Major biological parameters of high and low temperature strains of cotton mealybug Phenacoccus solenopsis Tinsley

The high and low temperature strains of cotton mealybug Phenacoccus solenopsis Tinsley fed on the cotton were built up, and their major biological parameters were studied in this paper. The populations were kept for generations under the laboratory conditions photoperiod 14L10D, RH 70(5)%, constant temperature 181and 32(1), and 3rd instar nymphs in each generation were sampled and treated by 4cold shock and 50heat shock for 30 min, and then the survival ratios were determined. We considered it was the temperature strain popultion when the survival ratio increased significantly compared to the control group. The supercooling points and freezing points of 3rd instar nymphs and female adults of high and low temperature strain populations were determined, and the body length, width and weight of female adults were also presented. Meanwhile, the development durations, survivorships, sex rations, fecundity were investigated, and the life tables of the laboratory populations were constructed. The results showed that the supercooling points and freezing points of the female adults of low temperature strain were the highest with -15.01and -13.93, and those of the female adult of high temperature strain were the lowest as -24.9 and -24.5. The female adult body length, width and weight (4.37 mm, 2.59 mm and 4.0 mg) of the low temperature strain were significantly higher than those (3.22 mm, 1.75 mm and 1.5 mg) of the high one. The generation durations of low temperature strain females and males were 54.10 d and 42.08 d, and the survival rate and population trend index were 42.72% and 47.47, while those of high temperature strain with 16.11 d, 12.08 d, 57.81% and 74.28.