Laboratory Study to Limitation Degree-Days Which Prerequisite for Stages Development of Waterhyacinth Chevroune weevil Neochetina bruchi (Hustache) Coleoptera: Curculiondeae and the Lowest Developmental Threshold

Abstract

The results of this study showed that the lowest developmental threshold of eggs, larvae and pupae of N. bruchi was 12, 12 and 11°C respectively at 20,25 and 30°C. While there were no hatching and development of larvae and pupae at 15°C ,While 35°C killed all the stages were tested. The results also showed that the lowest developmental threshold of male and female was 15 and 14°C respectively at 15,20,25 and 30°C While 35°C killed these stages tested too. The accumulated days degree for the development of egg, larvae and pupae was 143, 500 and 500 thermal units at 20,25 and 30˚C.While it was 333, and 333 thermal units of male and female respectively at 15,20,25 and 30°C. So there are no accumulated days degree for the development of egg, larvae, pupae, male and female at 35°C because it was killer for these stages. While there are no accumulated days degree for the development of egg, larvae and pupae at 15°C because there are no developing for these stages.