Steinernema carpocapsae strain All and Heterorhabditis bacterionphora strain HP88, Dipel-2X (Bacillus thuringiensis
variety kurstaki) and peppermint oil (Menthapepperita) were assayed for the control of S. cretica tested under laboratory and
evaluated on infested corn plants under field conditions. The efficiency of S. carpocapsae was a concentration dependent.
The lower concentrations (25 and 50 IJs/ml) had no effect within one day; while they showed mortality percentages between
60.0 and 73.3 % after to days. The higher concentration levels (100,200 and 400 IJs/ml) caused mortality percentages
ranged between 20.0 and 33.3 % within one day. H bacterionphora had no effect at concentrations between.25 and 200
IJs/ml within one day. The insecticidal activity of peppermint oil of S. cretica larvae increased as the applied concentration
was increased from 0l3 to 1% increased larval mortalities fronl 40 to 93.3%, respectively. While, increasing of Bt. var.
kurstaki concentration from 0.13 to 1.5%. led to increase of mortalities of S. cretica larvae from 33.3 to 86.7%, respectively.
Some morphological malformations were detected among S. cretica pupae and adults after larval treatments by BI. var.
kurstaki and peppermint oil. In the field,. The intensities of damagé after using the four assayed materials were statistically
insignificant Both S. carpocapsae and peppermint oil had approximately the same level of activity to the dead heart
phenomenoi . The mean reduction percentages of dead hearted plants were 62.5 and 56.3 %, respectively. While, the
entomopathogenic nematode, H bacteriophora, showed lowest level of reduction (28 %) of dead hearted plants than control.
the yield increased in the treated plants to (3.1 and3.2 ton/feddan) by applying the nematode suspension.
Key words: Steinernema spp., Heterorhabditis spp. Sesamia cretica, Peppermint oil, Bacillus thuringiensis, maize. |
