Insecticidal effects of Moroccan plant extracts on development, energy reserves and enzymatic activities of Plodia interpunctella

10 p.-3 tab.The aim of this work was to study the effects of methanol extracts of ten plant species used in traditional medicine in Morocco (Peganum harmala, Ajuga iva, Rosmarinus officinalis, Lavandula stoechas, Lavandula dentata, Cistus ladanifer, Cistus salviaefolius, Cistus monspeliensis, Centaurium erythraea and Launaea arborescens) on Plodia interpunctella Hübner (Lepidoptera: Pyralidae) larvae. Firstly, we studied the effects of the ingestion of these extracts at 500 ppm on post-embryonic development parameters. Most plant extracts provoked a notable decrease of larval weight 8 days after treatment (up to 33% weight loss with C. erythraea) and caused significant alterations on pupation (ranging from 5% to 85%) and adult emergence (below 2.5% with R. officinalis, C. erythraea and A. iva). The plant extracts that showed strongest effects on post-embryonic development were selected to test their effects on the following physiological parameters: larval reserve substances (at 500 ppm); and midgut activities of hydrolytic and detoxification enzymes (at 500, 750 and 1,000 ppm). All treatments provoked a significant reduction of protein and carbon hydrate larval contents, the inhibition of proteases and α-amylase activities in a dose depended manner, and the induction of glutathione Stransferase and esterase (using MtB as substrate) activities, whereas the activity of cytochrome P450 monooxygenases and esterases (using 1-NA as substrate) increase or decrease depending on the extract concentration and the plant analyzed.This work was supported by the cooperation program: CNRST (580/08)/CSIC (2007MA0011) and MAEC-AECI fellowship (Nº 0000536790 II.E Program).Peer reviewe

Insecticidal effects of Moroccan plant extracts on development, energy reserves and enzymatic activities of Plodia interpunctella

The aim of this work was to study the effects of methanol extracts of ten plant species used in traditional medicine in Morocco (Peganum harmala, Ajuga iva, Rosmarinus officinalis, Lavandula stoechas, Lavandula dentata, Cistus ladanifer, Cistus salviaefolius, Cistus monspeliensis, Centaurium erythraea and Launaea arborescens) on Plodia interpunctella Hubner (Lepidoptera: Pyralidae) larvae. Firstly, we studied the effects of the ingestion of these extracts at 500 ppm on post-embryonic development parameters. Most plant extracts provoked a notable decrease of larval weight 8 days after treatment (up to 33% weight loss with C. erythraea) and caused significant alterations on pupation (ranging from 5% to 85%) and adult emergence (below 2.5% with R. officinalis, C. erythraea and A. iva). The plant extracts that showed strongest effects on post-embryonic development were selected to test their effects on the following physiological parameters: larval reserve substances (at 500 ppm); and midgut activities of hydrolytic and detoxification enzymes (at 500, 750 and 1,000 ppm). All treatments provoked a significant reduction of protein and carbon hydrate larval contents, the inhibition of proteases and �¿-amylase activities in a dose depended manner, and the induction of glutathione Stransferase and esterase (using MtB as substrate) activities, whereas the activity of cytochrome P450 monooxygenases and esterases (using 1-NA as substrate) increase or decrease depending on the extract concentration and the plant analyzed

Two sugar isomers influence host plant acceptance by a cereal caterpillar pest

Plant sugars are often considered as primary feeding stimuli, conditioning host plant acceptance by herbivorous insects. Of the nine sugars identified from methanolic extracts of seven grass species, only turanose, a sucrose isomer, was negatively correlated with the survival and growth of the noctuid larva of cereal stemborer, Busseola fusca. Sucrose was the most abundant sugar, although it did not vary significantly in concentration among the plant species studied. Using Styrofoam (TM) cylinders impregnated with increasing concentrations of turanose or sucrose, the two sugars had opposing effects: turanose appeared phagodeterrent while sucrose was phagostimulatory. Electrophysiological studies indicated that B. fusca larvae were able to detect both sugars via their styloconic sensilla located on the mouthparts. The findings indicate that, whereas sucrose is a feeding stimulant and positively influences food choice by B. fusca larvae, turanose negatively contributes to larval food choice. The balance in concentrations of both sugars, however, somehow influences the overall host plant choice made by the larvae. This can partly explain host plant suitability and choice by this caterpillar pest in the field