Effectivity of Bacillus thuringiensis subsp. aizawai Protoxin, Beauveria bassiana Conidia, and Their Mixtures to Spodoptera litura F Armyworm.

Abstract

Armyworm or (Lepidoptera:Noctuidae) is one of main pest in plant crop. This pest might cause damage on the leaves and stems and reduce of crop production. Bacillus thuringiensis subsp. aizawai and Beauveria bassiana have been known as biocontrol agent to this pest. This research was aimed to observe the production time of B. thuringiensis subsp. aizawai toxin, measure the effect of toxin against Be. bassiana conidia, to test the activity of toxin, conidia and their mixture against S. litura. B. thuringiensis subsp. aizawai was grown on specific medium for B. thuringiensis. Toxin production of the isolate was measured every 4 hours up to 48 hours incubation. Be. bassiana was grown on the white rice medium and its conidia was grown on the Potato Dextrose Agar medium containing toxin. The activity test of toxin B. thuringiensis, Be. bassiana conidia, and their mixture was done by spraying them to S. litura larvae. The stasionary phase of B. thuringiensis was obtained at 16 hours incubation and the maximal toxin production at 48 hours. The highest mortality of S. litura larvae caused by toxin activity was 63.3% at 48 hours incubation. The highest mortality caused by conidia infection activity was 80% at the concentration of 108 conida ml-1. The highest mortality caused by their mixture was 96,7%.