Citrus sinensis (L.) Osbeck is an important economic product in South China, but the presence of quarantine pests in this product proposes the potential threat to international trade security. To find a proper phytosanitary cold treatment for Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), commonly called oriental fruit fly, one of the most serious quarantine insects in navel orange, eggs in petri dish and larvae in navel orange fruits were exposed to a 1.7 • C cold chamber for 0-11 days to compare the tolerance to cold treatment. The 2nd instar larva (4 days) is the most tolerant stage, and the estimated time for 99.9968% mortality at the 95% confidence level is 11.3 (9.5, 14.6) days. Then 15 days was selected as the target time for the confirmatory tests, resulting in no survivors from 37,792 treated larvae with the efficacy of 99.9921% mortality at the 95% confidence level. The quality assessments were conducted to compare the effect on the navel orange fruit between cold treatment and the conventional cold storage. Results indicated that the cold treatment did not negatively affect the fruit quality. Therefore, this cold treatment showed potential as a commercial quarantine treatment for navel orange in international trade.Insects 2019, 10, 452 2 of 10 workers on 104,000 ha that produced 1,170,000 tons [9]. Unfortunately, B. dorsalis is a potential pest in the navel orange, threatening the safety of the navel orange export [5].The risk of introducing exotic pests into new areas is rising in the wake of the increasing agricultural trade, and the development of postharvest treatment to control insects in commodities can improve the quarantine security and expedite new trade in agricultural products. The main pest management approaches for eliminating exotic insects from a commodity are applied broadly as chemical and physical treatments. These include fumigants, temperature treatments (heat and cold), irradiation, controlled atmospheres, and combinations of these [10]. Methyl bromide fumigation is the most common approach for controlling exotic pests but is expected to be replaced by physical treatments because of methyl bromide depleting the ozone layer [10]. Physical treatments are typically applied to fresh fruits because these commodities are infested by internally feeding pests, such as tephritid fruit flies, and cold treatment is an effective measure in cold-tolerant commodities [11,12]. The pupa and adult stages of tephritid fruit flies may hardly be found in infested fruit, and phytosanitary treatments target the egg and larval stages for disinfestation [13].Research studies have demonstrated that cold disinfestation is an effective approach in controlling Bactrocera zonata (Saunders) in orange [14,15]; Bactrocera invadens (Drew, Tsuruta, and White) (synonym of B. dorsalis) in orange, and "Hass" avocado [15][16][17]; Zeugodacus cucurbitae (Coquillett) (former Bactrocera cucurtitae (Coquillett)) in navel orange [13]; Bactrocera tryoni (Froggatt) in lemon, orange, mandarin, and blueberry [18][19][20]...