A study on the effect of Trichogramma principium releases on cotton bollworms and the Chrysopid Predator Chrysoperla carnea in Syrian cotton fields

الملخص EN

The cft'ect of the parasitoid, Trichogramma principium.

releases on the cotton bollworms and the chrysopid predator, Chrysoperla carnea.

were tested in Syrian cotton fields.

Tests were carried out during September 1998 and August 1999 near Aleppo (Al-Zcrbeh and Om-Houche).

In 1998, the investigated field (Al-Zerbeh) was infested by Helicoverpa armigera and protected by C.

carnea.

The nearby field was planted with cabbage infested with Pieris rapae.

Plastic capsules containing about 1000 parasitoids (not emerged adults of T.

principium) were hanged on cotton plants, one capsule for every 10 x 10 m.

In 1999, the studied fields (in Al-Zcrbeh and Om-Houche) were only settled by C.

carnea eggs, and 2 capsules were used at each release point.

In 1998 and 1999.

eggs of //.

armigera, C.

carnea and P.

rapae were collected several times (before the releasing date, on the releasing date and few days thereafter), and then observed in order to determine the level of their parasitism.

Results showed that T.

principium did not parasitize C.

carnea eggs in the field.

On the other hand, the level of parasitism of H.

armigera eggs reached 12.5%, and that of P.

rapae eggs 29%.

The presence of Telenomus acrobates was confirmed in Syria on C.

carnea eggs and the parasitism level ranged from 11 to 65% during the test period.