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    In Vitro Termiticidal Activity of Medicinal Plant Essential Oils Against Microcerotermes crassus
    (2025-12-01)
    Chantarapitak, Chaiamon
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    Pumnuan, Jarongsak
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    Chanpitak, Chaiwat
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    Termites are destructive structural pests causing significant economic losses worldwide. Although synthetic termiticides are effective, their extensive use raises environmental and health concerns, highlighting the need for safer, sustainable alternatives. This study evaluated the contact toxicity and repellency in a closed system of essential oils (EOs) from clove (Syzygium aromaticum), cinnamon (Cinnamomum zeylanicum), and star anise (Illicium verum) against Microcerotermes crassus workers. Chemical constituents (eugenol and anethole) were characterized by GC–MS/MS, and their activities were compared with those commercial termiticides (fipronil and cypermethrin). Clove and cinnamon oils exhibited strong toxicity, with LC<inf>50</inf> values decreasing from 208.6 to 70.6 µL/L and from 362.6 to 130.5 µL/L, respectively, over 24 h. Both achieved LT<inf>50</inf> values below 10 h at 250 µL/L and over 80% repellency at 100–500 µL/L within 3–12 h. Eugenol, the major constituent, showed comparable activity. In contrast, star anise oil, dominated by anethole, displayed weaker repellency but measurable termiticidal effects with a slower onset. These findings indicate that eugenol-rich oils may provide rapid-contact activity. In contrast, anethole-rich oils may offer slower but measurable termiticidal effects, suggesting distinct potential roles in future formulation development. The findings provide a foundation for developing nanoemulsion-based botanical termiticides with improved stability and field performance.
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    Antioxidant Potential, Phenolic Content, and Nitrate/Nitrite Content in Various Lettuce Varieties
    (2024-01-01)
    Pumnuan, Jarongsak
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    Sarapothong, Kritima
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    Doungnapa, Thanaporn
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    Pisutpiboonwong, Nattakarn
    Ten lettuce varieties are analyzed for antioxidant activity, total phenolic, nitrate, and nitrite contents, and the effects of harvest maturity and cold storage in selected varieties are determined. Antioxidant activity and total phenolic content (TPC) are the highest in Red Oak, Red Coral, Red Rapids, and Grand Rapids; intermediate in Green Oak, Green Cos, and Frillice Iceberg; and the lowest in Butterhead, Mini Green Cos, and Head lettuce. Nitrate content is the highest in Red Coral, while the other 9 varieties have comparably lower contents. Nitrite content is inadequate and does not differ with variety. Harvest maturity of 45 days after transplanting (DAT) produced the highest antioxidant activity and TPC, much higher in Red Bowl and Red Butterhead varieties than in Mini Green Cos, Butterhead, Frillice Iceberg, and Green Big Bowl varieties. Storage at 8<sup>o</sup>C for 21 days has no remarkable effects on antioxidant activity, TPC, nitrate, and nitrite contents. Stored Red Bowl lettuce has higher antioxidant activity and TPC than Butter-head and Green Big Bowl varieties. Nitrate content decreases at the end of storage, while nitrite content is below 1 mg/kg FW during the entire storage period, regardless of variety.
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    Effects of different compost manures application on growth of lettuces (Lactuca sativa L.)
    (2020-09-01) ;
    Jeakkhajorn, S.
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    The results showed that the difference of livestock manures showed differences in nutrients and amount. The composted chicken manures contained the highest nutrients and showed an optimum C/N ratio, in which the value was less than 1/20. Three lettuces (green oak, fillice iceberg, and green cos) were treated by different compost manures and they were a response to the compost manures in a similar trend. The three lettuce types grew after the application of chicken compost manure had higher on plant height, plant width, leaf length, leaf width, leaf number per plant, SPAD unit, root length, and plant fresh weight as well as chemical fertilizer. On the other hand, the three lettuces grown after the application of cow, goat compost manures, and bio-fermented fertilizer had the lowest of plant growth similar to control (without fertilizer). The results suggested that the chicken manure compost is suitable for lettuce production.
