Effects of temporary cooling on larvae of Idaea inquinata (Scopoli)(Lepidoptera: Geometridae)

Abstract: Idaea inquinata develops on dried plants with a preference for medicinal plants. Thesurvival of second and fourth instars larvae of I. inquinata exposed to 6 and -18 ± 1°C, fordifferent periods of time, was observed. Groups of 20 larvae were placed at 6 ± 1°C, 60 ± 5%R.H. for periods of 15, 18, 20, and 25 days and then put in thermostatic chamber at 26 ± 1°C,70 ± 5% R.H. Tests were controlled after 1, 2, 3, 8, 15 and 23 days until adults emergence. Thesame procedure was used for tests at -18°C with exposure times of 4, 8 and 24 hours. For all thetested periods at 6 ± 1°C, mortality higher than 95% was observed in second instar larvae after 1day at 26°C. A complete (100%) mortality was observed on the second day at 26 ± 1°C aftertreatment at 6 ± 1°C for 18, 20, 25, on the third day for 15 days treatment. Few fourth instarlarvae, placed for 25 days at 6 ± 1°C, were alive after 8 days at 26 ± 1°C, but they didn’t emergeas adult; when exposed for 15, 18 and 20 days few individuals developed to adult. Larvae ofI. inquinata were susceptible to the treatment at -18 ± 1°C. A complete (100%) mortality wasobserved after 24 hours, when second and fourth instar larvae were treated for 4 hours at-18 ± 1°C.