Pigments play a major role in many industries. Natural colors are usually much safer when compared to synthetic colors and may even possess some medicinal benefits. Synthetic colors are economical and can easily be produced compared to natural colors. In addition, raw plant materials for natural colors are limited and season dependent. Microorganisms provide an alternative source for natural colors and, among them, fungi provide a wide range of natural colorants that could easily be produced cheaply and with high yield. Along with pigment, some microbial strains are also capable of producing a number of mycotoxins. The commercial use of microbial pigments relies on the safety of colorants. This review provides a toxicity evaluation of pigments from fungal origins for food application.
The tomato pinworm, Tuta absoluta (Meyrick) (Gelechiidae: Lepidoptera), is an introduced serious pest of tomato in India. Management of this insect pest mainly relies on insecticides because of its high infestation levels on all plant parts and life stages of tomato crop. This laboratory study investigated the efficacy of Cry1Ac protein of Bacillus thuringiensis against T. absoluta. The LC 50 and LC 95 values for 2nd, 3rd, and 4th larval instars were 0.12, 0.27, and 0.43 μg/ml and 0.63, 0.71, and 2.64 μg/ml, respectively. Experimental results showed that Cry1Ac is effective against different larval instars of tomato pinworm.
Background
The tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the key pests of tomato worldwide, causing an estimated crop loss of 80 to 100%. This pest has developed resistance to several pesticides due to overuse, resulting in control failures in the field. The use of biological insecticides as Bacillus thuringiensis that expressed insecticidal proteins can be an alternative tool by insecticides to suppress the pest population.
Main body
Laboratory study investigated the efficacy of standard Bacillus thuringiensis (Bt) strains (4D1, 4D4, 4G1, 4K5 and 4XX4) against T. absoluta. Bioassay was conducted using tomato leaf discs treated with spore crystal lysates prepared from the standard strains, and mortality data was subjected to concentration-mortality probit analysis. The LC50 values for Bt 4D1, Bt 4D4 and Bt 4G1 were 6.10, 6.62 and 8.18 μg/ml for the 2nd instar; 9.90, 10.20 and 11.12 μg/ml for the 3rd instar; and 19.82, 23.16 and 24.54 μg/ml for the 4th instar, respectively, while the Bt 4K5 and Bt 4XX4 were not toxic to T. absoluta.
Conclusion
This study suggests that Bt strain 4D1 is effective against different larval instars of the pest and can be used in its management.
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