Pathogenicity on Erinnyis ello (Lep¡doptera:Sph¡ng¡dae) ¡n laboratory conditions of entomopathogen fungus collected ¡n comercial crops cassava Manihot esculenta in Cauca Valley, Colombia

Abstract

Infected insects with fungus were collec­ted in cassava crops in the Cauca Valley. In the laboratory, the fungus Beauveria bassiana (B.b.9601 and B.b.9602) and Aspergillus (Asp.9601) were isolated, purified, and identified. These native isolates together with one of Metarhizium anisopliae (M.a.9206), received from CENICAFE, were evaluated on larvae of E. ello. The methodology to select the more pathogenic isolates and the best method of inoculation between aspersión on larvae, leaf, and larvae-leaf was determined. The most susceptible larval instar of the selected isolate was also determined to establish the LD₅₀. The in­dividual separation of the treated insects in cardboard boxes with plástic sheet of 14 x 11.5x5 cm with the cap was the most adequate methodology to do pathogenic tests on E. Ello and was denominated “Experimental Unit Múnera - De Los Ríos”. B.b.9601 was the most pathogenic isolate causing mortality between 77.5% and 87.5% presenting significant differences (P<0.05) compared to the other isolates; M.a 9206 caused mortalities no greater than 67.9%; B.b.9602 caused lower mortality of 16.1% and Asp.9601 wasn’t pathogenic. There was no signi­ficant difference between inoculation methods (P<0.05); .hoosing aspersión to larval-leaf to be most similar to field application. Instar III showed the greatest susceptibility to B.b.9601. The LD₅₀ of B.b.9601 was 1x10^{4 .8018} viable conidia mi'¹ with confidence limits between 1x10^0.3523 and lxlO⁷⁴¹²⁰. B.b.960 sprinkled on fifth instar larvae produced a mortality of 40%, the survivors showed normal oviposition and eggs with high viability. B.b.9601 inoculated on eggs doesn’t cause considerable mortality. Th.e aspersión of a mixture of B.b.9601 and M.a 9206 caused 90% mortality in III instar larvae.