This study was conducted to evaluate the insecticidal effects of ethyl formate (EF), methyl bromide (MB), and phosphine (PH₃) fumigants against PH₃-susceptible and -resistant strains of the rice weevil (Sitophilus oryzae), a major rice pest. The highest lethal concentration time 50 (LCt₅₀) values of the PH₃-susceptible strains were 255.797, 21.104, and 6.171 mg h L⁻¹ for EF, MB, and PH₃, respectively, at pupal stage. The highest LCt₅₀ values of the PH₃-resistant strains were 149.028 and 48.170 mg h L⁻¹ for EF and PH₃, respectively, at late larval stage, and 43.520 mg h L⁻¹ for MB at pupal stage. In comparison to the susceptible strains, the PH₃-resistant strain collected in South Korea had a resistance level 4 to 56 times higher. Use of the major quarantine fumigants EF, MB, and PH₃ indicated the existence of PH₃-resistant rice weevils in South Korea for the first time.

Cotton aphid, Aphis gossypii Glover, is known as a quarantine pest that is hard to control with short periods of fumigation with phosphine (PH ₃ ) or low concentrations of ethyl formate. Moreover, low-temperature fumigation with ethyl formate can lead to phototoxic damage of some perishable commodities. Therefore, a laboratory study was conducted to evaluate the synergistic effect of mixing ethyl formate and PH ₃ for the treatment of adults and nymphs of A. gossypii . Combined toxicity was observed and compared with a single dose of either ethyl formate or PH ₃ . When insects were exposed to 0.5 g/m ³ of PH ₃ combined with different levels of ethyl formate from 1.6 to 16.3 g/m ³ at 5 and 20°C for 2 h, L(Ct) ₅₀ and L(Ct) ₉₉ values were greatly reduced in comparison with a single dose of either ethyl formate or PH ₃ . The synergistic ratio (SR) is described as L(Ct) of ethyl formate alone/L(Ct) of ethyl formate + PH ₃ . The SR values of L(Ct) ₅₀ and L(Ct) ₉₉ for adult A. gossypii at 5°C were 4.55 and 2.33, respectively. However, at 20°C the SR levels of L(Ct) ₅₀ and L(Ct) ₉₉ were 2.22 and 1.45, respectively, but still showed significant synergism (significant difference, P <  0.5). This new technology could meet quarantine and preshipment requirements for shorter exposure times and less damage of perishable commodities, and could also be extended for controlling other quarantine pests and thereby be a useful alternative to methyl bromide for fruit and vegetable applications.

Samples from three different mating stages (before, during and after mating) of the Mediterranean fruit fly Ceratitis capitata were used in this experiment. Samples obtained from whole insects were subjected to extraction with the two mixtures of solvents (acetonitrile/water (A) and methanol/acetonitrile/water (B)) and a comparative study of the extractions using the different solvents was performed. Direct immersion-solid phase microextraction (DI-SPME) was employed, followed by gas chromatographic-mass spectrometry analyses (GC/MS) for the collection, separation and identification of compounds. The method was validated by testing its sensitivity, linearity and reproducibility. The main compounds identified in the three different mating stages were ethyl glycolate, α-farnesene, decanoic acid octyl ester, 2,6,10,15-tetramethylheptadecane, 11-tricosene, 9,12-(Z,Z)-octadecadienoic acid, methyl stearate, 9-(Z)-tricosene, 9,11-didehydro-lumisterol acetate; 1,54-dibromotetrapentacontane, 9-(Z)-hexadecenoic acid hexadecyl ester, 9-(E)-octadecenoic acid and 9-(Z)-hexadecenoic acid octadecyl ester. The novel findings indicated that compound compositions were not significantly different before and during mating. However, new chemical compounds were generated after mating, such as 1-iodododecane, 9-(Z)-tricosene and 11,13-dimethyl-12-tetradecen-1-acetate which were extracted with both (A) and (B) and dodecanoic acid, (Z)-oleic acid, octadecanoic acid and hentriacontane which were extracted with (A) and ethyl glycolate, 9-hexadecenoic acid hexadecyl ester, palmitoleic acid and 9-(E)-octadecenoic acid, which were extracted with solvent (B). This study has demonstrated that DI-SPME is useful in quantitative insect metabolomics by determining changes in the metabolic compounds in response to mating periods. DI-SPME chemical extraction technology might offer analysis of metabolites that could potentially enhance our understanding on the evolution of the medfly.

