Isolation, fermentation, and formulation of entomopathogenic fungi virulent against adults of Diaphorina citri

Abstract

BACKGROUND Mycopesticides are important for integrated management of the Asian citrus psyllid, Diaphorina citri. However, there are few reports on the fermentation and formulation for mycopesticides with high virulence against D. citri. RESULTS From four different locations in South China, 12 fungal strains were isolated and classified into Beauveria bassiana (two isolates), Fusarium fujikuroi (five isolates), and Cordyceps javanica (five isolates) based on the phylogenetic analysis of ITS1‐5.8S rDNA‐ITS4 and morphology of colonies and conidia. Based on the highest initial virulence (86.52 ± 2.35%) and best growth characteristics, F‐HY002‐ACPHali was further optimized for biphasic fermentation (7.85 ± 2.62 × 109 g–1 dry substrate) with soybean meal + cottonseed flour (1:1) as the solid substrate and full light as the light/dark cycle. Furthermore, the oil‐based conidial formulation was optimized with sesame oil as an effective carrier, which significantly enhanced conidial shelf life up to 16 weeks at 26 °C and 4 °C, thermo‐stress (50 °C) and UV‐B stress resistance, and virulence against adults of D. citri with increased mortalities and decreased LT50 in comparison to that of unformulated conidia. CONCLUSION Our results not only provide a valuable native strain with high virulence against adults of D. citri, but also imply the soybean meal + cottonseed flour as valuable solid substrate, full‐light exposure as environmental stimuli for solid‐state fermentation, and the sesame oil as an effective carrier for the formulation of the C. javanica. These findings will facilitate the development of a potential mycopesticide for the biological control of Asian citrus psyllid.

Conidial Emulsion Formulation and Thermal Storability of Metarhizium anisopliae against Red Palm Weevil, Rhynchophorusferrugineus Olivier (Coleoptera: Dryophthoridae)

“…Different Met-Gra4 dry conidia (% w/w) and oil/glycerol (% w/w) ratios were used for developing a stable emulsion system. The conidia contents were varied (5,10,15,20,25, and 30% w/w) at different oil/glycerol ratios, selected from the isotropic region of the pseudo-ternary phase diagrams. A high-pressure homogenizer was used carefully to mix conidia at a maximum of 20,000 rpm.…”

“…In comparison with the non-formulated conidia, oil emulsion formulation prolongs the shelf life and improves the pathogenicity of entomopathogenic fungi against the insect pests, such as the citrus psyllids [ 10 ] and mealybugs [ 11 ]. Various oil carriers, namely mineral and sunflower oil, have been used to prepare oil-based formulations [ 12 , 13 ].…”

Optimization of Submerged Culture Parameters of the Aphid Pathogenic Fungus Fusarium equiseti Based on Sporulation and Mycelial Biomass

“…The blastospore, which differs from conidia, can produce copious mucilage, adhere readily to the cuticle surface, and invade through the gut following ingestion [ 31 ]. Typically, spore adhesion determines how successfully an infection spreads [ 7 , 36 ]. Fusarium species usually produce two types of conidia, namely macroconidia and microconidia [ 10 , 37 ].…”

Insecticide application using an unmanned aerial vehicle for Diaphorina citri control in citrus orchards

“…Several methods to control D. citri have been studied, including the application of processed kaolin (Miranda et al, 2018; Miranda, Eduardo, et al, 2021), use of trap crop treated with systemic insecticide (Tomaseto et al, 2019), combination of these control methods in a ‘push‐pull and kill’ strategy (Eduardo et al, 2023), biological control through parasitoids (Chow & Sétamou, 2022; Diniz et al, 2020) and entomopathogenic fungi (Awan et al, 2021; Saldarriaga Ausique et al, 2017). However, the principal method used by citrus growers is chemical control, mainly because it reduces D. citri populations rapidly and efficiently.…”