Monday, December 10, 2007 - 9:05 AM

Pathogenicity of Metarhizium anisopliae and Beauveria bassiana expressing the scorpion toxin (AaIT) against the coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae)

Monica Pava-Ripoll,, University of Maryland, Department of Entomology, 4112 Plant Sciences Building, College Park, MD, Francisco Posada, USDA-ARS Insect BioControl Laboratory, Room RM. 214, 10300 BALTIMORE AVENUE, BLDG 011A BARC-WEST, Beltsville, MD, Bahram Momen, University of Maryland, Environmental Science & Technology Department, 1108 H.J. Patterson Hall, College Park, MD, Chengshu Wang, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China, and Raymond St Leger, University of Maryland, Entomology, 4112 Plant Sciences Building, College Parrk, MD.

Coffee berry borer (CBB) is the Worlds most devastating coffee pest causing an estimated of US$500 million annually in losses and control costs. Beauveria bassiana and Metarhizium anisopliae have been employed to control this pest but their slow kill is an important factor constraining their use. M. anisopliae has been modified to express the scorpion toxin (AaIT) in insect haemolymph and this dramatically increased pathogenicity against Manduca sexta and Aedes aegypti. Here, we demonstrate that the recombinant M. anisopliae strain expressing AaIT (MaPcTox) was also dramatically more virulent to CBB. We evaluated several spore concentrations (1x101 through 1x107spores/ml) of both wild type and recombinant strains. Results demonstrated that at concentrations of 1x102 and 1x103 spores/ml, the recombinant strain significantly increased mortality of CBB by 40% and 55%, respectively. The medial lethal concentration (LC50) was reduced by 18 fold and the medial lethal time (LT50) was reduced by 21.5% at the highest concentration evaluated. The LT50 was reached in 2.85 0.08 days, a significant finding since it is the first occasion that an entomopathogenic fungus killed the CBB in less than 3 days. In future research we will insert the AaIT gene in B. bassiana and compare its efficacy against CBB.

Species 1: Coleoptera Curculionidae Hypothenemus hampei (coffee berry borer, broca)