FACTORS AFFECTING POPULATION OF SOFT SCALE INSECT, Pulvinaria tenuivalvata (NEWSTEAD) (HOMOPTERA: COCCIDAE) IN QUENA SUGARCANE FIELDS

The current study was carried out at two locallities (Esna and El-Namasa)in Quena governorate (Upper Egypt) during 2005/2006 growing season, in order to study the effect of two irrigation systems (the drown and the surface irrigation development systems) on the population density of the red stripped soft scale insect Pulvinaria tenuivalvata. The population density of P. tunivalvata in drown system was 88 and 87 individual/30 leaves in Esna and El-Namasa regions, while by using the surface irrigation development system, the population density was lower significantly with a mean of 38 and 41  individual/30 leaves in Esna and El-Namasa regions.
Three sugarcane varieties and a commercial variety were evaluated for their susceptibility to infestation with P. tenuivalvata. The varieties were pH/8013, F/160 and G.47/87, and the commercial one was C9/54. Results showed that C9/54 was significantly the most susceptible to infestation with P. tenuivalvata, with a mean of 14.6 individuals in Esna, while it was 17.6 individuals/100 leaves in El-Namasa. Followed by G47/87 with mean of 8.7 and 10.3 individuals/10 leaves in Esna and El-Namasa. F/160 recorded a mean of 6.1 and 6.55 individuals/10 leaves in Esna and in El-Namsa. PH/8013 was the least susceptible variety to infestation with a mean of 4.4 and 4.6 individuals/10 leaves in Esna and  El-Namasa.