The effectiveness of entomopathogenic fungi, beauveria bassiana (Balsamo) vuillemin and lecanicillium lecanii (Zimm.) (Viegas) zare & gams against the asiatic corn borer, ostrinia furnacalis guenée (Lepidoptera: Crambidae).

Abstract

This study was conducted at the Insect Pathology Laboratory, Plant Protection Department, Bogor Agricultural University, from March to September 2013. Tested insects,Ostrinia furnacalis, were collected from farmers cornfield in Dramaga, Bogor andthen reared in the laboratory. Isolates of Beauveria bassiana and Lecanicillium lecanii in this study were obtained from the collection of Insect Pathology Laboratory. Fungal suspension was innoculated to Tenebrio molitor adultsin order to increase the virulence after a long storage in the laboratory. Mycelia of the fungi from T. molitor cadavers were isolated and cultured on PDA (Potato Dextrose Agar) media, then colonies from PDA were subsequently transfered and maintained on rice media until± 21 days old. Fungi from this culture were used in this study. Bioassay were conducted with five levels of density, i.e. 105, 106, 107, 108 and 109 conidia/mL with ± 3 mL application volume for each treatment. Each treatment were made of four replicates. The number of larvae that were used for each replicate were 20 larvae, while the eggs treatment consistedof one egg mass per replicate. Probit analysis was used to analyze the mortality data and to estimate the value of LC. Result of this study indicated that B. bassiana with 109 conidia/mL caused 78.75% mortality of 2rd instar larvae, whereasthe same conidial density of L. lecanii caused 71.25% mortality. The value of LC50 were 1.39 x 106 conidia/mL for B. bassiana and 1.62 x 106 for L. lecanii; both LC values were calculated at 7 days observation. While 100% egg mortality was achieved by application of B. bassiana at 109 conidia/mL, the same degree of mortality could be achieved by L. lecanii at lower density,i.e. 108konidia/mL. Value of LC for both fungi against eggs at 3 days post treatment are 9.6 x 105 and 6.1 x 105 conidia/mL, respectively.