Hara, A.H., Yalemar, J.A., Jang, E.B., & Moy, J.H. 2002 Irradiation as a possible quarantine treatment for green scale Coccus viridis (Green) (Homoptera : Coccidae).. Postharvest Biology and Technology 25(3): 349-358.

Notes: The green scale, Coccus viridis (Green), can be controlled effectively by irradiation at a minimum absorbed dose of 250 Gy. Reproductive capacity of irradiated gravid adults was reduced greatly and any resulting offspring were not able to develop beyond the crawler stage. Development of nymphs to the adult stage was not arrested completely nor was development of immature stages eliminated, but all survivors were sterile. Generally, higher doses of irradiation (greater than or equal to 400 Gy) caused faster kill of all life stages than lower doses (250 Gy). At 250 Gy, there was prolonged survival of green scale, with 8.8-11.4% of nymphs and up to 8.8% of crawlers alive 3 months after irradiation; 100% mortality of the most resistant adult stage took longer than 20 weeks post-treatment. An absorbed dose of 500, 750 or 1000 Gy caused 100% mortality in all stages of the green scale by 7, 6, and 3 weeks post-treatment, respectively. Adults appeared to be more resistant to treatments greater than or equal to 500 Gy. Irradiation doses greater than or equal to 500 Gy killed crawlers by 3-5 weeks post-treatment and rendered nymphs and adult green scale sterile until their eventual death. When irradiated at 250 Gy, survival of non-infested gardenia plants and green scale-infested gardenia and coffee plants were reduced by 69, 56, and 18%, respectively, as compared with non-irradiated plants. Nonreversible, sublethal phytotoxicity included tip browning of young leaves, absence of new leaf growth in gardenia plants, failure to form new leaves in coffee plants, and eventual plant death. While irradiation at 250 Gy is sufficient to provide quarantine security for crops that are hosts of green scale, product quality will need to be evaluated on a case-by-case basis since certain commodities, such as gardenia seedlings, have sustained phytotoxic effects.