Laboratory experiments were conducted under hygrothermic conditions i.e. 27±1.10C, 65±5%RH and photoperiod of (12 hrs light and 12 hrs dark) to evaluate efficiency and persistence effect of plant extracts of black pepper (Piper nigrum) and hungarium chamomile (Matricaria chamomile) on the larval stage of Phthorimaea operculella (Zeller) dissolved in four solvents with different polarities, Petroleum ether, Chloroform, acetone and water. The present work is preformed to study the effect of one application at 3 concentrations ( 5, 10 and 15% )of the tested plant extracts on 4th and 5th larval instars of potato tuber moth Ph. operculella after different indicated times post treatment (0, 24, 48, 72, 96, and 120 hrs). Results revealed that the percent mortality increased significantly with an increasing in the applied concentrations. Also, the reduction in the larval body weight was increased significantly after 24 hrs, when treatment carried out with the tested plant extracts. Antifeeding or repellent effects were also observed and the decreasing in the larval body weight continues through the following 120 hrs, at the two concentrations (10 and 15%). Chloroform extract has a high effect in reducing in the body weight than other solvents.
Key words: Plant extracts, Potato tuber moth (Phthorimaea operculella), Insecticidal activity
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