Alginate embedding and subsequent sporulation of in vitro-produced Conidiobolus thromboides hyphae using a pressurised air-extrusion method

• Published in: Biological control Vol. 69; pp. 52 - 58
• Main Authors: Chen, Chun, Ye, Sudan, Wang, Danqi, Hatting, Justin Louis, Yu, Xiaoping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.02.2014; Elsevier
• Subjects: Air-extrusion; Alginate formulation; Animal, plant and microbial ecology; Aphididae; Applied ecology; Biological and medical sciences; Biological control; Conidiobolus; Conidiobolus thromboides; Fundamental and applied biological sciences. Psychology; Mycoinsecticide; Orthogonal experimental design; Phytopathology. Animal pests. Plant and forest protection; Orthogonal experimental design; Conidiobolus thromboides; Alginate formulation; Biological control; Air-extrusion; Mycoinsecticide; Air; Alginates; In vitro; Pressurizing; Experimental design; Sporulation; Formulation; Hypha; Extrusion; Biopesticide; Microbial insecticide
• ISSN: 1049-9644; 1090-2112
• DOI: 10.1016/j.biocontrol.2013.10.016

[Display omitted] •A novel method for formulation of Conidiobolus thromboides hyphae was developed.•An orthogonal experimental design was used to investigate the multiple parameters.•The optimal parameter combination was obtained upon hyphal density within pellets.•Pellets produced significantly more conidia than cadavers of comparable size. Conidiobolus thromboides is an entomophthoralean fungus with potential as a biological control agent of aphids. However, its application in biological control is limited due to its formulation requirements. The objective of this study was to develop and optimise a novel air-extrusion method to embed C. thromboides hyphae at high density in alginate pellets. An orthogonal experimental design was used to investigate selected combinations of parameters known to affect hyphal density within pellets. The diameter of pellets produced, and the calculated density of hyphae within them, ranged from 0.18±0.09 to 3.17±0.06mm and from 0.02 to 350.56mg/mm3 respectively. These data were used to predict the optimal parameter combination to deliver the greatest density of hyphae of C. thromboides per pellet: 1% sodium alginate, a 1:2 ratio of hyphae to sodium alginate, an orifice diameter of 0.232mm and an air pressure of 0.05MPa. Pellets made under the optimal conditions predicted produced a mean total of 4.3±0.6×105 conidia per pellet at 100% relative humidity which was significantly greater than the mean total number of conidia produced from infected aphid cadavers of comparable size (9.35±0.85×104) (p<0.001). In conclusion, air-extrusion embedding appears to be a promising method for formulating in vitro-produced hyphae of C. thromboides for use in biological control.