RESUMO
Endosymbionts are known to have significant effects on their insect hosts, including nutrition, reproduction, and immunity. Insects gut microbiota is a critical component that affects their physiological and behavioral characteristics. The black cutworm (BCW), Agrotis ipsilon, is an economically important lepidopteran pest that has a diverse gut microbiome composed of nine species belonging to three phyla: Proteobacteria, Actinobacteria, and Firmicutes. This study was conducted to investigate the diversity of gut bacteria isolated from BCW larvae and moths and their effects on metabolism and pesticide degradation. The bacterial isolates were identified using the 16 S rRNA gene. The study showed that the gut microbiome composition significantly affected the metabolism of BCW larvae. Based on the screening results of synthesis of digestive enzymes and pesticide degradation, Brachybacterium conglomeratum and Glutamicibacter sp were selected to perform the remaining experiments as single isolates and consortium. The consortium-fed larvae showed high metabolic indices compared to antibiotic-fed larvae and the control. The gut bacteria were also shown to degrade three pesticide groups. Concerns regarding the health risk of chlorpyrifos have been raised due to its extensive use in agriculture. The isolated B. conglomeratum was more effective in chlorpyrifos degradation than the consortium. Furthermore, the study also examined the presence of sex related endosymbionts (Wolbachia, Spiroplasma, and Rickettsia) in the reproductive tissues of adults. The outcomes demonstrated that none of the examined endosymbionts existed. In conclusion, the study highlights the importance of the gut microbiome in insect physiology and behavior and its potential applications in biotechnology. It provides insights into developing eco-friendly pest control and bioremediation strategies using gut bacteria.
RESUMO
PURPOSE: The study of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier), as an invasive pest of palm trees. METHODS: In this study, 36 RPW individuals were collected from 6 different locations in Egypt. The presences of endosymbionts in the RPW individuals were assayed. The phylogenetic analysis of the RPW inhabiting Egypt was conducted using Cytochrome c oxidase sub-unit 1 (CO1) gene. RESULTS: Spiroplasma was found, for the first time, in all individuals, while Rickettsia was found, for the first time, in individuals collected from only 3 of the 6 locations. Endosymbionts harbouring Egyptian RPW were closely related to those harbouring Diptera and\or Trombidiformes associated with palm trees. This may be due to horizontal transmission through palm sap or through ectoparasites living on the RPW. Finally, the phylogenetic analysis of the RPW inhabiting Egypt was conducted. The collected individuals were closely related to Saudi Arabia specimens collected from the eastern region. Thus, Saudi Arabia may be the origin of the RPW which invaded Egypt. Individuals from populations inhabiting the same geographical locations were closely related. This may be due to secondary invasion incidents that may have taken place through transportation of infested date palm trees and offshoots from infected to uninfected locations. CONCLUSION: This study reports the first incidence for the presence and coexistence of Spiroplasma and Rickettsia in RPW collected from Egypt. In addition, it was found that the collected individuals of RPW were closely related to a Saudi haplotype. Thus, Saudi Arabia may be the origin of infection which invaded Egypt.