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    Chili (Capsicum annuum L.) genotypes resistant to Pepper yellow leaf curl Thailand virus (PepYLCTHV)
    (2021-01-01) ;
    Masirayanan, Tawatchai
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    Khingkumpungk, Hathairat
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    Tsai, Wen Shi
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    Pepper yellow leaf curl Thailand virus (PepYLCTHV) causes leaf curl disease in chili production regions of the tropics and subtropics. Information on PepYLCTHV disease severity and resistance in chili pepper is still limited in Thailand. This study reports PepYLCTHV disease severity through graft inoculation and selection of single resistant plants for use in a chili breeding program. Twenty-one chili genotypes consisting of the local cultivar (5) collected from Thailand, breeding lines (9) developed at Khon Kaen University (KKU), Thailand and improved lines (7) obtained from the World Vegetable Center, Taiwan were used in this study. Forty-five-day-old seedlings of all the genotypes were graft inoculated with PepYLCTHV in a randomized complete block design (RCBD) with three replications and 10 plants per replication and kept in a plastic net house. Disease symptoms were scored at 20, 27, 34, 41 48, and 55 days after graft/inoculation (DAI). Disease severity was visually recorded using 0−5 scores. Results showed that the disease severity of 21 chili genotypes significantly differed at 48 days after grafting. High resistance and stability were shown by 9853-123 genotypes. Two genotypes, PSP11-7 and PSP11-10-1, showed resistant reaction with disease severity scores of 1.9 and 1.8, respectively. However, among 21 chili genotypes or 630 grafted plants, 302 plants were successfully grafted inoculated plants. Therefore, from the results of this work, highly resistant plants (69 single plants) can be selected, selfed and advanced for breeding.
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    Field Performance and ecological safety of botanical nanoemulsions against sweet potato weevil in Tropical smallholder systems
    (2026-06-01)
    Pumnuan, Jarongsak
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    Lakyat, Anuwat
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    Name, Janejira
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    Deemak, Jantra
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    Phutphat, Sudjai
    This study investigated the effectiveness of two nanoemulsion-based plant hexane extract formulations, S4L0 and S3L1, for managing sweet potato weevils (SPW) under field conditions. The formulations, derived from star anise and long pepper hexane extracts, were tested alongside a synthetic insecticide (imidacloprid) and an untreated control using a randomized complete block design (RCBD) on farmer plots in Sa Kaeo Province, Thailand. Key determination parameters included SPW infestation levels, crop yield, pesticide residue levels, diversity of non-target soil arthropods, and soil physicochemical properties. Field applications of S4L0 and S3L1 reduced SPW infestations to 3.6 ± 4.3 and 11.1 ± 5.0 insects per plant, respectively, significantly lower than in untreated plots (33.9 ± 11.8 insects/plant). No detectable imidacloprid residues were found in tubers treated with S4L0 or S3L1, whereas imidacloprid-treated tubers retained residues of 0.335 and 0.144 ppm at 5 and 7 days after application. Sweet potato yields ranged from 310 to 440 g/plant, with no significant differences among treatments. The untreated plots supported greater diversity and abundance of non-target soil arthropods, while the imidacloprid-treated plots showed the lowest diversity. Soil properties, including bulk density, pH, electrical conductivity, and organic matter content, remained stable across treatments. Overall, S4L0 and S3L1 demonstrated effective pest suppression and minimal environmental impact, highlighting their potential as sustainable alternatives to synthetic insecticides for integrated pest management in sweet potato production.
