The lowest lethal temperature for 50% of the individuals of three strains is listed in
Table 3. The LD50 of the GIFT line was higher (P < 0.05) than that of Sudan 78 and Egypt
88. The lethal temperature for Sudan 78 and Egypt 88 was not significantly different
(P > 0.05). The low lethal temperature of GIFT was significantly higher than that of Sudan
78 and Egypt 88. These results were coincident with results of mortality.