10.11 Enhancing the Efficiency and the Durability of Bt
Products
Ultra Violet (UV) radiation affects the survival and activity of Bt spores and
δ-endotoxins (Frye et al. 1973; Liu et al. 1993; McGuire et al. 2000) which leads
to instability of Bt-based products in the environment and inconsistency of the pest
control. Therefore, protectants need to be added to the formulations. The efficiency
of different materials in the protection of Bt spores and crystals from UV radiation
have been evaluated (Zareie et al. 2003; Moxtarnejad et al. 2014; Maghsoudi and
Jalali 2017; Jalali et al. 2020). In 2003, the efficiency of 16 formulations of Bt after
mixing with molasses and henna as the protectants from sunlight, particularly
ultraviolet radiation, were determined (Zareie et al. 2003). In the group I, Bt
formulations were not exposed to UV light, while group II and III were exposed to
UV for 1 and 2 days. The insecticidal activity of all these Bt formulations were
assessed against5th instar larvae of Galleria mellonella (Lep.: Pyralidae). The
highest mortality was observed in the formulations of group I. In group II, the
highest insecticidal activity was recorded in the molasses and henna encapsulated
formulations, as in group III. The efficiency of the Bt formulations decreased with
increasing exposure to UV. Interestingly, the addition of sugar increased the stability
of the tested Bt formulation (Zareie et al. 2003). The role of UV-protection of
different compounds such as henna, Congo red, rhodamine B, active carbon, molasses, conventional coal, sodium alginate, gelatin, starch, methyl green and gelatin
were evaluated by Moxtarnejad et al. (2014) under laboratory and field conditions.
The insecticidal activity of B. thuringiensis subsp. kurstaki strain ABTS-315 was
assessed alone and in combination with protectants against P. brassicae. Henna and
starch powder protected the Bt strain from UV radiation and can be suggested for
commercial use in mass production. In another study (Maghsoudi and Jalali 2017),
the protective effect of graphene oxide (GO) and olive oil from UV radiation was
examined. The spore viability and the toxicity were considered as the indicators for
evaluating the efficiency of the selected protectants. The mixture of GO and olive oil
was found to effectively protect Bt spores and retain the insecticidal activity of Bt
against E. kuehniella (Maghsoudi and Jalali 2017). In the next research, Jalali et al.
(2020) studied the effect different polymorphs of titanium dioxide (TiO 2 )
nanoparticles on the viability of Bt after exposure to UV radiation. Afterward the
biological activity of UV-exposed Bt was evaluated against E. kuehniella second
instar larvae. Based on their results, some polymorphs of titanium dioxide could
enhance the stability of Bt against UV radiation (Jalali et al. 2020). Salehi Jouzani
et al. (2011) prepared an optimized wettable powder formulation for two Bt isolates
(YD5 and KH4) in order to enhance their efficiency against lepidopteran and
coleopteran pests, and increase the durability of the bio-products. Mass production
of these strains was done in the batch fermenter based on the optimized conditions.
To improve the formulation for two Bt strains, different adjuvants including fillers,
surfactants, materials enhancing durability, UV protectants, suspensors, moisteners,
palatability materials and antimicrobials were mixed with 25 grams of spores and
420
A. Khorramnejad et al.
Products
Ultra Violet (UV) radiation affects the survival and activity of Bt spores and
δ-endotoxins (Frye et al. 1973; Liu et al. 1993; McGuire et al. 2000) which leads
to instability of Bt-based products in the environment and inconsistency of the pest
control. Therefore, protectants need to be added to the formulations. The efficiency
of different materials in the protection of Bt spores and crystals from UV radiation
have been evaluated (Zareie et al. 2003; Moxtarnejad et al. 2014; Maghsoudi and
Jalali 2017; Jalali et al. 2020). In 2003, the efficiency of 16 formulations of Bt after
mixing with molasses and henna as the protectants from sunlight, particularly
ultraviolet radiation, were determined (Zareie et al. 2003). In the group I, Bt
formulations were not exposed to UV light, while group II and III were exposed to
UV for 1 and 2 days. The insecticidal activity of all these Bt formulations were
assessed against5th instar larvae of Galleria mellonella (Lep.: Pyralidae). The
highest mortality was observed in the formulations of group I. In group II, the
highest insecticidal activity was recorded in the molasses and henna encapsulated
formulations, as in group III. The efficiency of the Bt formulations decreased with
increasing exposure to UV. Interestingly, the addition of sugar increased the stability
of the tested Bt formulation (Zareie et al. 2003). The role of UV-protection of
different compounds such as henna, Congo red, rhodamine B, active carbon, molasses, conventional coal, sodium alginate, gelatin, starch, methyl green and gelatin
were evaluated by Moxtarnejad et al. (2014) under laboratory and field conditions.
The insecticidal activity of B. thuringiensis subsp. kurstaki strain ABTS-315 was
assessed alone and in combination with protectants against P. brassicae. Henna and
starch powder protected the Bt strain from UV radiation and can be suggested for
commercial use in mass production. In another study (Maghsoudi and Jalali 2017),
the protective effect of graphene oxide (GO) and olive oil from UV radiation was
examined. The spore viability and the toxicity were considered as the indicators for
evaluating the efficiency of the selected protectants. The mixture of GO and olive oil
was found to effectively protect Bt spores and retain the insecticidal activity of Bt
against E. kuehniella (Maghsoudi and Jalali 2017). In the next research, Jalali et al.
(2020) studied the effect different polymorphs of titanium dioxide (TiO 2 )
nanoparticles on the viability of Bt after exposure to UV radiation. Afterward the
biological activity of UV-exposed Bt was evaluated against E. kuehniella second
instar larvae. Based on their results, some polymorphs of titanium dioxide could
enhance the stability of Bt against UV radiation (Jalali et al. 2020). Salehi Jouzani
et al. (2011) prepared an optimized wettable powder formulation for two Bt isolates
(YD5 and KH4) in order to enhance their efficiency against lepidopteran and
coleopteran pests, and increase the durability of the bio-products. Mass production
of these strains was done in the batch fermenter based on the optimized conditions.
To improve the formulation for two Bt strains, different adjuvants including fillers,
surfactants, materials enhancing durability, UV protectants, suspensors, moisteners,
palatability materials and antimicrobials were mixed with 25 grams of spores and
420
A. Khorramnejad et al.