Microencapsulation: A Strategy for Formulation of Inoculum

Abstract

A non-toxic phase separation method was developed for microencapsulation of inoculum used in biological control. Aqueous sodium alginate or gelatin and agar was mixed with inocula of various biopesticides and emulsified in a mixture of corn oil, n-hexadecane, and lecithin. Gelatin and agar globules gelled in the emulsion; alginate globules gelled after settling into a lower phase of aqueous CaCl 2 . A layer of gelatinous material thus surrounded the inoculum as 'capsules'. Mixing with n-hexadecane reduced the specific gravity and surface tension of the oil, allowing aqueous extraction of the capsules. Successful extraction of alginate capsules depended upon lecithin (/0.17%), n-hexadecane (/30%), and CaCl 2 ( /0.01 M) concentrations. Alginate-encapsulated macroconidia of Fusarium avenaceum caused 239/3% leaf area damage to seedlings of marsh reed grass, versus 49/3% for unformulated controls. In green foxtail seedlings, gelatin and agar-encapsulated conidia of Bipolaris sorokiniana caused 21.3 vs. 7.9 lesions per plant for encapsulated versus unformulated conidia. Mortality of Douglas-fir tussock moth larvae caused by a nuclear polyhedrosis virus was delayed when 23 polyhedral inclusion bodies (PIB) were incorporated into alginate capsules, but it proceeded normally for 2.3 PIB/ capsule, where efficacy was also higher versus positive controls. Microencapsulation enhances the activity of biological control agents and protects them from adverse conditions.

Storage and persistence of a candidate fungal biopesticide for use against adult malaria vectors

“…More advanced formulations of Lambda-cyhalothrin, such as capsulated suspensions, have been developed and shown to enhance performance in the field [52,53]. It is highly likely that with equivalent research effort, novel formulations of fungal pathogens (including microencapsulation [54-56]) could also be developed to further improve shelf life and persistence. Furthermore, in line with WHO protocols, assessments in the current study focused on mortality effects alone.…”

Pathogenicity of Microencapsulated Insecticide fromBeauveria bassianaandMetarhizium anisopliaeagainst Tobacco Budworm,Heliothis virescens(Fabricius)

“…bassiana and M. anisopliae are two of the most promising fungal species for biological control potentially effective against a wide range of pests (Legaspi et al 2000, Balanchander et al 2012, Zibaee and Sendi 2013, Contreras et al 2014). Effectiveness of fungi in the field can be affected by environmental factors, so microencapsulated formulations could protect active ingredients and increase spore viability (Winder et al 2003). Microencapsulated formulations consist of a bioactive substance (mycelia and spores) encapsulated into a matrix or wall system (Poshadri and Kuna 2010).…”

Effect of conditions and protectants on the survival ofPenicillium bilaiaeduring storage

“…A variety of techniques to produce solid formulations have been employed in published studies including: the Stabileze method using starch and oil (Quimby et al 1999), extrusion in alginate (Walker & Connick 1983), the Pesta method using extrusion of wheat flour (Connick et al 1991), grinding freeze-dried fermentation media to produce a powder (Costa et al 2000), microencapsulation in alginate (Winder et al 2003), and spray coating fermentation broth onto milk powder granules (Tadayyon et al 1997). The formulation technique selected for this study is based on the Pesta method described by Connick et al (1991).…”