Entomopathogenicity of endophytic Serratia marcescens strain SRM against larvae of Helicoverpa armigera (Noctuidae: Lepidoptera)

Abstract

An endophytic Serratia marcescens strain SRM (MTCC 8708) isolated from the flowers of summer squash was found to be entomopathogenic against the larvae of Helicoverpa armigera. Natural epizootic of this bacterial strain on the larvae collected from summer squash flowers ranged from 19.9 to 72.3%. Under laboratory conditions, a dose of 6 9 10 10 c.f.u./ml diet induced 66.3% mortality of first instar H. armigera larvae. Similarly all other growth and development parameters of the insect were severely retarded in a dose-dependent manner. The bacterium invaded the entire alimentary canal and haemolymph with successful replacement of all other gut-associated microflora. There was a great reduction in midgut proteinase activity due to inhibition of five major proteinase isozymes by S. marcescens infection. Further, a synergistic interaction between chitinases isolated from this strain and Bacillus thuringiensis Cry1Ac toxin was observed. The present findings suggest that this plant-associated S. marcescens strain SRM could be suitably exploited for the management of H. armigera.

Identifikasi Entomopatogen Bakteri Merah pada Wereng Batang Coklat (Nilaparvata lugens Stål.)

“…Pada umumnya, strain S. Marcescens yang diisolasi dari serangga dan lingkungan lainnya menghasilkan pigmen merah, sedangkan yang diisolasi dari manusia tidak berpigmen dan menjadi penyebab infeksi nosocomial (Mohan et al, 2011). Pigmen merah yang dihasilkan oleh S. marcescens adalah metabolit sekunder yang dikenal sebagai prodigiosin.…”

iTRAQ-Based Comparative Proteomic Analysis of Larval Midgut From the Beet Armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) Challenged With the Entomopathogenic Bacteria Serratia marcescens

“…S. marcescens is a gramnegative entomopathogenic bacterium, belongs to the family Enterobacteriaceae and is commonly found in different insects (Pineda-Castellanos et al, 2015;Bidari et al, 2018). It has been successfully applied to control S. litura (Aggarwal et al, 2015), Helicoverpa armigera (Mohan et al, 2011), Phyllophaga Blanchardi (Pineda-Castellanos et al, 2015), Heliothis virescens (Sikorowski et al, 2001), and other pests. The primary metabolite chitinases play a vital role in the insecticidal activities of S. marcescens by hydrolyzing the body wall and peritrophic membrane structure of the insects.…”

Common Virulence Factors and Tissue Targets of Entomopathogenic Bacteria for Biological Control of Lepidopteran Pests

“…In this respect, it has been hypothesized that the origin of toxin virulence factors in Bt more likely did not originate through its relationship with insects but through plasmid acquisition [ 37 , 88 , 89 ]. Interestingly, Bt toxins are reported to be synergistic with other insect pathogens, like Serratia , which exists as both a pathogen and symbiont of insects [ 90 ]. The ubiquity of Bt where potential insect hosts exist or where insect-associated organisms occur, could have resulted in the acquisition of insecticidal genes.…”

“…showed that S. marcescens produces insecticidal oral toxins [ 122 ]. Interestingly, there is a synergistic insecticidal effect between S. marcescens chitinases [ 123 ] and Bt Cry1Ac toxin [ 90 ]. There are also synergistic effects between Bt Cry1C and the supernatant of S. marcescens to tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuidae), but not cabbage moth, Mamestra brassicae (Lepidoptera: Noctuidae), P. xylostella , or the smaller tea tortrix, Adoxophyes honmai (Lepidoptera: Tortricidae) [ 124 ].…”