Alimentary Tract Bacteria Isolated and Identified with API-20E and Molecular Cloning Techniques from Australian Tropical Fruit Flies, Bactrocera cacuminata and B. tryoni

Bacteria were isolated from the crop and midgut of field collected Bactrocera cacuminata (Hering) and Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Two methods were used, firstly isolation onto two types of bacteriological culture media (PYEA and TSA) and identification using the API-20E diagnostic kit, and secondly, analysis of samples using the 16S rRNA gene molecular diagnostic method. Using the API-20E method, 10 genera and 17 species of bacteria in the family Enterobacteriaceae were identified from cultures growing on the nutrient agar. The dominant species in both the crop and midgut were Citrobacter freundii, Enterobacter cloacae and Klebsiella oxytoca. Providencia rettgeri, Klebsiella pneumoniae ssp ozaenae and Serratia marcescens were isolated from B. tryoni only. Using the molecular cloning technique that is based on 16S rRNA gene sequences, five bacteria classes were dignosed — Alpha-, Beta-, Gamma- and Delta- Proteobacteria and Firmicutes — including five families, Leuconostocaceae, Enterococcaceae, Acetobacteriaceae, Comamonadaceae and Enterobacteriaceae. The bacteria affiliated with Firmicutes were found mainly in the crop while the Gammaproteobacteria, especially the family Enterobacteriaceae, was dominant in the midgut. This paper presents results from the first known application of molecular cloning techniques to study bacteria within tephritid species and the first record of Firmicutes bacteria in these flies

Plant-insect interaction in underutilized horticultural crops for sustainable production

Plants and insects have been living together for more than 350 million years. In co-evolution, both have evolved strategies to avoid each other’s defense systems. This evolutionary arms race between plants and insects has resulted in the development of an elegant defense system in plants that can recognise the non-self-molecules or signals from damaged cells, much like animals. It activates the plant’s immune response against the herbivores. Differences in genotypes of plant characters may affect insect-plant herbivore interactions, and variations in genotype traits are responsible for modifying the bottom-up effects. Recent evidence shows that the simultaneous occurrence of abiotic and biotic stress can positively affect plant performance by reducing the susceptibility to biotic stress, a positive sign for pest management. Plant responses to these stresses are multifaceted and involve copious antibiosis, physiological, antixenotic, molecular, molecular and cellular adaptations. Plants with antibiosis characteristics such as flavonoids, phenols, tannins, alkaloids, etc., may cause reduced insect survival, prolonged development time, decreased size and reduced new generation fitness. Quality and quantity of constitutive secondary metabolites production is species as well as cultivar specific and can be expressed as the signature of a particular plant or species and leads to the phenomenon of host-plant resistance. Hence, such plant resistance mechanisms have been effectively and widely used for managing insect pests in fields of underutilized crops. Natural defences are mediated through plant characteristics that affect insect biology, such as mechanical protection on the surface of the plants (e.g., hairs, trichomes, thorns, spines and thicker leaves) that either kill or retard the development of the herbivores. These phenomena of host plant resistance to insects can be exploited for the development of resistance crop cultivars which readily produce the inducible response upon mild infestation and can perform as one of the integrated pest management for sustainable crop production

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Not AvailableMite management is a major problem in pomegranate (Punica granatum L.) cultivation in the arid and semi-arid regions of India and other Asian countries. The aim of this work was to investigate the susceptibility to the false spider mite (Tenuipalpus punicae) in a germplasm collection of Indian pomegranates. A field screening of 73 accessions allowed to define different classes of susceptibility (from very low to very high) based on the percentage of infested leaves. Twenty-two accessions, representative of the empirically identified five susceptibility classes, were further tested. The field screening against the mite, extended to another two years, showed that the infestation level did not display a significant interaction with the growing season, and highly correlated between the different growing seasons. The analysis of the tree vegetative growth (height, canopy size, and stem diameter), main phytochemical classes (total phenolics, flavonoids, and tannins) and the antioxidant activity of the leaves indicated strong significant negative correlations between the infestation level and the biochemical traits. Multidimensional reduction of the measured traits revealed that the extreme classes of susceptibility to mites are mainly separated according to the accumulation of phytochemicals in leaves. This work, for the first time, allowed the identification of pomegranate germplasm with low susceptibility to T. punicae, with positive and useful implications for the establishment of new orchards, plant breeding, and the identification of allelochemicals of the leaves directly affecting mites.Not Availabl

A Field Screening of a Pomegranate (Punica granatum) Ex-Situ Germplasm Collection for Resistance against the False Spider Mite (Tenuipalpus punicae)

Mite management is a major problem in pomegranate (Punica granatum L.) cultivation in the arid and semi-arid regions of India and other Asian countries. The aim of this work was to investigate the susceptibility to the false spider mite (Tenuipalpus punicae) in a germplasm collection of Indian pomegranates. A field screening of 73 accessions allowed to define different classes of susceptibility (from very low to very high) based on the percentage of infested leaves. Twenty-two accessions, representative of the empirically identified five susceptibility classes, were further tested. The field screening against the mite, extended to another two years, showed that the infestation level did not display a significant interaction with the growing season, and highly correlated between the different growing seasons. The analysis of the tree vegetative growth (height, canopy size, and stem diameter), main phytochemical classes (total phenolics, flavonoids, and tannins) and the antioxidant activity of the leaves indicated strong significant negative correlations between the infestation level and the biochemical traits. Multidimensional reduction of the measured traits revealed that the extreme classes of susceptibility to mites are mainly separated according to the accumulation of phytochemicals in leaves. This work, for the first time, allowed the identification of pomegranate germplasm with low susceptibility to T. punicae, with positive and useful implications for the establishment of new orchards, plant breeding, and the identification of allelochemicals of the leaves directly affecting mites