The efficacy of field releases of the egg parasitoid, Ttic ogramma
evanescens Westw. against Ostrinia nubila/is Hbn. on maize plant tion were
investigated at Giza region in 2000 and 2001 seasons. Fi.ve releases were made in 3
days intervals with a total release density of 60000 para sitoidslfeddan to control an
artificially placed egg masses of O. nubila/is. In 2000 season, the mean perpentage of
parasitism was 40.19% in the treated area and 2.88% in the untreated one. The died
and lost eggs averaged 7.9% and 4.1 % in the trealed plots in comparison with 6.6%
and 4.3% in control. The hatched eggs of O. nubi/alis were 29.2 and 66.3% in the
treated and untreated areas, respectively. For 2001 season, the highest percentage of
parasitism occurred by the end of the release period with 73% in the released area
and 29.83% natural parasitism in the unreleased one. The mean percentage of
parasitism was 59.39% and 15.03%. in both areas, respectively. The per<;entage of
died and lost eggs were 5.1 % and 1.8% in the treated plots in comparison 'with 5.5%
and 1.9% in untreated ones, in arrangement. The hatchability % of O. nub"a/is eggs
was 12.6 in the treated area and 55.8 in untreated one. The percentage of parasitoid
emergence hole from O. nubi/alis eggs ranged 72 to 80%. The role of predation with the natural predators on suppressing 9. nubi/alis
egg population were also determined. Direct observation of the predators on maize
plants showed the presence of Cocclne//a undecimpunctata L., Paederus a/fieri;
Kock., Lapidurs riparia Pail., Chrysoperla csme« (Steph.), Syrphus corrollae F., and
Scymnus subviJ/osus The percentage of predation ranged 18.61 to 21.8% d ring both
seasons.