Temperature effects on development and survival of the sweetpotato weevil,Cylas puncticollis Boheman (Coleoptera : Apionidae)

The effects of temperature on the development and survival of the sweetpota to weevil, Cylas puncticollis were studied in the laboratory at. six consta nt temperatures (16.03, 18.60, 24.11, 26.38, 31.23 and 35.82 degreesC). The photoperiod was maintained at 12L:12D for all temperatures, but RH was not controlled. Thermal requirements (r and k) of this pest species were estim ated for all the immature stages and for the total life-cycle. Duration of development from hatching to pupation was observed for individuals disturbe d at regular intervals to determine instar-specific development rate. This was compared with total development duration for sets of individuals not di sturbed in this way. As expected, development rate was slower at lower temp eratures. At 16.03 degreesC there was no development beyond the first larva l instar, The larval period was longer than other stages at all temperature s. A significant difference in total development rate of adults was observe d between the true treatments (disturbed and undisturbed), except at 18.60 degreesC. Mortalities were highest at 16.03, 18.60 and 35.82 degreesC. Temp erature had no effect on thr sex ratio of C. puncticollis.