Enzymatic comparison and mortality of Beauveria bassiana against cabbage caterpillar Pieris brassicae LINN

Abstract

Beauveria bassiana, an entomopathogenic fungus, is the alternative biocontrol agent exploited against major economic crop pests. Pieris brassicae L. is an emerging pest of the Brassicaceae family. Therefore, in the present study, fungal isolates of Beauveria bassiana, viz. MTCC 2028, MTCC 4495, MTCC 6291, and NBAII-11, were evaluated for their virulence against third instar larvae of P. brassicae. Among all these fungal isolates, maximum mortality (86.66%) was recorded in B. bassiana MTCC 4495 at higher concentration of spores (109 conidia/ml), and the minimum mortality (30.00%) was recorded in B. bassiana MTCC 6291 at a lower concentration (107 conidia/ml) after ten days of treatment. The extracellular cuticle-degrading enzyme activities of fungal isolates were measured. Variability was observed both in the pattern of enzyme secretion and the level of enzyme activities among various fungal isolates. B. bassiana MTCC 4495 recorded the maximum mean chitinase (0.51 U/ml), protease (1.12 U/ml), and lipase activities (1.36 U/ml). The minimum mean chitinase and protease activities (0.37 and 0.91 U/ml, respectively) were recorded in B. bassiana MTCC 6291. The minimum mean lipase activity (1.04 U/ml) was recorded in B. bassiana NBAII-11. Our studies revealed B. bassiana MTCC 4495 as the most pathogenic isolate against P. brassicae, which also recorded maximum extracellular enzyme activities, suggesting the possible roles of extracellular enzymes in the pathogenicity of B. bassiana against P. brassicae.

Assessment of the virulence and proteolytic activity of three native entomopathogenic fungi against the larvae of Oryctes agamemnon (Burmeister) (Coleoptera: Scarabaeidae)

“…Proteolytic activity of the three EPF isolates was similar to that reported by Petlamul and Prasertsa (2012). Different assays were performed to detect protease production by EPFs in cultures (Ali et al 2011: Dhawan andJoshi 2017). The high level of protease activity was detected in the culture filtrate of M. anisopliae (Petrisor and Stoian 2017) and B. bassiana (Donatti et al 2008).…”

“…They found that the optimum incubation period for protease activity was 4-6 days. Recently, Dhawan and Joshi (2017) recorded the maximum protease activity of B. bassiana to be 6-8 days of incubation.…”

“…The three common EPFs, B. bassiana, M. anisopliae, and L. lecanii (formerly known as Verticillium lecanii), produce a variety of extracellular hydrolytic enzymes in liquid cultures. Recent evidence indicates that the different species or isolates of the EPFs exhibited variation in the production of cuticle-degrading proteases (Dhar and Kaur 2010;Zare et al 2014;Dhawan and Joshi 2017). Isolates with high proteolytic activity have high virulence against their host.…”

Can plants mediate the humoral immunity and biochemical metabolism of entomopathogen‐infected caterpillars?

“…Moreover, we found that the protein content was much higher on day 1 than in subsequent days in both B. bassiana-infected and non-infected caterpillars as the larvae has just molted into 3rd-instar (Table S2). Dhawan and Joshi (2017) was higher at the fifth day compared with the other days 3-4 after treatment.…”

“…Several studies have documented that the infection of this pathogen can induce humoral immune responses in caterpillars and result in an increase in lysozyme activity in the hemolymph (Boucias, Hung, Mazet, & Azbell, 1994;Wojda, Kowalski, & Jakubowicz, 2009). Meanwhile, others have reported that such infection has led to an irregular change of the protein (Wang, Lv, Xie, & He, 2010) and a variation in lipid content (Dhawan & Joshi, 2017) in caterpillars. However, how plants affect these indicators linked to disease resistance against the infection of B. bassiana, has not been explored.…”