A Study on the Morphology and Biology of the Adelgid Aphid Pineus armandicola

The adelgid aphid Pineus armandicola is an important pest of Pinus armandii.The aphid has 8 generations each year in Kunming district.In average,it takes 42 days in spring and summer or 51 days in autumn and winter for the insect to finish one generation.The different generations are overlapping.The aphid has no distinct dormancy in Kunming district,in the cold area over altitude of 2600 m,most individuals overwinter by dealate adults(virginogeniae) and mature nymphs in one year old needle clumps or bud bracts of the top twigs,a few individuals overwinter by eggs on the lower surface of one or two years old needles.Each female adult produces 50 eggs in average.The egg stage lasts for 5 to 12 days.Hatching rate of eggs is over 90%.The nymph has 4 instars.After 2 to 4 days,the first instar nymphs fix on the new growing needles until they develop to adult stage.The aphid leads a parthenogenesis life.The al ate ad ults(virginogeniae) firstly appear in late March,and the peak period is observed from mid April to early May.The differentiation of alate adults is an important factor for the migratory dispersal and proliferation of the aphid population.