Phytosanitary irradiation of Jack Beardsley mealybug (Hemiptera: Pseudococcidae) females on rambutan (Sapindales: Sapindaceae) fruits

The Jack Beardsley mealybug, Pseudococcus jackbeardsleyi (Gimpel & Miller) (Hemiptera: Pseudococcidae), is a quarantine pest of fruits, vegetables, flowers and seedlings. Host commodities shipped from infested areas should undergo phytosanitary measures to reduce the risk of shipping viable mealybugs. Large-scale confirmatory tests on late stage female P. jackbeardsleyi (the most tolerant stage) irradiated with the target dose of 150 Gy were conducted to determine the minimum absorbed dose for the use of irradiation as a phytosanitary treatment. No F-1 generation 2nd stage nymphs emerged from an estimated 118,520 potato (Solanum tuberosum L.; Solanales: Solanaceae) reared females irradiated with 133.5-164.1 Gy, or 49,290 pumpkin (Cucurbita sp.; Cucurbitales: Cucurbitaceae) reared females irradiated with 131.3-166.0 Gy, resulting in an efficacy of 99.9975% (potato reared) and 99.9939% (pumpkin reared) and 99.9982% (all females) at the 95% confidence level. Quality determinations on 'Rongrien' rambutan (Nephelium lappaceum L.; Sapindales: Sapindaceae) fruits-the favorite host of P. jackbeardsleyi-were conducted 5, 10 and 15 days after gamma radiation at doses of 300, 600, 900, and 1,200 Gy with storage at 10 degrees C. Irradiation did not induce significant changes in ascorbic acid content, total acidity, total soluble solids, soluble protein, and weight loss. However, storage time had a significant negative effect on the chemical and nutritional contents and weight loss. A dose of 166 Gy is recommended as the minimum dose for phytosanitary treatment against the Jack Beardsley mealybug. 'Rongrien' rambutan can tolerate a dose of 900 Gy but at 1,200 Gy its sensory attributes are significantly affected.