The susceptibility of Lasioderma serricorne to phosphine (PH₃), ethyl formate (EF) and their combination (PH₃ + EF) was evaluated in this study. Eggs, larvae, pupae and adults were subjected to treatment with fumigants to determine the 90% lethal concentration time (LCt₉₀) values. Treatment with PH₃ for 20 h resulted in LCt₉₀ values of 1.15, 1.39, 14.97 and 1.78 mg h/L while treatment with EF resulted in values of 157.96, 187.75, 126.06 and 83.10 mg h/L, respectively. By contrast, the combination of PH₃ + EF resulted in LCt₉₀ values of 36.05, 44.41, 187.17 and 35.12 mg h/L after 4 h. These results show that, through treatment with PH₃ + EF, control can be achieved at lower concentrations than for treatment with EF alone and at lower exposure times than for treatment with PH₃ alone. The sorption rates of the fumigants on cured tobacco leaves were determined for filling ratios of 2.5%, 5.0% and 10.0% (w/v). Cured tobacco leaves were treated with either 2 mg/L PH₃, 114 mg/L EF or 0.5 mg/L PH₃ + 109 mg/L EF. Treatment with PH₃ showed sorption rates of 0.0%, 7.1% and 14.3%. EF, however, showed higher sorption rates of 64.9%, 68.5% and 75.5%, respectively, for the indicated filling ratios. When PH₃ and EF were combined, the sorption rate of PH₃ was 0.0%, while the sorption rates of EF were lower (9.1%, 12.0% and 23.2%) than treatment with only EF. EF required a ventilation time of longer than 22 h to desorb from cured tobacco leaves. Therefore, PH₃ + EF can effectively control L. serricorne in cured tobacco leaves, with sufficient ventilation time required after treatment for the safety of workers.

The study focused on the influence of the plant growth regulators (PGRs) benzyladenine (BA) and naphthalene acetic acid (NAA) on the production of volatile organic compounds (VOCs) from the flowers of two modern rose varieties, Hybrid Tea and Floribunda. Thirty-six plants of Hybrid Tea and Floribunda were tested. Benzyladenine and naphthalene acetic acid were applied at 0, 100 and 200 mg/L to both rose varieties. Gas chromatography, coupled with flame ionization detection and mass spectrometry, was used to analyze and identify the volatile organic compounds from the flowers. A three-phase fiber 50/30 µm divinylbenzene/carboxen/polydimethylsiloxane was used to capture VOCs, at 2, 4 and 8 weeks, and 4 weeks was selected as it had the highest peak area. In total, 81 and 76 VOCs were detected after treatment of both rose varieties with BA and NAA, respectively. In addition, 20 compounds, which had significant differences between different treatments, were identified from both rose varieties. The majority of VOCs were extracted after the application of 200 mg (BA and NAA) /L of formulation, and four important compounds, cis-muurola-4(141)5-diene, y-candinene, y-muurolene and prenyl acetate, increased significantly compared to the controls. These compounds are commercially important aroma chemicals. This study used the rapid and solvent-free SPME method to show that BA and NAA treatments can result in significant VOC production in the flowers of two rose varieties, enhancing the aromatic value of the flowers. This method has the potential to be applied to other valuable aromatic floricultural plant species.

Drosophila suzukii is a quarantine pest that is rapidly spreading in berries. This study evaluated the synergistic effect of combination treatment with ethyl formate (EF) and cold temperature for D. suzukii control on imported grapes. A higher insecticidal effect was observed at 1 °C than at 5 °C at all developmental stages, and the pupal stage showed the strongest tolerance to cold temperature. After EF fumigation alone, eggs showed the highest tolerance at 216.67 mg·h/L (LCT₉₉ value), and adults showed the highest susceptibility at <27.24 mg·h/L. Among the combination treatment methods, cold temperature after fumigation resulted in the best synergistic effect. The effect of this combination was significant, with 23.3% higher mortality for eggs, 22.4% for larvae, and 23.4% for pupae than observed with EF fumigation alone. Furthermore, the period of complete D. suzukii control in the 12 L desiccator was shorter in the combination treatment group at the LCT₈₀ value than at the LCT₅₀ value of the egg stage. EF showed a very high sorption rate (24%) after 4 h of exposure at a grape loading ratio of 15% in a 0.65 m³ fumigation chamber. As the grape loading ratio for combination treatment decreased, D. suzukii mortality increased, but when EF was administered at the LCT₈₀ value, there was little difference in the mortalities of the eggs and larvae but not the pupae. All D. suzukii developmental stages were completely controlled within 7 days after combination treatment, and phytotoxicity was not observed in grapes. These results suggest that the combination of cold-temperature treatment and EF fumigation could be used for D. suzukii control.