Effects of Temperature on the Development of Tropidothorax cruciger (Hemiptera: Lygaeidae) on Cynanchum wilfordii

Abstract

Tropidothorax cruciger (Motschulsky) was reared on buds and leaves of Cynanchum wilfordii Hemsley at constant temperatures of 15, 18, 23, 28, and 33±1°C in the laboratory. Eggs of T. cruciger did not hatch at 15°C. Egg periods were 21.9, 14.2, 8.5, and 7.8 days at 18, 23, 28, and 33°C, respectively. Nymphal periods were 69.4, 52.6, 30.5, and 20.2 days, and egg to adult emergence periods were 91.3, 66.8, 39.0, and 28.0 days at 18, 23, 28, and 33°C, respectively. Theoretical developmental threshold (DT) temperatures of T. cruciger were 10.1 and 13.3°C for egg and nymph stages, respectively. When the egg and nymphal stadia were pooled, the DT temperature turned out to be 12.6°C. Accumulated effective temperatures (ET) for stages of egg, nymph, and egg-nymph combined were 171.8, 420.7, and 589.9 day-degrees, respectively. Longevity of adults was 47.8, 54.4, 31.9, and 18.5 days, respectively, the longest being at 23°C. Pre-ovipositional periods were 38.5, 43.0, 26.3, and 17.4 days and the number of eggs laid per female was 27.8, 34.0, 30.8, and 23.4 at the above temperatures, respectively. The rates of hatching were 35.6, 85.1, 68.1, and 39.4%, respectively at the temperatures previously given.