COLD-HARDINESS OF FIRST INSTAR LARVAE OF THE FOREST TENT CATERPILLAR, MALACOSOMA DISSTRIA (LEPIDOPTERA: LASIOCAMPIDAE)

Abstract

AbstractUnfed forest tent caterpillar (Malacosoma disstria Hbn.) larvae were subjected to temperature treatments of −18°, −12°, −7°, −1°, 4°, and 22 °C, each at durations of 2 days, 7 days, and 14 days. Each temperature–duration treatment was initiated 3 days before expected hatch, and 3 days after hatch. Fed larvae were subjected to identical treatments 2 days after hatch. Temperature treatments of the before hatch group resulted in appreciable mortality only at −18 °C for 7 days and at −18 °C and −12 °C for 14 days. Temperature treatments of the after hatch group resulted in nearly 100% mortality at −18 °C for all durations, at −12 °C for 14 days, and about 50% mortality at −7 °C for 14 days. Other temperature–duration combinations caused little mortality. The mortality resulting from temperature treatments of fed larvae did not differ from unfed larvae of the after hatch group.