Cold Disinfestation of <i>Zeugodacus tau</i> (Diptera: Tephritidae) on Oranges Using Artificial Infestation Method.

Abstract

<i>Zeugodacus tau</i>, 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 <i>Z. tau</i> infesting oranges through artificial infestation. The results showed that the third instar of <i>Z. tau</i> was the most tolerant stage among all developmental stages. No survivors were found among 106,204, 96,168, and 9180 individuals of <i>Z. tau</i> 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 <i>Z. tau</i> through imported citrus. However, for other susceptible hosts of <i>Z. tau</i>, the cold treatment schedules against <i>Z. tau</i> 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 <i>Z. tau</i> exhibits the highest cold tolerance among the other tephritid species for which cold treatment have been reported.