Laborarory Studies on the Effect of Population Density of the Scale Insect Parlatoria blanchardi on Some Biological Aspects of the Predator Chilocorus bipustulatus

Abstract

Laboratory studies were conducted to evaluate the effect of the scale insect, Parlatoria blanchardi density on some biological aspects of predator Chilocorus bipustulatus. Result showed that larval development periods are inversely proportional to the density of the scale insect P. Blanchardi.   The shortest larval period was 20 days on  the  density  of 80  nymphs, However, the period  of larval development was increased to 33.5 days  on the density of 25 nymphs with significant  diffrences. No larvae can survive when reared on density of 10 nymphs. There  was  positive  correlation between Predator  efficiency  and its survival with  and P. blanchardi   density .The lowest consumption was  643.6 nymphs/ day with 40% survival percent when on the density of 25 nymphs, while  consumption increased to 1530.3 nymphs/ day with 60% survival  percent  when density  increased to 80 nymphs with significant diffrences.The density of 65 nymphs was the best to rear  the larvae because the the larval period was the lowest with high survival and no significant difference with the density of 80 nymphs.