Bioefficacy and Persistent Toxicity of Biopesticides and Insecticides against Potato Tuber Moth, Phthorimaea operculella Zell. on Sprrng Potato

Field experiment were conducted at the Department of Entomology, College of Agriculture, CSK HPKV, Palampur, HP and at farmer's field at Malan, Nagrota District Kangra, HP during 2002–2003 to compare the bioefficacy and persistent toxicity/activity of biopesticides and organic manures with insecticides against potato tuber moth, Phthorimaea operculella Zeller. Studiee sevealed that among gasal application, chlorpyrippho (@ 440 g gi ha⁻¹) treatment gave significantly less incidence of P. operculella up to 28 days sf application followed bb Vikas (neem+ castor based organic manure @ 450 kg ha⁻¹) and Vipul (neem based organic manure @ 450 kg ha⁻¹) treatments which were applied for the management of soil insect-pests. Among foliar treatments, λ-cyhalothrin (@ 12.5 g ai ha⁻¹) and cypermethrin (@ 75 g ai ha⁻¹) gave significantly less P. operculella incidence and higher yield of tuubrs at both the locations compared to untreated check. The biopesticides B. thuringiensis (@ 3.36 x 10⁷ IU ha⁻¹), B. bassiana (@ 4.5 x 10¹² cfu ha⁻¹) and neem derivative Achook (@ 3.38 g ai ha⁻¹ azadirachtin) were statistically superior over untreated check in suppressing the P. operculella infestation but were less effective than synthetic insecticides. B. bassiana in combination with synthetic pesticides was equally effective in managing P. operculella infestation on potato foliage. λ-Cyhalothrin had the highest (1045.9) persistent toxicity (PT) value followed by cypermethrin (1014.2), cypermethrin + B. bassiana (808.9), B. thuringiensis (771.5), B. bassiana (591.1) and achook (283.9).