Use of time series normalized difference vegetation index (NDVI) to monitor fall armyworm (Spodoptera frugiperda) damage on maize production systems in Africa

Publication Type

Journal Article

Journal Name

Biocontrol Science and Technology

Publication Date

1-1-1993

Abstract

Two exotic fungal isolates, one of Beauveria bassiana (268–86) and another of Metarhizium anisopliae (100–82), three local isolates of B. bassiana (isolates I, II, III) and one of the entomogenous bacteria, Serratia marcescens, were tested for pathogenicity against the banana weevil Cosmopolites sordidus. All four isolates of B. bassiana and the one of M. anisopliae were found to be pathogenic to third-instar larvae of C. sordidus, causing mortalities of 98-100% by 9 days post-exposure to dry fungal spores. M. anisopliae was the least pathogenic to larvae with LT5o of 4.2 days compared to 3.5, 3.3, 3.6 and 4.0 respectively for isolates I, II, III and 268–86. B. bassiana was also pathogenic to adult C. sordidus, causing mortalities varying from 63-97% by 35 days post-exposure depending on isolate. As for larvae, M. anisopliae exhibited low pathogenicity for the adult C. sordidus. In general, all the fungi tested were less pathogenic to adult weevils (LT50= 17.5; 12.5; 8.0 and 22.0 days) for isolates I II, III and 268–86 respectively, while isolate 100–82 failed to kill 50% of adults even by 35 days post-exposure. Incubation of dead weevils in a moist environment led to development of surface mycelia starting from intersegmental junctions. Histopathology revealed extensive destruction of internal organs by hyphae which invaded most of the organs. The LTsofor S. marcescens against C. sordidus larvae was 2.8 days. However, the bacterium did not kill adult C. sordidus even at 10 times the concentration applied on larvae. © 1993,, Taylor & Francis Group, LLC. All rights reserved.

Keywords

anisopliae, banana weevil, Beauveria bassiana, Cosmopolites sordidus, Metarhizium, pathogens, Serratia marcescens

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