides are commonly used to increase agricultural crop production to meet the growing demands of the world population. However, these chemicals pose significant threats to the health of people, livestock, plants, soil, and the entire environment. In contrast, seaweed-based products are emerging as a newer option for stress mitigation and reduction, offering an alternative to synthetic chemicals. This article explains the use of seaweed extracts to increase the tolerance of plants to biotic and abiotic stresses. We also address the functions of various bioactive compounds present in seaweed extracts and the mechanisms by which they promote plant growth and induce defense against different stresses.

Previous studies on two tropical Drosophila species (D. malerkotliana and D. bipectinata) have shown lower resistance to stress-related traits but the rapid colonization of D. malerkotliana in the past few decades is not consistent with its sensitivity to desiccation and cold stress. We tested the hypothesis that developmental acclimation at two growth temperatures (17 and 25°C) can confer adaptations to desiccation and thermal stresses. We found divergence in developmental plastic effects on cuticular traits, i.e. a significant increase of body melanisation (~2-fold) and of cuticular lipid mass (~3-fold) in D. malerkotliana but only 1.5-fold higher cuticular lipid mass in D. bipectinata when grown at 17°C compared with 25°C. A comparison of the water budget of these two species showed significantly higher effects of developmental acclimation on body water content, rate of water loss and dehydration tolerance resulting in higher desiccation resistance in D. malerkotliana than in D. bipectinata. When grown in cooler conditions (17°C), D. malerkotliana had greater resistance to cold as well as desiccation stress. In contrast, heat resistance of D. bipectinata was higher when grown at 25°C. These laboratory observations are supported by data on seasonally varying populations. Furthermore, adult D. malerkotliana acclimated to different stresses showed greater resistance to those stresses than D. bipectinata adults. Thus, significant increase in stress resistance of D. malerkotliana through developmental acclimation may be responsible for its invasion and ecological success on different continents compared with D. bipectinata.

Plant-based essential oils are hydrophobic, volatile concentrate extracted from aromatic plants. They are the upcoming alternative and appealing source of antimicrobial compounds, citral (major constituent of lemongrass oil) being one of them, whose antiquorum sensing, in vivo delivery, and insecticidal potential need further exploration. Pseudomonas aeruginosa is one of the most prevalent, clinically lethal pathogens, which is resistible toward various treatments because of the inherent resistance acquired by the organism to many classes of drugs (multidrug resistant (MDR)). Moreover, fruit flies have been considered as the vectors of potentially lethal and opportunistic pathogens, including multiantibiotic-resistant microbes. As a result, controlling both the pathogen and its host vector are of utmost importance. The present study focused on the efficacy of essential oil of citral (EOC) and its nanoencapsulated form on quorum sensing inhibition (QSI) of P. aeruginosa PAO1 and its insecticidal activity against Drosophila melanogaster. Chitosan-based citral nanoparticles were synthesized and characterized using hydrodynamic size, zeta potential, polydispersity index, and field-emission scanning electron microscopy (FE-SEM). Citral nanoparticles at sub-minimum inhibitory concentration (MIC) exhibited QSI potential by attenuating biofilm formation (p-value0.05), while insecticidal activity of citral tested against D. melanogaster demonstrated toxicity of the EOC at a concentration of 35. Hence, the results elucidated the prospects of citral nanoparticles in the delivery of citral, which can be applied as a strategy to specifically target clinically lethal pathogens, major insect pests, and associated microbes.

Laboratory selection of stress-related traits in adult flies of Drosophila melanogaster has resulted in contrasting phenotypes but coevolution of larval traits has received lesser attention. The hypothesis whether laboratory selection of adult body melanization to derive dark and light body color lines exhibit covariation of larval behavioral traits of D. melanogaster was tested. The larvae of selected light lines showed longer foraging path, higher relative feeding rate, and lower pupation height whereas opposite trend values were observed for the larvae of selected dark lines. The larvae of dark lines stored significantly higher level of carbohydrates while light lines stored lipids. Larval pupating behavior of selected dark and light lines also showed divergence. For water balance-related traits, significantly higher trait values in the larvae of selected darker lines were found while lighter body color lines showed greater starvation resistance. Thus, laboratory selection of adult body melanization led to correlated selection responses for larval behavioral traits which are adaptive in nature.