      3
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    Distribution of Wolbachia infection in butterflies (Lepidoptera): First systematic report from Thailand
    (2023-01-01)
    Boonsit, Panukorn
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    Wiwatanaratanabutr, Itsanun
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    Ross, Perran A
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    Grandjean, Frederic
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    Austin, Chris
    Wolbachia is a genus of Rickettsia-like bacteria that infects a broad range of insect species throughout the world. It often influences host reproduction to facilitate its transmission to their offspring and spread through populations. The occurrence and ecology of Wolbachia has not been surveyed in detail in Thai butterflies. In this study, we conduct the first systematic survey of Wolbachia infection by sampling 623 specimens from 46 butterfly species from 5 families obtained from tropical forests in 3 geographic regions of Thailand. Wolbachia infections were detected using three PCR primer sets: 16S rRNA, ftsZ and wsp. The results showed evidence for widespread Wolbachia infection in Thai butterflies. The Wolbachia presence was confirmed in 291 individuals from 17 butterfly species of 2 families, comprising 86 individuals from the Central Region (32 males and 54 females), 72 individuals from the Northeast Region (25 males and 47 females), and 133 individuals from the West Region (46 males and 87 females). This report will be useful for understanding the distribution of Wolbachia in butterflies from Thailand.
      1
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    Effect of Trichoderma harzianum against Fusarium oxysporum in resistant and susceptible tomato cultivars
    (2025-01-01) ;
    Mueangkhong, Manthana
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    Kawicha, Praphat
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    Thanyasiriwat, Thanwanit
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    Techawongstien, Suchila
    Fusarium wilt disease presents a substantial challenge to tomato production, especially in an open field environment. The peroxidase (POD) activity and total phenolic compounds (TPCs) play a crucial role in measuring the antioxidant capacity of plants. Understanding the variations in the POD and TPC levels during disease-induced stress becomes important for effectively managing Fusarium wilt and enhancing tomato production. This study investigates the impacts of Trichoderma harzianum inoculation through the root drip method on five tomato cultivars. It compares these cultivars to their non-treated counterparts when they are subjected to infection by Fusarium oxysporum f. sp. lycopersici (Fol). The results showed that the level of resistance to Fol is based on the specific tomato cultivar. Notably, 'MT26' exhibited the lowest disease severity index (DSI), indicating a strong response, whereas 'CLN3682F' showed notable susceptibility. Regarding the POD and TPC activity, its exhibition differed in compatibility with the response of each tomato cultivar to Fusarium wilt disease. The resistant cultivars increased the POD activity after the Trichoderma induction before the Fol inoculation, and this activity was further boosted when exposed to disease conditions. Consequently, enhancing the POD and TPC levels during the initial stages could potentially serve as a systemic defence mechanism of tomatoes against the Fusarium wilt disease.
      2
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    Nanoemulsion-based plant essential oil formulations: in vitro evaluation of pesticidal activity against ectoparasites in poultry
    (2024-01-01)
    Lakyat, Anuwat
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    Pumnuan, Jarongsak
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    Doungnapa, Thanaporn
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    Phutphat, Sudjai
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    Ectoparasite infestations significantly impact the health and productivity of poultry. Chemical applications, although common for pest control, lead to pesticide residues and parasite resistance in poultry. Nanoemulsion-based plant essential oil formulations (NEOFs) provide a promising alternative for controlling poultry ectoparasites. This study aimed to assess the efficacy of NEOFs from clove, cinnamon, and turmeric essential oils (EOs) against ectoparasites, Menopon gallinae and Megninia ginglymura, under laboratory conditions. The toxicity and repellent properties of the NEOFs were examined, with the major chemical compounds of the EOs analyzed using chromatography mass spectrometer. Results identified eugenol as the dominant component in clove and cinnamon EOs (84.60 and 75.19%, respectively), while turmerone (68.46%) was the major compound in turmeric EO. NEOFs with clove:cinnamon:turmeric ratios of 4:0:0, 2:2:0, and 2:0:2 had particle size of 20.76 nm, 20.66 nm, and 89.56 nm, respectively, while those based on eugenol and turmerone standards had sizes <21.0 nm. In addition, NEOFs at 0.3% concentration with ratios of 4:0:0 and 2:2:0 achieved full control of both ectoparasites. These formulas demonstrated exceptional potency in exterminating ectoparasites, with LC<inf>50</inf> and LC<inf>90</inf> at <0.160 and <0.250%, respectively, 6 h after treatments. Furthermore, both NEOFs showed higher repellence responses in M. gallinae compared to M. ginglymura. The toxicities of these NEOFs were comparably effective against both parasites, showing no significant difference compared with chemical insecticide treatment. Therefore, further research will explore the practicality of using clove and cinnamon-derived NEOFs under farm conditions.
