Preparation and Characterization of Azadirachtin Alginate-Biosorbent Based Formulations: Water Release Kinetics and Photodegradation Study

Abstract

The botanical insecticide azadirachtin was incorporated in alginate-based granules to obtain controlled release formulations (CRFs). The basic formulation [sodium alginate (1.47%) - azadirachtin (0.28%) - water] was modified by the addition of biosorbents, obtaining homogeneous hybrid hydrogels with high azadirachtin entrapment efficiency. The effect on azadirachtin release rate caused by the incorporation of biosorbents such as lignin, humic acid, and olive pomace in alginate formulation was studied by immersion of the granules in water under static conditions. The addition of the biosorbents to the basic alginate formulation reduces the rate of release because the lignin-based formulation produces a slower release. Photodegradation experiments showed the potential of the prepared formulations in protecting azadirachtin against simulated sunlight, thus improving its stability. The results showed that formulation prepared with lignin provided extended protection. Therefore, this study provides a new procedure to encapsulate the botanical insecticide azadirachtin, improving its delivery and photostability.

Development of an attract‐and‐kill co‐formulation containing Saccharomyces cerevisiae and neem extract attractive towards wireworms

“…Moreover, there is evidence that entrapped starch granules reduce the mean pore size as well as the relative porosity of Ca‐alginate hydrogels . The results obtained here are in line with Flores‐Céspedes et al . who showed that the addition of biosorbents to alginate‐based granules led to homogenous hybrid hydrogels with high AZA EE.…”

“…Unlike Cherry and Nuessly, who showed a repellent effect of AZA‐treated soil to Melanotus communis (Gyllenhal) wireworms, no repellent effect of encapsulated NAT towards A. sputator was shown in this study. Certainly, there is the possibility that a repellent effect of the neem extract was masked either by a high CO 2 concentration or due to encapsulation, because the encapsulation in a Ca‐alginate matrix (supplemented with different additives) slows the release of the neem extract active ingredients . It may be worth complementing such studies with other observational arenas as used by Van Herk and Vernon.…”

“…Despite the absence of photolytic degradation, it is well‐known that azadirachtin is degraded within several days in the soil . Different studies indicate that formulation is a key issue in the stabilization of neem extracts' active ingredients in soil, and encapsulation seems to be a proper way to achieve this goal . However, it is a common problem of pest control measures in soil that soil‐borne insect pests with a cryptic life stage are hard to target, such that insecticides have to be applied in higher doses than used for above‐ground pests .…”

Nano-Delivery Systems of Pesticides Active Agents for Agriculture Applications - An Overview

“…In addition to transport vehicles, nanocarriers in many cases act as a protective container for active components against adverse external conditions (high temperature, radiation, high humidity, oxidation, among others), increasing their physical and chemical stability. The nanodelivery systems must follow an intelligent principle of controlled release of the chemical compound at the destination site in a manner appropriate to the specific needs (COOPER, 2010;FLORES-CÉSPEDES et al, 2015;MARUYAMA et al, 2016). The main functions of the nanocarriers, in this case, are (i) to retain/protect the active compounds without release or loss before they reach the target; (ii) to improve the dissolution of the compounds when they reach the target, for example, improving the penetration in the plant tissues of the weeds; and (iii) to change/control the active release functions in neighboring environments.…”

“…The main functions of the nanocarriers, in this case, are (i) to retain/protect the active compounds without release or loss before they reach the target; (ii) to improve the dissolution of the compounds when they reach the target, for example, improving the penetration in the plant tissues of the weeds; and (iii) to change/control the active release functions in neighboring environments. These functions depend directly on the size, shape, and material from which the nanocarrier is made (COOPER, 2010;FLORES-CÉSPEDES et al, 2015;MARUYAMA et al, 2016).…”