Crystal (Cry) toxins produced from the soil bacterium, Bacillus thuringiensis (Bt), have gained worldwide attention for long due to their insecticidal potential. A number of receptor proteins located on the epithelial cells of the larval midgut were shown to be crucial for Cry intoxication in different insect pests belonging to order Lepidoptera, Diptera and Coleoptera. A beehive pest, Galleria mellonella, serves as an excellent insect model for biochemical research. However, information on the Cry receptor‐like genes in G. mellonella is limited. In the present study, the full‐length sequences of four putative Cry receptor genes (ABC transporter, alkaline phosphatase, aminopeptidase N and cadherin) were cloned from G. mellonella. All these receptor genes were substantially upregulated in the midgut tissue of fourth‐instar G. mellonella larvae upon early exposure (6 h) to a sub‐lethal dose of Cry1AcF toxin. Oral and independent delivery of bacterially‐expressed dsRNAs corresponding to four receptor genes in G. mellonella suppressed the transcription of target receptors which in turn significantly reduced the larval sensitivity to Cry1AcF toxin. As the laboratory populations of G. mellonella develop Bt resistance in a relatively short time, molecular characterization of Cry receptor genes in G. mellonella performed in the present study may provide some useful information for future research related to the genetic basis of Bt resistance in the model insect.
The extensive application of conventional chemical pesticides may result into several public health concerns as well as enviornmental hazards. To ensure food safety, use of alternative ecofriendly pesticide formulations is need of the hour. Nanocomposites, a special class of nanomaterials, having improved stability and barrier properties may be a viable option to develop environmentally benign slow/ controlled release pesticide formulations. Presently, the use of nanocomposites in preparation of insecticidal formulations is in early stage of research and development. Application of different nanocomposite materials as vector for chemical insecticides have been summarized in this review with major emphasis on application arenas in crop protection, along with addressing limitations and prospects of this domain.
Nematodes are the most abundant metazoans on the planet can be found in almost all the ecosystems on earth. They may be free-living, marine, bacterivorous, or parasites of plants and animals, including human beings. Nematodes always interact with other organisms, including- viruses, fungi, protozoa, rickettsia, tardigrades and bacteria in their microbiome. Nematodes are particularly well suited for investigating host associations with bacteria because they have a long history of evolution. Nematode-bacteria interaction is now being used as a model for investigating animal-microbe interaction and can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). In any disease complex, nematodes play important roles in association with bacteria to aggravate disease intensity. Bacteria is a potential food source for nematodes and pathogenic to nematodes. Bacterial antagonists are now getting importance as potential biocontrol agents in modern agriculture due to gradual phasing out of chemical nematicides. In addition to trophic and pathogenic interactions, bacteria can serve as mutualists by aiding nematodes in development, defense, reproduction and nutrient acquisition. Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved, their study can provide broader insights into other types of associations, including those relevant to plant and human diseases.
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