Cold storage of the green lacewing, Chrysoperla carnea eggs

Cold storage is a common technique to prolong the shelf life of the mass-reared natural enemies in insectaries. In this research, one-day and two-day old eggs of the common green lacewing, Chrysoperla carnea were stored in refrigerator (5±1°C, and full darkness) for 3, 5, 7, 10, 14, 21 and 30 days and egg hatching rate, survival and developmental times of larva and pupa as well as longevity and fecundity of adult females were subsequently assessed. Hatching percentage of both one-day and two-day old eggs did not negatively reduce for up to 7 days of cold storage (37.5 and 39.2 hatching percentages, respectively), but a significant reduction was observed in longer storage durations and reached to 0 percent after 30 days. The effect of “age” factor on egg hatching rate was largely dependent on cold storage duration. Therefore, there was no significant difference between hatching rates of one-day old eggs compared with that of two-day old eggs up to 14 days of cold storage, while hatching percentage of two-day old eggs was significantly lower compared with that of one-day old eggs at 21 days cold storage duration. Cold storage of one-day and two-day old eggs had no adverse effect on the larval survival rates up to 14 and 10 days, respectively. But larval developmental time increased significantly even after a short 3-days duration of cold storage.Moreover, cold storage of one-day old eggs for 7 days and two-day old eggs for 3 days significantly reduced female fecundity (37.5 and 66.1 percent, respectively).In conclusion, one-day old eggs can be cold stored for up to 5 days, and cold storing of two-day old eggs is not recommended because of its high subsequent adverse effects on female longevity and fecundity.