Effects and modes of action of citrus limonoids against Leptinotarsa decemlineata

Abstract

Limonin and its five derivatives were evaluated in feeding bioassays for depression effects on feeding, growth and development of the fourth stadium Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Epilimonol and limonin diosphenol were most effective in depression of feeding and growth, with ED50s 10 and 8 μg/cm2. At a dosage of 31.6 μg/cm2, epilimonol, limonin diosphenol and limonin caused both significant feeding reduction and developmental delay, while deoxylimonol, tetrahydrolimonin and limonol were not effective. Mouth‐part coating and antifeedant bioassays show that feeding inhibition at host acceptance level seems to be the primary mode of action of epilimonol and limonin diosphenol.

Isolation, characterization and biological activity of betulinic acid and ursolic acid from Vitex negundo L.

“…These compounds are effective against insects (Bentley et al, 1990;Liu et al, 1991) and bacteria (Bravo et al, 1997). For this reason the five pure compounds now isolated from leaves of Vitex negundo were tested for antifeedant and antibacterial activity.…”

“…Antifeedants, compounds that reduce feeding on plants by insect pests, are used as important components in the integrated pest management (IPM) strategies for agricultural pest control (Bentley et al, 1990;Huang et al, 1995). Some of these natural products have shown multiple types of activity, including toxicity (Jaglan et al, 1997), growth regulating activity (Liu et al, 1991) and antimicrobial activity (Bravo et al, 1997). The natural antifeedants and antimicrobial compounds have the property of biodegradation and do not cause any environmental toxicity or residue problems.…”

Effects of epilimonol and starvation on feeding and oviposition by Leptinotarsa decemlineata

“…One group was fed with epilimonol-treated potato foliage (10 #g/cm2), accomplished by wetting the upper surface of the foliage with 1.85 mg/ml epilimonol-3 ~o Tween emulsion using a paint brush, resulting in an approximate 10 #g/cm 2 dosage (Liu et al, 1989). The second group was not exposed to epilimonol and was fed with foliage coated with 3 ~o Tween, serving as control.…”

Effect of Artemisia Annua L. On Deterrence and Nutritional Efficiency Of Lesser Mulberry Pyralid (Glyphodes Pylolais Walker) (lepidoptera: Pyralidae)

“…These indices can provide valuable informa-tion about the positive or negative impact of ingredients or total food (Cohen 2005). The studies on feeding indices after feeding on secondary metabolites can help to determine whether a chemical compound is an antifeedant or toxic after feeding (Liu et al 1990). The general feeding indices used are: approximate digestibility (AD), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), relative growth rate (RGR) and consumption index (CI).…”