To cope with severe seasonal changes in climate and food availability, colonies of Apis mellifera L. generate two distinct worker phenotypes during winter and summer. The aim of this research was to evaluate the effect of oral exposure to insecticides on the toxic susceptibility of winter and summer honeybee workers (Apis mellifera L.) under laboratory conditions. In this work, under all tested conditions and seasons, emamectin benzoate was the most toxic compound and used as the standard (Toxicity Index = 100) for comparison with other compounds. It had the lowest LC50 (Lethal Concentration required to kill 50% of the tested honeybees) values, which decreased to 0.004 mg/L in winter bees after 48 h following oral exposure. Sulfoxaflor had moderate toxicity, and indoxacarb was the least toxic to honeybees. The results also revealed that the toxic effect was time-dependent, with lethal concentrations at 48 h significantly lower than those at 24 h. In addition, seasonal effects play a role; winter honeybees were, overall, more sensitive to the treatments than summer honeybees. Under the conditions of this study, it can be concluded that emamectin benzoate was the most toxic substance and indoxacarb the least toxic. Toxicity increased with exposure time. Winter honeybees showed greater sensitivity than summer honeybees. A field-relevant Hazard Quotient (HQ) analysis further indicated that indoxacarb, despite its lower acute toxicity, exhibited the narrowest margin relative to field-recommended spray concentrations, highlighting the value of incorporating field-relevant exposure metrics alongside LC50-based rankings in pollinator risk assessment. It is worth clarifying that this narrower margin reflects indoxacarb’s higher field-recommended application rate relative to its LC50, rather than a greater intrinsic toxicity than emamectin benzoate, and the two aspects of risk (intrinsic toxicity vs. use-rate-based field risk) should be interpreted separately.

Drought stress represents an immense global environmental challenge, disturbing plant growth and survival. Thiamine and salicylic acid (SA) have been frequently exhibited to boost drought tolerance in plants, but their precise role in improving citrus resistance to drought stress remains unclear. The current study assessed the effect of different treatments of thiamine (0, 50, and 100 µM) and SA (0, 10, and 20 µM) on drought stress (5% PEG) in three important citrus rootstocks, ‘sour orange’, ‘volcamariana’, and ‘lime’, under in vitro conditions. Results revealed that drought stress negatively altered citrus growth and performance; however, the supplementation of thiamine and SA, particularly at 100 and 20 µM, respectively, modulated these adverse effects, with variable responses among the tested rootstocks. Notably, thiamine and SA promoted the germination percentage as well as several growth parameters, including shoot length, root length, leaf area, fresh weight, dry weight, and water content. Moreover, thiamine and SA modulated the negative effect induced by PEG through increasing chlorophyll a, chlorophyll b, and carotenoids and regulating proline and phenolic levels. The activities of antioxidant enzymes i.e., PAL, PPO, CAT, and POD were also modified by thiamine and SA, resulting in an activation of defensive machinery against drought stress. This framework provides a valuable strategy for the development of citrus adaptation in three rootstocks to drought stress, highlighting the contribution role of thiamine and SA in achieving sustainability in water-limited environments.