Pathogenicity of Rhizobateria Pseudomonas against Ceratitis Capitata Wiedemann (Diptera: Tephritidae)

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera, Tephritidae), is one of the most destructive insect pests of citrus in the world. For decades, the control of C. capitata has primarily focused on the use of protein baits mixed with chemical insecticides in citrus orchards. However, more recently, increased health risks associated with pesticide residues on foods and emergence of insecticide resistance, has forced researchers and stakeholders to develop new strategies for control of this important economic pest. These have included new, more sustainable control alternatives to manage this insect pest, such as bioinsecticides. Therefore, four rhizobacteria Pseudomonas isolates, isolated from rhizospheric soil of tomato plants in Morocco, were evaluated for insecticidal effects on pupae and adults of C. capitata. Results indicated that among the four isolates tested, two isolates Q036B and Q172B, were most effective at providing the highest mortality to both C. capitata pupae and adults. The highest mortality rate of 71% was observed in C. capitata adults treated with Q172B after 72 h. In comparison, Q036B provided a high C. capitata pupae mortality rate, which was observed as a low adult emergence rate of 38% after 12 days. Additionally, all three isolates that provided high C. capitata mortality produced HCN, and exhibited protease and cellulose activities, although only Q036B and Q172B exhibited chitinase production. For Plant Growth-Promoting Rhizobacteria (PGPR) properties, all three isolates produced siderophores and solubilized phosphate. Besides stimulating plant growth, Rhizobacteria Pseudomonas have potential as effective bioinsecticides, which was further demonstrated in this study. Entomopathogenic bacteria-laced protein baits based on these microorganisms could aid in C. capitata control. Soil microorganisms, such as these Pseudomonas rhizobacteria isolates, can contribute to insect control, while reducing insecticide use and improving the sustainability of agricultural production systems.

Automated summary

This study evaluated the insecticidal effects of four rhizobacteria isolates on the pupae and adults of the Mediterranean fruit fly. The results showed that two isolates, Q036B and Q172B, were the most effective in causing mortality in both pupae and adults. These findings demonstrate the potential of these rhizobacteria as bioinsecticides for controlling the Mediterranean fruit fly and improving the sustainability of agricultural production systems.