COMPARATIVE TOXICITY AND TOLERANCE FOR SOME INSECTICIDES IN A LABORATORY AND FIELD STRAINS OF COTTON ‘LEAFWORM IN RELATION TO SOME ENZYME ACTIVITIES

Third instar larvae of Spodopfera iiitoralis (Boisd.) of susceptible. Behera.
Gharbia and spinosad resistant strains, were tested in the laboratory. Treatments
were done in the laboratory with profenofos, sumi-gold and spinosad insecticides.
before and after spraying programs in the fields of these areas. In general data
indicated that the LCso values of these insecticides after spraying programs were
higher than those before spraying. The results also indicated that no-cross resistance.
between spinosad. profenofos and sumigold insecticides.
With regard to the activity of a, (3 esterases acid and alkaline phosphatases in
4-1”1 instar larvae of S. liltoralis for each governorates and spinosad resistant strains at
giMinilarvae. it was clear that the enzyme activity increased gradually with increasing
the levels of resistance.
On the other hand. a positive correlation was recorded between resistance
values and esterases activity. Also a good correlation between phosphatases activity
and resistance to insecticides. As for the spinosad resistant -strain. there are a good
correlation between the activity of a. B esterases and alkaline phosphatase, while a
negative correlation between acid-phosphatase and a resistant to spinosad.