Abstract
Steinernema carpocapsae strain All and Heterorhabditis bacterionphora strain HP88, Dipel-2X (Bacillus thuringiensis subsp. kurstaki) and peppermint oil (Mentha piperita) were assayed for the control of Sesamia cretica Led. tested Under laboratory and field conditions. The efficacy 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 two days. The higher concentration levels (100,200 and 400 IJs/ml) caused mortality percentages ranged between 20.0 and 33.3 % within one clay. H. bacterionphora had no effect at concentrations between 25 and 200 IJs/ml within one day. The insecticidal activity of peppermint oil increased as the applied concentration was increased from 0.13 to 1% inducing larval mortalities from 40 to 93.3%, respectively. Increasing of B. t. 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 B. t. var. kurstaki mid peppermint oil. In die field, the intensities of damage after using the four assayed material were statistically insignificant. Both S. carpocapsae and peppermint oil had approximately the same level of activity to the dead heart phenomenon. The mean reduction Percentages of dead heart plants were 62.5 and 56.3 %, respectively. The entomopathogenic nematode, H. bacteriophora showed the lowest level of reduction (28 %) of dead heart plants than control. The yield increased in the treated plants to 3.1 and 3.2 tons/feddan by applying the nematode suspension.