Realized Heritability, Risk Assessment, and Inheritance Pattern in <i>Earias vittella</i> (Lepidoptera: Noctuidae) Resistant to Dipel (<i>Bacillus thuringiensis</i> Kurstaki).

<i>Earias vittella</i> Fabricius is a potential cotton and okra pest in South Asia. The realized heritability, risk assessment, and inheritance mode of <i>Bacillus thuringiensis</i> Kurstaki (Btk) resistance were determined in the Dipel-selected (DIPEL-SEL) <i>E. vittella</i>. The DIPEL-SEL strain had a 127.56-fold rise in Dipel resistance after nine generations compared to the laboratory reference strain (LAB-PK). The overlapping of 95% fiducial limits in the median lethal concentrations (LC₅₀s) of the F₁ (DIPEL-SEL♂ × LAB-PK♀) and F₁^ǂ (DIPEL-SEL♀ × LAB-PK♂) suggested a lack of sex linkage and an autosomal Dipel resistance. The dominance (D_LC) values for the F₁ (0.86) and F₁^ǂ (0.94) indicated incompletely dominant resistance to Dipel. Backcrossing of the F₁♀ × Lab-PK♂ revealed a polygenic response of resistance to Dipel. The realized heritability estimation (<i>h</i>²) of resistance to Dipel was 0.19. With 20% to 90% selection mortality, the generations required for a tenfold increase in LC₅₀ of Dipel were 4.7-22.8, 3.1-14.9, and 2.3-11.1 at <i>h</i>² of 0.19, 0.29, and 0.39, respectively, and a constant slope of 1.56. At slope values of 2.56 and 3.56 with a constant <i>h</i>² = 0.19, 7.7-37.4 and 10.6-52.0 generations were needed to increase the tenfold LC₅₀ of Dipel in the DIPEL-SEL <i>E. vittella</i>. It is concluded that the DIPEL-SEL <i>E. vittella</i> has an autosomal, incompletely dominant, and polygenic nature of resistance. The <i>h</i>² of 0.19 suggested that a high proportion of phenotypic variation for the Dipel resistance in <i>E. vittella</i> was heritable genetic variation. The present results will support the creation of an effective and suitable resistance management plan for better control of <i>E. vittella</i>.