Papaya is widely grown in tropical and subtropical climates due to its high yield potential and high returns. The vital hormone melatonin, regulating various biological processes in plants, is eco-friendly and less harmful to humans than other chemicals. This study aims to enhance the quality and antioxidant enzyme activities and lessen postharvest senescence in papaya cv. CO 8 fruits during both ambient (32 ± 2 °C and 55 ± 5% RH) and cold storage (10 ± 2 °C and 90–95% RH) as exogenous melatonin (EMT) is applied in varying concentrations. An optimum melatonin dose of 1.5 mM was applied as a pre-harvest spray 15 days before harvest and a postharvest dip proved effective in prolonging shelf life (under ambient it prolonged to day 9 and under cold storage up to 28 days) and delaying ripening and softening. Exogenous melatonin application enhanced antioxidant activity, reduced weight loss, maintained firmness, delayed ripening enzymes, and lowered ethylene and CO₂ levels. For instance, control fruits had weight losses between 7.42% and 10.09%, while fruits treated with 1.5 mM melatonin showed 5.74% and 9.06% weight loss under ambient and cold storage, respectively. In conclusion, applying EMT (1.5 mM) could be an economically viable and environmentally benign way to lessen senescence after harvest and preserve the qualities of the papaya fruit during ambient and cold storage.

Papaya (Carica papaya L.) is a highly nutritious fruit crop cultivated commercially in the tropical and subtropical regions of the world. Being a shallow rooted fruit crop, it requires frequent application of nutrients. Papaya is highly remunerative due to its high productivity and responds positively to nutrient application. Papaya Ring Spot Virus (PRSV) is a major threat to papaya production, which causes severe yield loss and reduces fruit quality. To combat PRSV and enhance productivity, a nutrient formulation was developed by combining organic, inorganic nutrient sources with biocontrol agents to improve the health and vigor of the plants. Experiments were conducted to standardize the application time and evaluate the efficacy of nutrient formulation in enhancing yield, and to combat papaya ring spot virus (PRSV) incidence in papaya from January 2021 to December 2023 at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. The results revealed that foliar application of nutrient formulation at monthly intervals from the 3rd to the 7th month after planting (MAP) along with regular application of recommended dose of fertilizers (RDF) at bimonthly intervals from the 3rd MAP significantly increased the yield (37.79% and 30.57% in TNAU Papaya CO 8 and Red Lady, respectively) and reduced PRSV disease incidence (22.49% in TNAU Papaya CO 8 and 16.53% in Red Lady). Metabolomics study indicates that foliar spray of nutrient formulation enhanced the activators and precursors of defense enzymes, viz., peroxidase (PO), polyphenol oxidase (PPO), phenyl ammonia lyase (PAL), catalase (CAT) and nitrate reductase (NRase) in the sprayed plants over unsprayed control. Therefore, the sprayed plants exhibited tolerance to PRSV incidence by maintaining vigor and induced systemic resistance by the defense enzymes.

Whiteflies (Bemisia tabaci) and thrips (Thrips tabaci) are significant sucking pests of tomatoes, posing increasing threats to crop health and leading to considerable economic losses, particularly in the context of climate change. These pests are also vectors for viral transmission, further diminishing crop quality and yield. A laboratory bioassay was conducted to assess the efficacy of several plant-derived insecticide formulations, including Adathoda leaf extract soap (10 %) @ 7 g/L, Azadirachtin (1000 ppm) @ 2 mL/L, Neem Seed Kernel Extract (NSKE) (5 %) @ 5 mL/L, Neem soap (10 %) @ 7 g/L and the microbial insecticide Lecanicillium lecanii (1 × 108 cfu/g) @ 5mL/L, along with Thiamethoxam 25% WG @ 0.3g/L as a chemical control. The results indicated that Thiamethoxam 25% WG achieved the highest mortality rate against whiteflies at 72 hr post-treatment (72 %), followed by Adathoda leaf extract soap (10%) (64.00 %), Azadirachtin (63.2 %), L. lecanii (60 %), Neem soap (61.5 %) and NSKE (59.2 %). For thrips, Thiamethoxam 25% WG again demonstrated the greatest effectiveness (71.20 %), with Adathoda leaf extract soap (10%) (65.60 %), Azadirachtin (64.25 %), L. lecanii (58.20%), Neem soap (60.80 %) and NSKE (59.80 %) following. This research highlights the potential of Adathoda leaf extract soap (10 %) as an eco-friendly alternative to traditional neem formulations, suggesting its suitability for integration into future Integrated Pest Management (IPM) programs for tomatoes.

The study evaluates the effectiveness of garlic essential oil as a fumigant and contact toxicant against adult rice weevils (Sitophilus oryzae L.) (Curculionidae: Coleoptera). Garlic essential oil demonstrated significant fumigant toxicity, causing 56.67% adult mortality at a concentration of 3 µl/96 cm³ air on the first day, which increased to 99.13% by the fifth day after treatment (DAT). In addition, garlic essential oil exhibited contact toxicity, achieving up to 100% mortality at doses of 4 and 5 µl/40 g seeds. Even at lower concentrations (1 µl), mortality rates were as high as 78.33%. The calculated LC50 value was 2.58 µl/40 g of seeds. Garlic essential oil also had a considerable effect on reproduction, as no adults emergence was observed from seeds treated with 4 µl/40 g. GC-EAD analysis identified 39 compounds in garlic essential oil, with male and female S. oryzae exhibiting different antennal responses. Females displayed stronger reactions to alcohols and esters, while males were more responsive to alkenes and alkanes. The presence of chemical constituents in garlic essential oil that influence insect behaviour underscores its potential as a viable pest management solution against stored-product pests and identified a set of compounds responsible for its insecticidal toxicity. Further exploration of these compounds for their insecticidal properties using GC-EAD studies and their development into the formulations could provide significant benefits to farmers and contribute to sustainable pest management practices.