Beauveria bassiana (Bals.) Vuill. strains pathogenic to Periplaneta americana (L.)

Abstract

A laboratory experiment was conducted in the Physiology Laboratory, Department of Entomology, Assam Agricultural University Jorhat-13 during 2014-2016 to study the comparison of Beauveria bassiana (KR855715) strains viz., KR855715, IMI335352 and MTCC-6095 against instars and adults of Periplaneta americana (L.) (Blattodea: Blattidae). The biological parameters of B. bassiana showed that the native strain, KR855715 radially grew highest (40.15±0.91 mm) and showed highest spore germination (83.13±1.06%) and conidial density (12.02×107 conidia/ml). All the strains were infectious to P. americana. However, instars were more susceptible than the adults. 100 percent mortality was recorded in case of 1st and 2nd instars (KR855715) and 40 (IMI335352) and 24 (MTCC-6095) per cent in 1st instars. With respect to 2nd instars, the mortality was found to be 36 (IMI335352) and 18 (MTCC-6095) per cent only. Similarly, mortality of 3rd, 4th, 5th instars and adults varied between 16 (MTCC-6095) to 72 (KR855715), 20 (MTCC-6095) to 68 (KR855715), 16 (MTCC-6095) to 36 (KR855715) and 6 (MTCC-6095) to 26 (KR855715) per cent respectively at 9 days after treatment. The histopathological study revealed the presence of mycelial network of the fungus inside the insect body.