Influence of Mentha spicata on the developmental growth-rate and oviposition of Trogoderma granarium (Everts)

The larval mortality in control increased from 4.41% (L₁) to 13.43% (L₄). At 1% treatment of M. spicata leaf powder the larval mortality at L₃ stage (16.89%) was the highest. In case of 2% M. spicata leaf powder treatment the maximal mortality was recorded 27.23% in L₄ stage. The maximum mortality of papae was recorded 7.54% in 2% treatment. The dry weights of individuals treated with 1% treatment (L₃ = 0.17, L₆ = 0.74, pupae = 0.73 and adult = 0.62 mg) as well as those recorded on 2% (L₃= 0.15, 1.4 = 0.28, L₅= 0.45, L₆= 0.51, pupae = 0.49 and adult = 0.38 mg) were significantly lower (P < 0.05 and < 0.01) than those of control (L₃= 0.23, L₄= 0.44, L₅= 0.80, L₆ = 1.10, pupae = 0.94 and adult = 0.91 mg). The absolute growth rates at L₅ stage (control = 0.089, 1% treatments 0.074 and 2% treatments = 0.043 mg/day) were maximal but afterward it declined negatively in pupae. (Control= 0.03, 1% treatment = −0.002 and 2% treatment = −0.004 mg/day) and adults (Control = −0.008, 1% treatment = −0.027 and 2% treatment = −0.026 mg/day). Observations indicated that dietary incorporation of M. spicata leaf powder exhibited 77.49% egg laying at 1% treatment and 58.82% at 2% treatment in comparison to those of control (100%) in total of 12 days.