Title : Influence of Growth Media to The Virulence of Beauveria bassiana (Balsamo) Vuillemin Against Tribolium castaneum (Tenebrionidae: Coleoptera)
Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) or red flour beetle is the main pest of wheat flour but can attack other processed food as well. One of the biological control that can be used is the use of entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin. The purpose of this study was to determine the virulence level of entomopathogenic B. bassiana to control T. castaneum pests as the fungi were grown in different media, namely PDA, Rice and Corn media. The conidia of the fungal culture of 21 days old were sprayed to the adult of T. castaneum. Virulence of B. bassiana was tested at four density levels 105, 106, 107, 108 conidia/mL against an adult. The conidial suspension was applied by using the small sprayer. Three replicates have been used. Daily mortality was recorded as an observation variable. The observations showed that the mortality of T. castaneum in the density of conidia 107 reached 44.44% in the PDA media, the conidia density of 106 in the rice media reached 40.00% mortality, and 26.67% in the density of 105 in the corn media. Cumulative mortality on 7 days post-treatment is different between the three media. Probit analysis showed LC50 values of B. bassiana is 5,896 × 107 conidia/mL on PDA media and 15.19 × 106 conidia/mL on Rice media. At the density of 107 conidia / mL, the value of LT50 B. bassiana on PDA media was 13,136 days while in the rice and corn media were 22. 41 days and 98,415 days. The results of this study showed that B. bassiana has higher infectivity on PDA media against T. castaneum than Rice and Corn Media.
Keywords: conidia density, infectivity, LC50, LT50, mortality