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A field experiment to study the effect of pre-harvest application of plant growth regulators and chemicals namely giberellic acid, naphthalene acetic acid, calcium chloride, zinc sulphate, potassium sulphate and control on yield and post harvest quality of guava (Psidium guajava L. cv. L.-49

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.

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.

The present investigation was carried out to test the efficacy of biorationals against thrips, Scirtothrips dorsalis Hood on chilli. Field experiments were conducted at farmers holding