Submitted to: Society for Invertebrate Pathology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/29/2001
Publication Date: 8/27/2001
Citation: GARCIA-GUTIERREZ, C., TAMEZ-GUERRA, P., MCGUIRE, M.R., JACKSON, M.A., BEHLE, R.W. TOXICITY OF PAECILOMYCES FUMOSOROSEUS PRODUCED IN LIQUID AND SOLID MEDIUM, USING A DIPPED LEAVE AND TOPIC BIOASSAY ON LARVAE OF MEXICAN BEAN BEETLE (COLEOPTERA: COCCINELLIDAE). SOCIETY FOR INVERTEBRATE PATHOLOGY MEETING. 2001.
Technical Abstract: Mexican bean beetle (MBB) Epilachna varivestis Mulsant (Coleoptera: Coccinellidae) is a main pest of soybean in Mexico. Testing the use of Beauveria bassiana for MBB control, Garcia, et al. (1999) found susceptibility of first instar larvae to ten strains of B. bassiana at doses of 1x10(9) spores/ml. However, information on the pathogenic effects of other fungi, such as Paecilomyces fumosoroseus (Pfr} is not available. In this study, we evaluated the toxicological effects of Pfr spores produced in liquid and solid medium. A dipped leaf and topical bioassay was used against first instar larvae of E. varivestis. Insects were incubated in a climate chamber at 24C and 83% RH, with continued light. Liquid culture-produced blastospores and solid substrate-produced conidia of Pfr ARSEF 3581 were used in this study. The blastospore and conidia concentration from liquid and solid samples were determined using a hemacytometer. Insects were inoculated with conidia or blastospores suspensions of 1.2x10(9), 2.4x10(8), 4.8x10(7), 9.6x10(6), and 1.92x10(6) spores/ml. In a dipped leaf bioassay (DLB), soybean leaves disk infested with first instar larvae of MBB were placed on moist filter paper. In the topic bioassay (TB), the pathogenic effects of Pfr conidia and blastospores were determined by exposing first instar larvae to 1 ul of each spore suspension. Treated MBB larvae were maintained in a rearing chamber at 27C and 75% RH. The colonization of the MBB with fungus was observed microscopically after 24-hr incubation.