In Vitro Evaluation of Antimicrobial Activity of Alimentary Canal Extracts from the Red Palm Weevil,Rhynchophorus ferrugineusOlivier Larvae

Abstract

The invasive red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae), is considered one of the world's most devastating insect pests to palm trees. It was observed that larvae of this pest are able to inhibit microbial growth on the rearing media when they start feeding and this observation has led us to study the effect of red palm weevils on various microbial species. The antimicrobial effect of extracts from different parts of the alimentary canal on Gram positive bacteria (Enterococcus faecalis and Staphylococcus aureus), Gram negative bacteria (Escherichia coli and Klebsiella spp.), Candida albicans, and Penicillium sp. was tested using the agar well diffusion method. All extracts inhibited the tested microbial species. Foregut extracts had the greatest zones of growth inhibition. Enterococcus faecalis, Staphylococcus aureus, and Penicillium sp. were significantly sensitive to the extracts and had the largest growth inhibition zones. It is concluded that the gut extracts contain potent antimicrobial activity and may provide a new source of antimicrobial peptides.

External Immune Inhibitory Efficiency of External Secretions and Their Metabolic Profiling in Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae)

“…It was reported that the antibacterial activity in larval salivary secretions of Polistes dominulus inhibited growth of the grampositive bacteria Bacillus subtilis and the gram-negative bacteria E. coli (Turillllazzi et al, 2004). Since then, these insects have often been deemed to be one of the main sources of antimicrobial peptides, having broad-spectrum activity against pathogens, including bacteria, fungi, viruses, nematodes, and some parasites (Pu et al, 2017a;Sewify et al, 2017). Not only has our work established that the external secretions (oral cavity or abdomen) of RPW larvae and adults have antimicrobial activity, we also found a large number of amino acids encoding proteins in the secretions.…”

“…The sensitivity of microorganisms can be attributed to the fact that gram-positive bacteria are surrounded by a cytoplasmic lipid membrane and lack the outer cell membrane which is present only in gram-negative bacteria (Gupta, 2000;Sewify et al, 2017). The absence of this outer membrane usually makes the bacteria vulnerable to the effect of antimicrobial peptides (Gupta, 2011).…”

Simultaneous Production of Multiple Antimicrobial Compounds by Bacillus velezensis ML122-2 Isolated From Assam Tea Leaf [Camellia sinensis var. assamica (J.W.Mast.) Kitam.]

“…Antibacterial activity was assayed using an agar well diffusion method according to the modified protocol of Sewify et al (2017). The indicator bacteria (listed in…”

Evaluation of the antimicrobial activity of purified Spodoptera littoralis hemolymph against some pathogenic bacteria

“…In this study the larvae of S. littoralis were more susceptible to gram positive bacterial than gram negative bacterial. This difference in pathogenicity came from the presence of an outer membrane in the cell wall of G -ve bacteria, made up of LPS and acted as an endotoxin, which was absent in gram positive bacterial (Sewify et. al.…”