Diversity of entomopathogenic fungi associated with Mediterranean fruit fly (Ceratitis capitata (Diptera: Tephritidae)) in Moroccan Argan forests and nearby area: impact of soil factors on their distribution

Abstract

Background Studying the ecology of biocontrol-agents is a prerequisite to effectively control medfly (Ceratitis capitata (Diptera: Tephritidae)) with entomopathogenic fungi. In this context, factors affecting the occurrence and distribution of medfly-associated entomopathogenic-fungi were studied. Soil samples (22) were collected from natural and cultivated areas of Souss-region Morocco. Results A total of 260 fungal isolates belonging to 22 species and 10 genera were obtained by using medfly pupae as bait. Medfly-associated fungi were detected in all studied soils and pupae infection percentages ranged from 3.33% to 48%. Two genera, Fusarium and Beauveria were the most frequent with 83 isolates (32%) and 50 isolates (19.23%) respectively. Pathogenicity test of isolated species against medfly pupae showed high mortality rates up to 91% for some strains. Principal component analysis (PCA) demonstrated a strong influence of origin, physical, and chemical properties of soil on the abundance of these fungi. In general, medfly-associated fungi were more abundant in soils with moderate pH (7.5 to 8) having high sand and organic content. High relative humidity negatively influenced the abundance of these fungi. Both factors directly affected the fungal infection percentages in pupae. The response of fungi to these parameters varied among species. According to principal component analysis (PCA), the soils of argan fields and forests were more suitable for the development of medfly-associated fungi than citrus orchards. Conclusions These results guide identifying suitable soils for the effective application of entomopathogenic fungi as biological control agents. In summary, isolated indigenous strains seem to be a promising option to control C. capitata.

Effect of Soil Chemical Properties on the Occurrence and Distribution of Entomopathogenic Fungi in Portuguese Grapevine Fields

“…In this study, soil physicochemical properties were analyzed for common soil EPF. Beauveria bassiana showed significant affinity to soils with less acidity or higher pH, a situation consistent with another study that also reported the association of B. bassiana with soils with higher pH [17,25]. In the present study, pH, TA, DBS, and CEC e did not show a significant effect on other EPF.…”

“…As the majority of soils had a medium texture (a balanced mix of sand, silt, and clay) rather than a gross texture (a high proportion of sand), we could not find a conclusive correlation for this parameter, although, it was noticed that M. robertsii was only isolated from medium-textured soils ( Table S1 ). Garrido-Jurado et al noticed that the availability of Metarhizium conidia was lower in sandy soils [ 20 ], and adequate sand content eventually promotes the conidia mobility and may promote percent infection [ 20 , 25 ]. Medium textured soils, with a balanced sand and clay content, can benefit EPF, as their adsorption onto clay particles can lead to a better nutrient availability for the fungus, due to enhanced iron solubility [ 20 ].…”

“…In this direction, only a few recent studies analyzed basic soil chemical constituents, such as total C and N, and correlated them with the occurrence of EPF other than M. anisopliae [ 23 , 24 , 25 , 26 ]. Few data are available on the natural presence of different EPF with respect to soil cation exchange capacity (a property which assists fungal conidia adsorption onto soils).…”

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

“…Currently, bacteria such as Bacillus thuringiensis and Fusarium as a biopesticide are essentially among the best alternatives to chemicals for controlling insect agricultural pests. 54 Recent investigations proposed that the soil from the Argan forests (from the Souss region) may be a promoting reservoir for future and more comprehensive screening programs to identify microorganisms that can effectively control pests. 54 It was previously published that most autochthonous strains of Beauveria bassiana isolated from Argania Spinosa endemic species to Morocco were highly infectious to medfly.…”

“…54 Recent investigations proposed that the soil from the Argan forests (from the Souss region) may be a promoting reservoir for future and more comprehensive screening programs to identify microorganisms that can effectively control pests. 54 It was previously published that most autochthonous strains of Beauveria bassiana isolated from Argania Spinosa endemic species to Morocco were highly infectious to medfly. 25 Therefore, these indigenous isolates might be a source of potential biological control for medfly.…”