حساسية الأطوار المختلفة لدودة ورق القطن Spodoptera littoralis (Boisd.)‎ للإصابة بالفطر Beauveria bassiana (Bals.)‎ Vuil. مخبريا

Abstract EN

This study was conducted to identify the most susceptible stages of the cotton leaf worm Spodoptera littoralis (Boisd.) to the entomopathogenic fungus Beauveria bassiana.

Conidial suspension from the fungal isolate was prepared as a spores suspension at concentration of 106 spores/ml.

The suspension was sprayed separately on each of the larvae (1st, 3rd, and 6th instars), pupae and adults.

Whereas, egg-masses were only dipped in the suspension.

Results showed that the fungus B.

bassiana was able to infect all the tested stages of the cotton leaf worm.

Both the 1st and 3rd instar larvae showed high susceptibility to infection with 100% mortality.

In addition, eggs and pupae mortality reached 83 and 58% after four and 15 days, respectively.

Mortality of adults reached 32% on the 5th day, whereas the 6th instar larvae showed less susceptibility to fungal infection with 18% mortality.

The values of lethal time 50 (LT50) increased with the increased age of larvae.

Keywords: Spodoptera littoralis, Beauveria bassiana, entomopathogenic fungi.