      1
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    Growth and Yield of Watermelon (Citrullus lanatus) in Plastic House in Response to White LED Supplementary Lighting
    (2023-01-01)
    Chamchum, Wasinee
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    Glahan, Somchai
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    Maniwara, Phonkrit
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    Watermelon plants cultivar ‘Kinaree 457’ were grown in plastic house under natural daylight only (control) or with nightly LED supplementary lighting for 6 h (6:00 pm-12:00 pm) or 12 h (6:00 pm-6:00 am) starting from transplanting up to fruit harvest. Plant height, leaf chlorophyll content and fruit yield significantly increased in response to 6 h supplementary LED lighting. Fruit mass, size (length x width) and flesh thickness at 6 h LED treatment were about 2.3 kg, 19.3 ×15.7 cm, and 15.7 cm, respectively, while the fruit of control had 1.7 kg, 16.0 × 14.3 cm, and 13.8 cm, respectively. No significant treatment effect was obtained on peel thickness, flesh color L* and b* values, juice pH and total soluble solids. However, 6 h LED treatment resulted in lower reddening flesh (lower a* values), firmness and higher titratable acidity relative to the control, suggesting the need for improvement in cultural management. Furthermore, multivariate statistics of principal component analysis (PCA) performed on physico-chemical quality revealed the variations among watermelons from lighting and control treatments regardless of lighting hour.
      2
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    Differential Biochemical Responses of Resistant and Susceptible Genotypes of Chili to Pepper Yellow Leaf Curl Thailand Virus
    (2025-09-01)
    Mueangkhong, Manthana
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    Techawongstien, Suchila
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    Tsai, Wen Shi
    Chili (Capsicum annuum L.) production is threatened by the pepper yellow leaf curl virus (PepLCV), transmitted by whiteflies, leading to reduced yields. This study investigated the biochemical changes in two chili genotypes, PEP6 (tolerant to PepLCV) and Homsuphan (susceptible to PepLCV), following inoculation with the Thailand strain of PepLCV (known as Pepper Yellow Leaf Curl Thailand Virus, PepYLCTHV). Inoculation was performed using whitefly transmission (WF) and graft transmission (GT) methods, and disease severity was evaluated using a standardized index. The level of total phenolic compounds and the activities of peroxidase (POD) and polyphenol oxidase (PPO) enzymes were analyzed in virus-infected plants and compared with those in uninoculated controls. Both chili genotypes exhibited a more rapid increase in disease severity when inoculated with WF than with GT. In PEP6, disease severity was lower than Homsuphan in both WF and GT inoculations. Disease severity in WT-inoculated PEP6 plants increased gradually, reaching 100% by day 36, whereas Homsuphan plants had a more rapid progression, attaining 100% by day 21. The GT method led to slower disease severity progression in both genotypes, reaching 80–85% by day 36. In PEP6 plants, total phenolic compound content increased significantly following WF, indicating an active defense response, whereas levels remained stable in GT plants. Phenolic content in the tolerant genotype Homsuphan remained stable across all conditions. Notably, peroxidase (POD) activity was elevated in GT plants of both genotypes, which correlated with reduced disease severity. Polyphenol oxidase (PPO) activity was lowest in control plants, but WT and GT increased the PPO level. Among the treatments, GT induced the highest PPO activity, which was associated with the lowest disease severity. These findings suggest that GT may enhance disease resistance by modulating phenolic compound accumulation and increasing POD and PPO activity.
      1