Insecticidal activity of a Moroccan strain ofStreptomyces phaeochromogenesLD-37 on larvae, pupae and adults of the Mediterranean fruit fly,Ceratitis capitata(Diptera: Tephritidae)

Abstract

The Mediterranean fruit fly (medfly), Ceratitis capitata, is considered the most important fruit pest worldwide. Its management is mainly based on the use of chemical insecticides. Although these conventional pesticides are effective at high doses, they cause considerable human health and environment problems. Thus, the aim of this study was to assess insecticidal activity of Moroccan actinobacteria against C. capitata. A total of 12 preselected actinobacteria isolated from various Moroccan habitats were screened for their insecticidal activity against larvae, pupae and adults of C. capitata. Four actinobacteria isolates were significantly active against the first-instar larvae, and nine were active against the medfly adult, while no significant mortality was obtained against the third-instar larval and pupal stages. Among the selected isolates, the biological screening revealed that strain Streptomyces LD-37, which showed 99.4% similarity with Streptomyces phaeochromogenes, exhibited the maximal corrected larval mortality of 98%. Moreover, the isolates AS1 and LD-37 showed the maximum significant corrected mortality against adults of 32.5 and 28.2%, respectively. The crude extract obtained from a fermented culture of strain S. phaeochromogenes LD-37 was separated into six fractions by thin layer chromatography. Fractions F3 and F4 caused a significant corrected larval mortality of 66.7 and 53.3%, respectively; whereas the maximum reduction in adult emergence was obtained with fraction F4. This finding could be useful for utilizing S. phaeochromogenes LD-37 as an alternative to chemical insecticides in pest management of C. capitata.

Insecticidal characteristics and structural identification of the potential active compounds from Streptomyces sp. KR0006: Strain improvement through mutagenesis

“…Although the antifeedant, larvicidal, and growth inhibitory activity of the secondary metabolites isolated from Streptomyces spp. has been reported [ 4 , 7 , 54 , 55 ], the inhibition of oviposition has not been adequately studied yet. Taking into account high-level insecticidal, larvicidal, and spawn suppressing the activities of the strain KR0006, interest has arisen in conducting additional experiments of increasing the activity of this strain.…”

“…Several studies reported that the antimycin family of compounds has exhibited a broad spectrum of insecticidal and antifungal activities. [4,7,54,55], the inhibition of oviposition has not been adequately studied yet. Taking into account high-level insecticidal, larvicidal, and spawn suppressing the activities of the strain KR0006, interest has arisen in conducting additional experiments of increasing the activity of this strain.…”

Screening and Characterization of Streptomyces spp. Isolated from Three Moroccan Ecosystems Producing a Potential Inhibitor of the Drug Efflux Pump AcrAB-TolC

“…The 210 Actinobacteria isolates used in this study were from the collection of the Laboratory of Biology and Biotechnology of Microorganisms, Cadi Ayyad University, Marrakesh, Morocco. They were isolated from various Moroccan habitats including rhizospheric soils and endophytes of endemic aromatic and medicinal plants [ 13 , 14 ]. All strains were maintained in glycerol (20%) at −20 °C.…”

Ceratitis capitata Wiedemann (Diptera: Tephritidae) in Moroccan Citrus orchards: Chemical and Sustainable Control Methods and Priorities for Future Research

“…These methods could be utilized as control measures to meet the new international market requirements regarding fruit protection, quality, healthy environment, and human health. 28,29 Consequently, sustainable approaches to chemical control like biopesticides, 30,31 the sterile insect technique (SIT), 19 cold treatment 32 and mass trapping 33 are used. Other methods, such as the continued release of self-limiting medfly strains, are also being studied.…”