Cold treatment has been extensively employed for the phytosanitary control of fruit flies for citrus cultivation worldwide. Trials with artificial infestation methods on navel and Valencia oranges at 3 °C and 2 °C against the oriental fruit fly (Bactrocera dorsalis) were conducted, following standard bioassay protocols and large-scale testing. The results showed that the third instar larval stage was the most tolerant stage in both cultivars. The maximum estimated cold treatment time at 3 °C required to produce 99.9968% mortality (LT_99.9968) with a 95% confidence level was 16.6 days and 16.2 days for the navel orange and Valencia orange, respectively. Meanwhile, the estimated cold treatment time at 2 °C was 14.8 days for both navel and Valencia oranges, with a 95% confidence level. Furthermore, it was also observed that no survivors came from a total of 104,420 estimated (51,396 for the navel cultivar and 53,024 for the Valencia cultivar) third instar larvae in orange fruits after being subjected to a cold treatment of 3 °C for 17 days. Meanwhile, there were also no survivors from a total of 100,556 (50,740 for the navel cultivar and 49,816 for the Valencia cultivar) third instar larvae in orange fruits after being subjected to a cold treatment of 2 °C for 15 days. The treatments at 3 °C for 17 days and 2 °C for 15 days on oranges, including navel and Valencia, against the oriental fruit fly, surpassed the required mortality assurance of 99.9968% at a 95% confidence level and also met the probit-9 mortality standard. Overall, the application of these results will provide more flexibility for the citrus industry to satisfy quarantine treatment requirements.

Bactrocera correcta is an important quarantine pest of mango, and the development of phytosanitary treatments that achieve quarantine security without compromising fruit quality remains a major challenge in fresh-fruit trade. Heat treatment is a residue-free phytosanitary option, but the temperatures required to control fruit flies often approach the tolerance limits of tropical fruit, leaving a narrow margin between quarantine security and commodity injury. In this study, a phosphine (PH₃)-assisted forced hot-air treatment was evaluated for the phytosanitary disinfestation of B. correcta in mango fruit. The developmental progression of B. correcta in mango fruit was characterized, the heat tolerance of different developmental stages was compared, and the efficacy of PH₃ followed by forced hot-air treatment (PH₃→Heat) against eggs was quantified using probit time–mortality analysis. Large-scale confirmatory validation and postharvest quality assessment were then conducted. Eggs were identified as the most heat-tolerant stage. PH₃ pre-fumigation significantly enhanced forced hot-air treatment, with 0.7 g m⁻³ PH₃ providing the most practical improvement at quarantine-relevant endpoints. According to this schedule, LT_99.9968 was reduced by 44 min for heat treatment alone, from 269.0 to 224.5 min, and the large-scale validation yielded no survivors. Postharvest quality evaluation showed that PH₃→Heat did not adversely affect firmness, total soluble solids, or titratable acidity during shelf life. These results demonstrate that PH₃-assisted forced hot-air treatment is a technically feasible and commercially promising phytosanitary strategy for mango fruit.

Zeugodacus tau, an economically important fruit fly species, exhibits a preference for infesting the fruits of cucurbitaceae, but it has also been reared from the fruits of several other plant families. Phytosanitary treatments are needed to ship the fruit from some of these host plants out of areas where populations of the fruit fly exist. Based on the guidelines for the development of cold disinfestation treatments for fruit fly host commodities, proposed by the International Plant Protection Convention (IPPC), the cold disinfestation trials were carried out with Z. tau infesting oranges through artificial infestation. The results showed that the third instar of Z. tau was the most tolerant stage among all developmental stages. No survivors were found among 106,204, 96,168, and 9180 individuals of Z. tau in oranges treated at 1.75 °C for 23 d, 2.34 °C for 25 d, and 1.8 °C for 22 d, respectively. These results support for the application of the 22-day treatment at ≤1.67 °C as an additional safety measure. Such a measure mitigates the risk of introduction and establishment of Z. tau through imported citrus. However, for other susceptible hosts of Z. tau, the cold treatment schedules against Z. tau required to achieve quarantine security with larval endpoint would need to be 23 d at 1.75 °C or 25 d at 2.34 °C. These results also indicated that Z. tau exhibits the highest cold tolerance among the other tephritid species for which cold treatment have been reported.