EFFECTS OF TEMPERATURE ON DEVELOPMENT OF THE IMMATURE STAGES OF THE CEREAL LEAF BEETLE, OULEMA MELANOPUS (COLEOPTERA: CHRYSOMELIDAE)

Survival and development rates were obtained for the cereal leaf beetle, Oulema melanopus (L.), at 12 constant temperatures. Rates of survival for eggs were high at temperatures ranging from 12°C to 32°C, but none hatched at 6°C or 34°C. Larvae survived at 8° to 32°C with no drastic rise in mortality at the extremes; mortality at 34°C increased with larval age. Pupal survival was low at all temperatures from 8°C to 32°C, ranging from about 3% at these limits to 40% at intermediate temperatures (14° to 30°C). Duration of egg and larval stages decreased with rise in temperature up to 30°C, and that for pupae, up to 32°C. Developmental rates plotted against temperature did not deviate significantly from fitted curves of the form 1/y = K/(1 + ea-bx).The threshold for complete development was at some point between 6°C and 8°C. Thermal requirements, with 7°C as developmental zero, were calculated at 105, 41, 36, 43, 46, and 282°D, respectively, for the eggs, the four larval instars and the pupae. Accumulated heat units (°D7) during development of O. melanopus in field plots at Ottawa did not differ significantly from those expected. Similar calculations using a base of 9°C (ca. 48°F) predicted development equally well.