Direct toxicity effect of Beauveria bassiana and emamectin benzoate on Pectinophora gossypiella eggs (Lepidoptera : Gelechiidae)‎ and Tetranychus urticae and their indirect effect on Euseius scutalis (Acari : Tetranychidae : Phytoseiidae)‎

Abstract EN

Two experiments were carried out to study the toxicity of the entomopathogenic fungus, Beauveria bassiana (10%) and the bioinsecticide, emamectin benzoate (2.15% EC) on eggs of the cotton pink bollworm, Pectinophora gossypiella (Saund.) (PBW) and two spotted spider mites Tetranychus urticae (Koch) (Acari: Tetranychidae) and their indirect effect on some biological parameters in addition to the feeding capacity of the predacious phytoseiid mite, Euseius scutalis (El-Badry) (Athisa-Henriot) (Acari: Phytoseiidae), under the laboratory conditions of 26 ±1°C and 65±5% RH.

The results revealed that the two pests were highly susceptible to Emamectin benzoate than Beauveria bassiana as the LC50svalues were 0.484 and 0.179 ppm on PBW eggs and T.

urticae, respectively, when treated with emamectin benzoate, while they were 43.3 and 11.07 ppm with Beauveria.

The incubation period of P.

gossypiella eggs prolonged to (4.66 days), when treated with B.

bassiana and increased to (6.7 days), with emamectin, compared with (3.3 days) in the untreated (control).

Feeding predacious mite, E.

scutalis on P.

gossypiella eggs and moving stages of T.

urticae treated with emamectin benzoate and B.

bassiana, showed a considerable prolongation in total immature stages to (6.1 and 7.4 days) on PBW than (5.4 days) in the control and (7.2 and 8.8 days) than (6.0 days) for control, when fed on T.

urticae treated with Emamectin benzoateand B.

bassiana, respectively.

Treatment with emamectin benzoate caused a higher reduction in the total food consumption of the predatory mite than that with B.

bassiana.