Effects of Various Plant Extracts on the Development of the Potato Beetle under Laboratory and Field Conditions: A Combined Study

Abstract

In this study, we examined the effects of ethanolic extracts obtained from the various parts of Liquidambar orientalis, Buxus sempervirens, Alnus glutinosa, Artemisia absinthium, Aesculus hippocastanum and Rhus coriaria on the egg-laying behavior of the potato beetle, Leptinotarsa decemlineata, under laboratory conditions at 25 +/- 2 degrees C and 60 +/- 5 % relative humidity, and tested the antifeedant and toxic effects of the two extracts leading to the smallest number of egg-laying, Liquidambar orientalis and Buxus sempervirens, with a field study. The field study showed that the average number of 6.2 larvae and 7.2 adults before treatment of the Liquidambar orientalis extract decrease to 1.2 larvae and 3.2 adults after treatment. With the use of the Buxus sempervirens extract, the 10.2 larvae and 8.4 adults that existed before the treatment were reduced to 2.6 larvae and 2.8 adults after treatment. As for the eggs laid in the plants, the control plants had 13 while Liqudambar orientalis decreased this number to 3 and Buxus sempervirens to 2. These results suggest that these two plant extracts can be used in the field as a potential alternative to chemical pesticides.