M.A.NADA, MONA A.A. HEWADY AND AMIRA M. RASHAD
Plant Prot. Res. Institute. Dokki, Giza , Egypt

ABSTRACT

Under natural conditions, the ectoparasitic mite, Pyemotes herfsi (Oudemans) appeared as an important agent against the diapausmg pink bollworm larvae resting in dry cotton boils in cotton stalk heaps stored on land or on top of farmers' houses. Evaluation of the efficacy of Pyemotes as a controlling agent was carried out at the end of April, May and June, 1993.
According to release of the parasitic mite on the cotton stalk heaps stored on land or on top of houses at El-Ebrahemea region, Sharkia Governorate, reduction rates of healthy diapausing larvae after three weeks in a height of 0.5 to 1.0 meter reached 40 and 66.7%, respectively. The reduction rate reached 68.1 and 85.5% when the parasite was released underneath the heaps on land in a level of 0.5-1.0 m and 1.0-1.5 m, respectively. Meanwhile, the reduction rate reached 88 1% after 3 weeks when it was released underneath the heaps on top of houses at the height of 0.5-1.0 m.
Percentage of parasitism reached 68.0 and 83.3% after 3 weeks from releasing the mite on the height of 0.5-1.0 m of cotton stalk heaps when releasing was on heaps, while it reached the maximum percent after 3 weeks post releasing the parasite underneath the heaps, where it was 85.7 and 95.2% in dry cotton boils in stalks on land or on top of houses, respectively.