Efficacy of a Lebanese isolate of beauveria sp. for the biocontrol of bemisia tabaci

Abstract EN

The sweetpotato/cotton whitefly, Bemisia tabaci (Gennadius) is a major pest of several crops worldwide.

In addition to the direct damage induced, it has the ability to transmit some of the most dangerous plant viruses rendering it a very critical pest.

The development of whitefly resistance to several groups of pesticides forced farmers and researchers to adopt integrated pest management strategies and to look for alternative control measures.

Studies using molecular markers showed the coexistence in Lebanon of two species, the “Middle East-Asia Minor 1 species” also known as biotype B and the “Mediterranean species” also known as biotype Q.

In greenhouse trials, the Beauveria pseudobassiana isolated in Lebanon was found to be quite efficient for the management of B.

tabaci.

Sprays containing spore suspensions of 107 spores/mL caused around 75% mortality of the early growth stages: egg, crawler, second and third instar larvae.

The addition of a surfactant such as corn oil improved the mortality level that reached 98% in the egg /crawler stage and 84% in the second and third instar larvae at a spore concentration as low as 105 conidia/mL.

In view of the promising results, further medium size trials under commercial greenhouse conditions are planned.