Efficacy of certain chemical and bio-insecticides on potato tuber moth (PTM), Phthorimaea operculella (Zeller) under laboratory conditions

The potato tuber moth Phthorimaea operculella (Zeller) is the most destructive pest of potato crop in Egypt. The effect of six compounds on this insect was studied under laboratory conditions. These compounds were Tracers 24% SC (spinosad), Coragen 20% SC (chlorantraniliprole), Malathion 57% EC (malathion) and three different commercial formulations from Bacillus thuringiensis such as Agerin 6.5% W.P., Dipel 2x 6.4% WP and Protecto 9.4% WP. The LC₅₀ values of the tested compounds were 0.2008, 0.8257, 1.0445, 0.1568, 0.2525 and 0.1844 ppm, respectively. These experiments were carried out in the same Department. Dipel 2x, Protecto and Agerin prolonged the duration of larval stage significantly when compared with other tested treatments including control, respectively. However, the tested compounds reduced the pupation rate when compared with the control, while, the highest pupation were 60% for both Malathion and Protecto insecticides, 56.67% for Dipel 2x, 53.33% for Agerin, 46.67% for Coragen and 43.33% for Tracer. The number of adults was significantly reduced in all treatments comparing with the untreated. Moreover, Tracer, Coragen and Malathion were significantly prolonged females preoviposition period compared to control. On the other hand, Tracer treatment was a significantly elongated oviposition comparing with reminds treatments including control. Moreover, there were significant decreases in the number of eggs laid females^-1 resulted from Tracer, Protecto, Agerin and Dipel 2x treatments, respectively. Also, there were high reduction percentages in eggs hatchability with Coragen treatment. Coragen have the highest significant elongation of life span when compared with other treatments including the untreated control.