Threshold and Degree Days for Colorado Potato Beetle Leptinotarsa decemlineata (Say.) Coleoptera: Chrysomelidae


The results of the laboratory study have showed that all biological aspects of Colorado potato beetle were affected when reared on different hosts (Potato, Eggplant, Tomato) and different temperature rates (20, 30, and 30Cº ±2) with constant relative humidity (70 ± 5%). The shortest life cycle of the insect was at 30 Cº on Potato crop (19.9 days). The results also showed that the development threshold was 9.04, 10.72 and 9.62 Cº on potato, eggplant and tomato respectively, and the degree days for development to adult stage were 416.76, 400 and 476.19 on the three host plants respectively.The adult obtain these temperature units at the end of the first week of February, and from this we can predict the date of adult appearance in the field. It’s also found that the correlation between temperature degrees, plant hosts and daily development rate was significant and positively correlated, R=0.99, 0.99 and 0.96 on the potato, eggplant and tomato respectively.